Summary
A hydrogen explosion occurred at a plant, damaging a wall adjacent to the hydrogen storage assembly. The investigation revealed that the explosion was the consequence of deficiencies in components integral to the hydrogen storage assembly, and that this assembly belonged to a supplier contracted to provide hydrogen to the plant. The analysis revealed that had the supplier properly installed and maintained this equipment, this incident would have been prevented. By receiving assurance, on an ongoing basis, that the supplier was properly maintaining this equipment, the company could have also reduced the chance of occurrence of this incident.

Background
A hydrogen supplier was awarded a contract in 1990 to supply the plant with hydrogen as well as to provide view more

A demolition technician noted an elevated combustible gas lower explosive limit (LEL) on a pipe that was being tested prior to cutting (No. 2 pipe). The No. 2 pipe was one of four pipes being tested. The other three pipes tested less than detectable for combustible hydrogen gas. Testing involves tapping the pipe and connecting the pipe to an Explosive Gas Detector via a tube. When an elevated LEL is identified, the pipe is allowed to vent and then retested prior to cutting. After tapping the No. 2 pipe, the work crew left the pipe open to vent and departed the area for the end of shift.

At approximately 7"45 PM on the same day, a crew was on overtime to support roofing activities. Since additional workers were available, the craft supervisor decided to re-enter the viewing view more