1、Lessons Learned Entry: 1432Lesson Info:a71 Lesson Number: 1432a71 Lesson Date: 1989-11-20a71 Submitting Organization: LARCa71 Submitted by: Grant WatsonSubject: 8-Foot High Temperature Tunnel Mishap (1989) Abstract: Mishap while preparing to perform pneumatic flushing of debris from high pressure ai
2、r lines in the 8-Foot High Temperature Tunnel (8HTT).Description of Driving Event: A mishap occurred at the 8HTT when a team of construction contractor personnel was preparing to perform a pneumatic flushing of debris from high pressure air lines by use of a low pressure, high velocity air. The blan
3、k flange was removed from air lines perceived to have been un-pressurized. Removal of the flange, under pressure, resulted in serious injury to two of the personnel involved in the operation.Lesson(s) Learned: There were formal approved procedures which were to control this activity. If they had bee
4、n followed, the accident could have been prevented. The procedures were written so as to ensure that the line was un-pressurized when the blank flanges were removed and that the flushing air source was not attached to the system unless the flanges were already removed. However, a failed valve and th
5、e use of an alternative source for the air apply allowed this mishap to occur. The new configuration used a larger volume air source which was not isolated prior to flange removal. The configuration also allowed a single order failure to pressurize the line upstream of the blank flange.Recommendatio
6、n(s): Survey your facility to verify that vents are present upstream of blank flanges used within your research systems/apparatus. Procedures dealing with the removal of these blank flanges must require Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,
7、verification of the venting of any such system to atmospheric pressure prior to flange removal. Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): a71 Exploration Systemsa71 Sciencea71 Space Operationsa71 Aeronautics ResearchAdditional Key Phras
8、e(s): a71 Accident Investigationa71 Facilitiesa71 Hardwarea71 Human Factorsa71 Mishap Reportinga71 Safety & Mission AssuranceAdditional Info: Approval Info: a71 Approval Date: 2004-06-04a71 Approval Name: Leslie Johnsona71 Approval Organization: LARCa71 Approval Phone Number: 757-864-9409Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
