Dan,

The operating temperature is 31 degC and even with it the system fails with 122% overstress.

With design temperature 61 DegC system fails with 140% overstress.

Client specification also restricts me saying: Piping flexibility and stress analysis shall consider the most severe specified temperature
and coincident design pressure.

Line list design temperature is 61 degC.

Additional Information: The pipes are with threaded connection.

Regards
Zhambul