My understanding is like this:

API 610 Nozzle loads are set based on the following two parameters:

1) Casing distortion.

2) Shaft deflection.

It can be expected ( although I feel that always need not be)that casing deflection and shaft deflection will be more when the running pump interacts with the piping loads than when the piping loads are imposed on idle pumps. But how to quantify? Hence , I feel that just because a pump is idle , higher loads can be imposed on them ( that too by a specified %) is not justified.

Regards

Regards