I am working on a tower line connected to an exchanger. The support next to the exchanger nozzle is getting lifted up. My nozzle qualifies for WRC 107 and is safe with the sustained loads of the system. The hot sustained case loads trouble my exchanger nozzle. Should i go in for a spring instead of a rigid support near the exchanger or should i consider the system to be safe since my nozzle qualifies for the normal operating as well as design condition.

I do not think this nozzle is safe at operating and design condition because you already found the hot sustained load have trouble.

First, you check if you took out the lift up rigid support to get more reasonable hot sustained case load on nozzle.
Second, if you have FEA program, you check the nozzle stress with FEA program since the result of WRC107, i think, is generally conservative comparing to FEA. If you can not use FEA, you would be better add a spring support adjacent of nozzle.

Thanks for your suggestions. I had to apply a spring at that location.