CODES

ADOPTS WITH AMENDMENTS:

International Mechanical Code 2012 (IMC 2012)

Copyright

Preface

Effective Use of the International Mechanical Code

Legislation

Chapter 1 Scope and Administration

Chapter 1 SCOPE AND ADMINISTRATION

Chapter 2 Definitions

Chapter 3 General Regulations

Chapter 4 Ventilation

Chapter 5 Exhaust Systems

Chapter 6 Duct Systems

Chapter 7 Combustion Air

Chapter 8 Chimneys and Vents

Chapter 9 Specific Appliances, Fireplaces and Solid Fuel-Burning Equipment

Chapter 10 Boilers, Water Heaters and Pressure Vessels

Chapter 11 Refrigeration

Chapter 12 Hydronic Piping

Chapter 13 Fuel Oil Piping and Storage

Chapter 14 Solar Systems

Chapter 15 Referenced Standards

Appendix A Chimney Connector Pass-Throughs

Appendix B Recommended Permit Fee Schedule

1001.1 Scope

STATE AMENDMENT
This chapter shall govern the installation, alteration and repairof, maintenance, testing and inspection of new and existing boilers, water heaters and pressure vessels.
Exceptions:
1. Pressure vessels used for unheated water supply.
2. Portable unfired pressure vessels and Interstate Commerce Commission containers.
3. Containers for bulk oxygen and medical gas.
4. Unfired pressure vessels having a volume of 5 cubic feet (0.14 m3) or less operating at pressures not exceeding 250 pounds per square inch (psi) (1724 kPa) and located within occupancies of Groups B, F, H, M, R, S and U.
5. Pressure vessels used in refrigeration systems that are regulated by Chapter 11 of this code.
6. Pressure tanks used in conjunction with coaxial cables, telephone cables, power cables and other similar humidity control systems.
7. Any boiler or pressure vessel subject to inspection by federal or state inspectors.

1001.1.1 Exceptions

STATE AMENDMENT
The following pressure vessels, boilers, tanks and containers are not covered by this chapter.
  1. Pressure vessels used for unheated water supply.
  2. Portable unfired pressure vessels and Interstate Commerce Commission containers.
  3. Containers for bulk oxygen and medical gas.
  4. Unfired pressure vessels having a volume of 5 cubic feet (0.14 m3) or less operating at pressures not exceeding 250 pounds per square inch (psi) (1724 kPa) and located within occupancies of Groups B, F, H, M, R, S and U.
  5. Pressure vessels used in refrigeration systems that are regulated by Chapter 11 of the Mechanical Code.
  6. Pressure tanks used in conjunction with coaxial cables, telephone cables, power cables and other similar humidity control systems.
  7. Any boiler or pressure vessel subject to inspection by federal inspectors.
Boilers, pressure vessels and their respective appurtenances and control systems shall be designed, constructed, installed, inspected, repaired or altered in accordance with the requirements of this chapter and of the specific provisions of the following standards, to the extent of their respective references contained in this chapter:
  1. ASME BPVC, Boiler and Pressure Vessel Code;
  2. ASME CSD-1;
  3. NFPA 8501, NFPA 8502, NFPA 8504;
  4. UL 726; and
  5. ANSI/NBBPVI NB-23 National Board Inspection Code, (NBIC).

1001.3 Permit requirement

STATE AMENDMENT
A permit shall be obtained from the code official for each boiler or unfired pressure vessel installed, erected, or moved and reinstalled, or re-erected in a new location in the District of Columbia before any work in connection with the equipment is performed.
The owner or user of a facility containing one or more boilers or pressure vessels shall be responsible for employing or contracting for the services of a an engineer holding the appropriate class of license for the size of the facility, issued by the Department in accordance with the requirements of the District of Columbia Board of Industrial Trades (Title 17 DCMR). The engineer’s license shall be framed, protected under a durable transparent material and prominently displayed in the boiler room or engine room. A daily log of plant operations documenting daily testing of all boiler safeties and controls for each tour of duty shall also be kept in the boiler room or engine room.
Any engineer licensed by the District of Columbia to operate boilers or pressure vessels covered by this code shall be subject to fines and other penalties for violation of the Construction Codes, and to suspension or revocation of his or her engineer’s license, if he or she shall operate, or cause to be operated, any boiler or unfired pressure vessel under his or her supervision without a certificate of inspection or with a certificate that has expired. Revocation or suspension of a license, shall be in accordance with the procedures laid out at D.C. Official Code §§ 47-2853.17 through 47-2853.30 (2012 Repl.).

1001.5 Inspection criteria

STATE AMENDMENT
The approval of the design and the inspection of the construction, installation and operation of power boilers, steam boilers, hot water boilers and pressure vessels in the District of Columbia, shall be performed in accordance with the requirements of the ASME Code, ANSI/NBBPVI NB-23 and ASME CSD-1, as specified by this chapter and the manufacturer’s inspection instructions. Inspections for compliance with specific District of Columbia safety requirements shall be performed in accordance with this chapter.
The inspection of boiler and pressure vessel equipment installed to replace inoperable equipment shall be performed in accordance with the inspection requirements for new construction as specified in Section 1001.5.

1001.5.2 Existing equipment

STATE AMENDMENT
Inspection of boilers and pressure vessels installed and operating in existing facilities shall be performed at a frequency in accordance with the requirements of ANSI/NBBPVI NB-23 and this chapter.

1002.1 General

STATE AMENDMENT
Potable water heaters and hot water storage tanks shall be listed and labeled and installed in accordance with the manufacturer’s installation instructions, the International Plumbing Code and this code. All water heaters shall be capable of being removed without first removing a permanent portion of the building structure. The potable water connections and relief valves for all water heaters shall conform to the requirements of the International Plumbing Code. Domestic electric water heaters shall comply with UL 174 or UL 1453. Commercial electric water heaters shall comply with UL 1453. Oil-fired water heaters shall comply with UL 732. Solid-fuel-fired water heaters shall comply with UL 2523. Thermal solar water heaters shall comply with Chapter 14 and UL 174 or UL 1453.
Water heaters utilized both to supply potable hot water and provide hot water for space-heating applications shall be listed and labeled for such applications by the manufacturer and shall be installed in accordance with the manufacturer’s installation instructions and the International Plumbing Code.
Water heaters utilized for both potable water heating and space-heating applications shall be sized to prevent the space-heating load from diminishing the required potable water-heating capacity.
Where a combination potable water-heating and space-heating system requires water for space heating at temperatures higher than 140°F (60°C), a temperature actuated mixing valve that conforms to ASSE 1017 shall be provided to temper the water supplied to the potable hot water distribution system to a temperature of 140°F (60°C) or less.
Potable water-heating devices that utilize refrigerant-to-water heat exchangers shall be approved and installed in accordance with the International Plumbing Code and the manufacturer’s installation instructions.

1003.1 General

STATE AMENDMENT
All pressure vessels shall be in accordance with the ASME Boiler and Pressure Vessel Code, shall bear the label of an approved agency and shall be installed in accordance with the manufacturer’s installation instructions.
No person shall use or cause to be used any steam boiler or unfired pressure vessel until a certificate of inspection has been issued and posted as required in this chapter. The certificate of inspection shall not be issued until it is determined that the boiler or pressure vessel condition is in conformity with the ASME Code and this chapter, and the provisions of the Construction Codes governing the installation of fuel burning equipment in the District of Columbia. A separate certificate of inspection shall be required for each equipment unit inspected. Each certificate shall be protected under a durable transparent material in a frame to be supplied by the owner or user and shall be prominently displayed in the boiler room or engine room near the equipment to which it pertains. Certificates for portable equipment shall be kept with the equipment at all times.

1003.2 Piping

STATE AMENDMENT
All piping materials, fittings, joints, connections and devices associated with systems utilized in conjunction with pressure vessels shall be designed for the specific application and shall be approved.

1003.2 Final inspection

STATE AMENDMENT
Upon installation, erection or alteration of any boiler or unfired pressure vessel in the District of Columbia for which a permit is required, including re-installation or erection of any used boiler or unfired pressure vessel, a final inspection by the code official is required to verify compliance with the applicable Construction Code provisions.
On all installations for which a permit has been issued, the contractor or person making the installation shall be responsible for notifying the code official, with sufficient advance notice so that the necessary inspections can be performed in a timely manner. The contractor or person making the installation shall be responsible for ensuring that no boiler or unfired pressure vessel shall be operated until final inspection has been performed and approved by the code official to operate the equipment.

1003.3 Welding

STATE AMENDMENT
Welding on pressure vessels shall be performed by approved welders in compliance with nationally recognized standards.
No person shall operate or cause to be operated any boiler or unfired pressure vessel requiring inspection under this code without a current certificate of inspection. Each certificate of inspection must be renewed annually, or at an interval specified by the code official, as long as the equipment is in service. Renewal will be granted upon satisfactory demonstration to the code official that the equipment or system has met all of the inspections and testing required by the Construction Codes and referenced standards. Inspections shall be made by the code official, or by an insurance company inspector as permitted by Section 1003.12, at the expense and responsibility of the owner or user.
Where a boiler or unfired pressure vessel subject to the provisions of this code is not covered by a current certificate of inspection, the owner or user of such boiler or pressure vessel shall immediately notify the code official in writing of the following information:
  1. The location of each boiler or unfired pressure vessel not covered by a current certificate of inspection;
  2. The date of the last inspection, if any;
  3. Whether or not the equipment is insured and inspected by an insurance company; and
  4. The name of the company that insures such equipment.

1003.5 Operating pressure

STATE AMENDMENT
No person shall operate or cause to be operated any boiler or unfired pressure vessel at a pressure in excess of the allowable pressure as stated on the certificate of inspection.
Unfired pressure vessels operated at a pressure in excess of 60 pounds per square inch (psi) (414 kPa) and having a capacity in excess of 15 gallons (57 L) shall bear the following information:
  1. The ASME symbol;
  2. The name of the manufacturer;
  3. The maximum allowable working pressure;
  4. The serial number and National Board Numbers;
  5. The year built; and
  6. Any other required data to indicate that it has been built in accordance with the provisions of Section VIII of the ASME Boiler and Pressure Vessel Code.
Exception: Marking of nonstandard pressure vessels shall not be required to contain the information indicated in Items 1, 4 and 6 of this section.

1003.6 Safety devices

STATE AMENDMENT
Boilers and unfired pressure vessels shall be equipped with safety appliances and piping as prescribed in the ASME Code. No person shall operate or cause a boiler or unfired pressure vessel to be operated unless equipped with the prescribed safety appliances and piping, and no person shall remove or tamper with any safety appliance or piping, except for the purpose of making repairs. Any adjustments to safety valves shall be made only by direction of the code official or an insurance company inspector.

1003.7 Tests

STATE AMENDMENT
When in the judgment of the inspector it is considered necessary to demonstrate the proper operation of the boiler safeties and controls, or to demonstrate the licensed engineer’s ability to properly operate the boiler, the safety-valve capacity of a boiler and/or the low water cutout shall be tested. An accumulation test shall be made by shutting off all other steam-discharge outlets from the boiler, and operating the fuel-burning equipment to produce the maximum steaming capacity of the boiler. An evaporation test shall be performed to demonstrate proper operation of the low water cutout.

1003.7.1 Safety-valve

STATE AMENDMENT
The safety-valve equipment shall be sufficient to prevent the pressure from rising more than (a) 6 percent above the maximum allowable working pressure, for power boilers, and (b) 5 pounds per square inch (psi) (34 kPa) above the maximum allowable working pressure, for heating boilers. Provision shall be made for piping the safety valve discharge out of the boiler room during a test pursuant to Section 1003.7.
No temporary portable boiler or unfired pressure vessel shall be used until it has been inspected by the code official or an insurance company inspector in accordance with this Chapter 10 and a certificate of inspection has been issued. Each owner or user of portable boilers or unfired pressure vessels shall furnish in writing to the code official, yearly, before December 27, the following information:
  1. A list of his or her portable boilers and unfired pressure vessels;
  2. The location of each portable boiler and unfired pressure vessel in the list; and
  3. A statement for each portable boiler and unfired pressure vessel in the list, indicating whether the boiler or pressure vessel is insured and inspected by an insurance company.
All steam boilers including hot water boilers shall be inspected annually by the code official or by an insurance company inspector as provided in Section 1003.15. The inspection shall include the following.
The internal inspection shall consist of a thorough examination of all tubes, seams, rivets, drums, stay bolts and other parts to insure that the boiler is in safe operating condition and able to carry the pressure allowed.
The external inspection, to determine the general condition of the boiler and its appurtenances as well as the adequacy of safety valves, pressure gauges, apparatus for determining water level and other appliances, shall be made under normal operating conditions at which time the steam pressure carried shall be observed and the operation of all valves, gauges, safety devices or other appliances shall be checked to ensure that they are in proper working order.

1003.9.3 Hydrostatic test

STATE AMENDMENT
A hydrostatic test shall be required when, in the judgment of the code official or insurance company inspector, it is considered necessary in the interest of safety. The test shall be conducted with water at a temperature of at least 70°F (21°C) but not higher than 120°F (49°C), with pressure applied to the vessel at 1.5 times the maximum allowable working pressure. The test pressure shall hold for 30 minutes.

1003.10 Boiler preparation

STATE AMENDMENT
A steam or hot water boiler shall be prepared for internal inspection by the owner or user on a date specified by the code official. Insofar as practicable, the internal inspection shall be made no later than 15 days prior to the expiration of the current certificate of inspection. In no case shall the internal inspection be deferred more than 30 days after the date of expiration of the certificate of inspection. The code official is authorized to order a steam or hot water boiler discontinued from service until the inspection is performed.
Preparation for internal inspection shall be made in the following manner:
  1. Water shall be drawn off and the boiler thoroughly washed out;
  2. All manhole and handhole plates, washout plugs and the water column connection plugs shall he removed and the furnace and combustion chambers thoroughly cooled and cleaned;
  3. All grates or stoker dead plates of internally-fired boilers shall be removed; and
  4. All leaks of steam or hot water into the boiler shall be stopped. The inspector is also authorized to require the removal of brickwork and insulation covering the seams of shell, drums or domes, sufficient to determine the size and pitch or rivets, their condition, and any other information as may be necessary to definitely determine the condition of the boiler and its fitness for safe operation.
A steam or hot water boiler shall be prepared for hydrostatic test by the owner or user, when required by the inspector by filling the boiler with water to the stop valve and blanking off the connections of the boiler to other boilers when that boiler is connected to other boilers that are under steam pressure. Arrangements shall be made with the inspector for the protection of the safety valve and under no circumstances shall the safety valve spring be screwed down for making hydrostatic tests.

