Heads up: There are no amended sections in this chapter.
The installation, storage, use, and handling of compressed gases and cryogenic fluids in portable and stationary containers, cylinders, equipment, and tanks in all occupancies shall comply with the requirements of Chapter 63; NFPA 55, Compressed Gases and Cryogenic Fluids Code, and Sections 60.1 through 60.4 of this Code.
Where the provisions of Chapter 63 or NFPA 55 conflict with the provisions of Chapter 60, the provisions of Chapter 63 and NFPA 55 shall apply.
The requirements in this chapter shall apply to users, producers, distributors, and others who are involved with the storage, use, or handling of compressed gases or cryogenic fluids. [55:1.3]
Chapter 63 shall not apply to the following:
  1. *Off-site transportation of materials covered by Chapter 63.
  2. Storage, use, and handling of radioactive gases in accordance with NFPA 801, Standard for Fire Protection for Facilities Handling Radioactive Materials.
  3. *Use and handling of medical compressed gases at health care facilities in accordance with NFPA 99, Health Care-Facilities Code.
  4. Systems consisting of cylinders of oxygen and cylinders of fuel gas used for welding and cutting in accordance with NFPA 51, Standard for the Design and Installation of Oxygen-Fuel Gas Systems for Welding, Cutting, and Allied Processes.
  5. *Flammable gases used as a vehicle fuel when stored on a vehicle.
  6. *Storage, use, and handling of liquefied and nonliquefied compressed gases in laboratory work areas in accordance with NFPA 45, Standard on Fire Protection for Laboratories Using Chemicals.
  7. Storage, use, and handling of liquefied petroleum gases in accordance with NFPA 58, Liquefied Petroleum Gas Code.
  8. Storage, use, and handling of compressed gases within closed-cycle refrigeration systems complying with the mechanical code.
  9. Liquefied natural gas (LNG) storage at utility plants under NFPA 59A, Standard for the Production, Storage, and Handling of Liquefied Natural Gas (LNG).
  10. Compressed natural gas (CNG)and liquefied natural gas (LNG), utilized as a vehicle fuel in accordance with NFPA 52, Vehicular Gaseous Fuel Systems Code.
  11. *Compressed hydrogen gas (GH2), or liquefied hydrogen gas (LH2) generated, installed, stored, piped, used, or handled in accordance with NFPA 2, Hydrogen Technologies Code, when there are no specific or applicable requirements in NFPA 55.
  12. Nonflammable mixtures of ethylene oxide with other chemicals.
  13. Ethylene oxide in chambers 10 scf (0.283 Nm3) or less in volume or for containers holding 7.05 oz (200 g) of ethylene oxide or less. [55:1.1.2]
Permits, where required, shall comply with Section 1.12.
The permit applicant shall apply for approval to close storage, use, or handling facilities at least 30 days prior to the termination of the storage, use, or handling of compressed or liquefied gases.
Such application shall include any change or alteration of the facility closure plan filed pursuant to 60.1.4.4.
This 30-day period shall be permitted to be waived by the AHJ if special circumstances require such waiver.
Permits shall not be required for routine maintenance.
For repair work performed on an emergency basis, application for permit shall be made within 2 working days of commencement of work.
See 3.3.17.
See 3.3.41.
See 3.3.160.
A container used for liquid oxygen not exceeding 0.396 gal (1.5 L) specifically designed for use as a medical device as defined by 21 USC Chapter 9, the United States Food, Drug and Cosmetic Act that is intended for portable therapeutic use and to be filled from its companion base unit which is liquid oxygen home care container.
A container used for liquid oxygen not exceeding 15.8 gal (60 L) specifically designed for use as a medical device as defined by 21 USC Chapter 9, the United States Food, Drug and Cosmetic Act that is intended to deliver gaseous oxygen for therapeutic use in a home environment.
See 3.3.190.
Hazardous materials shall be classified according to hazard categories as follows:
  1. Physical hazards, which shall include the following:
    1. Flammable gas
    2. Flammable cryogenic fluid
    3. Oxidizing gas
    4. Oxidizing cryogenic fluid
    5. Pyrophoric gas
    6. Unstable reactive (detonable) gas, Class 3 or Class 4
    7. Unstable reactive (nondetonable) gas
    8. Unstable reactive gas, Class 1 or Class 2
  2. Health hazards, which shall include the following:
    1. Corrosive gas
    2. Cryogenic fluids
    3. Highly toxic gas
    4. Toxic gas [55:5.1.1]
Although it is possible that there are other known hazards, the classification of such gases is not within the scope of Chapter 63 and they shall be handled, stored, or used as an other gas. [55:5.1.2]
Mixtures shall be classified in accordance with the hazards of the mixture as a whole. [55:5.1.3]
Classification shall be performed by an approved organization, individual, or testing laboratory. [55:5.1.4]
The toxicity of gas mixtures shall be classified in accordance with CGA P-20, Standard for the Classification of Toxic Gas Mixtures, or by testing in accordance with the requirements of 29 CFR 1910.1000, DOT 49 CFR 173, or ISO 10298, Determination of toxicity of a gas or gas mixture. [55:5.1.4.1]
For gas mixtures other than those containing ammonia and nonflammable gases, flammability of gas mixtures shall be classified in accordance with CGA P-23, Standard for Categorizing Gas Mixtures Containing Flammable and Nonflammable Components, or by physical testing in accordance with the requirements of ASTM E 681, Standard Test Method for Concentration Limits of Flammability of Chemicals (Vapors and Gases), or ISO 10156, Gases and gas mixtures — Determination of fire potential and oxidizing ability for the selection of cylinder valve outlets. [55:5.1.4.2]
Occupancies containing compressed gases and cryogenic fluids shall comply with Section 63.2 in addition to other applicable requirements of NFPA 55. [55:6.1.1.1]
The occupancy of a building or structure, or portion of a building or structure, shall be classified in accordance with the building code. [55:6.1.1.2]
Control areas shall be separated from each other by fire barriers in accordance with Table 63.2.2.1. [5000:34.2.5.1.1]

Table 63.2.2.1 Design and Number of Control Areas

Floor Level Maximum Allowable Quantity per Control Area (%)† Number of Control Areas per Floor Fire Resistance Rating for Fire Barriers‡ (hr)
Above grade
>9 5 1 2
7—9 5 2 2
4—6 12.5 2 2
3 50 2 1
2 75 3 1
1 100 4 1
Below grade
1 75 3 1
2 50 2 1
Lower than 2 NP NP N/A

NP:Not permitted.

N/A: Not applicable.

†Percentages represent the MAQ per control area shown in Table 60.4.2.1.1.3, with all of the increases permitted in the footnotes of that table.

‡Fire barriers are required to include floors and walls, as necessary, to provide a complete separation from other control areas. [400: Table 5.2.2.1]

The maximum number of control areas within a building shall be in accordance with Table 63.2.2.1. [5000:34.2.5.2]
Where only one control area is present in a building, no special construction provisions shall be required. [5000:34.2.5.1.2]
Indoor control areas with compressed gases or cryogenic fluids stored or used in quantities less than or equal to those shown in Table 63.2.3.1.1 shall be in accordance with 63.2.1, 63.2.3.1.6, 63.2.3.1.7, 63.2.7, 63.2.8, 63.2.12, 63.2.15, 63.2.16, and the applicable provisions of Chapters 1 through 5 and Chapters 7 through 15 of NFPA 55. [55:6.2.4]
Where the quantities of compressed gases or cryogenic fluids stored or used within an indoor control area exceed those shown in Table 63.2.3.1.1, the area shall meet the requirements for Protection Levels 1 through 5 in accordance with the building code, based on the requirements of 63.2.3.2. [55:6.3.1.1]

Table 63.2.3.1.1 Maximum Allowable Quantity (MAQ) of Hazardous Materials per Control Area (Quantity Thresholds for Gases Requiring Special Provisions)

