Forum: Reliability & Maintainability Questions and Answers

Topic: Reliability & Maintainability Questions and Answers

Topic Posted by: Reliability & Maintainability Forum (src_forum@alionscience.com )
Organization: System Reliability Center
Date Posted: Mon Aug 31 12:47:36 US/Eastern 1998
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Original Message:

Posted by: raja rizwan imtiaz (imtiazrr@petrokemya.sabic.com )
Organization:petrokemya
Date posted: Sun Feb 16 0:57:10 US/Eastern 2003
Subject: functinal failure of safety valves
Message:
Recently, we have faced recurring pressure safety valve popping problem in few of the safety valves installed in high pressure steam service. While conducting safety valve failure investigation, it was observed that the problematic psv's spring has reduced in height about 7.0mm compared to the original (new) spring. original spring height = 207 mm and the used (old) measured spring height = 200mm Currently, we are using only visual inspection criteria for the replacement of safety valve critical parts i.e. spring, spindle etc. However, we are looking for introducing the dimensional criteria as well to avoid such failures. If someone help answer following · Are you applying dimensional measurement criteria for the psv's critical parts or only visual inspections are done to adjudge the parts fitness. · What is the dimensional measurement criteria for spring replacement. Example could be for any service.

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