Mich. Admin. Code R. 29.7081
Rule 81. Sections 2-3.1, and 2-3.4 are reproduced from NFPA 50B, and sections 2-3.2, 2-3.2.1, 2-3.3, 2-3.5, 2-3.5.1, 2-3.6 to 2-3.17 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, and gasket and thread sealants shall be suitable for hydrogen service at the pressures and temperatures involved. Consideration shall be given to the thermal expansion and contraction of piping systems when exposed to temperature fluctuations of ambient to liquefied hydrogen temperatures.
2-3.2 Material specifications and thickness requirements for piping and tubing shall conform to ASME B31.3, "Process Piping." Piping or tubing for operating temperatures below -20 degrees Fahrenheit (-29 degrees Celsius) shall be fabricated from materials meeting the impact test requirements of Chapter III of ASME B31.3 when tested at the minimum operating temperature to which the piping can be subjected in service.
2-3.2.1 Aluminum shall not be used with liquefied H2 piping except for ambient air vaporizers.
2-3.3 Joints in piping and tubing shall be made by welding, brazing, or flanged. 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.
2-3.4 Means shall be provided to minimize exposure of personnel to piping operating at low temperatures and to prevent air condensate from contacting piping, structural members, and surfaces not suitable for cryogenic temperatures. Insulation shall be of noncombustible material and shall be designed to have a vaportight seal in the outer covering to prevent the condensation of air and subsequent oxygen enrichment within the insulation. The insulation material and outside shield also shall be of adequate design to prevent attrition of the insulation due to normal operating conditions.
2-3.5 Uninsulated piping and equipment that operate at liquid hydrogen temperatures shall not be installed above asphalt surfaces or other combustible materials to prevent contact of oxygen enriched liquefied air with such materials. Drip pans may be installed under uninsulated piping and equipment to control drips and vaporize condensed liquefied air.
2-3.5.1 Where insulation materials are used, the insulation shall be compatible with the equipment with which the insulation is in contact.
2-3.6 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.
2-3.7 Aboveground piping systems shall be protected from corrosion in compliance with recognized standards. Underground piping system shall be in compliance with section 5-3.
2-3.8 Aboveground piping systems shall be marked in accordance with the following:
2-3.9 Underground piping shall be installed on a bedding of at least 6 inches (15.24 centimeters) of well-compacted backfill material.
2-3.10 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: 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 can be reduced to not less than 8 inches (20.32 centimeters).
Exception: 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 can be reduced to not less than 4 inches (10.2 centimeters).
2-3.11 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.
2-3.12 Piping within the same trench shall be separated by more than 3 times the diameter of the larger adjacent pipe.
2-3.13 Piping to equipment shall be provided with an accessible, manual shutoff valve.
2-3.14 Pipe, tubing, fittings, and other piping components shall be capable of withstanding a hydrostatic test of at least 3 times the rated pressure without structural failure as documented by the manufacturer.
2-3.15 Underground liquefied H2 piping shall be vacuum-jacketed. Unjacketed piping shall not be buried and shall exit the container annular space above grade.
2-3.16 All natural gas piping shall be installed in accordance with R 29.4601 et seq.
2-3.17 All liquefied petroleum gas piping shall be installed in accordance with R 29.4001 et seq.
Mich. Admin. Code R. 29.7081