About this chapter: Chapter 7 is specific to hydrogen used as a fuel or feedstock for appliances, processes and fuel cells. Requirements address hydrogen generation, storage, dispensing, piping, location, operation and maintenance of hydrogen generation, storage and distribution systems.
The installation of gaseous hydrogen systems shall comply with this chapter and Chapters 53 and 58 of the International Fire Code. Compressed gases shall also comply with Chapter 50 of the International Fire Code for general requirements.
Permits shall be required as set forth in Section 106 and as required by the International Fire Code.
The following words and terms shall, for the purposes of this chapter and as used elsewhere in this code, have the meanings shown herein.
[F] GASEOUS HYDROGEN SYSTEM. An assembly of piping, devices and apparatus designed to generate, store, contain, distribute or transport a nontoxic, gaseous hydrogen containing mixture having at least 95-percent hydrogen gas by volume and not more than 1-percent oxygen by volume. Gaseous hydrogen systems consist of items such as compressed gas containers, reactors and appurtenances, including pressure regulators, pressure relief devices, manifolds, pumps, compressors and interconnecting piping and tubing and controls.
[F] HYDROGEN FUEL-GAS ROOM. A room or space that is intended exclusively to house a gaseous hydrogen system.
HYDROGEN-GENERATING APPLIANCE. A self-contained package or factory-matched packages of integrated systems for generating gaseous hydrogen. Hydrogen-generating appliances utilize electrolysis, reformation, chemical or other processes to generate hydrogen.
Hydrogen-generating and refueling appliances shall be installed and located in accordance with their listing and the manufacturer's instructions. Exhaust ventilation shall be required in public garages, private garages, repair garages, automotive motor fuel-dispensing facilities and parking garages that contain hydrogen-generating appliances or refueling systems in accordance with NFPA 2. For the purpose of this section, rooms or spaces that are not part of the living space of a dwelling unit and that communicate directly with a private garage through openings shall be considered to be part of the private garage.
Compressed gas containers, cylinders and tanks shall comply with Chapters 53 and 58 of the International Fire Code.
Flammable gas cylinders in occupancies regulated by the International Residential Code shall not exceed 250 cubic feet (7.1 m3) at normal temperature and pressure (NTP).
Compressed gas containers, cylinders and tanks shall be designed, constructed and tested in accordance with Chapter 50 of the International Fire Code, ASME Boiler and Pressure Vessel Code (Section VIII) or DOTn 49 CFR, Parts 100-180.
Valves including shutoffs, check valves and other mechanical restrictions shall not be installed between the pressure relief device and container being protected by the relief device.
Containers shall be provided with pressure relief devices in accordance with the ASME Boiler and Pressure Vessel Code (Section VIII), DOTn 49 CFR, Parts 100-180 and Section 703.3.7.
Vessels other than containers shall be protected with pressure relief devices in accordance with the ASME Boiler and Pressure Vessel Code (Section VIII), or DOTn 49 CFR, Parts 100-180.
Pressure relief devices and any associated vent piping shall be designed, installed and located so that their operation will not be affected by water or other debris accumulating inside the vent or obstructing the vent.
Pressure relief devices shall be located such that they are provided with ready access for inspection and repair.
Pressure relief devices shall be arranged to discharge unobstructed in accordance with Section 2309 of the International Fire Code. Discharge shall be directed to the outdoors in such a manner as to prevent impingement of escaping gas on personnel, containers, equipment and adjacent structures and to prevent introduction of escaping gas into enclosed spaces. The discharge shall not terminate under eaves or canopies.
Exception: This section shall not apply to DOTn-specified containers with an internal volume of 2 cubic feet (0.057 m3) or less.
Relief device vents shall be terminated in an approved location in accordance with Section 2309 of the International Fire Code.
Compressed gas containers, cylinders, tanks and systems shall be secured against accidental dislodgement in accordance with Chapter 53 of the International Fire Code.
Electrical wiring and equipment shall comply with NFPA 70.
Piping, tubing, valves and fittings conveying gaseous hydrogen shall be designed and installed in accordance with Sections 704.1.2.1 through 704.1.2.5.1, Chapter 50 of the International Fire Code, and ASME B31.12. Cast-iron pipe, valves and fittings shall not be used.
