Finite element analysis of residual strain of the dissimilar metal branch pipe joint on the primary pipe in nuclear power plant

ZHAO Liang; TU Shandong

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Finite element analysis of residual strain of the dissimilar metal branch pipe joint on the primary pipe in nuclear power plant
Vol. 49, Issue 8, Pages: 76-82(2019)
Published：2019
DOI：
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DOI：

ZHAO Liang, TU Shandong. Finite element analysis of residual strain of the dissimilar metal branch pipe joint on the primary pipe in nuclear power plant[J]. Eletric Welding Machine2019, 49(8): 76-82. DOI：

摘要

某核电厂主管道异种金属支管接头发生应力腐蚀开裂泄漏

对核安全构成一定影响

并造成了巨大的经济损失。导致接头应力腐蚀开裂的原因为接头不锈钢侧存在过高的残余应变。利用有限元方法对比分析不同焊材、热输入和结构的接头焊接残余应变

发现通过将Alloy82镍基合金焊材更换为ER309L不锈钢焊材、尽可能降低热输入、增加碳钢过渡管段等方式能够有效降低接头不锈钢侧熔合线附近的残余应变

从而缓解接头的应力腐蚀开裂敏感性。

Abstract

A dissimilar metal branch pipe joint on primary pipe in a nuclear power plant has leaked

which had certain impact on nuclear safety and caused huge economic losses. The main cause of the leakage is stress corrosion cracking（SCC） due to excessive residual strain on the stainless steel side of the weldment. In this paper

the welding residual stresses of joints with different welding materials

heat input and structures are analyzed by finite element method. It is found that the residual strain near the bond line on the joint stainless steel side could be effectively reduced with the improvements such as replacing 82 filler metal with 309L

reducing heat input and adding a carbon steel transition section

thus the SCC susceptibility of joint can be mitigated.