1003.10.3 Test gauges

STATE AMENDMENT
An indicating test gauge shall be connected directly to the boiler or pressure vessel where it is visible to the operating engineer throughout the duration of the test. The pressure gauge scale shall be graduated over a range of not less than 1.5 times and not greater than four times the maximum test pressure. All gauges utilized for testing shall be calibrated and certified by the operating engineer.
Each unfired pressure vessel operating at a pressure in excess of 60 pounds per square inch (psi) (414 kPa) and having a capacity in excess of 15 gallons (57 L) shall be inspected annually by the code official or an insurance company inspector as permitted by Section 1003.12. Any unfired pressure vessel as described herein shall be subjected to inspection if it is connected to a source of supply.
The annual inspection of unfired pressure vessels shall consist of an external inspection including safety devices and other appurtenances. When a vessel is provided with manholes, an internal inspection shall also be performed.

1003.11.2 Hydrostatic test

STATE AMENDMENT
A hydrostatic test shall be required when, in the judgment of the inspector, it is considered necessary in the interest of safety. This test shall be conducted with water at a temperature of at least 70°F (21°C) but not higher than 120°F (49°C), and shall consist of applying to the vessel a pressure of 1.5 times the maximum allowable working pressure. The test pressure shall hold for 30 minutes.
Any steam or hot water boiler or unfired pressure vessel which is insured and inspected at least once annually by an insurance company inspector shall be exempt from annual inspection by the code official, provided that the requirements of Sections 1003.12.1 through 1003.12.3 are satisfied.

1003.12.1 ASME Code

STATE AMENDMENT
The insurance company inspector shall apply the inspection provisions in Section I, Part PG, paragraph PG-90, “Inspection and Tests—General” in the ASME Code.

1003.12.2 Qualifications

STATE AMENDMENT
In order to perform inspection of boilers or pressure vessels in the District of Columbia, the inspector shall hold a current certificate of competency issued by the code official in accordance with this code.
The insurance company inspector shall file reports of inspections and other data relating to an insured boiler or unfired pressure vessel, as may be required, with the code official within 10 business days after the inspection, on the standard forms and in the manner prescribed by the code official; provided, that the internal inspection report shall be filed in time to prevent the certificate of inspection from becoming more than 30 days overdue. Each report shall be printed or typewritten, bear the original inspector’s signature in ink and state unambiguously whether or not the certificate of inspection should be issued, and the equipment working pressure allowed.
If the inspector has ordered or recommended changes or repairs to be made following inspection, the inspection report filed with the code official in accordance with Section 1003.12.3 shall state the nature of all changes or repairs ordered or recommended. No later than 30 days after the inspection during which the deficiencies were identified, the insurance company inspector shall re-inspect the insured boiler or pressure vessel and submit a supplemental report to the code official stating whether the changes or repairs have been completed. If the work has not been completed within the time allowed, the code official is authorized to order operation of the equipment to be discontinued, or to take any other actions authorized by the Construction Codes.

1003.13.1 Application

STATE AMENDMENT
In order to obtain or renew a certificate of competency, each inspector employed or retained, by an insurance company licensed to operate in the District of Columbia, to inspect boilers and pressure vessels located in the District of Columbia that are insured by the company shall submit an application to the code official, in the form prescribed and provided by the code official. The application shall include the following:
  1. Name, age, qualifications, experience and local address of the inspector;
  2. Documentation evidencing employment or retention by an insurance company licensed to operate in the District of Columbia for the inspection of boilers and pressure vessels in the District of Columbia;
  3. A copy of a valid current certificate issued by the National Board to the inspector; and
  4. Such other data and information as may be required by the code official.
The code official is authorized to accept a certificate issued by the National Board, upon proper substantiation, and to issue a certificate of competency based on such National Board certificate.

1003.13.3 Filing fee

STATE AMENDMENT
All applications for a new or renewed certificate of competency shall be accompanied by a filing fee of $200, or such amount as may be established in the applicable fee schedule published in the D.C. Register.

1003.13.4 Expiration

STATE AMENDMENT
The certificate of competency shall be issued for a two-year period, provided, however, any certificate of competency issued shall become null and void if the inspector holding the certificate of competency ceases to be employed or retained by the insurance company upon which his or her National Board eligibility is based, or if the National Board certification on which the inspector’s certificate of competency is based is cancelled or invalidated.
An insurance company that insures any boiler or pressure vessel in the District of Columbia shall immediately report the following information to the code official by written notice:
  1. The name of the owner or user and the location of every boiler and unfired pressure vessel on which insurance is refused, canceled or discontinued by the company and the reason therefore;
  2. The location and name of the owner or user of each new boiler or pressure vessel upon which coverage is taken, whether the new equipment has been inspected by the code official and whether an installation permit has been obtained;
  3. The names of the DC-licensed engineers working on all watches, and the grade of license held by each engineer, and if there is none, the report shall so state; and
  4. The termination or cessation of any employment or contractual relationship with an insurance company inspector and the reasons therefore.

1003.15 Internal inspection

STATE AMENDMENT
In the case of boilers that can be internally inspected, certificates of inspection shall not be issued until after the internal inspection has been performed.
If upon inspection by the code official it is found that repairs, alterations or cleaning are necessary to ensure the safe operation of a steam boiler, hot water boiler or unfired pressure vessel, and its conformity to the ASME Code and this Chapter, a written notice stating the work required to be done and the time allowed for completion shall be sent to the owner or user.
Repairs, alterations or cleaning required under Section 1003.16 shall be made as directed. Upon completion of the work ordered, the owner or user shall notify the code official. If the work has not been completed within the time allowed, the code official is authorized to order operation of the equipment to be discontinued, and to take any other actions authorized by the Construction Codes.
Whenever the code official finds that a boiler or unfired pressure vessel, or its necessary appurtenances, is in such a defective or unsafe condition that life or property is endangered, he or she shall immediately order its further use and operation discontinued. A boiler or unfired pressure vessel which has been declared unsafe or condemned by the code official shall be distinctly labeled as “Unsafe to Use” or condemned by the Department. The provisions of Sections 115 and 116 of the Building Code and Sections 108 and 109 of the Property Maintenance Code shall also apply to defective, unsafe or dangerous boilers and unfired pressure vessels.
No person shall operate or cause to be operated any boiler or unfired pressure vessel which is known to be unsafe or which has been condemned by the code official. No person shall operate or cause to be operated any boiler or unfired pressure vessel, the further use and operation of which has been ordered discontinued by the code official, until the defective or unsafe condition which was the reason for such action has been corrected and a new certificate of inspection is issued.
If an insurance company inspector finds that a boiler or unfired pressure vessel, or its necessary appurtenances, are in such a defective or unsafe condition that life or property is endangered, and which, in his or her opinion cannot be repaired and made safe, he or she shall immediately notify the code official.

1003.17.3 Abatement

STATE AMENDMENT
The owner or user of the equipment deemed unsafe shall abate or cause to be abated or corrected such unsafe condition.
Every boiler and unfired pressure vessel installed in the District of Columbia shall be given a District of Columbia number. Numbers assigned to cast-iron boilers shall be of metal not less than 1 inch (25.4 mm) in height and shall be securely attached to a metal plate which in turn shall be securely attached to the front of the boiler. Miniature boilers shall have sufficient space provided so that the District of Columbia boiler number can be stamped on the shell and be clearly visible when the insulating jacket is in place. Numbers on condemned boilers shall not be reassigned.

Section 1004 Boilers

STATE AMENDMENT
Oil-fired boilers and their control systems shall be listed and labeled in accordance with UL 726. Electric boilers and their control systems shall be listed and labeled in accordance with UL 834. Solid-fuel-fired boilers shall be listed and labeled in accordance with UL 2523. Boilers shall be designed and constructed in accordance with the requirements of ASME CSD-1 and as applicable, the ASME Boiler and Pressure Vessel Code, Section I or IV; NFPA 8501; NFPA 8502 or NFPA 8504.
In addition to the requirements of this code, the installation of boilers shall conform to the manufacturer’s instructions. Operating instructions of a permanent type shall be attached to the boiler. Boilers shall have all controls set, adjusted and tested by the installer. The manufacturer’s rating data and the nameplate shall be attached to the boiler.
Clearances shall be maintained around boilers, generators, heaters, tanks and related equipment and appliances so as to permit inspection, servicing, repair, replacement and visibility of all gauges. When boilers are installed or replaced, clearance shall be provided to allow access for inspection, maintenance and repair. Passageways around all sides of boilers shall have an unobstructed width of not less than 18 inches (457 mm), unless otherwise approved.
Clearances from the tops of boilers to the ceiling or other overhead obstruction shall be in accordance with Table 1004.3.1.

TABLE 1004.3.1
BOILER TOP CLEARANCES

BOILER TYPEMINIMUM
CLEARANCES
FROM TOP OF
BOILER TO
CEILING OR
OTHER
OVERHEAD
OBSTRUCTION
(feet)
All boilers with manholes on top of the boiler except where a greater clearance is required in this table.3
All boilers without manholes on top of the boiler except high-pressure steam boilers and where a greater clearance is required in this table.2
High-pressure steam boilers with steam generating capacity not exceeding 5,000 pounds per hour.3
High-pressure steam boilers with steam generating capacity exceeding 5,000 pounds per hour.7
High-pressure steam boilers having heating surface not exceeding 1,000 square feet (93 m2).3
High-pressure steam boilers having heating surface in excess of 1,000 square feet (93 m2).7
High-pressure steam boilers with input not exceeding 5,000,000 Btu/h (1465 kW).3
High-pressure steam boilers with input in excess of 5,000,000 Btu/h (1465 kW).7
Steam-heating boilers and hot water-heating boilers with input exceeding 5,000,000 Btu/h (1465 kW).3
Steam-heating boilers exceeding 5,000 pounds of steam per hour (2268 kg/h).3
Steam-heating boilers and hot water-heating boilers having heating surface exceeding 1,000 square feet (93 m2).3
For SI: 1 foot = 304.8 mm, 1 square foot = 0.0929 m2, 1 pound per hour = 0.4536 Kg/h.
Equipment shall be set or mounted on a level base capable of supporting and distributing the weight contained thereon. Boilers, tanks and equipment shall be secured in accordance with the manufacturer’s installation instructions.
Boilers shall be mounted on floors of noncombustible construction, unless listed for mounting on combustible flooring.
Boiler rooms and enclosures and access thereto shall comply with the International Building Code and Chapter 3 of this code. Boiler rooms shall be equipped with a floor drain or other approved means for disposing of liquid waste.
Hot water and steam boilers shall have all operating and safety controls set and operationally tested by the installing contractor. A complete control diagram and boiler operating instructions shall be furnished by the installer for each installation.
No person shall erect, install, re-erect or reinstall or cause to be erected, installed, re-erected or reinstalled any steam or hot water boiler or unfired pressure vessel until he or she shall have made application on the form provided by the code official, and obtained an installation permit.
Applications for permits shall be accompanied by a form U-1, “Manufacturer’s Data Report,” as specified in the ASME Code, properly filled out and signed by an authorized boiler inspector employed by an insurance company, showing that the boiler or unfired pressures vessel has been constructed and inspected in accordance with the requirements of the ASME Code. When an application is made to install a used boiler or unfired pressure vessel sufficient specific information shall be furnished to show that the boiler or unfired pressure vessel has been built in accordance with all the requirements of the ASME Code and is so stamped.
Before an installation permit for a used boiler or unfired pressure vessel shall be issued, the code official shall cause the boiler or unfired pressure vessel to be inspected in order to determine whether it is safe to operate, and any repairs or changes that shall be deemed necessary.
The code official is authorized to require the payment of fees, pursuant to the applicable fee schedule published in the D.C. Register, for permits, inspections and other miscellaneous services related to boilers and unfired pressure vessels, including, but not limited to, fees for permit processing, inspections, welding qualification tests and issuance of certificates of competency and certificates of inspection.

1005.1 Valves

STATE AMENDMENT
Every boiler or modular boiler shall have a shutoff valve in the supply and return piping. For multiple boiler or multiple modular boiler installations, each boiler or modular boiler shall have individual shutoff valves in the supply and return piping.
Exception: Shutoff valves are not required in a system having a single low-pressure steam boiler.

1005.1 Steel platforms

STATE AMENDMENT
To provide access to the top of every power boiler setting, a steel platform shall be provided, reached by means of a stationary steel stairway or ladder. The platform shall be provided with a 4-inch (102 mm) high toe guard, with a steel railing not less than 36 inches (914 mm) in height, and shall have a runway not less than 30 inches (762 mm) in width, made of steel grating or other approved material.

1005.2 Potable Water Supply

STATE AMENDMENT
The water supply to all boilers shall be connected in accordance with the International Plumbing Code.

1005.2 Platform access

STATE AMENDMENT
The stairway or ladder shall not be less than 16 inches (406 mm) in width and shall provide easy access to and from the platform. Where more than one boiler is served by the same platform, or where otherwise deemed necessary, a second stairway or ladder, remote from the first one, shall be provided.

1005.3 Means of egress

STATE AMENDMENT
Two unobstructed and accessible means of egress remote from each other shall be provided in every room housing power boilers with an aggregate capacity of 75 horsepower (56 kW) or over, or heating boilers with an aggregate capacity of 2,400,000 btu/h (703 kW) or over. Blow off pits, ash pits, alleyways, steam pipe tunnels and other places where there would be danger of personnel being trapped shall have adequate ventilation, lighting and a number of means of egress deemed adequate by the code official.

1005.4 Blow-off discharge

STATE AMENDMENT
Blow-off piping from power boilers shall not discharge directly into a sewer. A blow-off tank or sump shall be used where conditions do not provide an adequate and safe open discharge.

