Evaluation of Allowable External Pressure for Branch Pipe Connections

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

Section: Introductionmentioning

confidence: 99%

Pressure Tests for Thickness Management of Wall Thinning Tees

Teshima

Iwamoto

Hojo

et al. 2012

“…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].…”

Section: Introductionmentioning

confidence: 99%

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

Miura

Yamakami

Iwahara

et al. 2012

Self Cite

T-pipe is one of the typical structural elements of LWR piping as well as T-joint. In the present situation, the evaluation of wall thinning for T-pipe is accomplished by assuring the sufficient strength around the opening area by using the design and construction code. This evaluation often assumes the replacement of a local wall thinning with a global wall thinning, which leads to excessively conservative prediction of burst pressures. In this study, three-dimensional finite element analysis was conducted to simulate the fracture behavior of a pressurized T-pipe test. The accuracy of the predicted burst pressures and appropriate modeling of the welded joint at the junction of the main and branch pipes were investigated. It was found that the burst pressure could be adequately predicted by applying a proper fracture criterion.

“…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-joints (Tees) mock-ups [1] , FE analyses for the T-joints mock-ups [2] , evaluation of external pressure for T-joints [3] and developed a guideline for management of wall thinning of tees [4] . Also this project studied T-pipes (welding Tbranch connection) by an experimental mock-up test and FE analysis [5] and the management of wall thinning of the T-pipes (branch connection).…”

mentioning

confidence: 99%

The Proposal of Wall Thickness Management Criteria of T-Pipes

Tsunokawa

Ohira

Miura

et al. 2012

Self Cite

Although the reinforcement for openings is checked in accordance with design / construction standard when thinning was observed in T-pipes, this evaluation becomes too conservative or requires much time and effort.This paper describes additional parametric study results and proposes a guideline for thickness management of wall thinning T-pipes. On the other papers related to this project, the experiment and numerical simulation results are reported. This paper referred these results and performed further investigation. 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-joints (Tees) mock-ups [1] , FE analyses for the T-joints mock-ups [2] , evaluation of external pressure for T-joints [3] and developed a guideline for management of wall thinning of tees [4] . Also this project studied T-pipes (welding Tbranch connection) by an experimental mock-up test and FE analysis [5] and the management of wall thinning of the T-pipes (branch connection).This paper explains the proposals of wall thickness management criteria of T-pipes. When the wall thinning was observed in T-pipes, reinforcement for openings based on reduced thickness is checked in accordance with existing Japanese design / construction standard [6] . However, this evaluation becomes too conservative and requires much time and effort. Therefore, rational criteria of wall thickness management for T-pipes were desired.