Severity
Incident
Was Hydrogen Released?
Yes
Was There Ignition?
No
Incident Date
Describe the incident, including corrective steps taken and their result.
The contractor was replacing a needle valve and a check valve on the nitrogen purge line to the dispenser because of a small leak at the connection between the needle valve and the check valve. On reinstalling the valves, the contractor installed the check valve backwards, causing the pressure disk in the regulator to fail, venting about 1000 psig hydrogen into the air for about 10 seconds. This was found during testing of the contractor's work before the system was returned to normal service.
Lessons Learned
Proper installation of check valves and other equipment should be visually inspected prior to pressurization.