1005.5 Blow-off tanks

STATE AMENDMENT
Blow-off tanks shall be designed for at least 50 percent of the working steam pressure of the boiler to which it is connected and shall be built in accordance with the ASME Code. The tanks shall have a discharge connection at least 6 inches (152 mm) above the maximum water level with a water seal, a vent from the top of the tank and a coldwater connection to the top of the tank. The vent shall be routed to a safe point of discharge above the roof of the building where it is located or the roof of any adjoining building, so as not to constitute a hazard or nuisance. The vent shall be substantially supported. The design of each tank and appurtenant piping shall be submitted to the Department for approval. Tank, outlet and vent sizes shall not be less than indicated in Table 1005.5.

TABLE 1005.5
REQUIREMENTS FOR POWER BOILERS BLOW-OFF TANKS
BOILER RATING TANK SIZE OUTLET
(inches nom.)
VENT
(inches nom.)
2 to 25
horsepower
24 in. diameter by 36 in. long 2 2
26 to 75
horsepower
30 in. diameter by 48 in. long 3 3
76 to 150
horsepower
36 in. diameter by 54 in. long 5 4
151 to 250
horsepower
36 in. diameter by 60 in. long 5 5
251 to 600
horsepower
42 in. diameter by 66 in. long 5 6
601 to 1,000
horsepower
48 in. diameter by 72 in. long 6 6
For SI: 1 inch = 25 mm, 1 horsepower = 0.7457 kW.
All steam boilers shall be protected with a safety valve.
Hot water boilers shall be protected with a safety relief valve.
All pressure vessels shall be protected with a pressure relief valve or pressure-limiting device as required by the manufacturer’s installation instructions for the pressure vessel.
Safety and safety relief valves shall be listed and labeled, and shall have a minimum rated capacity for the equipment or appliances served. Safety and safety relief valves shall be set at a maximum of the nameplate pressure rating of the boiler or pressure vessel.
Safety or relief valves shall be installed directly into the safety or relief valve opening on the boiler or pressure vessel. Valves shall not be located on either side of a safety or relief valve connection. The relief valve shall discharge by gravity.
Safety and relief valve discharge pipes shall be of rigid pipe that is approved for the temperature of the system. The discharge pipe shall be the same diameter as the safety or relief valve outlet. Safety and relief valves shall not discharge so as to be a hazard, a potential cause of damage or otherwise a nuisance. High-pressure-steam safety valves shall be vented to the outside of the structure. Where a low-pressure safety valve or a relief valve discharges to the drainage system, the installation shall conform to the International Plumbing Code.
Boilers shall be equipped with controls and limit devices as required by the manufacturer’s installation instructions and the conditions of the listing.
The power supply to the electrical control system shall be from a two-wire branch circuit that has a grounded conductor, or from an isolation transformer with a two-wire secondary. Where an isolation transformer is provided, one conductor of the secondary winding shall be grounded. Control voltage shall not exceed 150 volts nominal, line to line. Control and limit devices shall interrupt the ungrounded side of the circuit. A means of manually disconnecting the control circuit shall be provided and controls shall be arranged so that when deenergized, the burner shall be inoperative. Such disconnecting means shall be capable of being locked in the off position and shall be provided with ready access.

1007.1 General

STATE AMENDMENT
All steam and hot water boilers shall be protected with a low-water cutoff control.
The return water connection to every low pressure steam or hot water heating boiler shall be arranged to form what is known as a “Hartford Loop” so that the water cannot be forced out of the boiler below the safe water level. This connection shall be installed on each boiler, with the inside bottom of the return pipe close nipple, where it connects to the equalizing loop, at the same level as the top of the bottom nut of the water gauge glass.

1007.2 Operation

STATE AMENDMENT
The low-water cutoff shall automatically stop the combustion operation of the appliance when the water level drops below the lowest safe water level as established by the manufacturer.

1007.2 Equalizer pipe

STATE AMENDMENT
Each boiler shall have a separate equalizer pipe installed between the bottom opening of the boiler and the boiler stop valve, when used. The equalizer pipe shall not have a valve in it at any point and shall not be used as a means to connect two or more boilers together below the water line. Equalizer pipe sizes shall not be less than the schedules indicated in Table 1007.2.

TABLE 1007.2
EQUALIZER PIPE SIZES
GRATE AREA
(square feet)
S.V.R.C. a
(pounds per hour)
PIPE SIZE
(inches nom.)
Under 4 250 or less
4 to 15 251 to 2000
Over 15 2001 or over 4
For SI: 1 square foot = 0.0929 m2, 1 inch = 25 mm, 1 pound/hour = 0.4536 kg/h.
  1. S.V.R.C., Safety Valve Relieving Capacity, for this purpose, shall be the capacity of the boiler as stamped on a steel boiler or on the name plate of a cast iron boiler.

1007.3 Stop valve

STATE AMENDMENT
When a stop valve is used in the return line of the loop it shall be located within 6 feet (1829 mm) of the floor. A drain valve shall be provided at the lowest point of the return line. Galvanized pipe and fittings shall not be used in any part of the equalizer pipe or return line.
Each boiler shall be provided with a mechanical feed line supplied from a reliable public water system. The feed line shall not connect directly into any part of a boiler exposed to the direct radiant heat from the heat source. It shall be connected to the equalizing line between the boiler and the condensate return connection and shall have a check valve in the line as close to the boiler as possible.

1007.5 Boiler feed line

STATE AMENDMENT
The boiler feed line shall be designed so as to adequately take care of the maximum demand of the boiler.
All connections from the public water system shut-off valve shall be made of brass pipe with screwed fittings. Tubing shall not be used.

Exceptions:
  1. Low-pressure heating boilers bearing the ASME stamp that are trimmed by the manufacturer.
  2. Low-pressure heating boilers rated less than 100 horsepower (74.6 kW).
A condensate return pump shall have capacity to supply the boiler or boilers it serves with sufficient water to maintain a normal water level when the boilers are operating at maximum capacity. When more than one boiler is served by the pump, the condensate return line shall be arranged to supply all boilers adequately.

1007.8 Stop valve

STATE AMENDMENT
A stop valve shall be installed in each supply and return connection of two or more boilers connected to a common system. When a stop valve is used in the supply pipe connection of a single boiler, there shall be one used in the return pipe connection and vice versa. If there are multiple branch connections, each one shall be valved. When stop valves over 2 inches in nominal size are used they shall be of the outside screw-and-yoke type.
Stop valves shall be located as close to the boiler as possible and when over 7 feet (2134 mm) above the floor shall be made accessible for operation by means of either (1) a permanent steel ladder and platform; or (2) a chain or motor operated mechanism.

1007.9 Blow-off connections

STATE AMENDMENT
Each boiler shall have one or more blow-off connections fitted with straightway valves connected directly with the lowest water space. Plug or bob cocks shall not be used. A discharge pipe shall be run to the floor, full size, with an “ell” at the bottom to direct the water away from the operator, or to a blow-off tank. A “tee” fitting shall be used at the boiler in order to provide a cleanout for the line. Blow-off valves and discharge pipes shall not be smaller than the schedule indicated in Table 1007.9 based on the equivalent direct radiation rating of the boiler. If a surface blow down is used, it shall be run full size to the floor with an “ell” at the bottom, or to an approved drain.

TABLE 1007.9
BLOW-OFF VALVES AND DISCHARGE PIPES
BOILER RATING
(square feet E.D.R.)
VALVE AND PIPE SIZE
(inches nom.)
Under 1000 ¾
1001 to 3500 1
3501 to 8500
8501 and over 2
For SI: 1 square foot = 0.0929 m2, 1 inch = 25 mm.
All wash-out and hand-hole openings shall be accessible and shall not be obstructed or blocked by pipe or other obstacle. Capped pipe nipples and plugs shall be installed in wash-out openings.

1007.11 Cross connections

STATE AMENDMENT
There shall be no cross connection below the water line, for any purpose, between two or more boilers.

1008.1 General

STATE AMENDMENT
Every steam boiler shall be equipped with a quick-opening blowoff valve. The valve shall be installed in the opening provided on the boiler. The minimum size of the valve shall be the size specified by the boiler manufacturer or the size of the boiler blowoff-valve opening.

1008.1 Steam limit control

STATE AMENDMENT
Every steam boiler, when mechanically fired, shall be provided with a steam limit control (pressure regulator) that shall operate to prevent the steam pressure from rising above the allowable working pressure of the boiler. All connections shall be on non-ferrous pipe with screwed fittings. There shall not be any valve between the boiler and the control.

Exceptions:
  1. Boilers that bear the ASME stamp and are trimmed by the manufacturer are exempt from the non-ferrous pipe with screwed fittings requirement.
  2. Boilers rated less than 100 horsepower (74.6 kW) are exempt from the non-ferrous pipe with screwed fittings requirement.

1008.2 Discharge

STATE AMENDMENT
Blowoff valves shall discharge to a safe place of disposal. Where discharging to the drainage system, the installation shall conform to the International Plumbing Code.

1008.2 Master limit control

STATE AMENDMENT
When two or more boilers are connected to a common header, a master limit control connected into the main steam header shall be provided to control all boilers simultaneously.
Each steam boiler, when mechanically fired, shall be equipped with an approved lowwater fuel cut-off, so arranged as to automatically cut off the fuel supply in case the water-level gauge indicates low-water level.
The operation of automatic operational controls shall not be dependent upon the functioning of any other device.
When an oil burner is manually operated, the cut-off valve shall be located in the oil line close to the burner and shall only be reset manually.
No valves shall be permitted between the low-water fuel cut-off and the boiler.
Each steam boiler shall have one or more water-gauge glasses attached to the water column or directly to the boiler by means of valved fittings, with the lower fitting provided with a drain valve of the straightway type with opening not less than ¼-inch (6.4 mm) diameter. The gauge glasses shall be visible from the operating floor and without the removal of any cover or casing. There shall be no obstruction to interfere with visibility of the gauge glasses.
When gauge cocks or gauge glass shut off cocks are located 78 inches (1981 mm) or more above the operating floor, they shall be of the quick opening type with chains or rods attached for operation from the floor. The gauge glass and pressure gauge shall be illuminated by a light with an approved type of reflector so that they can be easily read.
An automatic water feeder shall be installed on each mechanically fired steam heating boiler. It shall have sufficient capacity to take care of the water demand for maximum boiler output.

1008.10 Feed pump capacity

STATE AMENDMENT
A boiler feed pump, when used, shall have capacity to supply sufficient water to all boilers served to maintain a normal water level when the boiler or boilers are operating at maximum capacity.
A public water system by-pass valve, with the valve accessible from the floor, shall be installed around a feeder and shall have a valved drain extended to within 6 inches (152 mm) of the floor. A mechanical water feeder supplied from a public water system shall be installed with a bypass valve, with inlet and outlet valves accessible from the floor, with cross tees for inspection and with the drain valve piping extended to within 6 inches (152 mm) of the floor.

1008.12 Feed-water level

STATE AMENDMENT
A water feeder shall be installed so that it will not cause the water level to rise above the normal operating level specified by the manufacturer of the boiler.
On low-pressure steam heating boilers, the water gauge glass shall be located so that the lowest permissible water level in the glass shall be as specified in Sections 1008.13.1 through 1008.13.4.
For multiple firetube boilers at least ½ inch (13 mm) of water shall be maintained over the top row of tubes or the fusible plug, if used, whichever is higher.
For package type Scotch Marine boilers at least ½ inch (13 mm) of water shall be maintained over the top row of tubes or the fusible plug, if used, whichever is higher.
For fire-box, horizontal water tube boilers at least 1 inch (25 mm) of water shall be maintained over the highest point of the crown sheet.
For any other type boiler the minimum water level shall be maintained in accordance with the manufacturer’s recommendations.
Two or more boilers that share any appurtenance shall be arranged so that the low water lines of all boilers are at the same level.

Exception: When each boiler is provided with an individual pump control and an individual automatically operated feed water control valve, operation with different water levels shall be allowed.
Every boiler shall have a pressure gauge connected to its steam space, or to its water column, or to its steam connection by means of a siphon or equivalent device exterior to the boiler, and of sufficient capacity to keep the gauge tube filled with water. The pressure gauge shall be arranged so that the gauge cannot be shut off from the boiler except by a cock with a “tee” or lever handle installed in the pipe near the gauge.
The handle of the cock for the pressure gauge shall be parallel to the pipe in which it is located when the cock is open.
The scale on the dial of a gauge on a low pressure boiler shall be graduated to not less than 30 pounds per square inch (psi) (210 kPa), in 5 psi (35 kPa) increments. Connections to steam gauge siphons shall be of non-ferrous pipe. The gauge shall be visible at all times without the removal of any cover or casing, and shall be of such size and so located as to be easily readable from the operating floor.

Exceptions:
  1. Boilers that bear the ASME stamp and are trimmed by the manufacturer are exempt from the non-ferrous pipe connection requirement.
  2. Boilers rated less than 100 horsepower (74.6 kW) are exempt from the non-ferrous pipe connection requirement.
When two or more mechanically fired steam boilers are connected to the same system, each boiler shall have independent low-water fuel cut-offs, pressure controls, pressure gauges and water feeders.
All of the connections for the water column, water feeder, low-water fuel cutoff and make up water line to the boiler, shall be of non-ferrous pipe and screwed fittings, with a cross at each right angle turn and with a check valve in the feed line as close to the boiler as possible. High pressure boilers shall have a valve between the boiler and the check valve. Tubing shall not be permitted on boiler piping or fittings. All piping shall be firmly braced and supported.

Exceptions:
  1. Boilers that bear the ASME stamp and are trimmed by the manufacturer are exempt from the non-ferrous pipe with screwed fittings requirement.
  2. Boilers rated less than 100 horsepower (74.6 kW) are exempt from the non-ferrous pipe with screwed fittings requirement.