Material Class Storage Use — Closed Systems Use — Open Systems
High Hazard Protection Level Solid Pounds Liquid Gallons Gasa scf (lb) Solid Pounds Liquid Gallons Gasa scf (lb) Solid Pounds Liquid Gallons
Cryogenic fluid Flammable 2 NA 45b,c NA NA 45b,c NA NA 45b,c
Oxidizing 3 NA 45d,e NA NA 45d,e NA NA 45d,e
Inert NA NA NL NA NA NL NA NA NL
Flammable, gasf Gaseous 2 NA NA 1000d,e NA NA 1000d,e NA NA
Liquefied 2 NA NA (150)d,e NA NA (150)d,c NA NA
LP 2 NA NA (300)g,h,i NA NA (300)g NA NA
Inert gas Gaseous NA NA NA NL NA NA NL NA NA
Liquefied NA NA NA NL NA NA NL NA NA
Oxidizing gas Gaseous 3 NA NA 1500d,e NA NA 1500d,e NA NA
Liquefied 3 NA NA (150)d,e NA NA (150)d,e NA NA
Pyrophoric gas Gaseous 2 NA NA 50d,j NA NA 50d,j NA NA
Liquefied 2 NA NA (4)d,j NA NA (4)d,j NA NA
Unstable (reattive) gas Gaseous
4 or 3 detonable 1 NA NA 10d,j NA NA 10d,j NA NA
3 nondetonable 2 NA NA 50d,e NA NA 50d,e NA NA
2 3 NA NA 750d,e NA NA 750d,e NA NA
1 NA NA NA NL NA NA NL NA NA
Unstable (reactive) gas Liquefied
4 or 3 detonable 1 NA NA (1)d,j NA NA (1)d,j NA NA
3 nondetonable 2 NA NA (2)d,e NA NA (2)d,e NA NA
2 3 NA NA (150)d,e NA NA (150)d,e NA NA
1 NA NA NA NL NA NA NL NA NA
Corrosive gas Gaseous 4 NA NA 810d,e NA NA 810d,e NA NA
Liquefied NA NA (150)d,e NA NA (150)d,e NA NA
Highly toxic gas Gaseous 4 NA NA 20e,k NA NA 20e,k NA NA
Liquefied NA NA (4)e,k NA NA (4)e,k NA NA
Toxic gas Gaseous 4 NA NA 810d,e NA NA 810d,e NA NA
Liquefied NA NA (150)d,e NA NA (150)d,e NA NA

NA: Not applicable within the context of NFPA 55 (refer to the applicable building or fire code for additional information on these materials).

NL: Not limited in quantity.

Notes:

(1) For use of control areas, see Section 6.2 of NFPA 55.

(2) Table values in parentheses or brackets correspond to the unit name in parentheses or brackets at the top of the column.

(3) The aggregate quantity in use and storage is not permitted to exceed the quantity listed for storage. In addition, quantities in specific occupancies are not permitted to exceed the limits in the building code.

aMeasured at NTP [70°F (20°C) and 14.7 psi (101.3 kPa)].

bNone allowed in unsprinklered buildings unless stored or used in gas rooms or in approved gas cabinets or exhausted enclosures, as specified in this code.

cWith pressure-relief devices for stationary or portable containers vented directly outdoors or to an exhaust hood.

dQuantities are permitted to be increased 100 percent where stored or used in approved cabinets, gas cabinets, exhausted enclosures, gas rooms, as appropriate for the material stored. Where Footnote e also applies, the increase for the quantities in both footnotes is permitted to be applied accumulatively.

eMaximum quantities are permitted to be increased 100 percent in buildings equipped throughout with an automatic sprinkler system in accordance with NFPA 13, Standard for the Installation of Sprinkler Systems. Where Footnote d also applies, the increase for the quantities in both footnotes is permitted to be applied accumulatively.

fFlammable gases in the fuel tanks of mobile equipment or vehicles are permitted to exceed the MAQ where the equipment is stored and operated in accordance with the applicable fire code.

gSee NFPA 58, Liquefied Petroleum Gas Code, and Chapter 69 for requirements for liquefied petroleum gas (LP-Gas). LP-Gas is not within the scope of NFPA 55 or Chapter 63.

hAdditional storage locations are required to be separated by a minimum of 300 ft (92 m).

iIn mercantile occupancies, storage of LP-Gas is limited to a maximum of 200 lb (91 kg) in nominal 1 lb (0.45 kg) LP-Gas containers.

jPermitted only in buildings equipped throughout with an automatic sprinkler system in accordance with NFPA 13.

kAllowed only where stored or used in gas rooms or in approved gas cabinets or exhausted enclosures, as specified in this code.

[55: Table 6.3.1.1]

Building-related controls in areas with compressed gases or cryogenic fluids stored or used within an indoor area in quantities greater than those shown in Table 63.2.3.1.1 shall be in accordance with the requirements of Section 63.2. [55:6.3.1.2]
The aggregate quantity in use and storage shall not exceed the quantity listed for storage. [55:6.3.1.3]
When the classification of materials in individual containers requires the area to be placed in more than one protection level, the separation of protection levels shall not be required providing the area is constructed to meet the requirements of the most restrictive protection level and that the incompatible materials are separated as required by 63.3.1.11.2. [55:6.3.1.4]
Where a compressed gas or cryogenic fluid has multiple hazards, all hazards shall be addressed and controlled in accordance with the provisions for the protection level for which the threshold quantity is exceeded. [55:6.3.1.5]
Flammable and oxidizing gases shall not be stored or used in other than industrial and storage occupancies. [55:6.3.1.6.1]
Cylinders, containers, or tanks not exceeding 250 scf (7.1 Nm3) content at normal temperature and pressure (NTP) and used for maintenance purposes, patient care, or operation of equipment shall be permitted. [55:6.3.1.6.2]
Except for containers or cylinders not exceeding 20 ft3 (0.6 m3) content at NTP stored or used within gas cabinets or exhausted enclosures of educational occupancies, toxic or highly toxic compressed gases shall not be stored or used in other than industrial and storage occupancies. [55:6.3.1.7]
The protection level required shall be based on the hazard class of the material involved as indicated in 63.2.3.2.1 through 63.2.3.2.5. [55:6.3.2]
Occupancies used for the storage or use of unstable reactive Class 4 and unstable reactive Class 3 detonable compressed gases in quantities that exceed the quantity thresholds for gases requiring special provisions shall be classified Protection Level 1. [55:6.3.2.1]
Occupancies used for the storage or use of flammable, pyrophoric, and nondetonable, unstable reactive Class 3 compressed gases or cryogenic fluids in quantities that exceed the quantity thresholds for gases requiring special provisions shall be classified as Protection Level 2. [55:6.3.2.2]
Occupancies used for the storage or use of oxidizing and unstable reactive Class 2 compressed gases or cryogenic fluids in quantities that exceed the quantity thresholds for gases requiring special provisions shall be classified as Protection Level 3. [55:6.3.2.3]
Occupancies used for the storage or use of toxic, highly toxic, and corrosive compressed gases in quantities that exceed the quantity thresholds for gases requiring special provisions shall be classified as Protection Level 4. [55:6.3.2.4]
Buildings and portions thereof used for fabrication of semiconductors or semiconductor research and development and containing quantities of hazardous materials exceeding the maximum allowable quantities of high hazard level 5 contents permitted in control areas shall be classified as Protection Level 5. [55:6.3.2.5]
Where a gas room is used to increase the threshold quantity for a gas requiring special provisions or where otherwise required by the material- or application-specific requirements of Chapters 7 through 15 of NFPA 55, the room shall meet the requirements of 63.2.4.1 through 63.2.4.5. [55:6.44]
Gas rooms shall operate at a negative pressure in relationship to the surrounding area. [55:6.4.1]
Gas rooms shall be provided with an exhaust ventilation system. [55:6.4.2]
Gas rooms shall be constructed in accordance with the building code. [55:6.4.3]
Gas rooms shall be separated from other occupancies by a minimum of 1-hour fire resistance. [55:6.4.4]
The function of compressed gas rooms shall be limited to storage and use of compressed gases and associated equipment and supplies. [55:6.4.5]
Occupancies used for the storage or use of compressed gases, including individual bulk hydrogen compressed gas systems in quantities exceeding those specified in Table 63.2.5, shall be in detached buildings constructed in accordance with the provisions of the building code. [55:6.5]

Table 63.2.5 Detached Buildings Required Where Quantity of Material Exceeds Amount Shown

Gas Hazard Class Quantity of Material
scf Nm3
Individual bulk hydrogen compressed gas systems NA 15,000 425
Unstable reactive (detonable) 4 or 3 Quantity thresholds for gases requiring special provisions*
Unstable reactive (nondetonable) 3 2,000 57
Unstable reactive (nondetonable) 2 10,000 283
Pyrophoric gas NA 2,000 57

NA: Not applicable.

