Storage and Piping

System Design Features

Piping systems should be designed, fabricated, installed, examined and tested in accordance with the applicable code. Examples of such codes are ASME B31.1, ASME B31.3 and ASME B31.12.
Piping systems should be designed and installed by a person qualified by specific training and experience with hydrogen piping systems.
Manual shutoff valves should be provided near each point of use. Where possible, such valves should be easy to activate quickly and positively and give a visual indication of position. For example, a quarter-turn valve is preferred over a needle valve or gate valve.
Point-of-use shutoff valves should be located away from the potential hazards and within immediate reach.
Line regulators that have their source away from the point of use should have a manual shutoff valve near the point of use.
An emergency gas shutoff device in an accessible location outside the use area should be provided in addition to the manual point-of-use valve in each laboratory space that has a piped gas supply system.
Piping should be designed for a pressure greater than the maximum system pressure that can be developed under abnormal conditions and should be protected by appropriately vented Pressure Relief Devices (PRDs) – see below.
Piping systems, including regulators, should not be used for gases other than those for which they are designed unless a thorough review of the design specifications, materials of construction, and service compatibility is conducted. See Material Compatibility.
Shut-down controls should be provided and linked to a heat detection alarm system so that the temperature rise from an exothermic reaction can be managed.
Plastic tubing should
- not be used near heat sources
- not be used for vent lines
- be tested for hydrogen permeability to minimize leakage
- have secure connections
Because of their leak and joint separation potentials, quick connect joints should be avoided
Excess flow valves or flow restrictors should be considered for controlling maximum hydrogen flow
For more information, see Compressed Gas Piping Systems.

Pressure Relief

Each system should have pressure relief in accordance with the applicable code.
Piping designed to withstand the maximum excursion pressures may not need to be equipped with a relief device.
A pressure relief system should be designed to provide a discharge rate sufficient to avoid further pressure increase and should vent to a safe location. See Venting.

Labeling

All shutoff valves should be clearly marked.
Permanent hydrogen piping should be labeled as such at the supply point, at each discharge point, and at regular intervals along its length. Where hydrogen gas piping penetrates a wall, the piping should be labeled on both sides of the wall. Color-coding may be another way to mark hydrogen piping.
Note: Good general guidance is available in ASME A13.1 Scheme for the Identification of Piping Systems

System Checkout

In addition to the leak test required by the codes to prove a system is suitable for service, systems should be leak checked immediately prior allowing any hydrogen to enter the system.
A common method to do the leak check is to pressurize the system with an inert gas such as nitrogen and use a soap bubble solution to locate leaks during system/vessel checkout. Use of helium gas along with helium leak detectors to find the smaller leaks is recommended if available.

References

ASME A13.1 Scheme for the Identification of Piping Systems

ASME B31.1 Power Piping

ASME B31.3 Process Piping

ASME B31.12 Hydrogen Piping and Pipelines

NFPA 45, Standard on Fire Protection for Laboratories Using Chemicals

NFPA 55, Standard for the Storage, Use, and Handling of Compressed Gases and Cryogenic Fluids in Portable and Stationary Containers, Cylinders, and Tanks

Storage and Piping

System Design Features

Pressure Relief

Labeling

System Checkout

References

Contact

Gallery

Contact info

Recent Posts