Thermal Mixing Points: A Thermomechanical Stress FEA Procedure

This paper outlines a procedure for calculating and evaluating the stresses in piping thermal mixing points, which combine process streams of significantly different temperatures. The temperatures and stresses in the pipe at the mixing point are calculated using 3-D finite element analysis. The temperature field calculations use a pipe flow heat transfer correlation. Once the temperature field is determined, it is used to calculate the thermal stresses. The stress results are calculated using the methodology of WRC-429 and compared to the allowable limits. The results of two sample mixing points are shown.