The failure of a high pressure industrial water valve actuator assembly at a NASA test stand underscored the need for disciplined configuration control practices to ensure facility systems are built and maintained to the specified design.
In March 2013 technicians were working on modifications to the gaseous nitrogen actuation system supplying the actuator on High Pressure Industrial Water (HPIW) Bypass Valve M-344-IW at the A-1 Test Stand at Stennis Space Center when a failure of the actuator assembly occurred. The failure resulted in ejection of multiple hardware components and impact to surrounding structure and piping, but no personal injury.
The heritage HPIW valve configuration is Flexflo valves, which are plumbed to the Fail-Open position that requires actuation pressure to maintain the valve in the closed position. Due to difficulty in repair or replacement of the Flexflo valve, a Fail-Closed butterfly valve configuration was explored. Multiple engineers were involved with the valve actuator assembly and system configuration changes from 2007 to 2013. When the A-1 Test Stand HPIW water system was brought back online in 2013 and it was discovered the butterfly valve was not cycling properly, initial troubleshooting efforts were hampered by the unique configuration and a lack of full understanding of the original engineer’s intent in the design.
It was later learned that the installation of the butterfly valve was intended to be a temporary change. The system drawings had not been updated to reflect the new valve/actuator type, the addition of a pressure regulator and pressure gauge, and the change from a Fail-Open to a Fail-Closed actuation configuration.
Stennis Space Center CKO John Stealey on the importance of this lesson learned:
A temporary change should be treated with the same discipline and rigor as a permanent change. It can be very easy for a short-term change to remain installed for a greater length of time than originally anticipated. Whether the change is short-duration or long-duration, the best guidance is to always adhere to the same requirements and good engineering practices.