1008.20 Drain locations

STATE AMENDMENT
Boiler drains shall be located so that the discharge will not impinge on the boiler setting or electrical equipment. Water column, water feeder and low-water fuel cut-off shall each have separate full size straightway valve drains extended to within 6 inches (152 mm) from the floor or to a visible approved drain, with the valves located so as to be conveniently accessible for operation. Plug cocks shall not be used.
An expansion tank shall be installed in every hot water system. For multiple boiler installations, a minimum of one expansion tank is required. Expansion tanks shall be of the closed or open type. Tanks shall be rated for the pressure of the hot water system.
Closed-type expansion tanks shall be installed in accordance with the manufacturer’s instructions. The size of the tank shall be based on the capacity of the hot-water-heating system. The minimum size of the tank shall be determined in accordance with the following equation:
(Equation 10-1)

For SI:

where:

Vt=Minimum volume of tanks (gallons) (L).
Vs= Volume of system, not including expansion tanks (gallons) (L).
T= Average operating temperature (°F) (°C).
Pa=Atmospheric pressure (psi) (kPa).
Pf=Fill pressure (psi) (kPa).
Po=Maximum operating pressure (psi) (kPa).
Open-type expansion tanks shall be located a minimum of 4 feet (1219 mm) above the highest heating element. The tank shall be adequately sized for the hot water system. An overflow with a minimum diameter of 1 inch (25 mm) shall be installed at the top of the tank. The overflow shall discharge to the drainage system in accordance with the International Plumbing Code.

Section 1010 Gauges

STATE AMENDMENT

Section 1010 SAFETY VALVES

STATE AMENDMENT
Every hot water boiler shall have a pressure gauge and a temperature gauge, or a combination pressure and temperature gauge. The gauges shall indicate the temperature and pressure within the normal range of the system’s operation.

1010.1 General

STATE AMENDMENT
Each steam boiler shall be provided with one or more safety valves of the spring-pop type, having side outlet discharge, adjusted and sealed to discharge at a pressure not to exceed 15 pounds per square inch (psi) (103 kPa). Seals shall be attached so as to prevent the valve from being taken apart or reset to relieve at a higher pressure without breaking the seal.

1010.2 Steam Boiler Gauges

STATE AMENDMENT
Every steam boiler shall have a water-gauge glass and a pressure gauge. The pressure gauge shall indicate the pressure within the normal range of the system’s operation.

1010.2 Lever-lifting device

STATE AMENDMENT
Each valve shall have a substantial lever-lifting device which will positively lift the disk from its seat at least 116 inch (1.6 mm) when there is no pressure on the boiler. Where the lever is more than 78 inches (1981 mm) above the floor, a flexible chain or cable operating over a pulley shall be provided so that the valve can be tested.

1010.2.1 Water-Gauge Glass

STATE AMENDMENT
The gauge glass shall be installed so that the midpoint is at the normal boiler water level.

1010.3 Safety valve marking

STATE AMENDMENT
Each steam safety valve shall bear the ASME symbol to indicate that it complies with the requirements of the ASME Code in regard to construction, testing and rating, and shall be plainly and permanently marked by the manufacturer in such a way that the marking will be readable when the valve is installed and will not be obliterated in service.

1010.3.1 Marking data

STATE AMENDMENT
The marking shall include the following information:
  1. The manufacturer’s name;
  2. The type and catalog number;
  3. The pressure at which it is set to open; and
  4. The capacity in pounds of steam per hour as certified by the National Board.

1010.4 Valve capacity

STATE AMENDMENT
The steam safety valve capacity for each steam boiler shall be such that with the fuel burning equipment installed and operating at maximum capacity, the pressure cannot rise more than 5 psi (34 kPa) above the maximum allowable working pressure of the boiler.

1010.5 Non-compliant valves

STATE AMENDMENT
When a safety valve no longer meets the provisions of Sections 1010.1 through 1010.4, such as when there is no stamping on a valve or it is not legible, or when a safety valve does not function properly, a new safety valve or valves as required in Section 1010 shall be installed.

1010.6 Installation

STATE AMENDMENT
It shall be the responsibility of the contractor making the installation or changes to a system to provide and install the necessary safety valves, as required by this chapter and/or recommended by the manufacturer.

1010.7 Accumulation test

STATE AMENDMENT
In case of dispute over the safety valve capacity or when, in the judgment of the code official or insurance company inspector, it is considered necessary to test the capacity of the safety valves, an accumulation test shall be conducted by the contractor, owner or operator in the presence of the code official or insurance company inspector.

1010.7.1 Test procedure

STATE AMENDMENT
The accumulation test shall be conducted by closing off all other discharge outlets from the boiler and operating the fuel burning equipment at maximum capacity. The safety valves shall be sufficient to prevent the pressure from rising more than 5 psi (34 kPa) above the maximum allowable working pressure of the boiler. Provision shall be made for piping the steam discharge from the boiler room during the test.

1010.8 Minimum capacity

STATE AMENDMENT
The minimum required capacity of the safety valve or valves, in pounds of steam per hour, shall be determined as follows:
  1. For steel or cast iron boilers, multiply the area of heating surface in square feet, if available, by 5 or use the maximum rating output of the boiler as specified by the manufacturer, whichever is greater.
  2. If the fuel burning equipment installed will produce a greater output than the minimum obtained in Item 1 of Section 1010.8 the minimum capacity of the safety valve or valves shall be based on the maximum output obtainable. In any event the requirements of Section 1010.4 shall be met.
Safety valves shall be connected to boilers, with the spindle in a vertical position, in any one of the following ways:
  1. Directly to a tapped or flanged opening in the boiler;
  2. To a fitting connected to the boiler by a close nipple;
  3. To a Y-base;
  4. To a valveless steam pipe between the adjacent boilers; or
  5. To a valveless header connecting steam outlets on the same boiler.

1010.9.1 Y-base connection

STATE AMENDMENT
When a Y-base is used pursuant to Item 3 of Section 1010.9 above, the inlet area shall not be less than the combined outlet areas.

1010.9.2 Clearance

STATE AMENDMENT
There shall be sufficient clearance above and around safety valves so that they can be removed and replaced without dismantling. The identification plate shall be located so as to be readable.
No shut-off or connection of any description shall be placed between a safety valve and the boiler, nor on the valve discharge pipe between such valve and the atmosphere. A safety valve shall not be connected to an internal pipe in the boiler. Tubing or galvanized pipe shall not be used between the valve and boiler.

1010.11 Discharge pipe

STATE AMENDMENT
A discharge pipe shall not be used on safety valves on low pressure equipment, except where a boiler is located in a restricted space or where the discharge from the valve might constitute a hazard to persons or to equipment. A discharge pipe shall be designed to accommodate the opening of a single valve or the aggregate area of all valves, based on the nominal diameter of the discharge openings of the valves with which it connects. The cross section of the discharge pipe shall be equal to the area of all of the safety valves discharging into it.
The discharge pipe shall be fitted with an open drain to prevent water from lodging in the upper part of the valve or in the pipe. When an elbow is placed on a safety valve discharge pipe, it shall be located close to the valve outlet and 45-degree turns shall be used. The discharge pipe shall be braced and supported so that no weight or strain is placed on the valve body. The discharge shall be arranged so there will be no danger of scalding attendants. A safety valve shall not be installed so as to discharge inside the casing of a self-contained boiler.
The safety valve or valves of each high-pressure boiler shall be provided with a full size discharge pipe leading to a safe point of discharge, which shall be above the roof of the building where it is located, or of any adjoining building to which it could constitute a hazard or nuisance. Visible, non-valved drains shall be provided to receive the discharge from the valve discharge piping.
Boilers of 25 horsepower (18.6 kW) or less shall not be required to have safety valve discharge pipes if the discharge from the safety valve will not constitute a hazard.
When two or more boilers with different allowable working pressures are connected to a common steam main, safety valves shall be allowed to be set at a pressure exceeding the lowest allowable pressure, provided that the boilers with allowable working pressures below the safety valves’ set pressure shall be protected by a safety valve or valves placed on the connecting pipe to the steam main.

1010.12.1 Connecting pipe

STATE AMENDMENT
The area or combined area of the safety valve or valves placed on the connecting pipe to the steam main, as provided for in Section 1010.12, shall not be less than the area of the connecting pipe or the area of the steam main, whichever is smaller. Each safety valve placed on the connecting pipe shall be set at the lowest allowable pressure of any of the connected boilers.

Section 1011 Tests

STATE AMENDMENT

1011.1 Tests

STATE AMENDMENT
Upon completion of the assembly and installation of boilers and pressure vessels, acceptance tests shall be conducted in accordance with the requirements of the ASME Boiler and Pressure Vessel Code. Where field assembly of pressure vessels or boilers is required, a copy of the completed U-1 Manufacturer’s Data Report required by the ASME Boiler and Pressure Vessel Code shall be submitted to the code official.

1011.1 Explosion doors

STATE AMENDMENT
Each boiler burning fuel in suspended or gaseous form shall have one or more self-closing explosion doors located in the boiler setting and breeching as required. This section shall apply to new installations and to existing installations that are changed to burn fuel in suspended or gaseous form.

1011.2 Test Gauges

STATE AMENDMENT
An indicating test gauge shall be connected directly to the boiler or pressure vessel where it is visible to the operator throughout the duration of the test. The pressure gauge scale shall be graduated over a range of not less than one and one-half times and not greater than four times the maximum test pressure. All gauges utilized for testing shall be calibrated and certified by the test operator.

1011.2 Deflectors

STATE AMENDMENT
Explosion doors, when located in the walls of the boiler setting within 7 feet (2134 mm) of the firing floor or of any platform or walkway, shall be provided with substantial deflectors to divert the blast of exploding gas so that it will not constitute a hazard.
Miniature boiler is a power or high-temperature water boiler that does not exceed the size and pressure limits specified in its definition. Where any one of the limits specified in the definition is exceeded, the rules for power boilers shall apply.

1012.2 Clearance

STATE AMENDMENT
Each boiler shall be located so that adequate space will be provided for the proper operation of the boiler and appurtenances, for the inspection of all surfaces and for their necessary maintenance and repair. Each miniature boiler shall have the following minimum clearances:
  1. 18 inches (457 mm) on all sides;
  2. 3 feet (914 mm) from electric meters and main-line switches;
  3. 18 inches (457 mm) from all other switches and fuse boxes; and
  4. 3 feet (914 mm) horizontally from any gas meter.

1012.3 Feed pump

STATE AMENDMENT
Each miniature boiler operating at a pressure in excess of 25 pounds per square inch (psi) (172 kPa) shall be provided with at least one feed pump or other approved feeding device except where the steam generator is operated with no extraction of steam (closed system).

1012.4 Blow-off connection

STATE AMENDMENT
Each miniature boiler shall be provided with a blow-off connection that shall not be reduced in size and shall be led to a safe point of discharge. Whenever, in the judgment of the boiler inspector a safe place of discharge cannot be provided, a blow-down tank shall be installed, and a 1-inch (25 mm) vent leading to a safe point of discharge shall be provided on the tank. The blow-off shall be fitted with a valve or cock in direct connection with the lowest water space practicable.
Each mechanically fired miniature boiler shall be provided with an automatic low-water fuel cut-off so located as to automatically cut off the fuel supply in case the water level falls to the level of the bottom of the water glass.

1012.6 Gas-fired boilers

STATE AMENDMENT
Where miniature boilers are gasfired, the burners used shall conform to the requirements of the Fuel Gas Code. The burner shall be equipped with an automatic fuel-regulating governor that shall be regulated by the steam pressure. This governor shall be so constructed that, in the event of its failure, there shall be no possibility of steam from the boiler entering the gas chamber or gas supply pipe. A manual stop or throttle valve shall be located in the inlet pipe ahead of the fuel-regulating governor. All applicable requirements of the Fuel Gas Code shall be satisfied.
Each gas-fired miniature boiler shall be connected to a vent or flue, or to a chimney, extended to an approved location outside of the building. The venting arrangement shall be of approved design and in accordance with the boiler manufacturer’s installation instructions.
Each unfired pressure vessel shall be installed so that it is available for complete external inspection of shell and heads and shall be located so that, wherever possible, there will be not less than 12 inches (305 mm) between the vessel and any floor, wall, ceiling or other obstruction. There shall be no piping or other obstructions to prevent proper access. Any manhole or inspection opening shall be located so that it is readily accessible. All stamping and longitudinal welded or riveted joints shall be located in a position so as to be readily visible to the inspector. Where necessary to install a vessel underground, it shall be enclosed in a concrete or brick pit with a removable cover so that inspection of the entire shell and heads of the vessel can be performed.

1013.2 Structural supports

STATE AMENDMENT
Each unfired pressure vessel shall be supported by masonry or structural supports of sufficient strength and rigidity to safely support the vessel and its contents. Provisions shall be made to reduce vibration in both the vessel and its connecting piping.
All piping and connections to an unfired pressure vessel shall be supported in a substantial and safe manner so that there is no strain placed upon the vessel. Provision shall be made for expansion, contraction and drainage.

1013.4 Protection

STATE AMENDMENT
Each unfired pressure vessel shall be painted with two coats of approved paint, so that it is protected from rust and corrosion. It shall not be in contact with any corrosive material or moisture.

1013.5 Drip pipe

STATE AMENDMENT
Each unfired pressure vessel shall have a bottom drip pipe fitted with a valve or cock in direct connection with the lowest space practicable. The minimum size of pipe and fittings shall be ¾ inch (19 mm) except for tanks 20 inches (508 mm) in diameter or less, in which the minimum size of the pipe and fittings shall be ¼ inch (6.4 mm). If a plug cock is used, the plug shall be held in place with a guard or gland. Globe valves and cocks shall not be used.

1013.6 Pressure gauge

STATE AMENDMENT
Each unfired pressure vessel shall have a pressure gauge connected in a manner that the gauge cannot be shut off from the vessel, except by a cock with a “tee” or lever handle, which shall be placed on the pipe near the gauge. Connections to gauges shall be placed on the pipe near the gauge. Connections to gauges shall be made of nonferrous pipe and fittings from the tank to the gauge. Tubing shall not be used. The dial of the gauge shall be graduated to not less than 1.5 times the maximum pressures allowed for the vessel. A ¼-inch (6.4 mm) test gauge connection shall be provided for attaching the inspector’s test gauge.

