Any guide lines to decide maintenance cycle ?

[swlee]

I'm preparing a maintenance planning. I want to know if there is any guide lines or practices to classify each instrument depend on the influences due to the failure of instruments in the refinery or petrochemical plants. How can I decide the period of maintenance of each instrument ?
There are several web pages introducing computerized maintenance scheduler however I couldn’t find any tips.

 

[rbcoulter]

The "benchmark" maintenance cycle should be determined
by the vendor/supplier of the instrument.

 

[SooCS]

API RP 14C has a very good guideline for safety devices and for offshore application in GOM, 30CFR.

If you are know what SIL level you are trying to achieve, OREDA might be a good source of information.

Best of luck

 

[saxon]

SWLEE, The best approach is to establish a real world, empirical approach to preventive maintenance requirements and cycle times. Such that, the original bench mark is to establish the manu'f. recommended maintenance cycle, then adjust it either up or down, depending on operational experience and failure rate. Over time you will hit the optimal cycle. In some situations, maintenance cycles can be established on a predicative basis, but this requries much more installed diagnostic equipment and instrumentation.

Hope this helps.

saxon

 

[riskfree]

What you need is basically a reliability study. You determine what the probability of failure is of each equipment and decide whether this is acceptable for you. If it is not acceptable you make sure you test (maintain) the equipment periodically until your reach a probability of failure which is acceptable. Now in practice this does not mean that you need to do that for all you equipment. Normally you test your equipment based on the periodic scheduled plant maintenance. If you have a goal to go down only once in five years then you make sure you also test all your equipment for that. If it turns out that certain equipment is sensitive you need to check those more frequent without having to put the plant down. You need to rank your equipment based on risk factors. You can do that for example with an FMEA.

The software to schedule is only the next step. First you need to figure out on what frequency. So firs the reliability studies, then scheduling. There are many tools and techniques that you can use for reliability study but the best one is to put the burden on your supplier. Let them proof to you with a report what the probability of failure is. Don't let them just give you MTBF and those kind of numbers. Risknowlogy
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