Thanks above.
"Chinese Power station steam&water pipe stress analysis technical rules" is coming from ASME B31.1,but I can not find informaion about the relaxation cold state case in ASME B31.1.But according to our rules,we should compare relaxation cold state case with initial cold state case,and select the bigger result(Force&moment)to match the requirement of equipement nozzle.
So,it's not about stress,it's only about the force&moment acting on the nozzles.There are some manufacturing company need these data to check their nozzles.So maybe it's only the equipment factory's requirement,and maybe they know how to calculate these.