REG NASA-LLIS-0525-1994 Lessons Learned Acceptance Testing Inspection and Securing of Air Lines.pdf

1、Lessons Learned Entry: 0525Lesson Info:a71 Lesson Number: 0525a71 Lesson Date: 1994-08-23a71 Submitting Organization: LARCa71 Submitted by: Bernard LewisSubject: Acceptance Testing, Inspection, and Securing of Air Lines Description of Driving Event: On 1-20-93, contractor technicians were tracing a

2、1/4“ stainless steel air line in Building 1247E. The line, part of the 5000 PSI air system, was in an overhead support channel and the technician was tracing it with his fingers while standing on a 4 step ladder.While tracing the line, the pressure of the technicians fingers was sufficient to cause

3、the line to separate at a union fitting. The tubing was clamped into the support channel on one side of the fitting and this section of tubing held fast. On the other side of the fitting the tubing was not clamped into the channel; on this side, after separation, a section of line approximately 10 l

4、ong whipped into the air and became lodged in other piping in the area. Damage was minor (a 1/4“ plastic water line was severed) and there were no injuries. Fortunately, neither technician was in the path of the loose tubing. Had they been, serious injury could have occurred.It appears that the caus

5、e of the fitting separation was the result of improper assembly of the union. A “bite“ ferrule in the fitting failed to secure the stainless steel tubing in the union. Thus, the line was only secured by air pressure. Movement of the line for any reason would have been sufficient to cause joint separ

6、ation.Lesson(s) Learned: There are two lessons learned as a result of this event:1. Thoroughly inspect, prior to acceptance, work done by outside contractors.2. Secure tubing in support channels by clamping on both sides of the fittings.Recommendation(s): Provided by IHSNot for ResaleNo reproduction

7、 or networking permitted without license from IHS-,-,-To preclude future incidents such as this, it is recommended to:1. Inspect, before acceptance, work done by outside contractors.2. Secure tubing in support channels by clamping on both sides of fittings.3. Use fittings only where necessary (on th

8、e failed fitting line, distance between fittings ranged from inches to feet. It appeared as if fitting placement was determined in some cases by length of tubing available, not by where fitting was actually needed).4. Always let facility personnel know you are in their building, what you will be doi

9、ng while there, and where you will be located.Evidence of Recurrence Control Effectiveness: This incident has been documented and a record made of it. Appropriate personnel have been made aware of it.Documents Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Facilitiesa

10、71 Industrial Operationsa71 Pressure VesselsAdditional Info: Approval Info: a71 Approval Date: 1997-04-02a71 Approval Name: Elijah C. Kenta71 Approval Organization: 421a71 Approval Phone Number: 757-864-3345Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-