*See Table 63.2.3.1.1

[55: Table 6.5]

For other than explosive materials and hazardous materials presenting a detonation hazard, a weather protection structure shall be permitted to be used for sheltering outdoor storage or use areas, without requiring such areas to be classified as indoor storage or use. [55:6.6.1]
Weather protected areas constructed in accordance with 63.2.6.4 shall be regulated as outdoor storage or use. [55:6.6.2]
Weather protected areas that are not constructed in accordance with 63.2.6.4 shall be regulated as indoor storage or use. [55:6.6.2.1]
Buildings or structures used for weather protection shall be in accordance with the following:
  1. The building or structure shall be constructed of noncombustible materials.
  2. Walls shall not obstruct more than one side of the structure.
  3. Walls shall be permitted to obstruct portions of multiple sides of the structure, provided that the obstructed area does not exceed 25 percent of the structure's perimeter area.
  4. The building or structure shall be limited to a maximum area of 1500 ft2 (140 m2), with increases in area allowed by the building code based on occupancy and type of construction.
  5. The distance from the structure constructed as weather protection to buildings, lot lines, public ways, or means of egress to a public way shall not be less than the distance required for an outside hazardous material storage or use area without weather protection based on the hazard classification of the materials contained.
  6. Reductions in separation distance shall be permitted based on the use of fire barrier walls where permitted for specific materials in accordance with the requirements of Chapters 7 through 11 of NFPA 55. [55:6.6.3]
Electrical wiring and equipment shall be in accordance with this subsection and NFPA 70. [55:6.7]
Where the following systems are required by NFPA 55 for the storage or use of compressed gases or cryogenic fluids that exceed the quantity thresholds for gases requiring special provisions, such systems shall be connected to a standby power system in accordance with NFPA 70:
  1. Mechanical ventilation
  2. Treatment systems
  3. Temperature controls
  4. Alarms
  5. Detection systems
  6. Other electrically operated systems [55:6.7.1.1]
The requirements of 63.2.7.1.1 shall not apply where emergency power is provided in accordance with 63.2.7.2 and NFPA 70. [55:6.7.1.2]
When emergency power is required, the system shall meet the requirements for a Level 2 system in accordance with NFPA 110, Standard for Emergency and Standby Power Systems. [55:6.7.2]
Where required by government regulations, an employee alarm system shall be provided to allow warning for necessary emergency action as called for in the emergency action plan required by 4.2.1.1 of NFPA 55, or for reaction time for safe egress of employees from the workplace or the immediate work area, or both. [55:6.8]
Explosion control shall be provided as required by Table 63.2.9 in accordance with NFPA 68, Standard on Explosion Protection by Deflagration Venting, or NFPA 69, Standard on Explosion Prevention Systems, where amounts of compressed gases in storage or use exceed the quantity thresholds requiring special provisions. [55:6.9]

Table 63.2.9 Explosion Control Requirements

Material Class Explosion Control Methods
Barricade Construction Explosion Venting or Prevention Systems
Flammable cryogenic fluid Not required Required
Flammable gas Nonliquefied Not required Required
Liquefied Not required Required
Pyrophoric gas Not required Required
Unstable reactive gas 4 Required Not required
3 (detonable) Required Not required
3 (nondetonable) Not required Required

[55: Table 6.9]

Except as provided in 63.2.10.1, buildings or portions thereof required to comply with Protection Levels 1 through 5 shall be protected by an approved automatic fire sprinkler system complying with Section 13.3 and NFPA 13. [55:6.10]
Rooms or areas that are of noncombustible construction with wholly noncombustible contents shall not be required to be protected by an automatic fire sprinkler system. [55:6.10.1]
When sprinkler protection is required, the area in which compressed gases or cryogenic fluids are stored or used shall be protected with a sprinkler system designed to be not less than that required by NFPA 13 for Ordinary Hazard Group 2. [55:6.10.2.1]
When sprinkler protection is required, the area in which the flammable or pyrophoric compressed gases or cryogenic fluids are stored or used shall be protected with a sprinkler system designed to be not less than that required by NFPA 13 for Extra Hazard Group 1. [55:6.10.2.2]
Approved lighting by natural or artificial means shall be provided for areas of storage or use. [55:6.11]
Hazard identification signs shall be placed at all entrances to locations where compressed gases are produced, stored, used, or handled in accordance with NFPA 704, Standard System for the Identification of the Hazards of Materials for Emergency Response. [55:6.12.1]
Ratings shall be assigned in accordance with NFPA 704. [55:6.12.1.1]
Rooms or cabinets containing compressed gases shall be conspicuously labeled as follows:

COMPRESSED GAS

The AHJ shall be permitted to waive 63.2.12.1.1 where consistent with safety. [55:6.12.1.2]
Signage shall be provided as specified in 63.2.12.2.1 and 63.2.12.2.2. [55:6.11.2]
Signs shall not be obscured or removed. [55:6.12.2.1]
Signs prohibiting smoking or open flames within 25 ft (7.6 m) of area perimeters shall be provided in areas where toxic, highly toxic, corrosive, unstable reactive, flammable, oxidizing, or pyrophoric gases are produced, stored, or used. [55:6.12.2.2]

Spill control, drainage, and secondary containment shall not be required for compressed gases. [55:6.13]

Shelves used for the storage of cylinders, containers, and tanks shall be of noncombustible construction and designed to support the weight of the materials stored. [55:6.14.1]
In seismically active areas, shelves and containers shall be secured from overturning. [55:6.14.2]
The termination point for piped vent systems serving cylinders, containers, tanks, and gas systems used for the purpose of operational or emergency venting shall be located to prevent impingement exposure on the system served and to minimize the effects of high temperature thermal radiation or the effects of contact with the gas from the escaping plume to the supply system, personnel, adjacent structures, and ignition sources. [55:6.15]
Indoor storage and use areas and storage buildings for compressed gases and cryogenic fluids shall be provided with mechanical exhaust ventilation or fixed natural ventilation, where natural ventilation is shown to be acceptable for the material as stored. [55: 6.16]
The requirements of 63.2.16 shall not apply to cylinders, containers, and tanks containing compressed air. [55:6.16.1]
In addition to the requirements of 63.2.16, ventilation systems shall be designed and installed in accordance with the requirements of the mechanical code. [55:6.16.2]
Where mechanical exhaust ventilation is provided, the system shall be operational during the time the building or space is occupied. [55:6.16.3]
When operation of ventilation systems is required, systems shall operate continuously unless an alternative design is approved by the AHJ. [55:6.16.3.1]
Mechanical exhaust or fixed natural ventilation shall be provided at a rate of not less than 1 scf/min/ft2 (0.3048 Nm3/min/m2) of floor area over the area of storage or use. [55:6.16.3.2]
Where powered ventilation is provided, a manual shutoff switch shall be provided outside the room in a position adjacent to the principal access door to the room or in an approved location. [55:6.16.3.3]
The switch shall be the break-glass or equivalent type and shall be labeled as follows:

WARNING:

VENTILATION SYSTEM EMERGENCY SHUTOFF

[55:6.16.3.3.1]

