I have an question for piping inside power boiler limit is it right too perform stress analysis according to ASME B31.1

What do you mean by "inside power boiler limit?"

In general, piping inside equipment aren't considered obligatory to the scope of piping standards - it's considered part of the equipment.

But if the equipment specification says to follow a piping code, then yes, it is.

According to ASME b31.1 boiler proper piping , for example piping fom boiler nozzle to first shut off valve shall follow ASME I and AASME I didn't talk about piping stress analysis

Power boiler external piping is typically governed by B31.1

However, you are still going to have to determine the scope of supply and engineering responsibility. There should be some kind of interface point delineated.

You will need to account for the movements, restraints, and any allowable loads at the interface given by the vendor as part of the analysis of the general steam piping that is beyond the block valve - assuming your firm is the one doing the overall piping design of the plant.