Proposal of a Guideline for Thickness Management of Wall Thinning T-Joints

Abstract

Although the required minimum thickness (tsr) of T-joints (tees) of class 2, 3 and lower classes of nuclear power plants in Japan is calculated from the design pressure and temperature for design, there are neither any rules nor standards for thickness management of wall thinning T-joints for facilities maintenance. This paper describes additional parametric study results and proposes a guideline for thickness management of wall thinning T-joints. In other papers related to this project, the experiment and numerical simulation results are reported. This paper refers to these results and performs further investigation under the consideration of JSME (The Japan Society of Mechanical Engineers) design, construction and maintenance codes and standards.

Evaluation of Fracture Behavior for Pressurized T-Pipe by Finite Element Analysis

“…Figure 13 shows the relation between the burst pressure, P b , normalized by the true tensile strength,  u , and the thickness-toouter diameter ratio, T/D, of the main pipe. The figure also shows the analysis result obtained from another series of finite element analysis for T-pipes with the same diameter of main and branch pipes [5], and the prediction line applied to T-joints (not T-pipes) with the same diameter of main and branch pipes [4]. The prediction line is given by:…”

“…This group consists of eleven Japanese electric power companies, one research institute, and three nuclear plant fabricators. This project performed burst experimental tests for T-joint mock-ups [1], finite element analyses for the T-joint mock-ups [2], evaluation of external pressure for T-joints [3], and developed a guideline for the management of wall thinning of T-joints [4]. Also this project studied T-pipes (welding Tbranch connections) by an experimental mock-up test and finite element analysis, which will be presented in this paper, and the management of wall thinning of T-pipes [5].…”