The exhaust ventilation system design shall take into account the density of the potential gases released. [55:6.16.4.1]
For gases that are heavier than air, exhaust shall be taken from a point within 12 in. (305 mm) of the floor. The use of supplemental inlets shall be allowed to be installed at points above the 12 in. (305 mm) threshold level. [55:6.16.4.2]
For gases that are lighter than air, exhaust shall be taken from a point within 12 in. (305 mm) of the ceiling. The use of supplemental inlets shall be allowed to be installed at points below the 12 in. (305 mm) threshold level. [55:6.16.4.3]
The location of both the exhaust and inlet air openings shall be designed to provide air movement across all portions of the floor or ceiling of the room to prevent the accumulation of vapors within the ventilated space. [55:6.16.4.4]
Exhaust ventilation shall not be recirculated within the room or building if the cylinders, containers, or tanks stored are capable of releasing hazardous gases. [55:6.16.5]
Ventilation discharge systems shall terminate at a point not less than 50 ft (15 m) from intakes of air-handling systems, air-conditioning equipment, and air compressors. [55:6.16.6]
Storage and use of compressed gases shall be located not less than 50 ft (15 m) from air intakes. For material-specific requirements, see 63.3.4 through 63.3.10. [55:6.16.7]
Where a gas cabinet is required, is used to provide separation of gas hazards, or is used to increase the threshold quantity for a gas requiring special provisions, the gas cabinet shall be in accordance with the requirements of 63.2.17.1 through 63.2.17.5. [55:6.17]
The gas cabinet shall be constructed of not less than 0.097 in. (2.46 mm) (12 gauge) steel. [55:6.17.1.1]
The gas cabinet shall be provided with self-closing limited access ports or noncombustible windows to give access to equipment controls. [55:6.17.1.2]
The gas cabinet shall be provided with self-closing doors. [55:6.17.1.3]
The gas cabinet shall be provided with an exhaust ventilation system designed to operate at a negative pressure relative to the surrounding area. [55:6.17.2.1]
Where toxic, highly toxic, pyrophoric, unstable reactive Class 3 or Class 4, or corrosive gases are contained, the velocity at the face of access ports or windows, with the access port or window open, shall not be less than 200 ft/min (61 m/min) average, with not less than 150 ft/min (46 m/min) at any single point. [55:6.17.2.2]
Gas cabinets used to contain toxic, highly toxic, or pyrophoric gases shall be internally sprinklered. [55:6.17.3]
Gas cabinets shall contain not more than three containers, cylinders, or tanks. [55:6.17.4]
Incompatible gases, as defined by Table 63.3.1.11.2, shall be stored or used within separate gas cabinets. [55:6.17.5]
Where an exhausted enclosure is required or used to increase the threshold quantity for a gas requiring special provisions, the exhausted enclosure shall be provided with an exhaust ventilation system designed to operate at a negative pressure in relationship to the surrounding area. [55:6.18.1]
Where toxic, highly toxic, pyrophoric, unstable reactive Class 3 or Class 4, or corrosive gases are contained, the velocity at the face openings providing access shall be not less than 200 ft/min (61 m/min) average, with not less than 150 ft/min (46 m/min) at any single point. [55:6.18.1.1]
Cylinders, containers, and tanks within enclosures shall be separated in accordance with Table 63.3.1.11.2. [55:6.18.1.2]
Exhausted enclosures shall be internally sprinklered. [55:6.18.1.3]
Incompatible gases, as defined by Table 63.3.1.11.2, shall be stored or used within separate exhausted enclosures. [55:6.18.2]
Bulk gas systems shall be provided with a source valve. [55:6.19]
The source valve shall be marked. [55:6.19.1]
The source valve shall be designated on the design drawings for the installation. [55:6.19.2]
The storage, use, and handling of compressed gases in containers, cylinders, and tanks shall be in accordance with the provisions of Chapters 1 through 7 of NFPA 55. [55:7.1]
Compressed gas systems shall be designed for the intended use and shall be designed by persons competent in such design. [55:7.1.1.1]
Installation of bulk compressed gas systems shall be supervised by personnel knowledgeable in the application of the standards for their construction and use. [55:7.1.1.2]
Insulated liquid carbon dioxide systems shall be in accordance with Chapter 13 of NFPA 55. [55:7.1.2]
Listed and approved hydrogen generating and consuming equipment shall be in accordance with the listing requirements and manufacturers' instructions. [55:7.1.4.1]
Such equipment shall not be required to meet the requirements of Chapter 7 of NFPA 55. [55:7.1.4.2]
The storage and use of metal hydride storage systems shall be in accordance with 63.3.1.5. [55:7.1.5.1.1]
Those portions of the system that are used as a means to store or supply hydrogen shall also comply with Chapter 7 and Chapter 10 of NFPA 55 as applicable. [55:7.1.5.1.2]
The hazard classification of the metal hydride storage system, as required by 63.1.4.1 and 63.1.4.3, shall be based on the hydrogen stored without regard to the metal hydride content. [55:7.1.5.1.3]
Metal hydride storage systems shall be listed or approved for the application and designed in a manner that prevents the addition or removal of the metal hydride by other than the original equipment manufacturer. [55:7.1.5.1.4]
Compressed gas cylinders, containers, and tanks used for metal hydride storage systems shall be designed and constructed in accordance with 63.3.1.6.1. [55:7.1.5.1.5]
Metal hydride storage system cylinders, containers, or tanks shall be inspected, tested, and requalified for service at not less than 5-year intervals. [55:7.1.5.1.6]
Marking and labeling of cylinders, containers, tanks, and systems shall be in accordance with 63.3.1.6 and the requirements in 63.3.1.5.1.7.1 through 63.3.1.5.1.7.4. [55:7.1.5.1.7]
Metal hydride storage systems shall be marked with the following:
  1. Manufacturer's name
  2. Service life indicating the last date the system can be used
  3. A unique code or serial number specific to the unit
  4. System name or product code that identifies the system by the type of chemistry used in the system
  5. Emergency contact name, telephone number, or other contact information
  6. Limitations on refilling of containers to include rated charging pressure and capacity [55:7.1.5.1.7.1]
Metal hydride storage system valves shall be marked with the following:
  1. Manufacturer's name
  2. Service life indicating the last date the valve can be used
  3. Metal hydride service in which the valve can be used or a product code that is traceable to this information [55:7.1.5.1.7.2]
Metal hydride storage system pressure relief devices shall be marked with the following:
  1. Manufacturer's name
  2. Metal hydride service in which the device can be used or a product code that is traceable to this information
  3. Activation parameters to include temperature, pressure, or both [55:7.1.5.1.7.3]

(A) Pressure Relief Devices Integral to Container Valves. The required markings for pressure relief devices that are integral components of valves used on cylinders, containers, and tanks shall be allowed to be placed on the valve. [55:7.1.5.1.7.3(A)]

Cylinders, containers, and tanks used in metal hydride storage systems shall be marked with the following:
  1. Manufacturer's name
  2. Design specification to which the vessel was manufactured
  3. Authorized body approving the design and initial inspection and test of the vessel
  4. Manufacturer's original test date
  5. Unique serial number for the vessel
  6. Service life identifying the last date the vessel can be used
  7. System name or product code that identifies the system by the type of chemistry used in the system [55:7.1.5.1.7.4]
Metal hydride storage systems, whether full or partially full, shall not be exposed to artificially created high temperatures exceeding 125°F (52°C) or subambient (low) temperatures unless designed for use under the exposed conditions. [55:7.1.5.1.8]
Metal hydride storage systems shall not be placed in areas where they are capable of being damaged by falling objects. [55:7.1.5.1.9]
Piping, including tubing, valves, fittings, and pressure regulators, serving metal hydride storage systems shall be maintained gastight to prevent leakage. [55:7.1.5.1.10]
Leaking systems shall be removed from service. [55:7.1.5.1.10.1]
The refilling of listed or approved metal hydride storage systems shall be in accordance with the listing requirements and manufacturers' instructions. [55:7.1.5.1.11]
The refilling of metal hydride storage systems serving powered industrial trucks shall be in accordance with NFPA 2, Hydrogen Technologies Code. [55:7.1.5.1.11.1]
The purity of hydrogen used for the purpose of refilling containers shall be in accordance with the listing and the manufacturers' instructions. [55:7.1.5.1.11.2]
Electrical components for metal hydride storage systems shall be designed, constructed, and installed in accordance with NFPA 70, National Electrical Code. [55:7.1.5.1.12]
Containers, cylinders, and tanks shall be secured in accordance with 63.3.1.9.5. [55:7.1.5.2.1]
Where a metal hydride storage system is used on mobile equipment, the equipment shall be designed to restrain containers, cylinders, or tanks from dislodgement, slipping, or rotating when the equipment is in motion. [55:7.1.5.2.1.1]
Metal hydride storage systems used on motorized equipment shall be installed in a manner that protects valves, pressure regulators, fittings, and controls against accidental impact. [55:7.1.5.2.1.2]

(A) Protection from Damage. Metal hydride storage systems, including cylinders, containers, tanks, and fittings, shall not extend beyond the platform of the mobile equipment. [55:7.1.5.2.1.2(A)]

