This incident illustrates how difficult it is to completely purge hydrogen out of a large, complex piece of equipment. Uniform mixing and dilution is unlikely in all the partially enclosed spaces, crevices, etc. If a hazardous operation such as…

1. Follow the rules (e.g., using a torque-amplifying device requires supervisor approval).
2. Some valves are susceptible to disassembly, with potentially significant consequences, if excessive torque is applied to the handwheel.…

The investigation determined that hydrogen was formed by the reaction of hot aluminum and water, air was admitted via the inspection door, and the mixture was ignited by the hot clinker or sparks from the chisel. Aluminum should have been…

The ignition of the fireball could have been caused by any of the following mechanisms:

• The inverse Joule-Thompson effect of hydrogen (i.e., heating upon expansion)
• Some of the oil and light ends were above their auto-…

In addition to the probable causes listed above, the lack of a standard operating procedure for hydrogen leak detection was one of the probable causes of this incident. Additional contributing factors included the following:
- Severe pipe…

The incident was the result of a combination of factors leading to exceptional temperature conditions that were not taken into account in the mechanical design of the reactor. Corrective actions that were implemented by the plant management…

The following actions were proposed as a result of this incident:

•  The company in charge of valve calibration and maintenance will be subject to approval of the plant service inspection team.
•  Plant operating…

Three root-causes were noted during the investigation: (1) the use of incompatible materials in the manufacturing of the PRD valve, (2) improper assembly resulting in over-torquing of the inner assembly, and (3) over-hardening of the inner…

Maintain an internal process for verifying component wetted material compatibility for intended use as part of the procurement process for hydrogen system equipment. It is critical that component parts be appropriately rated for the materials,…

Implement rigorous assembly, verification, and documentation procedures for equipment.

Increase automated leak detection frequency.

Maintain an internal process for verifying component wetted material compatibility for intended use as part of the procurement process for hydrogen system equipment. 

Don’t rely solely on a manufacturer to provide appropriately rated…