1014.1 General

STATE AMENDMENT
Each unfired pressure vessel shall be protected by safety and relief valves and shall be provided with indicating and controlling devices to ensure its safe operation. These valves and devices shall be so constructed, located and installed that they cannot readily be rendered inoperative.

1014.2 Safety valves

STATE AMENDMENT
The relieving capacity of safety valves shall be such as to prevent pressure in the vessel from rising to more than 10 percent above the maximum allowable working pressure, taking into account the effect of static head. Safety valve discharge shall be carried to a safe place.

1014.3 Type of safety valve

STATE AMENDMENT
Each pressure vessel safety valve shall be of the direct spring-loaded type, having a substantial lever-lifting device so that the disk can be lifted from its seat by the spindle not less than ⅛ of the diameter of the valve when the pressure of the vessel is 75 percent of that at which the safety valve is set to open.

1014.4 Marking

STATE AMENDMENT
Every pressure vessel valve shall be marked “ASME” or “National Board Standard,” and shall bear the following information:
  1. The name or identifying mark of the manufacturer;
  2. The pipe size of valve inlet;
  3. The pressure at which the valve is set to open; and
  4. The relieving capacity.
Safety valves having either the seat or disk of cast iron shall not be used.
If more than one safety valve is used, the discharge capacity shall be taken as the combined capacity of all valves.
For vessels in which pressure is not generated but is derived from an outside source, each safety valve shall be so connected to the vessel, vessels or system which it protects as to prevent pressure from rising beyond the maximum allowable pressure in any vessel protected by the safety valve.
For vessels in which pressure may be generated, the safety valve or valves shall be connected directly to the vessel that is to be protected or to a pipe line leading to the vessel. The internal cross-sectional area of the pipe line shall be not less than the nominal area of the safety valve or valves used, and without any intervening valve between the vessel and the safety valve or valves protecting it.
When an escape pipe is used, it shall be full-sized and fitted with an open drain to prevent liquid from lodging in the upper part of the safety valve, and no valve of any description shall be placed on the escape pipe between the safety valve and the atmosphere.
When an elbow is placed on an escape pipe, it shall be located close to the safety valve outlet or the escape pipe shall be securely anchored and supported. When two or more safety valves are placed on one connection, this connection shall have a cross-sectional area at least equal to the combined area of these safety valves.

1014.11 Freeze protection

STATE AMENDMENT
Each safety valve which is exposed to a temperature of 32°F (0°C) or less shall have a drain at least ⅜ inch (9.5 mm) in diameter at the lowest point where water can collect.

1014.12 Spring adjustment

STATE AMENDMENT
Safety-valve springs shall not be adjusted to carry more than 10 percent greater pressure than that for which the springs were made.

1014.13 Valve testing

STATE AMENDMENT
Each safety valve shall be tested at least once every day by raising the disk from its seat.

1014.14 Valve sizing

STATE AMENDMENT
Safety valves for compressed air tanks shall not exceed 3 inches (75 mm) in diameter and shall be sized for the maximum flow of free air that can be supplied, as determined in Section VIII, Division 1, Part UG, paragraph UG-133, “Determination of Pressure Relief Requirements” in the ASME Code.
Rupture disks or heads used for supplemental protection of pressure vessels shall be designed to fail at a pressure above the safety or relief valve setting.

1014.16 Multiple vessels

STATE AMENDMENT
When two or more unfired pressure vessels that are allowed different pressures are connected to a common source of pressure, all safety valves shall be set at a pressure not exceeding the lowest vessel working pressure allowed.
Each hot water storage tank, range boiler, or automatic storage water heater, having a nominal water-containing capacity of 120 gallons (454 L) or less shall be built for a minimum working pressure of 125 pounds per square inch (psi) (862 kPa) and shall be tested hydrostatically to 300 pounds per square inch (psi) (2069 kPa). Each tank shall have clearly and indelibly stamped or stenciled thereon the name of the manufacturer, the maximum allowable working pressure for which it is built, and the test pressure.

1015.2 Tank labeling

STATE AMENDMENT
Each hot water tank shall be stamped with the ASME symbol to indicate that it is constructed in accordance with the ASME Code. It shall also be stamped with the name of the manufacturer, the maximum allowable working pressure, the year built and the identifying number of the National Board.
Applications for permits for hot water storage tanks as described in Section 1015.1 shall be accompanied by the manufacturer’s data report, which shall be signed by an inspector licensed by the National Board to inspect boilers and pressure vessels.
Gasfired automatic storage water heaters shall bear a label indicating approval and listing in accordance with the Fuel Gas Code.
Oilfired or electrically-heated automatic storage water heaters shall be listed and labeled, and shall bear the label of an approved listing agency.
Each storage water heater shall bear the manufacturer’s trade name or trademark, the catalog number, the input rating in Btu/h (W), the output in gallons per hour at 100°F rise in temperature, and the nominal capacity of the storage tank, in gallons (L).
Storage tanks shall be substantially supported by one of the following methods:
  1. Installed on steel supports constructed of pipe or structural steel and resting upon a structurally sound floor;
  2. Hung from supports attached to structural steel or concrete beams that have been determined to be of sufficient strength to support the additional weight; or
  3. Installed upon concrete saddles.
     In all cases, provision shall be made to take care of expansion. Tanks shall not be supported by their piping system. Manhole openings shall be kept clear of all walls, pipes or other obstructions.
Each gas-fired water heater shall be provided with an approved draft diverter installed in accordance with the manufacturer’s installation instructions and connected to an effective chimney. Connection to a common chimney shall be made above the entrance of other larger vent connectors or breechings, in accordance with Section 803.7.
In commercial and industrial establishments, when a connection to a chimney is impracticable, the installation of an automatic unvented water heater shall be approved by the code official if all of the following requirements are met:
  1. The flow of gas supply shall be limited, by fixed orifices, to the maximum flow values specified in Table 1015.9 as a function of the net interior volume of the space in which the heater is located the maximum input rating of the heater shall not exceed 10,000 BTU per hour (3 kW); and
  2. The heater shall otherwise conform to the Construction Codes.
TABLE 1015.9
MAXIMUM ALLOWABLE GAS FLOW FOR UNVENTED
COMMERCIAL AND INDUSTRIAL WATER HEATERS
NET VOLUME OF
ROOM OR SPACE
(cubic feet)
MAXIMUM ALLOWABLE GAS FLOW
(cubic feet per hour, CFH)
Column No. 1a Column No. 2b
1000 to 1500 2 3
1501 to 2000 3 4
2001 to 2500 4 5
2501 to 3000 5 6
3001 to 3500 6 7
3501 to 4000 7 8
Over 4000 8 8
For SI: 1 cubic foot = 0.028 m3, 1 CFH = 0.028 m3/h.
  1. Column No.1 applies to appliances located in spaces that do not have openings to other spaces.
  2. Column No. 2 applies to appliances located in spaces that have permanent openings of at least 15 square feet (1.4 m2) leading to another space of equal or greater volume.

1015.10 Prohibited use

STATE AMENDMENT
Water from a hot water supply boiler, automatic water heater coil or tank shall not be used for building heating, except for auxiliary space heating, permitted to have a by-pass from any such boiler or heater, provided that there is no actual withdrawal of water from the unit and that all surfaces and connections in contact with the water are of copper or other approved corrosion-resistant material.

1015.11 Existing tanks

STATE AMENDMENT
A tank currently in use shall not be painted, lined or repaired on the inside with any material or in any manner that will affect either the color or taste of the water supply after the tank is put into service. Any material intended for use as a lining or protective coating for the interior of tanks shall be submitted to the code official for approval.
The water supply connections to and from the tank shall be disconnected or plugged while the tank is being cleaned, painted, lined or repaired, to prevent any foreign fluid or substance from entering the distribution piping. Adequate measures shall be taken for the protection of workers in the tank.

1015.13 Welding repair

STATE AMENDMENT
Any repair by welding on a tank shall be done by a qualified welder licensed by the Department and the work shall be witnessed by the code official.
When changes or additions are made to an existing hot water supply system or when a storage tank is replaced or moved, compliance with the provisions of this chapter shall be required.

Exception: When there is no available opening in the top of an automatic storage water heater with a nominal water containing capacity 120 gallons (454 L) or less, it shall be permissible to install the relief valve in the outlet header from the heater, with only one fitting between the relief valve and the tank.
Each hydro-pneumatic tank shall be constructed for a minimum working pressure of 150 pounds per square inch (psi) (1034 kPa).

1016.2 Label

STATE AMENDMENT
Each hydro-pneumatic tank shall be stamped with the ASME symbol to indicate that it is constructed in accordance with the ASME Code. It shall also be stamped with the name of the manufacturer, the maximum allowable working pressure, the year built and the identifying number of the National Board.
Applications for permits shall be accompanied by the manufacturer’s data report, which shall be signed by an inspector licensed by the National Board to inspect boilers and pressure vessels.

1016.4 Gauges and manhole

STATE AMENDMENT
Each hydro-pneumatic tank shall be provided with a gauge-glass to show the level of the water in the upper section of the tank, and a pressure gauge. The tank shall also be provided with an 11-inch (280 mm) manhole opening, which shall be kept clear of walls, pipes or other obstructions.

1016.5 Safety relief valves

STATE AMENDMENT
Each hydro-pneumatic tank shall be equipped with a lever lifting safety valve bearing the ASME symbol, suitable for use with air, installed in a vertical position on the top of the tank, and set to relieve at or below the maximum allowable working pressure of the tank. The valve shall be sealed to prevent tampering and there shall be no shut-off valve between the tank and the relief valve.

1016.6 Pressure gauge

STATE AMENDMENT
Each hydro-pneumatic tank shall be provided with a pressure gauge not less than 4 inches (102 mm) in diameter connected directly to the tank by means of non-ferrous pipe. A cock with a “tee” handle shall be placed in the pipe near the gauge. The gauge shall be graduated to not less than 1.5 times the maximum allowable working pressure of the tank.

1016.7 Valve by-pass

STATE AMENDMENT
Each hydro-pneumatic tank shall be piped to include a full-size valved by-pass so that domestic water can be used in the building when the tank is not in service.
Each hydro-pneumatic tank shall be provided with a vacuum relieving device located on the top of the tank, and a horizontal swing check valve in the water supply line from the pump to the tank, and in the domestic water supply by-pass line to the tank. A valved sludge drain pipe shall be installed at the bottom of the tank and it shall discharge through an air break into the drainage system of the building.

1017.1 General

STATE AMENDMENT
Each hot water storage tank and automatic water heater shall be equipped with safety controls to prevent the temperature of the water in the tank from exceeding 200°F (93°C) and the pressure from exceeding the maximum allowable working pressure for which the tank is built. Each such unit shall be equipped with the following:
  1. A pressure relief valve and a separate temperature relief valve of the spillage type;
  2. A combination temperature-pressure relief valve of the spillage type; or
  3. In the case of automatic water heaters manufactured as a unit, a thermostat and a pressure relief valve.
Each pressure relief valve shall be of the lever lifting, spring-loaded type without disk on the pressure side of the valve. The valves shall be set to relieve at a pressure at or below the maximum allowable working pressure of the tank and shall be so arranged that they cannot be reset to relieve at a higher pressure than that stamped thereon.
The pressure relief valve or valves shall have sufficient capacity to prevent the pressure in the tank from rising to more than 10 percent above the maximum allowable working pressure. The rated capacity of the valve or valves shall be equal to the maximum gross output of the heating unit installed. The gross output shall be determined from the data supplied on the manufacturer's nameplate or catalog data, or from the fuel input.

1017.4 Labeling

STATE AMENDMENT
Pressure relief valves shall bear the ASME symbol to indicate that they comply with the requirements of the ASME Code in regard to construction, testing and rating, and shall be plainly and permanently marked by the manufacturer in a way that the marking will be readable when the valve is installed and will not be obliterated in service. Pressure relief valves used on non-ASME approved, gas-fired equipment shall bear the seal or mark of an approved agency to indicate listing under the requirements of an approved testing agency. Pressure relief valves shall bear the ASME symbol for equipment using other fuels. The marking on pressure relief valves shall include the following information:
  1. The manufacturer’s name;
  2. The type and catalog number;
  3. The pressure at which it is set to open; and
  4. The capacity in pounds of steam per hour (kg/hr) or BTU per hour (W) as certified by the National Board.

1017.5 Valve size

STATE AMENDMENT
No pressure relief valve shall be less than ¾ inch (19 mm) standard pipe size.

1017.6 Valve installation

STATE AMENDMENT
Each pressure relief valve shall be installed in a vertical position, directly on the top of the tank, or if there is no opening available, on a fitting in the hot water service line, within 2 inches (51 mm) of the tank. Each pressure relief valve shall have a full size discharge pipe of nonferrous metal, with an unthreaded open end, extended to an approved plumbing fixture or, if none is available, to within 6 inches (152 mm) of the floor. When the discharge pipe is over 1 inch (25 mm) in diameter it shall be supported and braced to prevent any strain being placed on the valve.

1017.7 Multiple valves

STATE AMENDMENT
If more than one relief valve is used, it shall be permissible to connect them to a manifold whose inlet pipe area shall be equal to the sum of the areas of the inlet openings of all the connected valves. There shall be no restriction to pipe cross sectional area on either the inlet or discharge side of the relief valve or valves, and there shall be no shut-off valve or check valve between the relief valve and the tank.
Each temperature relief valve shall bear a label indicating approval and listing by ASME, and shall be approved by the Department.
Each temperature relief valve shall be of the automatic self-closing type with a test lever and shall be designed to open at 200°F (93°C) or lower and be of sufficient capacity to limit the temperature to not over 200°F (93°C). The valve shall be non-adjustable and shall not be less than ¾ inch (19 mm) standard pipe size.

1017.8.2 Label

STATE AMENDMENT
Each temperature relief valve shall bear a plate permanently attached, giving the following information:
  1. The name of the manufacturer;
  2. The model or type number of the valve;
  3. The temperature at which the valve will open; and
  4. The rated capacity in BTU per hour (W).

