Michigan Administrative Code
Department - Licensing and Regulatory Affairs
Bureau of Fire Services
Storage and Handling of Gaseous and Liquefied Hydrogen Systems
Part 2 - STORAGE AND HANDLING OF GASEOUS HYDROGEN NFPA 50A
Chapter 2 - Design of Gaseous Hydrogen Systems
Section R. 29.7022 - Piping, tubing, and fittings
Current through Vol. 24-16, September 15, 2024
Rule 22. Sections 2-3.1 is reproduced from NFPA 50A, and sections 2-3.1.1, 2-3.1.2, and 2-3.2 to 2-3.13 of the storage and handling of gaseous and Liquefied H2 code are added as follows:
2-3 Piping, tubing, and fittings.
2-3.1 Piping, tubing, and fittings shall be suitable for H2 service and for the pressures and temperatures involved. Cast-iron pipe and fittings shall not be used.
2-3.1.1 A piping system shall be substantially supported and protected against physical damage and excessive stresses arising from settlement, vibration, expansion, or contraction. Supports for aboveground piping shall be constructed of noncombustible material.
2-3.1.2 Aboveground piping systems shall be protected from corrosion in compliance with recognized standards. Underground piping systems shall be in compliance with section 5-4.
2-3.2 Material specifications and thickness requirements for piping and tubing shall conform to ASME B31.3, "Process Piping," adopted by reference in section 8-1.
2-3.3 Brazing materials shall have a melting point above 1,000 degrees Fahrenheit (538 degrees Celsius). Flanged connection shall use a gasket that is suitable for H2. When making joints in piping and tubing, thread sealants, when used, shall be suitable for H2 service and shall be applied to male pipe threads prior to assembly.
2-3.4 Aboveground piping systems shall be marked in accordance with the following:
(a) Marking shall include the name of the gas and direction of flow arrow.
(b) Marking for piping systems shall be provided at the following locations:
2-3.5 Threaded or flanged connections shall not be used in areas other than outdoors.
2-3.6 Underground piping shall be installed on a bedding of at least 6 inches (15.24 centimeters) of well-compacted backfill material.
2-3.7 In areas subject to vehicle traffic, the pipe trench shall be of sufficient depth to permit a cover of not less than 18 inches (45.72 centimeters) of well compacted backfill material and pavement.
Exception 1: In paved areas where a minimum of 8 inches (20.32 centimeters) of asphalt paving is used, the depth of the backfill between the topmost tier of piping and the paving may be reduced to not less than 8 inches (20.32 centimeters).
Exception 2: In paved areas where a minimum of 6 inches (15.24 centimeters) of reinforced concrete paving is used, the depth of backfill between the topmost tier of the piping and the paving may be reduced to not less than 4 inches (10.16 centimeters).
2-3.8 In areas not subject to vehicle traffic, the pipe trench shall be of sufficient depth to permit 6 inches (15.24 centimeters) each of bedding and cover of well-compacted backfill material. A greater burial depth shall be provided when required by the manufacturer's instructions.
2-3.9 Piping within the same trench shall be separated by more than 3 times the diameter of the larger adjacent pipe.
2-3.10 Piping to equipment shall be provided with an accessible, manual shutoff valve.
2-3.11 Pipe, tubing, fittings, and other piping components shall be capable of withstanding a hydrostatic test of at least 3 times the rated service pressure without structural failure as documented by the manufacturer.
2-3.12 All natural gas piping shall be installed in accordance with R 29.4601 et seq.
2-3.13 All liquefied petroleum gas piping shall be installed in accordance with R 29.4001 et seq.
