The OP vanished long ago (no wonder)

In real terms, one should not (IMHO) be doing any hand calcs or rules of thumb to validate nozzles etc. At the Purchasing stage, the vendor should clearly indicate REASONABLE nozzles forces (or design codes) allowed on his equipment.

The Stress Engineer then has to validate the resultant forces with Ceaser and Job done.

Anything alse is accepting risk of failure from the vendor and is not best practice