11.01 What are the requirements for mission critical fuel system design?

The requirements of mission critical design is that failure of a single component is monitored by the fuel system, and the system responds with a redundant component to perform the required function. In short, the requirement is 2 of everything with the ability to monitor and switch.

In some instances, designers will use a single fuel supply and fuel return piping system aboveground to generators. The thinking is that welded steel aboveground pipe does not have a relevant failure mechanism. However many designers will provide dual parallel piping paths.

Underground piping systems, we believe should always have redundant parallel paths. The reason is that underground piping is continually subject to ground and surface loads, and that secondary containment test failure, whether real or a false positive, can triggure a shutdown of the piping system as a regulatory requirement.