Hydrogen piping systems shall be marked in accordance with ANSI A13.1. Markings used for piping systems shall consist of the name of the contents and shall include a direction-of-flow arrow. Markings shall be provided at all of the following locations:
- At each valve.
- At wall, floor and ceiling penetrations.
- At each change of direction.
- At intervals not exceeding 20 feet (6096 mm).
Piping and tubing materials shall be 300 series stainless steel or materials listed or approved for hydrogen service and the use intended through the full range of operating conditions to which they will be subjected. Piping systems shall be designed and constructed to provide allowance for expansion, contraction, vibration, settlement and fire exposure.
Except for through penetrations, piping located inside of buildings shall be installed in exposed locations and provided with ready access for visual inspection.
Underground piping shall not penetrate the outer foundation or basement wall of a building.
Where piping other than stainless steel piping, stainless steel tubing or black steel is installed through holes or notches in wood studs, joists, rafters or similar members less than 11/2 inches (38 mm) from the nearest edge of the member, the pipe shall be protected by shield plates. Shield plates shall be a minimum of 1/16-inch-thick (1.6 mm) steel, shall cover the area of the pipe where the member is notched or bored and shall extend a minimum of 4 inches (102 mm) above sole plates, below top plates and to each side of a stud, joist or rafter.
Piping installed above ground, outdoors, shall be securely supported and located where it will be protected from physical damage. Piping passing through an exterior wall of a building shall be encased in a protective pipe sleeve. The annular space between the piping and the sleeve shall be sealed from the inside such that the sleeve is ventilated to the outdoors. Where passing through an exterior wall of a building, the piping shall be protected against corrosion by coating or wrapping with an inert material. Below-ground piping shall be protected against corrosion.
Piping passing through concrete or masonry walls shall be protected against differential settlement.
Joints in piping and tubing in hydrogen service shall be listed as complying with ASME B31.3 to include the use of welded, brazed, flared, socket, slip and compression fittings. Gaskets and seal-ants used in hydrogen service shall be listed as complying with ASME B31.12. Threaded and flanged connections shall not be used in areas other than hydrogen cutoff rooms and outdoors.
Brazing alloys shall have a melting point greater than 1,000°F (538°C).
Mechanical joints shall maintain electrical continuity through the joint or a bonding jumper shall be installed around the joint.
Valves, regulators and piping components shall be listed or approved for hydrogen service, shall be provided with access and shall be designed and constructed to with-stand the maximum pressure to which such components will be subjected.
Shutoff valves shall be provided on all storage container and tank connections except for pressure relief devices. Shutoff valves shall be provided with ready access.
Compressed gas containers, cylinders and tanks, except those with a water volume less than 1.3 gallons (5 L) and those designed for use in a horizontal position, shall be used in an upright position with the valve end up. An upright position shall include conditions where the container, cylinder or tank axis is inclined as much as 45 degrees (0.79 rad) from the vertical.
In addition to the requirements of this section, indoor and outdoor use of hydrogen compressed gas shall comply with the material-specific provisions of Chapters 53 and 58 of the International Fire Code.
The handling of compressed gas containers, cylinders and tanks shall comply with Chapter 50 of the International Fire Code.
Prior to acceptance and initial operation, all piping installations shall be inspected and pressure tested to determine that the materials, design fabrication and installation practices comply with the requirements of this code.
Inspections shall consist of a visual examination of the entire piping system installation and a pressure test. Hydrogen piping systems shall be inspected in accordance with this code. Inspection methods such as outlined in ASME B31.12 shall be permitted where specified by the design engineer and approved by the code official. Inspections shall be conducted or verified by the code official prior to system operation.
A hydrostatic or pneumatic leak test shall be performed. Testing of hydrogen piping systems shall utilize testing procedures identified in ASME B31.12 or other approved methods, provided that the testing is performed in accordance with the minimum provisions specified in Sections 705.3.1 through 705.4.1.
The hydrostatic test pressure shall be not less than one-and-one-half times the maximum working pressure, and not less than 100 psig (689.5 kPa gauge).
The pneumatic test pressure shall be not less than one-and-one-half times the maximum working pressure for systems less than 125 psig (862 kPa gauge) and not less than 5 psig (34.5 kPa gauge), whichever is greater. For working pressures at or above 125 psig (862 kPa gauge), the pneumatic test pressure shall be not less than 110 percent of the maximum working pressure.
