While research staff were working in a lab, a staff member opened the primary valve to a 0.2" (1500 psi) hydrogen gas line connected to a manifold supplying instruments in the lab. Upon opening the valve, the hydrogen gas line failed at a fitting on the switching manifold, releasing a small amount of hydrogen gas. The staff member closed the valve immediately, then inspected the gas line and found the front ferrule (of the compression-style fitting) to be missing. There were no injuries or damage to equipment.
In the follow-on discussion with research staff, it was learned that approximately one month earlier, a similar condition (front ferrule missing from a fitting) was found while performing a modification to a similar manifold. Following a critique, management expressed concerns relative to the installation and commissioning of compressed gas systems, specifically in regard to proper system installation and responsibility for required leak testing. Elevating this issue to a management concern will ensure that procedures and processes are reviewed and revised as necessary to clarify roles and responsibilities for compressed gas systems, further assuring users of new or modified systems that they have received proper reviews and testing.
Start-up testing was considered less than adequate because the appropriate level of testing did not occur for the type of system being installed or its intended use. The person installing the compressed gas line into a compression style fitting tee failed to include the front ferrule. Later, when the line was pressurized at 1500 psi, the fitting and line separated.
Fittings need to be visually inspected to insure ferules are in place and correctly positioned prior to swageing.
Research staff are responsible for communicating system specifications [gas type, Maximum Allowable Working Pressure(MAWP)] and testing requirements to service provider.
Lines that run through ceilings and chases should be pressure-tested at the MAWP of the materials of that line.
System owners/users should specify QA requirements such as leak testing and service providers/installers must provide appropriate documentation.
System owners/users should document that they have accepted work.
The system owner is responsible for tracking, through safety documentation such as IOPS or SOPs, system modifications and procedural changes. Use of safety documentation prevents off normal events that could arise through staff turnover.
Best practices related to fittings and joints in compressed hydrogen gas piping systems are discussed in the Hydrogen Safety Best Practices Manual.