1、Lessons Learned Entry: 0635Lesson Info:a71 Lesson Number: 0635a71 Lesson Date: 1999-08-17a71 Submitting Organization: MSFCa71 Submitted by: John NebrigSubject: MSFC Building 4672 Pressure Reducing Statin Grayloc Clamp Removal Description of Driving Event: On June 29, 1999, personnel were removing a
2、Grayloc blind hub that had been used to temporarily isolate a portion of the gaseous hydrogen system. As a result of a sudden release of 2800 psig gaseous nitrogen, sand and debris kicked up from the concrete pad and caused minor injury to two technicians.Lesson(s) Learned: Work documentation (work
3、orders and baseline drawings) should reflect the current system configuration. During the investigation, it was found that:1. The temporary configuration change to the gaseous hydrogen system was initiated on multiple work orders and by different individuals. There was no single document that docume
4、nted the temporary system configuration.2. The procedure for performing the work was written using a drawing that had not been updated to show the actual system configuration. Verbal field direction was given when it was discovered the system was not configured per the work order.3. Incorrect Graylo
5、c clamp removal techniques were used. Upon pressure release, the Grayloc clamp, blind hub, and seal ring became projectiles that had the potential to cause significant personnel injury.Recommendation(s): 1. Develop procedures for temporary change configuration control of high-pressure systems. Provi
6、ded by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-The overall work process should be included in one work authorization document.2. Re-emphasis to all personnel that current procedures be followed. If the work order is not written to reflect the current sys
7、tem configuration, stop work, revise work order, and have the work order properly reviewed prior to continuing work.3. Write a procedure for proper Grayloc removal and installation and train technicians to the procedure.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/
8、AMission Directorate(s): a71 Exploration Systemsa71 Aeronautics ResearchAdditional Key Phrase(s): a71 Energetic Materials - Explosive/Propellant/Pyrotechnica71 Ground Equipmenta71 Pressure Vesselsa71 Test FacilityAdditional Info: Approval Info: a71 Approval Date: 1999-09-29a71 Approval Name: Frank Hepburna71 Approval Organization: CR10a71 Approval Phone Number: 205-544-1806Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
