1、Lessons Learned Entry: 0499Lesson Info:a71 Lesson Number: 0499a71 Lesson Date: 1996-12-09a71 Submitting Organization: JSCa71 Submitted by: L. UnderwoodSubject: Pressure Verification During Pressure Systems Operations and Maintenance Description of Driving Event: A maintenance team was removing a gat
2、e valve from a high pressure (5000 pounds per square inch) nitrogen trailer at the fill end of the trailer. After the valve bolts were removed and the employee tapped on the valve to loosen it, the valve flew off and hit one of the maintenance employees. The employee was thrown 15 feet through the a
3、ir and against an I-beam, resulting in a fatality. Preliminary information indicated that the system was not under pressure and the valve gauge reading was zero pressure.This event occurred during work external to NASA but includes information that is pertinent to NASA operations.Lesson(s) Learned:
4、Verification of pressure status is critical when working on energized systems.Recommendation(s): 1. Always assume a pressure system is under pressure until otherwise verified. Verify that it is unpressurized and then recheck the verification.2. Look for valves in the system that may be open or close
5、d, giving an erroneous verification.3. Obtain the drawings and configuration control documents.4. Take the time to review the documentation, drawings, or schematic.5. Consult local experts for pressure system configuration and requirements.When performing general maintenance tasks:Provided by IHSNot
6、 for ResaleNo reproduction or networking permitted without license from IHS-,-,-1. Energized systems require lockout/tagout prior to performing maintenance.2. Read and honor the warning signs while conducting your work.3. Be concerned for the safety of your co-workers and act accordingly.4. Stop the
7、 task if you encounter a potential hazard and check with your supervisor.5. Do not take chances!Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Pressure Vesselsa71 Safety & Mission AssuranceAdditional Info: Approval Info: a71 Approval Date: 1997-03-31a71 Approval Name: Ronald A. Montaguea71 Approval Organization: NA3a71 Approval Phone Number: 281-483-8576Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