1017.8.3 Installation

STATE AMENDMENT
Each temperature relief valve shall be installed in a vertical position on the top of the tank. Temperature relief valves shall be screwed directly into the tank without intervening fittings unless the dip tube extension type is used, in which case the tube shall project into the tank. If a fitting is used, it shall be of non-ferrous material. Each valve shall have a full size discharge pipe with an unthreaded open end, extended to within 6 inches (152 mm) of the floor or to an approved receptor fixture. There shall be no restrictions to pipe cross section area on either the inlet or discharge side of the relief valve, and there shall be no shut-off or check valve between the relief valve and the tank.
When a combination temperature-pressure relief valve is used, it shall conform with the requirements of Section 1017 for pressure relief valves and for temperature relief valves. It shall bear the ASME symbol, meet the labeling requirements of Sections 1017.4 and 1017.8.2, and bear the symbol of the American Gas Association for the temperature relief element.

1017.10 Aquastat

STATE AMENDMENT
Each aquastat used on an automatic gas water heater shall be listed by the American Gas Association, unless provided as part of a complete American Gas Association approved unit, and shall operate to shut off the gas supply to limit the temperature of the heated water to not over 210°F (99°C).
Hot water supply boilers, tankless heaters, electric heaters, immersion heating coils in boilers and any other type of heater shall be protected against excessive pressure, as provided herein.

1017.11.1 Pressure gauge

STATE AMENDMENT
Each hot water supply boiler and hot water storage tank shall be provided with a pressure gauge connected directly to the boiler or tank by means of non-ferrous pipe. A cock with a “tee” handle shall be placed in the pipe near the gauge. The gauge shall have a dial not less than 4 inches (102 mm) in diameter and shall be so located that it can be easily read from the floor. It shall be graduated to not less than one and onehalf (1½) times the maximum allowable working pressure of the boiler or tank. Gauges shall not be required for range boilers and domestic type water heaters.

1017.11.2 Thermometer

STATE AMENDMENT
Each hot water supply boiler, hot water storage tank, tankless heater, immersion type heater or any other type of heater shall be provided with a thermometer capable of providing readings up to 300°F (149°C), of a size and so located that it can be easily read from the floor. It shall be located in a well so that it will indicate the temperature of the water at or near the outlet and shall be accurate within 2 percent. Thermometers shall not be required for range boilers or domestic type water heaters.
When hot water is used by the general public or by persons not in control of the heating equipment, an approved water mixing valve shall be installed to limit the temperature of the water at the fixtures to not over 140°F (60°C). A thermometer shall be installed on the discharge side of the mixing valve and shall be of a size and so located as to be easily read from the floor.
The construction, installation, repair or alteration of a boiler or unfired pressure vessel by welding shall be made in accordance with the section of the ASME Code governing the particular kind of vessel or work to be done, or by the specific requirements in this section for welded repairs.
A contractor desiring to make repairs shall have a written welding procedure specification that shall be prepared and qualified in accordance with the Welding Qualification of Section IX of the ASME Code. Alternatively, the contractor shall have the option to use the standard District of Columbia welding procedure specification. The selected procedure shall then be used for qualifying each welder and shall be strictly adhered to in making repairs under this chapter. A welder shall be limited to the type of steel and thickness of plate for which he or she is qualified.
Welding repairs or alterations on boilers or unfired pressure vessels and connections thereto, performed by unqualified contractors or welding operators, shall not be accepted for either new or existing installations.
Each welder shall pass satisfactory qualification tests as required by the ASME Code.
The qualification test for individual welders shall be made in accordance with the ASME Code. The test shall be made in the presence of the code official who shall stamp the specimens with an identifying number. The code official shall have the option of accepting a welder without further examination, provided that the applicant submits proof of a satisfactory welding procedure and operator qualification test, made in accordance with the ASME Code and these regulations, for approval prior to any welding.

1018.1.4 Specimens testing

STATE AMENDMENT
After the specimens have been prepared as required by the ASME Code, they shall be tested either by the code official or the National Institute of Standards and Technology (NIST). The test shall be made in accordance with the guided-bend jig test as described in the ASME Code. A report shall be made on a form similar to the data recording forms in Section IX, Appendix B of the ASME Code.

1018.1.5 Authorization card

STATE AMENDMENT
If the report indicates that the welder has passed the test, the code official shall issue a card authorizing him or her to perform welding on boilers or unfired pressure vessels in the District of Columbia. This authorization shall be valid for a period of two years from the date of the test.
The qualification test does not qualify a welder to do welding on pressure piping.

1018.2 Qualification retest

STATE AMENDMENT
A welder who fails to meet the requirements for one or more of the test specimens shall be allowed to be retested unless, in the judgment of the code official, the welder requires further training or practice, in which case a complete retest of the welder shall be performed after completion of such additional training or practice. When a request for an immediate retest is approved, the welder shall make two test welds of each type for each position on which the welder has failed. To become qualified, all of the retest weld specimens shall pass the specimen test specified in Section 1018.1.4.
Notwithstanding the issuance of a qualification card, the code official has the authority to request a new test under any the following circumstances:
  1. When a welder has not welded under the procedure specification for a period of three months or more;
  2. When there is a specific reason to question the welder's ability to make welds that meet the specification; or
  3. At the expiration of the welder's two year qualification period.

1018.3.1 Questionable welds

STATE AMENDMENT
If any question arises as to the quality of a weld, the code official is authorized to require that test specimens be trepanned from the weld. Preparation and testing of the specimens shall be done by NIST, and the contractor shall be responsible for all expenses incidental to this testing.
No welding on any boiler or unfired pressure vessel shall be done before an inspection has been made by the code official or an insurance company inspector, and the method of welding has been sanctioned by the code official or the insurance company inspector. If, in the opinion of the code official, or the insurance company inspector a hydrostatic test is necessary, that test shall be applied after the repairs have been completed.
Before repairs are started, the insurance company inspector shall examine the written welding procedure and records of qualification tests, to verify that procedures and welders have been properly approved, tested and qualified. The insurance company inspector who authorized and witnessed the repair shall submit a written report to the code official on every welded repair.

Section 1019 TEST METHODS

STATE AMENDMENT
The qualification tests described herein shall be specifically devised to determine a welder’s ability to produce sound welds. In order to determine the welder’s ability to make groove welds in various plate positions, tests with the groove in the following three positions shall be required:
  1. Test Position I—Plates placed in a vertical position with the welding groove horizontal. This test shall qualify the welder to make horizontal flat welds.
  2. Test Position II—Plates placed in a vertical position with the welding groove vertical. This test shall qualify the welder to make vertical flat welds.
  3. Test Position III—Plates placed in a horizontal position with the weld metal deposited form the underside of the plates. This test shall qualify the welder to make flat welds in the overhead position.
The base material of the plates to be welded shall be of flange or firebox steel quality, ⅜-inch (9.5 mm) thick and having a tensile strength of not less than 55,000 pounds per square inch (psi) (379 MPa). The plates shall be 5 inches (127 mm) long by 6 inches (152 mm) wide, and shall be prepared for a single “V” groove butt joint.
The method of preparing test specimens shall be as follows:
  1. When the welding has been completed, specimens shall be removed as directed, by machine or flame cutting. They shall be approximately 1½ inches (38 mm) wide.
  2. The weld reinforcement shall be removed by machine or grinding, flush with the surface of the base material.
  3. The corners of the edges of all test specimens shall be rounded to a radius of not more than 115 inch (1.7 mm).
     In addition to (1), (2) and (3) above, the test specimens shall be prepared as specified in Section IX, paragraph QW- 462, “Test Specimens,” of the ASME Code.
The method of testing specimens shall be as follows:
  1. Specimens shall be bent in a bending jig called the “guided bend test,” until the curvature of the specimen is such that a 132-inch (0.8 mm) wire cannot be passed between the curve portion of the plunger and the specimen.
  2. Face bend specimens shall be placed with the face of the weld toward the gap in the jig; root bend specimens shall be placed with the root of the weld toward the gap.
After removal from the jig, the convex surface of the specimens shall be examined for the appearance of cracks or other open defects. Any specimen in which a crack or other open defect exceeding ⅛ inch (3.2 mm) measured in any direction is present after the bending shall be cause for failure to pass the test.
These rules shall be applicable only to repairs to steel having a known weldable quality, and are further limited to carbon steel having a carbon content of not more than 0.35 percent and to low alloy steel having a carbon content of not more than 0.25 percent. A welder shall not make repairs in a plate with thickness in excess of that permitted under the qualification tests in the ASME Code. A welder shall not make repairs on a material for which the welder is not qualified, or in a thickness of plate that exceeds that permitted under the welder's qualification conditions.

1020.2 Groove welding

STATE AMENDMENT
Groove welds shall completely penetrate the material being welded. If possible, welding shall be applied from both sides of the plate, or a backing strip or ring may be used to ensure complete penetration. Welds shall have a convex surface on both sides if applied on both sides of the plates being joined, or on the weld side if welding is applied from one side only. No valleys or undercutting at edges or welded joints shall be permitted. The reinforcement may be chipped, ground or machined off flush with the base material, if so desired, after the welding has been completed.
In making a repair to a weld that has failed in service, the defective weld material shall be removed by chipping or grinding until sound material is reached on all sides. The resulting groove shall be filled as required by the applicable welding procedure.
In the repair of carbon or low alloy steel, thermal stress-relieving shall be applied to the completed work when required by these rules and when considered necessary by the code official or insurance company inspector. The heat may be applied by any means that will raise the temperature of the material, in the region of the weld, gradually and uniformly, to approximately 1200°F (649°C). In the absence of a more accurate means of determining temperature, reaching a dull “red glow” in daylight will suffice. This temperature shall be maintained for a period of 1 hour/inch (1 hour/25 mm) of thickness of the joined material.
For circumferential joints, the area heated shall comprise a band extending completely around the cylinder and having a width on each side of the center line of the weld not less than three times the greatest width of the finished weld.

1020.4.2 Nozzles

STATE AMENDMENT
For nozzles, the heated area shall comprise a circumferential band of the shell of the vessel extending around the entire joint, including the nozzle of the welded attachment, and shall extend at least six times the vessel plate thickness beyond the weld that connects the nozzle or other attachment to the vessel.
Upon completion of the stress-relieving operation, the plate shall be allowed to cool at a rate not greater than 500°F (278°C) per hour divided by the maximum thickness of the welded part in inches, until the temperature of 500°F (260°C) is reached, after which normal cooling by exposure to air in a still atmosphere shall be permitted.
Where conditions are such that thermal stress relieving as outlined above is inadvisable, another method of stress-relieving acceptable to the code official or insurance company inspector shall be used. When deemed necessary, preheating shall be used.
Cracks in stayed areas shall be allowed to be repaired by welding, provided that no multiple or star cracks radiating from rivet or stay bolt holes shall be welded.
Cracks in unstayed shells, drums or headers of boilers or pressure vessels shall be allowed to be repaired by welding, provided that the cracks do not extend between rivet holes in a longitudinal seam, or parallel to a longitudinal riveted seam within 8 inches (203 mm), measured from the nearest caulking edge. The total length of any one such crack shall not exceed 8 inches (203 mm). A crack of greater length shall be allowed to be welded provided the complete repair is radiographed and stressrelieved. Any crack that is allowed to be welded shall be properly prepared to permit fusion through the entire plate thickness.
Cracks of any length in unstayed furnaces shall be allowed to be welded, provided that the welds are thermally stress-relieved. Welds shall be applied from both sides of the plate wherever possible. Welds applied from one side only shall be allowed to be used if expressly permitted by the inspector. Repair of cracks by welding at the knuckle or turn of flange of furnace openings openings shall be prohibited except upon special prior approval by the boiler inspector.
Corroded areas in stayed furnaces shall be allowed to be built up by welding, provided that the remaining uncorroded plate material has an average thickness of not less than 50 percent of the original plate thickness, and further provided that the areas so affected are not deemed by the inspector to be sufficiently extensive to impair the safety of the object. In cased furnaces, the stays and stay bolts shall come completely through the reinforcing metal and the original ends of the stay bolts shall be plainly visible to the inspector.
Corroded areas around manholes or handhole openings, in either stayed or unstayed plates, shall be allowed to be built up by welding, provided that the average loss of thickness does not exceed 50 percent of the original plate thickness and that the area to be repaired does not extend more than 3 inches (76 mm) from the edge of the hole.
Corroded areas in unstayed shells, drums or headers of boilers or pressure vessels shall be allowed to be built up by welding, provided that the remaining uncorroded plate material has an average thickness of not less than 50 percent of the original plate thickness, and further provided that the inspector has deemed that the safety of the object has not been impaired.
Edges of butt straps, of plate laps, of nozzles, or of connections, attached by riveting, shall be allowed to be restored to their original thickness by welding. No seal welding shall be used except upon special prior approval by the boiler inspector, and in no case shall seal welding be used where cracks are present in riveted areas.

1021.8 Welding tube ends

STATE AMENDMENT
The ends of tubes in fire-tube and water-tube boilers shall be allowed to be welded, provided that they have not been reduced more than 10 percent in thickness and they comply with the requirements of paragraphs PWT-11 and PFT-12 in Section I, Parts PWT and PFT of the ASME Code.
Re-ending of piecing tubes or pipes in either fire-tube or water-tube boilers shall be permitted, provided that the thickness of the tube or pipe has not been reduced by more than 10 percent from the thickness required by the ASME Code for the approved pressure. In all cases they shall comply with the requirements in Section I, Part PWT, paragraph PWT-10, “Tube Wall Thickness” of the ASME Code.

1021.10 Patch material

STATE AMENDMENT
The material used for patches shall be of the same general quality and have at least the same yield strength of the plate to be patched. The thickness of any patch shall be at least equal to, but not more than ⅓ inch (8.5 mm) greater than, the plate being patched.

