Desktop version

Home arrow Health arrow Case Studies in Maintenance and Reliability: A Wealth of Best Practices


The Case for Change

We had achieved a 100% failure rate with two tests and two failures. With this ammunition, it was not difficult to convince Operations of the need to test the final executive element. However, we had to limit or avoid production loss. In cases where it was possible, we agreed to limit the movement of the final element by restricting its stroke with a mechanical stop. This would allow the executive element, namely the actuator or valve, to move slightly, by 1/16" to 1/8". This movement shows that had the mechanical stop not been installed, it would almost certainly have moved its full stroke. The small movement did not affect production in any way, but it would de-gum moving parts. While this test was better than a functional test, it still did not guarantee, for example, that a shutdown valve would close fully and be leak-tight. Such tests could only be carried out just prior to a scheduled shutdown if we had to avoid production losses. Operations agreed with the proposal.

Found a mistake? Please highlight the word and press Shift + Enter  
< Prev   CONTENTS   Next >

Related topics