Incident Synopsis
During pressure testing of a H2 tank for investigation of quick-release manhole cover, the tank burst at a pressure between 60-67 psig. Flow regulators indicated peak pressure of 67 psig.

Cause
The tank was over pressurized. A mistake was made in interpreting the blueprint, believing the tank was designed to withstand 150 psig, yet the actual design limit was 50.7 psig.