SRC Forum - Message Replies

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

Original Message:

Posted by: Ray
Date posted: Mon Mar 5 16:24:37 US/Eastern 2007
Subject: Edge Welded Bellows
Message:
How can the reliability of edge-welded metal bellows be calculated with the following inputs: number of convolutions; inches of weld (inner and outer); percent of full range flex motion; number of application flexures? for some reason (no confidence?), the industry is not overwhelming us with life test data.

Reply:

Subject: Edge Welded Bellows
Reply Posted by: David Dylis (ddylis@alionscience.com )
Organization: Alion SRC
Date Posted: Thu Jun 7 13:29:05 US/Eastern 2007
Message:
Few models exist that specifically predict the failure rate of mechanical components. There is a standard developed by the US Navy entitled: NSWC Standard 06/LE10: Handbook of Reliability Prediction Procedures for Mechanical Equipment. This document includes failure rate prediction models for Seals and Gaskets, Springs, Solenoids, Valve Assemblies, Bearings, Gears and Splines, Actuators, Pumps, Filters, Brakes and Clutches, Compressors, Electric Motors, Accumulators, Threaded Fasteners, Mechanical Couplings, Slider-Crank Mechanisms, and Sensors and Transducers. Unfortunately, the standard does not include models specifically for bellows. It is recommended that if test or field data can not be obtained from the manufacturer that independent life testing be performed to assess the life of the device.

If you have any additional questions, or require assistance developing a test to assess life, feel free to contact me.