API RP14C C&E Diagrams

[apatjr]

I'd like to know if there is a guide explaining how the C&E diagrams are to be created. On simple cause effect systems it looks straight forward. However, in systems where one cause can have multiple effects which in turn can have secondary effects it becomes more difficult.

Any help would be appreciated.

 

[jsummerfield]

Study the current version of API RP 14C. It provides a reasonable guide.

Try to only list the measurement device as a cause once. As a process shutdown for a vessel, the high level switch may close the inlet to the vessel; or low level switch may stop the outlet pump.

Many process trips may affect the same equipment. Thus, the same shutdown devices may appear on several cause and effect diagrams.

A cascading trip occurs if you close a valve, and that valve closed status stops a pump. Try to have the device that causes the valve to close also cause the pump to trip. I think that this documentation may be required by API RP 14C. Otherwise, specification notes could require the programmer to address the some cascading shutdowns that are not obvious on the cause and effect diagrams. Consider developing the cause and effects using equipment based process shutdowns. One effect may be an emergency shutdown. A confirmed fire may cause an emergency shutdown. As "emergency shutdown" may trip nearly everything it could also be listed as a cause within each group of cause and effects. This violates my first sentence. However, you want to avoid cause and effect diagrams with hundreds of effects on the same page.

John