Periodic Inspection

"Valve malfunctions and/or valve leaks" is the single largest cause of hydrogen incidents at NASA, accounting for 20% of the incidents. "Leaking connections" is the second largest, accounting for 16% of the incidents [1].

Leak testing using soap bubble solution or a hand-held hydrogen detector should be performed on a regular basis, and every time joints are re-assembled. Connections should be regularly inspected for any sign of corrosion, erosion, cracking, bulging, blistering, or other deterioration. Any identified problems should be corrected as soon as possible.

There should be planned inspections for all mechanical and electrical equipment, and instruments. Maintenance staff should review the inspection list and make sure the entire inspection plan is actually completed.

Maintenance staff should frequently inspect, test, and maintain all components of hydrogen systems. Any system deficiencies found during an inspection should be identified (tracked and stewarded), corrected, and reviewed by a trained second party before future tests are conducted. Inspections should include the following:

  • Check all relief valve set points.
  • Test the function of relief devices on a preventive basis.
  • Check for continuous leaks from vent systems.
  • Check all other relevant operational characteristics.
  • Chronic maintenance issues may be the result of design flaws, which should be addressed and corrected as soon as possible.