Calculation and Analysis of structural stress optimization of high temperature reheated steam pipe

Abstract

Based on the analysis of the cracking failure cause of the large-thick wall tee fittings of the high-temperature reheat steam pipe of a 670MW unit in a power plant, it is found that the stress concentration of the weld structure deviating from the design size was the main reason for the failure of the weld. Through the optimization design of the structure of the failed weld, the finite element stress analysis method was used to reasonably calculate the stress distribution at the weld, and the on-site non-destructive testing technology and the support and hanger adjustment technology was accurately guided, and then the peak stress before and after the optimization of the weld structure was reduced from 295.55 MPa to 112.64 MPa, and the reduction ratio reached 162.38%. At the same time, the verification requirements of the third strength theory of materials was met, and a reliable safety status risk assessment for the safe operation of the unit was provided.