The failure frequency rate are not uniform. It depends more on data available on hand. What is observed in Europe may not be true in Asia or in US. These rate can be taken from your company or group of company in your region. Or select a rate from a region that is close to you so that the predictions are more realistic.

As earlier, one sr. member brought out, there are various size of leaks (one such scenario), fire, rupture & explosions are also possible. You need to predict exactly from the statistics available in hand "the Failure rates". Moreover there are chances for you to calculate the failure rates of various accessories such as pumps, flanges, com pressures, valves etc.. In total, you need to analysis the risk rating.

Deutch Risk models as explained in blue, purple,yellow book may be consulted. or PHAST / CIRRUS can be used if you have knowledge on these.









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