Valves on containers, cylinders, and tanks shall remain closed except when containers are connected to closed systems and ready for use. [55:7.1.5.2.2]
Cylinders, containers, and tanks shall be designed, fabricated, tested, and marked (stamped) in accordance with regulations of DOT, Transport Canada (TC) Transportation of Dangerous Goods Regulations, or the ASME Boiler and Pressure Vessel Code,"Rules for the Construction of Unfired Pressure Vessels," Section VIII. [55:7.1.6.1]
Defective cylinders, containers, and tanks shall be returned to the supplier. [55:7.1.6.2.1]
Suppliers shall repair the cylinders, containers, and tanks, remove them from service, or dispose of them in an approved manner. [55:7.1.6.2.2]
Suppliers shall ensure that defective cylinders, containers, and tanks that have been repaired are evaluated by qualified individuals to verify that the needed repairs and any required testing has been performed and that those repaired or tested are in a serviceable condition before returning them to service. [55:7.1.6.2.3]
Stationary cylinders, containers, and tanks shall be provided with engineered supports of noncombustible material on noncombustible foundations. [55:7.1.6.3]
Compressed gas cylinders, containers, and tanks containing residual product shall be treated as full except when being examined, serviced, or refilled by a gas manufacturer, authorized cylinder requalifier, or distributor. [55:7.1.6.4]
When required by 63.3.1.6.5.2, pressure relief devices shall be provided to protect containers and systems containing compressed gases from rupture in the event of overpressure from thermal exposure. [55:7.1.6.5.1]
Pressure relief devices to protect containers shall be designed and provided in accordance with CGAS-1.1, Pressure Relief Device Standards - Part 1 - Cylinders for Compressed Gases, for cylinders; CGAS-1.2, Pressure Relief Device Standards - Part 2 - Cargo and Portable Tanks for Compressed Gases, for portable tanks; and CGAS-1.3, Pressure Relief Device Standards - Part 3 - Stationary Storage Containers for Compressed Gases, for stationary tanks or in accordance with applicable equivalent requirements in the country of use. [55:7.1.6.5.2]
Pressure relief devices shall be sized in accordance with the specifications to which the container was fabricated. [55:7.1.6.5.3]
The pressure relief device shall have the capacity to prevent the maximum design pressure of the container or system from being exceeded. [55:7.1.6.5.4]
Pressure relief devices shall be arranged to discharge unobstructed to the open air in such a manner as to prevent any impingement of escaping gas upon the container, adjacent structures, or personnel. This requirement shall not apply to DOT specification containers having an internal volume of 2.0 scf (0.057 Nm3) or less. [55:7.1.6.5.5]
Pressure relief devices or vent piping shall be designed or located so that moisture cannot collect and freeze in a manner that would interfere with operation of the device. [55:7.1.6.5.6]
Where required, cathodic protection shall be in accordance with 63.3.1.7. [55:7.1.7]
Where installed, cathodic protection systems shall be operated and maintained to continuously provide corrosion protection. [55:7.1.7.1]
Container systems equipped with cathodic protection shall be inspected for the intended operation by a cathodic protection tester. The frequency of inspection shall be determined by the designer of the cathodic protection system. [55:7.1.7.2]
The cathodic protection tester shall be certified as being qualified by the National Association of Corrosion Engineers, International (NACE). [55:7.1.7.2.1]
Systems equipped with impressed current cathodic protection systems shall be inspected in accordance with the requirements of the design and 63.3.1.5.1.12. [55:7.1.7.3]
The design limits of the cathodic protection system shall be available to the AHJ upon request. [55:7.1.7.3.1]
The system owner shall maintain the following records to demonstrate that the cathodic protection is in conformance with the requirements of the design:
  1. The results of inspections of the system
  2. The results of testing that has been completed [55:7.1.7.3.2]
Repairs, maintenance, or replacement of a cathodic protection system shall be under the supervision of a corrosion expert certified by NACE. [55:7.1.7.4]
The corrosion expert shall be certified by NACE as a senior corrosion technologist, a cathodic protection specialist, or a corrosion specialist or shall be a registered engineer with registration in a field that includes education and experience in corrosion control. [55:7.1.7.4.1]
Individual compressed gas containers, cylinders, and tanks shall be marked or labeled in accordance with DOT requirements or those of the applicable regulatory agency. [55:7.1.8.1]
The labels applied by the gas manufacturer to identify the liquefied or nonliquefied compressed gas cylinder contents shall not be altered or removed by the user. [55:7.1.8.2]
Stationary compressed gas containers, cylinders, and tanks shall be marked in accordance with NFPA 704. [55:7.1.8.3.1]
Markings shall be visible from any direction of approach. [55:7.1.8.3.2]
Except as provided in 63.3.1.8.4.2, piping systems shall be marked in accordance with ASME A13.1, Scheme for the Identification of Piping Systems, or other applicable standards as follows:
  1. Marking shall include the name of the gas and a direction-of-flow arrow.
  2. Piping that is used to convey more than one gas at various times shall be marked to provide clear identification and warning of the hazard.
  3. Markings for piping systems shall be provided at the following locations:
    1. At each critical process control valve
    2. At wall, floor, or ceiling penetrations
    3. At each change of direction
    4. At a minimum of every 20 ft (6.1 m) or fraction thereof throughout the piping run [55:7.1.8.4.1]
Piping within gas manufacturing plants, gas processing plants, refineries, and similar occupancies shall be marked in an approved manner. [55:7.1.8.4.2]
Compressed gas containers, cylinders, tanks, and systems shall be secured against accidental dislodgement and against access by unauthorized personnel. [55:7.1.9.1]
Storage, use, and handling areas shall be secured against unauthorized entry. [55:7.1.9.2]
Administrative controls shall be allowed to be used to control access to individual storage, use, and handling areas located in secure facilities not accessible by the general public. [55:7.1.9.2.1]
Compressed gas containers, cylinders, tanks, and systems that could be exposed to physical damage shall be protected. [55:7.1.9.3.1]
Guard posts or other means shall be provided to protect compressed gas cylinders, containers, tanks, and systems indoors and outdoors from vehicular damage in accordance with Section 4.11 of NFPA 55. [55:7.1.9.3.2]
Compressed gas containers, cylinders, and tanks in use or in storage shall be secured to prevent them from falling or being knocked over by corralling them and securing them to a cart, framework, or fixed object by use of a restraint, unless otherwise permitted by 63.3.1.9.5.1 and 63.3.1.9.5.2. [55:7.1.9.4]
Compressed gas containers, cylinders, and tanks in the process of examination, servicing, and refilling shall not be required to be secured. [55:7.1.9.4.1]
At cylinder-filling plants, authorized cylinder requalifier's facilities, and distributors' warehouses, the nesting of cylinders shall be permitted as a means to secure cylinders. [55:7.1.9.4.2]
Compressed gas container, cylinder, and tank valves shall be protected from physical damage by means of protective caps, collars, or similar devices. [55:7.1.10.1]
Valve protection of individual valves shall not be required to be installed on individual cylinders, containers, or tanks installed on tube trailers or similar transportable bulk gas systems equipped with manifolds that are provided with a means of physical protection that will protect the valves from physical damage when the equipment is in use. Protective systems required by DOT for over the road transport shall provide an acceptable means of protection. [55:7.1.10.1.1]
Valve protection of individual valves shall not be required on cylinders, containers, or tanks that comprise bulk or non-bulk gas systems where the containers are stationary, or portable equipped with manifolds, that are provided with physical protection in accordance with Section 4.11 of NFPA 55 and 63.3.1.9.3 or other approved means. Protective systems required by DOT for over the road transport shall provide an acceptable means of protection. [55:7.1.10.1.1.1]
Where compressed gas containers, cylinders, and tanks are designed to accept valve-protective caps, the user shall keep such caps on the compressed gas containers, cylinders, and tanks at all times, except when empty, being processed, or connected for use. [55:7.1.10.2]
Gastight valve outlet caps or plugs shall be provided and in place for all full or partially full containers, cylinders, and tanks containing toxic, highly toxic, pyrophoric, or unstable reactive Class 3 or Class 4 gases that are in storage. [55:7.1.10.3.1]
Valve outlet caps and plugs shall be designed and rated for the container service pressure. [55:7.1.10.3.2]
Compressed gas containers, cylinders, tanks, and systems in storage or use shall be separated from materials and conditions that present exposure hazards to or from each other. [55:7.1.11.1]
Gas cylinders, containers, and tanks shall be separated in accordance with Table 63.3.1.11.2. [55:7.1.11.2]

Table 63.3.1.11.2 Separation of Gas Containers, Cylinders, and Tanks by Hazard Class

Gas Category Other Gas Unstable Reactive Class 2, Class 3, or Class 4 Corrosive Oxidizing Flammable Pyrophoric Toxic or Highly Toxic
ft m ft m ft m ft m ft m ft m
Toxic or highly toxic NR 20 6.1 20 6.1 20 6.1 20 6.1 20 6.1
Pyrophoric NR 20 6.1 20 6.1 20 6.1 20 6.1 20 6.1
Flammable NR 20 6.1 20 6.1 20 6.1 20 6.1 20 6.1
Oxidizing NR 20 6.1 20 6.1 20 6.1 20 6.1 20 6.1
Corrosive NR 20 6.1 20 6.1 20 6.1 20 6.1 20 6.1
Unstable reactive Class 2, Class 3, or Class 4 NR 20 6.1 20 6.1 20 6.1 20 6.1 20 6.1
Other gas NR NR NR NR NR NR

NR: No separation required.

[55: Table 7.1.11.2]

