B31.3, par 345.3 states "Where the test pressure of piping attached to a vessel is the same as or less than the test pressure for the vessel, the piping may be tested with the vessel at the piping test pressure".

My question is: when hydrotest of a line connected to a vessel, to a rotating machine, to a filter, and so on is made, is the piping always, or sometimes connected to the equipment?
If yes, do you think that the nozzles load should be checked for HYD case too?

And, what about steam out condition?
Thank you.

I found something else.
B31.9, par.937.2.4 states "Equipment that is not to be subjected to the test pressure shall be isolated from the piping. If a valve is used to isolate
the equipment, its closure shall be capable of sealing against the test pressure without damage to the valve. Flanged joints at which blinds are inserted to isolate equipment need not be tested."

Chakot,
Sometimes connected to equipment.
Piping and instrument components such as control valve, steam trap, strainers, etc. are replaced with temporary spool. Thus, nozzle evaluation under this case is evaluated.
Hydro test for short lines with expansion joint and any other especial components are done on the ground. Evaluation of nozzle under this case is not considered.
For equipment that is separated for hydro test but piping is connected during hydro testing, blind plate should be inserted in the nozzle face and still nozzle evaluation is consider.
Pressure under hydro test is 1.5xdesign pressure; I think it is greater compare to the pressure used for steam out condition. If the pressure used for stream out condition is greater than the hydro test then you can add another load case in order for you to evaluate.