Pressure Tests for Thickness Management of Wall Thinning Tees

Abstract

Although the minimum thickness of pipe wall required (t sr ) 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, there is no rule or standard of wall thinning Tjoints for thickness management.This paper describes the pressure tests procedure and six test results with parameters of T-joint geometry such as outer diameter D, thickness T and T/D to establish structural integrity of wall thinning T-joints. Based on the fracture surface observation, a ductile crack initiation of each test mock-ups was confirmed. INTRODUCTIONThe working group that studies management of wall thinning of branch pipe connections has been established in Japan. This group consists of 11 Japanese electric power companies, 1 research institute, and 3 nuclear plant fabricators. This project performed burst experimental tests for T-joint mock-ups (this paper), FE analyses for the T-joint mock-ups [1], evaluation of external pressure for T-joints [2] and developed a guideline for management of wall thinning of T-joints [3]. Also this project studied T-pipes (welding T-branch connections) by a experimental mock-up test and FE analysis [4] and the management of wall thinning of the T-pipes [5].In Japan, the minimum thickness required of carbon steel piping at the time of the design is t sr by the technical standards. t sr is evaluated by standard formula using pressure, temperature, material, an outer diameter, and allowable stress. The allowable

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

“…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].…”