All experts;
I encountered a strange case while chekcing piping stress for furnace unit . If a rest on support is put at some specified node , code stress check fails to be qualified for sustained load case, and if the support be removed , all code stress is qualified.

Whether from mechanical theory or practice point of view, I can not understand the case written above.
Model file is too big (over 2M) to be attched.
Anyone has the similiar experience?
Any instruction and help is highly appreciated.

Regards

Gino