Ethanol SCC Research on PWHT Effects and Threshold Stress Determination

Recently a laboratory testing program was completed that covers an important and yet unexplored area of ethanol SCC (eSCC) of steel equipment in ethanol distribution and blending facilities. This program aimed at generating new data on the effects of post weld heat treatment (PWHT) on eSCC and also attempted to determine the threshold stresses required for eSCC. These two topics are related as the effectiveness of PWHT is based on lowering of the levels of welding-induced residual stresses in the fabricated piece to less than the threshold stress of SCC. Therefore, these two tasks will help identify acceptable guidelines for PWHT and increase confidence in field practices, thereby (a) reducing the risk of future SCC failures, and (b) providing better definition of PWHT time and temperature parameters appropriate for eSCC. The paper describes in detail the various testing methodologies and the important findings of this research program.