Subparagraph 63.3.1.11.2 shall not apply to gases contained within closed piping systems. [55:7.1.11.2.1]
The distances shown in Table 63.3.1.11.2 shall be permitted to be reduced without limit where compressed gas cylinders, tanks, and containers are separated by a barrier of noncombustible construction that has a fire resistance rating of at least 0.5 hour and interrupts the line of sight between the containers. [55:7.1.11.2.2]
The 20 ft (6.1 m) distance shall be permitted to be reduced to 5 ft (1.5 m) where one of the gases is enclosed in a gas cabinet or without limit where both gases are enclosed in gas cabinets. [55:7.1.11.2.3]
Cylinders without pressure relief devices shall not be stored without separation from flammable and pyrophoric gases with pressure relief devices. [55:7.1.11.2.4]
Spatial separation shall not be required between cylinders deemed to be incompatible in gas production facilities where cylinders are connected to manifolds for the purposes of filling, analysis of compressed gases or, manufacturing procedures, assuming the prescribed controls for the manufacture of gas mixtures are in place. [55:7.1.11.2.5]
Combustible waste, vegetation, and similar materials shall be kept a minimum of 10 ft (3 m) from compressed gas containers, cylinders, tanks, and systems. [55:7.1.11.3]
A noncombustible partition without openings or penetrations and extending sides not less than 18 in. (457 mm) above and to the sides of the storage area shall be permitted in lieu of the minimum distance. [55:7.1.11.3.1]
The noncombustible partition shall be either an independent structure or the exterior wall of the building adjacent to the storage area. [55:7.1.11.3.2]
Compressed gas containers, cylinders, and tanks shall not be placed near elevators, unprotected platform ledges, or other areas where compressed gas containers, cylinders, or tanks could fall distances exceeding one-half the height of the container, cylinder, or tank. [55:7.1.11.4]
Compressed gas containers, cylinders, and tanks, whether full or partially full, shall not be exposed to temperatures exceeding 125°F (52°C) or subambient (low) temperatures unless designed for use under such exposure. [55:7.1.11.5]
Compressed gas cylinders, containers, and tanks that have not been designed for use under elevated temperature conditions shall not be exposed to direct sunlight outdoors where ambient temperatures exceed 125°F (52°C). The use of a weather protected structure or shaded environment for storage or use shall be permitted as a means to protect against direct exposure to sunlight. [55:7.1.11.5.1]
Compressed gas containers, cylinders, and tanks shall not be placed in areas where they are capable of being damaged by falling objects. [55:7.1.11.6]
Compressed gas containers, cylinders, and tanks, whether full or partially full, shall not be heated by devices that could raise the surface temperature of the container, cylinder, or tank to above 125°F (52°C). [55:7.1.11.7]
Electrical heating devices shall be in accordance with NFPA 70. [55:7.1.11.7.1]
Devices designed to maintain individual compressed gas containers, cylinders, or tanks at constant temperature shall be designed to be fail-safe. [55:7.1.11.7.2]
Open flames and high-temperature devices shall not be used in a manner that creates a hazardous condition. [55:7.1.11.8]
Compressed gas cylinders, containers, and tanks shall not be exposed to corrosive chemicals or fumes that could damage cylinders, containers, tanks, or valve-protective caps. [55:7.1.11.9]
Compressed gas containers, cylinders, and tanks shall not be placed where they could become a part of an electrical circuit. [55:7.1.11.10]
Electrical devices mounted on compressed gas piping, cylinders, containers, or tanks shall be installed, grounded, and bonded in accordance with the methods specified in NFPA 70. [55:7.1.11.10.1]
Service, repair, modification, or removal of valves, pressure relief devices, or other compressed gas container, cylinder, or tank appurtenances shall be performed by trained personnel and with the permission of the container owner. [55:7.1.12]
Compressed gas containers, cylinders, and tanks shall not be used for any purpose other than to serve as a vessel for containing the product for which it was designed. [55:7.1.13]
Compressed gas containers, cylinders, and tanks exposed to fire shall not be used or shipped while full or partially full until they are requalified in accordance with the pressure vessel code under which they were manufactured. [55:7.1.14]
Leaking, damaged, or corroded compressed gas containers, cylinders, and tanks shall be removed from service. [55:7.1.15.1]
Leaking, damaged, or corroded compressed gas systems shall be replaced or repaired. [55:7.1.15.2]
Compressed gas containers, cylinders, and tanks that have been removed from service shall be handled in an approved manner. [55:7.1.15.3]
Compressed gas systems that are determined to be leaking, damaged, or corroded shall be repaired to a serviceable condition or shall be removed from service. [55:7.1.15.4]
To prevent bottom corrosion, containers, cylinders, and tanks shall be protected from direct contact with soil or surfaces where water might accumulate. [55:7.1.16.1]
Surfaces shall be graded to prevent accumulation of water. [55:7.1.16.2]
Storage area temperatures shall not exceed 125°F (52°C). [55:7.1.17.1]
Underground piping shall be of welded construction without valves, unwelded mechanical joints, or connections installed underground. [55:7.1.18.1]
Valves or connections located in boxes or enclosures shall be permitted to be installed underground where such boxes or enclosures are accessible from above ground and where the valves or connections contained are isolated from direct contact with earth or fill. [55:7.1.18.1.1]
Valve boxes or enclosures installed in areas subject to vehicular traffic shall be constructed to resist uniformly distributed and concentrated live loads in accordance with the building code for areas designated as vehicular driveways and yards, subject to trucking. [55:7.1.18.1.1.1]
Piping installed in trench systems located below grade where the trench is open to above shall not be considered to be underground. [55:7.1.18.1.2]
Gas piping in contact with earth or other material that could corrode the piping shall be protected against corrosion in an approved manner. [55:7.1.18.2]
When cathodic protection is provided, it shall be in accordance with 63.3.1.7. [55:7.1.18.2.1]
Underground piping shall be installed on at least 6 in. (150 mm) of well-compacted bedding material. [30:27.6.5.1]
In areas subject to vehicle traffic, the pipe trench shall be deep enough to permit a cover of at least 18 in. (450 mm) of well-compacted backfill material and pavement. [30:27.6.5.2]
In paved areas where a minimum 2 in. (50 mm) of asphalt is used, backfill between the pipe and the asphalt shall be permitted to be reduced to 8 in. (200 mm) minimum. [30:27.6.5.3]
In paved areas where a minimum 4 in. (100 mm) of reinforced concrete is used, backfill between the pipe and the concrete shall be permitted to be reduced to 4 in. (100 mm) minimum. [30:27.6.5.4]
In areas not subject to vehicle traffic, the pipe trench shall be deep enough to permit a cover of at least 6 in. (150 mm) of well-compacted backfill material. [30:27.6.5.5]
A greater burial depth shall be provided when required by the manufacturer's instructions or where frost conditions are present. [30:27.6.5.6]
Piping within the same trench shall be separated horizontally by at least two pipe diameters. Separation shall not need to exceed 9 in. (230 mm). [30:27.6.5.7]
Two or more levels of pipes within the same trench shall be separated vertically by a minimum 6 in. (150 mm) of well-compacted bedding material. [30:27.6.5.8]
Piping systems shall be cleaned and purged in accordance with the requirements of 63.3.1.19 when one or more of the following conditions exist:
  1. When the system is installed and prior to being placed into service
  2. When there is a change in service
  3. *When there are alterations or repair of the system involving the replacement of parts or addition to the piping system and prior to returning the system to service
  4. *Where specified by the design standards or written procedures [55:7.1.19.1.1]
Cleaning and purging of the internal surfaces of piping systems shall be conducted by qualified individuals trained in cleaning and purging operations and procedures, including the recognition of potential hazards associated with cleaning and purging. [55:7.1.19.1.2]
A written cleaning or purging procedure shall be provided to establish the requirements for the cleaning and purging operations to be conducted. [55:7.1.19.1.3]
An independent or third-party review of the written procedure shall be conducted after the procedure has been written and shall:
  1. Evaluate hazards, errors, and malfunctions related to each step in the procedure
  2. Review the measures prescribed in the procedure for applicability
  3. Make recommendations for additional hazard mitigation measures if deemed to be necessary [55:7.1.19.1.3.1]
The completed written procedure shall be:
  1. Maintained on site by the facility owner/operator
  2. Provided to operating personnel engaged in cleaning or purging operations
  3. Made available to the AHJ upon request [55:7.1.19.1.3.2]
Where generic cleaning or purging procedures have been established, a job-specific operating procedure shall not be required. [55:7.1.19.1.3.3]
Generic procedures shall be reviewed when originally published or when the procedure or operation is changed. [55:7.1.19.1.3.4]
Written procedures to manage a change in process materials, technology, equipment, procedures, and facilities shall be established by the facility owner/operator. [55:7.1.19.1.4]
The management-of-change procedures shall ensure that the following topics are addressed prior to any change in the configuration or design of the piping system:
  1. The technical basis for the proposed change
  2. The safety and health implications
  3. Whether the change is permanent or temporary
  4. Whether modifications to the cleaning and purging procedures are required as a result of the changes identified [55:7.1.19.1.4.1]
When modifications to the cleaning and purging procedures are required, the written procedure shall be updated to incorporate any elements identified by the management-of-change procedures. [55:7.1.19.1.4.2]
Prior to cleaning or purging, piping systems shall be inspected and tested to determine that the installation, including the materials of construction, and method of fabrication, comply with the requirements of the design standard used and the intended application for which the system was designed. [55:7.1.19.1.5]
Inspection and testing of piping systems shall not be required to remove a system from service. [55:7.1.19.1.5.1]
Purging of piping systems shall not be required for systems that are utilized for operations designated by written operating procedures when systems are utilized in accordance with the requirements of the cleaning or purging procedure specified in 63.3.1.19.1.1. [55:7.1.19.1.5.2]
Personnel in the affected area(s), as determined by the cleaning or purging procedure, shall be informed of the hazards associated with the operational activity and notified prior to the initiation of any such activity. [55:7.1.19.1.5.3]
Piping system designs shall be documented to specify the requirements for the internal cleaning of the piping system prior to installation and initial use. [55:7.1.19.2]
The internal surfaces of gas piping systems shall be cleaned to ensure that the required standard of cleanliness specified by the design is met prior to placing the gas piping system into service. [55:7.1.19.2.1]
When piping systems are cleaned in stages during installation or assembly, the interior of the cleaned piping shall be protected against the infiltration of unwanted contaminants. [55:7.1.19.2.2]
Piping systems used to contain gases with a physical or health hazard in any of the categories specified by 63.1.4 shall be purged prior to being placed into service for initial use. [55:7.1.19.3]
Piping systems shall be purged to remove the internal contents preceding the following activities or operations to:
  1. activate or place a piping system into service
  2. deactivate or remove a piping system from service
