Thermal expansion range and friction force direction Thermal expansion range and friction force direction KevinNZ (Mechanical) (OP) 15 Jul 13 19:23 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 RE: Thermal expansion range and friction force direction 4Pipes (Mechanical) 6 Aug 13 10:52 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. RE: Thermal expansion range and friction force direction BigInch (Petroleum) 10 Aug 13 01:38 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. RE: Thermal expansion range and friction force direction DSB123 (Mechanical) 13 Aug 13 07:23 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.