REG NASA-LLIS-0459-1996 Lessons Learned - Removing the gaseous nitrogen Pressure Control Valve 214(PCV-214) in the A-2 Test Stand Pressure Reducing Area (PRA).pdf

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1、Lessons Learned Entry: 0459Lesson Info:a71 Lesson Number: 0459a71 Lesson Date: 1996-10-9a71 Submitting Organization: SSCa71 Submitted by: Mike RewisDescription of Driving Event: On August 1,1996, contractor personnel were removing the gaseous nitrogen Pressure Control Valve 214(PCV-214) in the A-2 T

2、est Stand Pressure Reducing Area (PRA). As a result of a sudden pressure release of 3000 psi nitrogen, one technician suffered a fractured right forearm, and another suffered a small puncture wound to his right neck area and abrasions to his arm. Both the aforementioned employees and another are bei

3、ng monitored over time to determine if there are any auditory threshold shifts.Lesson(s) Learned: Work documentation should reflect most up to date system configuration and specifically detail any necessary work operations to be engaged in. It was found that:1. Insufficient and out of sequence, isol

4、ation, vent, and bleed procedures were specified, reviewed and approved for use. Specific work instructions trapped system pressure in the up stream leg between PCV-214 and the isolation valve VA-231.2. Incorrect Graylock clamp removal procedures were used. Upon pressure release, the unrestrained Gr

5、aylock clamps and a seal became projectiles thereby producing the injuries.3. Personnel misunderstood the configuration and operation of the system. Dome loading pressure gauges reading 0 psi were thought to be line pressure, erroneously giving the impression that the pipe was not pressurized and wa

6、s safe to work on.Recommendation(s): 1. Investigate the process plan review system to evaluate the adequacy of the current technical reviews and review system.2. Issue safety bulletin regarding similarly configured systems including the operation, function and proper steps to bleed and vent.Provided

7、 by IHSNot for Resale-,-,-3. Reemphasize or reeducate personnel on the importance of holding meaningful pre-work meetings.4. Include Graylock installation and removal procedures on all process plans involving Graylocks or write a Graylock procedure and conduct Graylock procedure classes.Evidence of

8、Recurrence Control Effectiveness: No similar event recurrence.Documents Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Facilitiesa71 Pressure Vesselsa71 Safety & Mission AssuranceAdditional Info: Approval Info: a71 Approval Date: 1996-10-9a71 Approval Name: Mike Rewisa71 Approval Organization: QA00a71 Approval Phone Number: 601-688-2663Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS