Compressed Gas Piping Systems

Recommendations for compressed gas piping systems include the following:

  • Piping systems should conform to a recognized code such as ASME B31.1 Power Piping, ASME B31.3 Process Piping, or ASME B31.12 Hydrogen Piping and Pipelines.
  • To prevent leaks when exposed to an external fire, the piping system should be fire resistant.
  • The piping material should be selected for robustness, low permeability, and fire resistance. The material chosen should be specifically rated or approved for use with hydrogen at the planned pressure.
  • Optimum material selection depends on:
    • The temperature range
    • The pressure
    • Purity and cleaning requirements
    • Installation factors (structure, environment)
  • In most instances, austenitic stainless steels such as Type 304 or 316 are satisfactory for end use applications.
  • See Material Compatibility for more information regarding material selection.
Hydrogen Transport Piping System
Piping system for hydrogen transport (Source: Department of Energy Fuel Cell Technology Program)
  • Design of the piping system should consider ways to facilitate internally cleaning the piping when needed.
  • Considerations for underground piping include:
    • External corrosion
    • Protection from inadvertent excavation
    • Preventing hydrogen from entering an enclosed space if a leak occurs
    • Using only welded joints
  • Alternates to direct burial of piping include:
    • Route the pipe in open trenches with removable grating so that it can be inspected and maintained.
    • When pipe can be routed without any mechanical joints, place the pipe in a corrosion resistant sleeve that is open at both ends.
  • Piping should not be left open to the atmosphere. Openings should be plugged, capped, or flanged or routed to a vent stack.
  • To assure dispersion of small leaks, piping should be routed outdoors whenever possible.
  • Piping should be routed so that it is:
    • Not covered by wall, floor, or ceiling finishes
    • Readily available for visual inspection and leak detection, and
    • Protected from physical damage
  • The hydrogen system should have the necessary connections for isolating, venting, purging and leak testing, along with those needed to prepare the equipment for maintenance.
  • When part of the system will remain operational while another part needs work, consider a double block and bleed arrangement to isolate active parts of the system from equipment being maintained and to facilitate purging.

Double Block and Bleed Line

Regardless of system design, a procedure for purging any piping to remove all air, moisture, or oxidizing gas or substance must be developed and documented.