1021.11 Permitted patches

STATE AMENDMENT
Flush or butt-welded patches or new sections shall be allowed to be applied to stayed plates without limitation of size or plate thickness. Lapped or filletwelded patches shall be allowed to be applied to stayed plates, provided that they are not exposed to radiant heat. Lapped and fillet-welded patches shall be allowed to be applied on the pressure side of the sheet in unstayed areas, provided that the maximum diameter of the opening so repaired does not exceed 16 times the thickness of the plate, but in no case shall the opening be larger than 8 inches (203 mm) in diameter.
No flush or butt-welded patches shall be permitted in unstayed shells, drums or headers.
Threaded stays shall be allowed to be replaced by welded-in stays, provided that, in the judgment of the code official or insurance company inspector, the plate adjacent to the stay bolt has not been materially weakened by deterioration or wastage. All requirements of the applicable sections of the ASME Code governing welded-in stays, including Section I, Part PW, paragraph PW- 19, “Welded-in Stays” shall be met.
The maximum allowable working pressure on the shell or drum of a power boiler shall be determined by the strength of the weakest section of the structure, computed from the following information.
  1. The thickness of the plate;
  2. The tensile strength of the plate;
  3. The efficiency of the longitudinal joint or tube ligaments, whichever is least;
  4. The inside diameter of the course; and
  5. The factor of safety allowed by this chapter.

1022.1.1 Computation

STATE AMENDMENT
The maximum allowable working pressure shall be determined in accordance with the following equation:

(TS x t x E) ÷ (R x FS) = Pm

Where:

Pm = Maximum allowable working pressure (psi) (kPa).
TS = Ultimate tensile strength of shell plates (psi) (kPa).
t = Minimum thickness of shell plate in weakest course (inch) (mm).
E = Efficiency of longitudinal joint, per Section VIII, Division 1, Part UW, paragraph UW-12 of the ASME Code.
R = Inside radius of the weakest course of the shell or drum (inch) (mm).
FS = Factor of safety required by Chapter 10 of the Mechanical Code.
The factor of safety for nonstandard boilers with longitudinal joints of butt or double strap construction shall be not less than the following:
  1. 4.5 for boilers not more than 20 years old;
  2. 5 for boilers more than 20 years old, but not more than 25 years old; and
  3. 5.5 for boilers more than 25 years old, but not more than 30 years old.
     At the beginning of each subsequent 5-year period, the factor of safety shall be increased by not less than 0.5.
In no case shall the maximum allowable working pressure on old boilers be increased unless they are being operated at a lesser pressure than would be allowable for similar new boilers, in which case the changed pressure shall not exceed that allowable for new boilers of the same construction.
The factor of safety for standard boilers with longitudinal joints of butt or double strap construction shall be five for boilers not more than 25 years old. At the beginning of each subsequent 5-year period, the factor of safety shall be increased by not less than 0.5.

Exception: When a thorough internal and external inspection of a boiler more than 25 years old is conducted, and a hydrostatic pressure test is performed at 1½ times the allowed working pressure of the boiler, during which no leakage or signs of distress develop, the allowed working pressure shall be allowed to continue to be calculated with a factor of safety of five.
The factor of safety for nonstandard boilers of the water-tube type with longitudinal joints of lap riveted construction shall be not less than the following:
  1. 5 for boilers not more than 20 years old;
  2. 5.5 for boilers more than 20 years old, but not more than 25 years old; and
  3. 6 for boilers more than 25 years old, but not more than 30 years old.
     At the beginning of each subsequent 5-year period, the factor of safety shall be increased by not less than 0.5.
The factor of safety for nonstandard fire tube, flue and cylinder boilers, the shells of which are exposed to the products of combustion and which have continuous longitudinal joints of lap-riveted construction exceeding 12 feet (3658 mm) in length, shall be not less than the following:
  1. 6 for boilers not more than 10 years old;
  2. 6.5 for boilers more than 10 years old, but not more than 15 years old; and
  3. 7 for boilers more than 15 years old, but not more than 20 years old.
     At the beginning of each subsequent 5-year period, the factor of safety for boilers specified in this section shall be increased by not less than 0.5.

1022.5.1 Reinstallation

STATE AMENDMENT
When a boiler regulated by Section 1022.5 is removed from an existing setting, it shall not be reinstalled for an allowable working pressure in excess of 15 pounds per square inch (psi) (103 kPa).
The maximum allowable working pressure on water-tube boilers, the tubes of which are secured to cast-iron or malleable- iron headers or which have cast-iron mud drums, shall not exceed 160 pounds per square inch (psi) (1103 kPa).
When the tensile strength of steel or wrought iron shell plates is not known, it shall be taken as 55,000 pounds per square inch (psi) (379 212 kPa) for steel and 45,000 pounds per square inch (psi) (310 264 kPa) for wrought iron.
The resistance to crushing of mild steel shall be taken at 95,000 pounds per square inch (psi) (655 000 kPa).

1022.9 Rivets

STATE AMENDMENT
In computing the ultimate strength of rivets in shear, the cross-sectional area of the rivet shank shall be used to determine the value of the shear strength of the rivet, based upon the provisions in Section I of the ASME Code.

1022.9.1 Size of rivets

STATE AMENDMENT
When the diameter of the rivet holes in the longitudinal joints of a boiler is not known, the diameter of rivets, after driving, shall be selected from Table 1022.9.1, or ascertained by cutting out one rivet in the body of the joint.

TABLE 1022.9.1
MINIMUM SIZES OF RIVETS BASED ON PLATE THICKNESS
THICKNESS OF PLATE
(inch)
DIAMETER OF RIVET
AFTER DRIVING
(inch)
¼ 1116
932 1116
516 ¾
1132 ¾
1316
1332 1316
716 1516
1532 1516
½ 1516
916 1116
1116
For SI: 1 inch = 25 mm.
When the heads of water tube boiler mud drums or headers are not accessible for inspection, the brick work shall be removed after the boiler has been in service for 10 years to facilitate inspection and at not more than 5-year intervals thereafter. Seams and parts of fire-tube boilers that are not accessible for inspection shall be exposed whenever the code official or insurance company inspector deems that the general condition of the boiler warrants further examination.

1022.11 Safety valves

STATE AMENDMENT
Each power boiler shall be equipped with one or more safety valves of the spring-pop type with a lifting device, placed as close to the boiler as possible. No valve of any description shall be placed between the safety valve and the boiler, nor on the escape pipe between the safety valve and the atmosphere. When an elbow is placed on a safety valve escape pipe, it shall be located close to the safety valve outlet or the escape pipe shall be securely anchored and supported. When an escape pipe is used, it shall be full size and fitted with an indirect drain to prevent water from lodging in the upper part of the safety valve or escape pipe. Safety valves having either the seat or disk of cast iron shall not be used. Dead weight and lever weight safety valves shall be prohibited.
The capacity of the safety valve or valves installed on each boiler shall be such that the safety valve or valves will discharge all the steam that can be generated by the boiler without allowing the pressure to rise to more than 6 percent above the maximum allowable working pressure, nor to more than 6 percent above the highest pressure to which any safety valve is set.
One or more safety valves on every boiler shall be set at or below the maximum allowable working pressure. The remaining valves may be set within a range of 3 percent above the maximum allowable working pressure, but the range of setting of all the safety valves on a boiler shall not exceed 10 percent of the highest pressures to which any safety valve is set.
Where fire-actuated fusible plugs are used, they shall conform to the rules of the ASME Code for new construction.

1023.2 Water glass

STATE AMENDMENT
Each steam boiler shall have at least one water glass, the lowest visible part of which shall be as required by the ASME Code for new construction.

1023.3 Gauge cocks

STATE AMENDMENT
Each boiler with an allowable working pressure in excess of 15 pounds per square inch (psi) (103 kPa) shall have three or more gauge cocks located within the range of the visible length of the water glass, except when such boiler has two water glasses with independent connections to the boiler located on the same horizontal plane and not less than 2 feet (610 mm) apart.

1023.4 Outlet connections

STATE AMENDMENT
No outlet connections shall be placed on the pipes connecting a water column to a boiler, except for connections for a damper regulator, a feed water regulator, a low water fuel cut-off, drains or a steam gauge. Each water column shall have a valved drain extended to within 6 inches (152 mm) of the floor.

1023.5 Steam gauges

STATE AMENDMENT
Each steam boiler shall have a steam gauge connected to the steam space or to the steam connection to the water column. The steam gauge shall be connected to a siphon or equivalent device of sufficient capacity to keep the gauge tube filled with water and so arranged that the gauge cannot be shut off from the boiler except by a cock placed near the gauge and provided with a “T” or lever handle arranged to be parallel to the pipe in which it is located when the cock is open.

1023.6 Low-water cut-off

STATE AMENDMENT
Each mechanically fired steam boiler shall be equipped with a low-water fuel cut-off so located as to automatically cut off the fuel supply when the water level falls below the top of the bottom nut of the water glass. Each cut-off shall have a drain extended to within 6 inches (152 mm) of the floor. When two or more mechanically- fired boilers are connected to the same system, each boiler shall have independent low-water cut-offs, controls, and gauges.

1023.7 Stop valve

STATE AMENDMENT
Each steam outlet from a high-pressure boiler shall be fitted with a stop valve located as close as practicable to the boiler. This requirement shall not apply to safety-valve connections.

1023.8 Blow drains

STATE AMENDMENT
When a stop valve is so located that water can accumulate, free blow drains shall be provided, the discharge of which shall be visible to the operator while manipulating the valve.

1023.9 Blow-off connection

STATE AMENDMENT
Each boiler shall have a full-size blow-off connection, fitted with a valve or cock connected directly with the lowest water space practicable. When cocks are used, they shall be of the gland or guard type and suitable for the pressure allowed. Globe valves shall not be used for this purpose.
When the maximum allowable working pressure exceeds 100 pounds per square inch (psi) (689 kPa), the blow-off shall be extra heavy from boiler to valve or valves, and shall extend full size without reducers or bushings. Blow-off piping shall be of black wrought iron or black steel and shall be extra heavy pipe. Galvanized pipe shall not be used for this purpose.

1023.9.2 Fittings

STATE AMENDMENT
All fittings between the boiler and valve shall be steel or extra heavy fittings of bronze, brass or malleable iron. Replacement of pipe or fittings in the blow-off lines shall be installed in accordance with the ASME Code for new installations.

Exceptions:
  1. Low-pressure heating boilers bearing the ASME stamp that are trimmed by the manufacturer are exempt from the fittings material requirements.
  2. Low-pressure heating boilers rated less than 100 horsepower (74.6 kW) are exempt from the fittings material requirements.
When the maximum allowable working pressure exceeds 100 pounds per square inch (psi) (689 kPa), each bottom blow-off pipe shall be fitted with two valves or a valve and cock, such valves and cocks to be of the extra heavy type.
A bottom blow-off pipe, when exposed to direct furnace heat, shall be protected by fire-brick or other heat-resisting material, arranged so as to allow the pipe to be inspected. An opening in the boiler setting for a blow-off pipe shall be arranged to provide for free expansion and contraction.
The feed pipe of a steam boiler shall be provided with a check valve near the boiler and a valve or cock between the check valve and the boiler. When two or more boilers are fed from a common source, there shall also be a globe valve on the branch to each boiler, between the check valves and the main feed pipe. When a globe valve is used on a feed pipe, the inlet shall be under the disk from the valve. In all cases where the safety valve is set above 25 pounds per square inch (psi) (172 kPa), there shall be a second means of feeding water against the maximum approved working pressure of the boiler.

1023.11 Hydrostatic test

STATE AMENDMENT
When a hydrostatic test is applied, test pressure shall not exceed 1½ times the maximum allowable working pressure of the boiler. During a hydrostatic test of a boiler, suitable provisions shall be made to attain the test pressure without using the compression screw of the safety valve spring.
Where repairs or replacements are made or fittings or appliances are renewed or attached to a boiler, they shall comply with the provisions of the ASME Code for new installations.
Installation conditions of power boiler parts and equipment not specifically covered in Chapter 10 of the Mechanical Code shall be regulated as determined by the code official.
The maximum allowable working pressure of heating boilers shall be determined as follows:
  1. Riveted Heating Boilers. The maximum allowable working pressures on the shell or drum of a riveted heating boiler shall be determined in accordance with Section 1022, except that in no case shall the maximum allowable working pressure of a steam boiler exceed 15 pounds per square inch (psi) (103 kPa).
  2. Cast Iron Heating Boilers. The maximum allowable working pressure of a boiler composed principally of cast iron shall not exceed 15 pounds per square inch (psi) (103 kPa), unless such boiler complies with all the requirements of the Mechanical Code for power boilers. The maximum allowable working pressure of a boiler having cast-iron shell or heads and steel or wrought-iron tubes shall not exceed 15 pounds per square inch (psi) (103 kPa).
A radiator in which steam pressure is generated at a pressure of 15 pounds per square inch (psi) (103 kPa) or less shall be considered a low pressure boiler.
The maximum allowable working pressure shall in no case exceed the pressure indicated by the manufacturer’s identification stenciled or cast upon the boiler or upon a plate secured to it. In the absence of a manufacturer’s identification stencil or plate, the maximum allowable working pressure shall not exceed that recommended in the manufacturer’s specification or catalog.
If, in the judgment of the code official or an insurance company inspector, a steam-heating boiler is not safe for operation at the pressure previously approved, the operating pressure shall be reduced to a pressure deemed safe by the code official or insurance company inspector, or proper repair shall be made, or the boiler shall be retired from service, as determined by the code official or insurance company inspector.

1024.2 Safety valves

STATE AMENDMENT
Each steam-heating boiler shall be provided with one or more safety valves with a total area of not less than 1 square inch (645 mm2) for each 5 square feet (0.46 m2) of grate area or equivalent if grates are not used. The steam-relieving capacity of the safety valve or valves on any boiler shall be sufficient to prevent the boiler pressure from rising to more than 5 pounds per square inch (psi) (34 kPa) above the maximum allowable working pressure of the boiler.

1024.2.1 Capacity

STATE AMENDMENT
If there is any doubt as to the capacity of the safety valve, an accumulation test shall be run. No safety valve shall be smaller than ¾ inch (19 mm) in diameter nor larger than 4.5 inches (114 mm) in diameter.

1024.2.2 Stop valve

STATE AMENDMENT
No stop valve of any type shall be located between a boiler and its safety valve, nor in the safety valve discharge pipe.