Deionized water shall be utilized to perform hydrostatic pressure testing and shall be obtained from a potable source. The medium utilized to perform pneumatic pressure testing shall be air, nitrogen, carbon dioxide or an inert gas; oxygen shall not be used.
The minimum test duration shall be 1/2 hour. The test duration shall be not less than 1/2 hour for each 500 cubic feet (14.2 m3) of pipe volume or fraction thereof. For piping systems having a volume of more than 24,000 cubic feet (680 m3), the duration of the test shall not be required to exceed 24 hours. The test pressure required in Sections 705.3.1 and 705.3.2 shall be maintained for the entire duration of the test.
Gauges used for testing shall be as follows:
- Tests requiring a pressure of 10 psig (68.95 kPa gauge) or less shall utilize a testing gauge having increments of 0.10 psi (0.6895 kPa) or less.
- Tests requiring a pressure greater than 10 psig (68.98 kPa gauge) but less than or equal to 100 psig (689.5 kPa gauge) shall utilize a testing gauge having increments of 1 psi (6.895 kPa) or less.
- Tests requiring a pressure greater than 100 psig (689.5 kPa gauge) shall utilize a testing gauge having increments of 2 psi (13.79 kPa) or less.Exception: Measuring devices having an equivalent level of accuracy and resolution shall be permitted where specified by the design engineer and approved by the code official.
Pipe joints, including welds, shall be left exposed for examination during the test.
Expansion joints shall be provided with temporary restraints, if required, for the additional thrust load under test.
Where the piping system is connected to appliances, equipment or components designed for operating pressures of less than the test pressure, such appliances, equipment and components shall be isolated from the piping system by disconnecting them and capping the outlet(s).
Where the piping system is connected to appliances, equipment or components designed for operating pressures equal to or greater than the test pressure, such appliances, equipment and components shall be isolated from the piping system by closing the individual appliance, equipment or component shutoff valve(s).
The piping system shall withstand the test pressure specified for the test duration specified without showing any evidence of leakage or other defects. Any reduction of test pressures as indicated by pressure gauges shall indicate a leak within the system. Piping systems shall not be approved except where this reduction in pressure is attributed to some other cause.
Where leakage or other defects are identified, the affected portions of the piping system shall be repaired and retested.
Prior to placing the system into operation, the air in the piping system shall be displaced with inert gas. The inert gas flow shall be continued without interruption until the vented gas is free of air. The inert gas shall then be displaced with hydrogen until the vented gas is free of inert gas. The point of discharge shall not be left unattended during purging. After purging, the vent opening shall be closed.
The open end of piping systems being purged shall not discharge into confined spaces or areas where there are sources of ignition except where precautions are taken to perform this operation in a safe manner by ventilation of the space, control of purging rate and elimination of all hazardous conditions.
Vent pipe outlets for purging shall be located such that the inert gas and fuel gas is released outdoors and not less than 8 feet (2438 mm) above the adjacent ground level. Gases shall be discharged upward or horizontally away from adjacent walls to assist in dispersion. Vent outlets shall be located such that the gas will not be trapped by eaves or other obstructions and shall be at least 5 feet (1524 mm) from building openings and lot lines of properties that can be built on.
After the piping has been placed in operation, all equipment shall be purged in accordance with Section 707.2 and then placed in operation, as necessary.
The location and installation of gaseous hydrogen systems shall be in accordance with Sections 706.2 and 706.3.
Exception: Stationary fuel-cell power plants in accordance with Section 633.
Gaseous hydrogen systems shall be located in indoor rooms or areas constructed in accordance with this code, the International Building Code, the International Mechanical Code or NFPA 2.
Gaseous hydrogen systems shall be located outdoors in accordance with Section 2309.3.1.1 of the International Fire Code.
Gaseous hydrogen systems and detection devices shall be maintained in accordance with the International Fire Code and the manufacturer's installation instructions.
Purging of gaseous hydrogen systems, other than piping systems purged in accordance with Section 705.5, shall be in accordance with Sections 2309.6 and 2309.6.1 of the International Fire Code or in accordance with the system manufacturer's instructions.
The design of liquefied hydrogen systems shall comply with Chapter 55 of the International Fire Code.