Thermal expansion range and friction force direction

[KevinNZ]

Does anyone have a good rule/method for accounting for the change in friction force direction between line heating and cooling? This change increases then thermal moment range.

Should we even bother?

Kevin

 

[4Pipes]

No - but IMHO this is very good question.
Probably yes - especially for systems that are are not sufficiently controlled. However, it normally goes in the too difficult file.

 

[BigInch]

Make your tie-in temperature somewhere between hi and low temp. Then check expansion stress to the hot direction and contraction stresses in the cold direction based on the differences from the tie-in temperature.

Independent events are seldomly independent.

 

[DSB123]

Biginch,
It's the thermal Stress Range (from Hot temp to Cold temp) that is important. Going from tie-in temp to hot OR from tie-in temp to cold is only significant for thermal loads on supports or displacements. The Full thermal stress range is the check for Code compliance.