  3. change the service of a piping system from one gas to another, except when such gas is supplied to a manifold or piping system designed for the purpose of filling or otherwise processing cylinders, containers, or tanks in a process with established procedures
  4. perform service, maintenance or modifications on a system where personnel or designated areas will potentially be exposed to the internal contents of the piping system
  5. perform hot work including but not limited to welding, cutting or brazing on the piping system. [55:7.1.19.3.1]
The termination point for the release of purged gases shall be in accordance with 63.2.15. [55:7.1.19.3.2]
The release of purged gases or mixtures containing any quantity of corrosive, toxic, or highly toxic gases shall be through a treatment system in accordance with the applicable requirements of 63.3.5.3.4 or 63.3.9.3. [55:7.1.19.3.2.1]
The termination point for the release of purged gases resultant from the purging of piping systems out of service, other than those in accordance with 63.3.1.19.3.2.1, shall not be required to be in accordance with 63.2.15 where the contained volume of the piping system when released to indoor areas does not result in a concentration in the room or area that exceeds any of the following limits or that will reduce the oxygen concentration in the room or area below a level of 19.5%:
  1. Ceiling limit
  2. Permissible exposure limit
  3. Short term exposure limit
  4. 25% of the lower flammable limit [55:7.1.19.3.2.2]
The storage of compressed gas containers, cylinders, and tanks shall be in accordance with 63.3.2. [55:7.2.1.1]
Cylinders, containers, and tanks containing liquefied flammable gases and flammable gases in solution shall be positioned in the upright position. [55:7.2.1.2]
Containers with a capacity of 1.3 gal (5 L) or less shall be permitted to be stored in a horizontal position. [55:7.2.1.2.1]
Containers, cylinders, and tanks designed for use in a horizontal position shall be permitted to be stored in a horizontal position. [55:7.2.1.2.2]
Containers, cylinders, and tanks, with the exception of those containing flammable liquefied compressed gases, that are palletized for transportation purposes shall be permitted to be stored in a horizontal position. [55:7.2.1.2.3]
For other than explosive materials and hazardous materials presenting a detonation hazard, a weather protection structure shall be permitted to be used for sheltering outdoor storage or use areas without requiring such areas to be classified as indoor storage. [55:7.2.1.3]
Indoor storage of compressed gases shall be in accordance with the material-specific provisions of 63.3.4 through 63.3.10. [55:7.2.2.1]
Exterior storage of compressed gases shall be in accordance with the material-specific provisions of 63.3.4 through 63.3.10. [55:7.2.2.2.1]
Distances from property lines, buildings, and exposures shall be in accordance with the material-specific provisions of 63.3.4 through 63.3.10. [55:7.2.2.2.2]
The use and handling of compressed gas cylinders, containers, tanks, and systems shall be in accordance with 63.3.3.1. [55:7.3.1.1]
Compressed gas system controls shall be designed to prevent materials from entering or leaving the process at an unintended time, rate, or path. [55:7.3.1.2.1]
Automatic controls shall be designed to be fail-safe. [55:7.3.1.2.2]
Piping, tubing, fittings, and related components shall be designed, fabricated, and tested in accordance with the requirements of ANSI/ASME B31.3, Process Piping, or other approved standards. [55:7.3.1.3]
Piping, tubing, pressure regulators, valves, and other apparatus shall be kept gastight to prevent leakage. [55:7.3.1.3.1]
Backflow prevention or check valves shall be provided when the backflow of hazardous materials could create a hazardous condition or cause the unauthorized discharge of hazardous materials. [55:7.3.1.3.2]
Valves utilized on compressed gas systems shall be designed for the gas or gases and pressure intended and shall be accessible. [55:7.3.1.4.1]
Valve handles or operators for required shutoff valves shall not be removed or otherwise altered to prevent access. [55:7.3.1.4.2]
Venting of gases shall be directed to an approved location. [55:7.3.1.5.1]
The termination point for piped vent systems serving cylinders, containers, tanks, and gas systems used for the purpose of operational or emergency venting shall be in accordance with 63.2.15. [55:7.3.1.5.2]
Compressed gas cylinders, containers, and tanks containing flammable liquefied gas, except those designed for use in a horizontal position and those compressed gas cylinders, containers, and tanks containing nonliquefied gases, shall be used in a "valve end up" upright position. [55:7.3.1.6.1]
An upright position shall include a position in which the container, cylinder, or tank axis is inclined as much as 45 degrees from the vertical and in which the relief device is always in direct communication with the gas phase. [55:7.3.1.6.2]
Cylinders, containers, and tanks containing nonflammable liquefied gases shall be permitted to be used in the inverted position when the liquid phase is used. [55:7.3.1.7]
Flammable liquefied gases at processing plants shall be permitted to use this inverted position method while transfilling. [55:7.3.1.7.1]
The container, cylinder, or tank shall be secured, and the dispensing apparatus shall be designed for use with liquefied gas. [55:7.3.1.7.2]
Containers or cylinders with a water volume of 1.3 gal (5 L) or less shall be permitted to be used in a horizontal position. [55:7.3.1.8]
Transfer of gases between containers, cylinders, and tanks shall be performed by qualified personnel using equipment and operating procedures in accordance with CGA P-1, Safe Handling of Compressed Gases in Containers. [55:7.3.1.9]
Inflatable equipment, devices, or balloons shall only be pressurized or filled with compressed air or inert gases. [55:7.3.1.10]
Accessible manual valves or automatic emergency shutoff valves shall be provided to shut off the flow of gas in case of emergency. [55:7.3.1.11.1]
Manual emergency shutoff valves or the device that activates an automatic emergency shutoff valve on a bulk source or piping system serving the bulk supply shall be identified by means of a sign. [55:7.3.1.11.1.1]
Emergency shutoffs shall be located at the point of use and at the tank, cylinder, or bulk source, and at the point where the system piping enters the building. [55:7.3.1.11.2]
Where compressed gases having a hazard ranking in one or more of the following hazard classes in accordance with NFPA 704 are carried in pressurized piping above a gauge pressure of 15 psi (103 kPa), an approved means of either leak detection with emergency shutoff or excess flow control shall be provided:
  1. Health hazard Class 3 or Class 4
  2. Flammability Class 4
  3. Instability Class 3 or Class 4 [55:7.3.1.12.1]
Where the piping originates from within a hazardous material storage room or area, the excess flow control shall be located within the storage room or area. [55:7.3.1.12.1.1]
Where the piping originates from a bulk source, the excess flow control shall be located at the bulk source at a point immediately downstream of the source valve. [55:7.3.1.12.1.2]
The controls required by 63.3.3.1.12 shall not be required for the following:
  1. Piping for inlet connections designed to prevent backflow at the source
  2. Piping for pressure relief devices
  3. Where the source of the gas is not in excess of the quantity threshold indicated in Table 63.2.3.1.1 [55:7.3.1.12.2]
The location of excess flow control shall be as specified in 63.3.3.1.12.1.1 and 63.3.3.1.12.1.2. [55:7.3.1.12.3]
Where piping originates from a source located in a room or area, the excess flow control shall be located within the room or area. [55:7.3.1.12.3.1]
Where piping originates from a bulk source, the excess flow control shall be as close to the bulk source as possible. [55:7.3.1.12.3.2]
The requirements of 63.3.3.1.12 shall not apply to the following:
  1. Piping for inlet connections designed to prevent backflow
  2. Piping for pressure relief devices
  3. Systems containing 430 scf (12.7 m3) or less of flammable gas [55:7.3.1.12.4]
Indoor use of compressed gases shall be in accordance with the requirements of 63.3.4 through 63.3.10. [55:7.3.2.1]
Exterior use of compressed gases shall be in accordance with the requirements of 63.3.4 through 63.3.10. [55:7.3.2.2.1]
Distances from property lines, buildings, and exposure hazards shall be in accordance with the material-specific provisions of 63.3.4 through 63.3.10. [55:7.3.2.2.2]
The handling of compressed gas containers, cylinders, and tanks shall be in accordance with 63.3.3.3. [55:7.3.3.1]
Containers, cylinders, and tanks shall be moved using an approved method. [55:7.3.3.2.1]
Where containers, cylinders, or tanks are moved by hand cart, hand truck, or other mobile device, such carts, trucks, or devices shall be designed for the secure movement of containers, cylinders, or tanks. [55:7.3.3.2.2]
Ropes, chains, or slings shall not be used to suspend compressed gas containers, cylinders, and tanks unless provisions at time of manufacture have been made on the container, cylinder, or tank for appropriate lifting attachments, such as lugs. [55:7.3.3.3]
Medical gas systems for health care shall be in accordance with NFPA 99, Health Care Facilities Code. [55:7.4]
The storage or use of corrosive compressed gases exceeding the quantity thresholds for gases requiring special provisions as specified in Table 63.2.3.1.1 shall be in accordance with Chapters 1 through 6 of NFPA 55 and 63.3.1 through 63.3.3 and 63.3.5. [55:7.5.1]
The outdoor storage or use of corrosive compressed gas shall not be within 20 ft (6.1 m) of buildings not associated with the manufacture or distribution of corrosive gases, lot lines, streets, alleys, public ways, or means of egress. [55:7.5.2]
A 2-hour fire barrier wall without openings or penetrations and that extends not less than 30 in. (762 mm) above and to the sides of the storage or use area shall be permitted in lieu of the 20 ft (6.1 m) distance. [55:7.5.2.1]
Where a fire barrier is used to protect compressed gas systems, the system shall terminate downstream of the source valve. [55:7.5.2.1.1]
The fire barrier wall shall be either an independent structure or the exterior wall of the building adjacent to the storage or use area. [55:7.5.2.1.2]
The 2-hour fire barrier shall be located at least 5 ft (1.5 m) from any exposure. [55:7.5.2.1.3]
The 2-hour fire barrier wall shall not have more than two sides at approximately 90 degree (1.57 rad) directions or not more than three sides with connecting angles of approximately 135 degrees (2.36 rad). [55:7.5.2.1.4]
The indoor use of corrosive gases shall be provided with a gas cabinet, exhausted enclosure, or gas room. [55:7.5.3]
Gas cabinets shall be in accordance with 63.2.17. [55:7.5.3.1]
Exhausted enclosures shall be in accordance with 63.2.18. [55:7.5.3.2]
Gas rooms shall be in accordance with 63.2.4. [55:7.5.3.3]
Treatment systems, except as provided for in 63.3.5.3.4.1, gas cabinets, exhausted enclosures, and gas rooms containing corrosive gases in use shall be provided with exhaust ventilation, with all exhaust directed to a treatment system designed to process the accidental release of gas. [55:7.5.3.4]
Treatment systems shall not be required for corrosive gases in use where provided with the following:
  1. Gas detection in accordance with 63.3.9.3.2.1.1
  2. Fail-safe automatic closing valves in accordance with 63.3.9.3.2.2 [55:7.5.3.4.1]
Treatment systems shall be capable of diluting, adsorbing, absorbing, containing, neutralizing, burning, or otherwise processing the release of corrosive gas in accordance with 63.3.9.3.4.1. [55:7.5.3.4.2]
Treatment system sizing shall be in accordance with 63.3.9.3.4. [55:7.5.3.4.3]
The storage or use of flammable gases exceeding the quantity thresholds for gases requiring special provisions as specified in Table 63.2.3.1.1 shall be in accordance with Chapters 1 through 6 of NFPA 55 and 63.3.1 through 63.3.3 and 63.3.6. [55:7.6.1.1]
Storage, use, and handling of gaseous hydrogen shall be in accordance with 63.3.6.1 and Chapter 10 of NFPA 55. [55:7.6.1.2]
The outdoor storage or use of non-bulk flammable compressed gas shall be located from lot lines, public streets, public alleys, public ways, or buildings not associated with the manufacture or distribution of such gases in accordance with Table 63.3.6.2. [55:7.6.2]

