Chapter 7 Gaseous Hydrogen Systems
Section 701 (IFGC) General
Section 702 (IFGC) General Definitions
702.1 Definitions.
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.
Section 703 (IFGC) General Requirements
703.1 Hydrogen-generating and refueling operations.
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.
[F] 703.2 Containers, cylinders and tanks.
Compressed gas containers, cylinders and tanks shall comply with Chapters 53 and 58 of the International Fire Code.
[F] 703.2.1 Limitations for indoor storage and use.
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).
[F] 703.3 Pressure relief devices.
Pressure relief devices shall be provided in accordance with Sections 703.3.1 through 703.3.8. Pressure relief devices shall be sized and selected in accordance with CGA S-1.1, CGA S-1.2 and CGA S-1.3.
[F] 703.3.1 Valves between pressure relief devices and containers.
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.
Exception: A locked-open shutoff valve on containers equipped with multiple pressure relief device installations where the arrangement of the valves provides the full required flow through the minimum number of required relief devices at all times.
[F] 703.3.2 Installation.
Valves and other mechanical restrictions shall not be located between the pressure relief device and the point of release to the atmosphere.
[F] 703.3.5 Sizing.
Pressure relief devices shall be sized in accordance with the specifications to which the container was fabricated. The relief device shall be sized to prevent the maximum design pressure of the container or system from being exceeded.
[F] 703.3.6 Protection.
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.
[F] 703.3.7 Access.
Pressure relief devices shall be located such that they are provided with ready access for inspection and repair.
[F] 703.3.8 Configuration.
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.
Section 704 (IFGC) Piping, Use and Handling
704.1 Applicability.
Use and handling of containers, cylinders, tanks and hydrogen gas systems shall comply with this section. Gaseous hydrogen systems, equipment and machinery shall be listed or approved.
704.1.1 Controls.
Compressed gas system controls shall be designed to prevent materials from entering or leaving process or reaction systems at other than the intended time, rate or path. Automatic controls shall be designed to be fail safe in accordance with accepted engineering practice.
704.1.2 Piping systems.
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.
704.1.2.1 Sizing.
Gaseous hydrogen piping shall be sized in accordance with approved engineering methods.
704.1.2.2 Identification of hydrogen piping systems.
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:
- 1.
At each valve.
- 2.
At wall, floor and ceiling penetrations.
- 3.
At each change of direction.
- 4.
At intervals not exceeding 20 feet (6096 mm).
704.1.2.3 Piping design and construction.
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.
piping shall not be installed in or through a circulating air duct; clothes chute; chimney or gas vent; ventilating duct; dumbwaiter; or elevator shaft. piping shall not be concealed or covered by the surface of any wall, floor or ceiling.
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, including joints and fittings, shall be protected from corrosion and installed in accordance with approved engineered methods.
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 1 1/2 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.
704.1.2.4 Joints.
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 sealants 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.
704.1.2.5 Valves and piping components.
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 withstand 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.
704.2 Upright use.
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.
Section 705 (IFGC) Testing of Hydrogen Piping Systems
705.1 General.
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.
705.2 Inspections.
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.
705.3 Pressure tests.
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.
705.3.1 Hydrostatic leak tests.
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).
705.3.2 Pneumatic leak tests.
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.
705.3.3 Test limits.
Where the test pressure exceeds 125 psig (862 kPa gauge), the test pressure shall not exceed a value that produces hoop stress in the piping greater than 50 percent of the specified minimum yield strength of the pipe.
705.3.4 Test medium.
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.
705.3.5 Test duration.
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.
705.3.6 Test gauges.
Gauges used for testing shall be as follows:
- 1.
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.
- 2.
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.
- 3.
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.
705.3.7 Test preparation.
Pipe joints, including welds, shall be left exposed for examination during the test.
705.3.7.1 Expansion joints.
Expansion joints shall be provided with temporary restraints, if required, for the additional thrust load under test.
705.3.7.2 Equipment disconnection.
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).
705.3.7.3 Equipment isolation.
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).
705.4 Detection of leaks and defects.
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.
705.4.1 Corrections.
Where leakage or other defects are identified, the affected portions of the piping system shall be repaired and retested.
705.5 Purging of gaseous hydrogen piping systems.
705.5.1 Removal from service.
Where piping is to be opened for servicing, addition or modification, the section to be worked on shall be isolated from the supply at the nearest convenient point and the line pressure vented to the outdoors. The remaining gas in this section of pipe shall be displaced with an inert gas.
705.5.2 Placing in operation.
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.
705.5.3 Discharge of purged gases.
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.
705.5.3.1 Vent pipe outlets for purging.
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.