1024.3 Parts and equipment

STATE AMENDMENT
Each steam-heating boiler shall be equipped with the following parts and equipment that shall meet the requirements of Sections 1024.3.1 through 1024.3.8, as applicable.
Each steam-heating boiler shall have a steam pressure gauge connected to the steam space of the boiler itself or on steam pipe near the boiler. The graduations of the steam gauge shall not have a range of less than 15 pounds per square inch (psi) (103 kPa) nor more than 30 psi (207 kPa).

1024.3.2 Water gauge glass

STATE AMENDMENT
Each heating boiler shall have at least one water gauge glass with the lowest visible part above the heating surfaces in the primary combustion chamber. When, in the judgment of the code official or an insurance company inspector, the heating surfaces above the low-water line may be damaged by contact with high temperature gases, the water gauges shall be raised until the lowest visible part of the glass gauge is above the testing surface.

1024.3.3 Gauge cocks

STATE AMENDMENT
Each steam-heating boiler shall have two or more gauge cocks located within the visible length of the water gauge glass.

Exception: Steam-heating boilers provided with two water gauge glasses.

1024.3.4 Steam stop valve

STATE AMENDMENT
Heating boilers that can be closed off from the heating system by closing a steam stop valve shall be equipped with a check valve in the condensate return line, between the boiler and the system. Any part of a heating system that can be closed off from the remainder of the system by closing a steam stop valve, shall be provided with a check valve in the condensate return pipe from that part of the system.
Feed-water connections shall be independent of any water gauge connections. Where possible, feed-water connections shall be made to the condensate return pipe of the reservoir of the condensate return pump. There shall be a check valve in the feedwater line, close to the boiler.
Each mechanically fired heating boiler shall be equipped with a low-water cut-off so located as to automatically cut off the fuel supply in case the water level falls below the top of the bottom nut of the water glass. Each cut-off shall have a drain extended to within 6 inches (152 mm) of the floor. When two or more mechanically fired heating boilers are connected to the same system, each boiler shall have independent low-water cut-offs, controls and gauges.
If a low-water fuel cut-off device is electrically operated, it shall be so connected that it will fail-safe in the “cut-off” position both when the electric current is switched off and upon loss of electric power supply.
Each condensate return pump shall be provided with an automatic water level control, set to maintain the water level between two gauge cocks.
When repairs or replacement of parts or piping are made, or fittings or appliances are replaced or attached to a heating boiler, the rules applying to new installations shall be followed as nearly as practicable.
When a safety valve is replaced the requirements of Section 1010 shall be met. No safety valve shall be smaller than ¾ inch (19 mm) in diameter nor larger than 4.5 inches (114 mm) in diameter.
The maximum allowable working pressure on the shell or drum of a miniature boiler shall be determined in accordance with the following equation:

(TS x t x E) ÷ (R x FS) = Pm

where:

Pm = Maximum allowable working pressure (psi) (kPa).
TS = Ultimate tensile strength of shell plates (psi) (kPa).
t = Minimum thickness of shell plate in weakest course (inch) (mm).
Ea = Efficiency of longitudinal joint, per Section VIII, Division 1, Part UW, paragraph UW-12, “Joint Efficiencies” of the ASME Code.
Ea = Efficiency for tube ligaments between openings as calculated in Section I, Part PG, paragraphs PG-52 and PG-53 of the ASME Code.
R = Inside radius of the weakest course of the shell or drum (inch) (mm).
FS = Factor of safety required by Chapter 10 of the Mechanical Code.
  1. Where there are both riveted joints and tube ligaments to consider, the lowest calculated efficiency, E, shall be used.

1025.2 Parts and equipment

STATE AMENDMENT
Each miniature boiler shall be equipped with the following parts and equipment that shall meet the requirements of Sections 1025.2.1 through 1025.2.13, as applicable.

1025.2.1 Feed pump

STATE AMENDMENT
Each miniature boiler operating at a pressure in excess of 25 pounds per square inch (psi) (172 kPa) shall be provided with at least one feed pump or other approved water-feeding device.

Exception: Where the steam generator is operated as a closed system with no extraction of steam, in lieu of a feeding device, a suitable connection or opening, not less than ½ inch (13 mm) nominal pipe size, shall be provided to fill the generator when cold.
Each miniature boiler shall be fitted with feed water and blow-off connections that shall not be less than ½ inch (13 mm) iron pipe size, unless operated on a closed system. The feed pipe shall be provided with a check valve and a stop valve. The blow-off shall be fitted with a valve or cock and shall be in direct connection with the lowest water space practicable. When the boiler is under pressure, feed water shall not be introduced through the openings or connections used for the column, the water gauge glass or gauge cocks. All valves, pipe fittings and appliances shall be rated at a minimum of 125 pounds per square inch (psi) (862 kPa) standard pressure.
Each miniature boiler shall be equipped with a water gauge glass and one or more gauge cocks. The lowest permissible water level shall be at a point one-third of the height of the shell.

Exceptions:
  1. Where the miniature boiler is equipped with internal furnace, the lowest permissible water level shall be not less than one-third of the length of the tube above the top of the furnace.
  2. In the case of small generating units operated as a closed system, where there is insufficient space for the usual water gauge, water-level indicators of the glass bull's eye type shall be allowed to be used.

1025.2.4 Steam gauge

STATE AMENDMENT
Each miniature boiler shall be equipped with a steam gauge having its dial graduated to not less than 1½ times the maximum allowable working pressure. The gauge shall be connected to the steam space or to the steam connection to the water column by a brass or bronze composition siphon tube, or equivalent device that will keep the gauge tube filled with water.

1025.2.5 Safety valve

STATE AMENDMENT
Each miniature boiler shall be equipped with a sealed, spring loaded, “pop” safety valve not less than ½ inch (13 mm) diameter connected directly to the boiler. To ensure the safety valve is unrestricted, each valve shall have a substantial lifting device by which the valve disk can be lifted from its seat when the pressure in the boiler is at least 75 percent of full working pressure. All safety valves shall be mounted with their spindles vertical and shall be accessible.
The safety valve shall be plainly marked by the manufacturer with the following information:
  1. Manufacturer name or identifying trademark;
  2. The nominal diameter;
  3. The steam pressure at which it is set to open; and
  4. The capacity in pounds of steam per hour (kg/hr) and ASME Standard.
The minimum relieving capacity for the safety valve shall be determined on the basis of 3 pounds of steam per hour per square foot (lb/hr/ft2) (14.65 kg/hr/m2) of heating surface and shall be sufficient to discharge all the steam that can be generated by the miniature boiler without allowing the pressure to rise to more than 6 percent above the maximum allowable working pressure.
Each steam line from a miniature boiler shall be provided with a 125 pounds per square inch (psi) (862 kPa) standard stop valve located as close to the boiler shell or drum as practicable.
Each miniature boiler shall be provided with a blow-off connection that shall not be reduced in size and shall be extended to a safe point of discharge. Whenever, in the judgment of the code official, a safe point of discharge is not available, a blow-down tank shall be provided. The blow-off shall be fitted with a valve or cock and shall be connected directly to the lowest water space practicable.
Each miniature boiler mechanically-fired by any fuel other than gas shall be provided with an automatic low-water fuel cutoff, so located as to automatically cut off the fuel supply in case the water level falls below the bottom of the water glass.

1025.2.9 Gas-fired boilers

STATE AMENDMENT
The burners of gas-fired miniature boilers shall conform to the listing requirements of the American Gas Association. Such burners shall be equipped with an automatic fuel-regulating governor regulated by the steam pressure. The governor shall be so constructed that, in the event of its failure, there can be no possibility of steam from the boiler entering the combustion chamber or the gas supply pipe. A manual stop cock or throttle valve shall be provided, located in the inlet pipe ahead of the fuel-regulating governor. Each gas-fired miniature boiler shall be equipped with a 4-inch (102 mm) vent or flue, extended to an approved location outside of the building or connected to a chimney, in accordance with the Fuel Gas Code. Where the horizontal run of the vent is more than 10 feet (3048 mm), its size shall be increased to 6 inches (152 mm).

1025.2.10 Replacement

STATE AMENDMENT
All miniature boiler replacements shall conform to the requirements of the Mechanical Code for new installations.
Each retubed miniature boiler shall be inspected and approved by the code official before the boiler is again put in service.

1025.2.12 Used boilers

STATE AMENDMENT
Each used miniature boiler brought into the District of Columbia shall be inspected and approved by the code official before being installed. Installation shall require a permit pursuant to Section 1001.3 and Section 105 of the Building Code.
Moving a miniature boiler and reinstalling it in the same or another building shall require a boiler installation permit.
The maximum allowable working pressure for a pressure vessel shall be determined in accordance with Sections 1026.1.1 or 1026.1.2.
The maximum allowable working pressure for standard pressure vessels shall be determined in accordance with the applicable provisions of the ASME Code or the API-ASME Code under which they were constructed but shall not exceed the working pressure shown on the manufacturer’s nameplate stamping and data report.
The maximum allowable working pressure for a non-standard pressure vessel shall be determined by the calculated strength of its weakest course. The computation shall be determined by the formula that follows, based on the thickness of the plate, the tensile strength of the plate, the efficiency of the longitudinal joint, the radius of the course and the factor of safety required by the Mechanical Code.

(TS x t x E) ÷ (R x FS) = Pm

where:

Pm = Maximum allowable working pressure (psi) (kPa).
TS = Ultimate tensile strength of shell plates (psi)(kPa).
t = Lowest thickness of shell plate in weakest course (inch) (mm).
Ea = Efficiency of longitudinal joint depending upon construction.
Use values as follows:

For riveted joints = calculated riveted efficiency

For fusion welded joints:

- Single “V” weld = 50%

- Double “V” weld = 70%

- Single lap weld = 40%

-Double lap weld = 50%

- Forge weld = 80%

- Brazed steel = 80%

- Brazed copper = 90%
Ea = Efficiency for tube ligaments between openings as calculated in Section I, Part PG, paragraphs PG-52 and PG-53 of the ASME Code.
R = Inside radius of the weakest course of the shell (inch) (mm). If the thickness of the shell exceeds 10 percent of the inside radius, the outer radius shall be used.
FS = Factor of safety required by Chapter 10 of the Mechanical Code.
  1. Where there are both riveted joints and tube ligaments to consider, the lowest calculated efficiency, E, shall be used.
The maximum allowable working pressure for cylindrical vessels subjected to external or collapsing pressure shall be determined by methods in Section I, Part PG, paragraph PG- 28 of the ASME Code, except that the factor of safety used to calculate the working pressure shall be in accordance with the requirements of Section 1026.3.

1026.3 Factor of safety

STATE AMENDMENT
The maximum permissible exterior working pressure for existing pressure vessels of other than lap-seam construction shall be calculated using a factor of safety of not less than 4.5.
The maximum permissible exterior working pressure for existing pressure vessels with longitudinal lap joints shall be calculated based on the age of the vessel, using the factors of safety in Table 1026.3.1.

TABLE 1026.3.1
MINIMUM SAFETY FACTORS FOR EXISTING PRESSURE VESSELS WITH LONGITUDINAL LAP SEAMS
AGE OF THE VESSEL SAFETY FACTOR
0 to 10 years 4
10 to 20 years 4.5
20 to 25 years 5
25 to 30 years 5.5

1026.3.2 Age limit

STATE AMENDMENT
The age limit of a pressure vessel having a longitudinal lap joint and a working pressure over 50 pounds per square inch (psi) (345 kPa) shall be 30 years.

1026.4 Stress limits

STATE AMENDMENT
In checking the tensile stresses in the walls of existing vessels, the effect of static head shall be considered in order to verify that such tensile stresses do not exceed the ultimate tensile strength of the material, divided by the applicable factor of safety required by the Mechanical Code.
Where, in the opinion of the code official, as the result of conditions disclosed at the time of an inspection, it is deemed necessary to remove interior or exterior lining, covering or brick work to expose certain parts of the vessel not visible at the time of regular inspection, the code official is authorized to require the removal of such material to permit proper inspection and to ascertain hidden conditions and remaining thicknesses.

1026.6 Lap-seam cracks

STATE AMENDMENT
The shell or drum of a pressure vessel in which a lap seam crack is discovered along a longitudinal riveted joint shall be immediately discontinued from use. If the vessel is not more than 15 years of age, and when approved by the code official, the owner or user is authorized to make repairs consisting of the installation of a complete new course of the original shell thickness. Patching shall be prohibited. For the purpose of this section, a “lap-seam crack” is the typical crack frequently found in lap seams, extending parallel to the longitudinal joints and located either between or adjacent to rivet holes.

1026.7 Tensile strength

STATE AMENDMENT
When the ultimate tensile strength of steel shell plates is not known, it shall be taken as 55,000 pounds per square inch (psi) (379000 kPa) for equipment operating at temperatures not exceeding 700°F (371°C).
The resistance to crushing of mild steel shall be taken at 95,000 pounds per square inch (psi) (655000 kPa).

1026.9 Rivets

STATE AMENDMENT
In computing the ultimate strength of rivets in shear, the values of the material shear strength contained in Table 1026.9, to be applied to the cross-sectional area of the rivet shank, shall be used.

TABLE 1026.9
ULTIMATE STRENGTH OF RIVETS IN SHEAR
POUNDS PER SQUARE INCH
(psi)
Steel rivets in single shear 44,000
Steel rivets in double shear 88,000
The cross-sectional area used in the computations shall be that of the rivet shank after driving.

1026.9.2 Diameter

STATE AMENDMENT
When the diameter of the rivet holes in the longitudinal joints of a pressure vessel is not known, the diameter of the rivet after driving shall be ascertained from Table 1022.9.1 or by cutting out one rivet in the body of the joint, and the cross-sectional area of the rivet shall be calculated from the obtained diameter.

1026.10 Safety appliances

STATE AMENDMENT
Each unfired pressure vessel shall be protected by such safety and relief valves and indicating and controlling devices as will ensure its safe operation. These valves and devices shall be so constructed, located and installed that they cannot readily be rendered inoperative. The relieving capacity of safety valves shall be such as to prevent a rise in pressure in the vessel to more than 10 percent above the maximum allowable working pressure, taking into account the effect of static head. Safety valve discharges shall be carried to a safe place of disposal.
Resources