Table 63.3.6.2 Distance to Exposures for Nonbulk Flammable Gases

Maximum Amount per Storage Area (ft3) Minimum Distance Between Storage Areas (ft) Minimum Distance to Lot Lines of Property That Can Be Built Upon (ft) Minimum Distance to Public Streets, Public Alleys or Public Ways (ft) Minimum Distance to Buildings on the Same Property
Less Than 2-Hour Construction 2-Hour Construction 4-Hour Construction
0—4225 5 5 5 5 0 0
4226—21,125 10 10 10 10 5 0
21,126-50,700 10 15 15 20 5 0
50,701-84,500 10 20 20 20 5 0
84,501-200,000 20 25 25 20 5 0

For SI units, 1 ft = 304.8 mm; 1 ft3 = 0.02832 m3.

Note: The minimum required distances shall not apply when fire barriers without openings or penetrations having a minimum fire resistive rating of 2 hours interrupt the line of sight between the storage and the exposure. The configuration of the fire barriers shall be designed to allow natural ventilation to prevent the accumulation of hazardous gas concentrations. [55: Table 7.6.2]

Bulk hydrogen gas installations shall be in accordance with Chapter 10 of NFPA 55. [55:7.6.2.1]
Where a protective structure is used to protect compressed gas systems, the system shall terminate downstream of the source valve. [55:7.6.2.1.1]
The fire barrier wall shall be either an independent structure or the exterior wall of the building adjacent to the storage or use area. [55:7.6.2.1.2]
Bulk gas systems for flammable gases other than hydrogen shall be in accordance with Table 10.3.2.1(a), Table 10.3.2.1(b), or Table 10.3.2.1(c) of NFPA 55 where the quantity of flammable compressed gas exceeds 5000 scf (141.6 Nm3). [55:7.6.2.2]
Where fire barriers are used as a means of distance reduction, fire barriers shall be in accordance with 10.3.2.4 of NFPA 55. [55:7.6.2.2.1]
Mobile acetylene trailer systems (MATS) shall be located in accordance with 15.2.2 of NFPA 55. [55:7.6.2.2.2]
The configuration of the protective structure shall be designed to allow natural ventilation to prevent the accumulation of hazardous gas concentrations. [55:7.6.2.3]
Storage and use of flammable compressed gases shall not be located within 50 ft (15.2 m) of air intakes. [55:7.6.2.4]
Storage and use of flammable gases outside of buildings shall also be separated from building openings by 25 ft (7.6 m). Fire barriers shall be permitted to be used as a means to separate storage areas from openings or a means of egress used to access the public way. [55:7.6.2.5]
Hydrogen systems of less than 3500 scf (99 Nm3) and greater than the MAQ, where located inside buildings, shall be in accordance with the following:
  1. In a ventilated area in accordance with the provisions of 63.2.16
  2. Separated from incompatible materials in accordance with the provisions of 7.1.11.2 of NFPA 55
  3. A distance of 25 ft (7.6 m) from open flames and other sources of ignition
  4. A distance of 50 ft (15 m) from intakes of ventilation, air-conditioning equipment, and air compressors located in the same room or area as the hydrogen system
    1. The distance shall be permitted to be reduced to 10 ft (3.1 m) where the room or area in which the hydrogen system is installed is protected by a listed detection system per Article 500.7(K) of NFPA 70, National Electrical Code, and the detection system shuts down the fuel supply in the event of a leak that results in a concentration that exceeds 25 percent of the LFL.
    2. Emergency shutoff valves shall be provided in accordance with 63.3.3.1.11.
  5. A distance of 50 ft (15 m) from other flammable gas storage
  6. Protected against damage in accordance with the provisions of 63.3.1.9.3. [55:7.6.3.1]
More than one system of 3500 scf (99 Nm3) or less shall be permitted to be installed in the same room or area, provided the systems are separated by at least 50 ft (15 m) or a full-height fire-resistive partition having a minimum fire resistance rating of 2 hours is located between the systems. [55:7.6.3.2.1]
The separation distance between multiple systems of 3500 scf (99 Nm3) or less shall be permitted to be reduced to 25 ft (7.6 m) in buildings where the space between storage areas is free of combustible materials and protected with a sprinkler system designed for Extra Hazard, Group 1 in accordance with the requirements of Section 6.10 of NFPA 55. [55:7.6.3.2.2]
The required separation distance between individual portable systems in the process of being filled or serviced in facilities associated with the manufacture or distribution of hydrogen and its mixtures shall not be limited by 63.3.6.3.2.1 or 63.3.6.3.2.2 when such facilities are provided with Protection Level 2 controls and the applicable requirements of Chapters 1 through 7 of NFPA 55. [55:7.6.3.2.3]
Ignition sources in areas containing flammable gases shall be in accordance with 63.3.6.4. [55:7.6.4]
Static producing equipment located in flammable gas areas shall be grounded. [55:7.6.4.1]