管道环焊缝结构性应力集中效应与拘束度评估  

Structural stress concentration effect and constraint evaluation of girth weld in pipeline

作　　者：杨辉 王富祥 戴联双 李梓溦 YANG Hui;WANG Fuxiang;DAI Lianshuang;LI Ziwei(Pipechina Institute of Science and Technology,Langfang 065000,China;China Oil&Gas Pipeline Network Corporation,Beijing 100000,China;School of Materials Science and Engineering,Tianjin University,Tianjin 300072,China)

机构地区：[1]国家管网集团科学技术研究总院,河北廊坊065000 [2]国家石油天然气管网集团有限公司,北京100000 [3]天津大学材料科学与工程学院,天津300072

出　　处：《压力容器》2022年第10期78-86,共9页Pressure Vessel Technology

基　　金：国家管网集团重大专项“高钢级管道环焊缝缺陷检测评价技术研究”(WZXGL202104)。

摘　　要：多起管道环焊缝失效事故表明,当焊缝韧性储备不足的情况下,结构性应力集中效应极其危险,且在结构安全评定过程中易被低估。为验证这一推断及研究结构性应力集中效应对管道环焊缝承载能力的影响,选用应力三轴度作为统一拘束表征参数,采用有限元模拟方法,定量研究了含错边、不等壁厚、裂纹及其组合模型与单边缺口拉伸试样(SENT)、单边缺口弯曲试样(SENB)、紧凑拉伸试样(CT)以及中心裂纹板(CCP)4种类型标准试样的拘束差异。结果表明:焊根处应力三轴度与错边量、壁厚比、内坡角度成正比,且叠加裂纹后应力三轴度显著增大;相同宽度和厚度的标准试样的应力三轴度的水平排序为CT>SENB>SENT>CCP;应力三轴度越大,拘束水平越高,结构完整性评估中确有低估结构性应力集中效应影响的可能性,应选择与实际结构裂尖拘束度相匹配的标准试样进行断裂评估,可大大增加评估结果的准确性。A number of girth weld failure accidents show that the structural stress concentration effect is extremely dangerous and easy to be underestimated in the process of structural safety assessment when the weld toughness reserve is insufficient.In order to verify this inference and study the influence of structural stress concentration effect on the bearing capacity of girth weld of pipeline,stress triaxiality was selected as a unified constraint characterization parameter,and the constraint differences between the misalignment,unequal wall thickness and crack models and combined model of them and four types of standard specimens,i.e.,SENT,SENB,CT and CCP,were quantitatively studied us finite element simulation method.The results show that the stress triaxiality at the weld root is proportional to misalignment,wall thickness ratio and inner groove angle,and the stress triaxiality increases significantly after superposition of cracks.The order of stress triaxiality levels of standard specimens with the same width and thickness is CT>SENB>SENT>CCP.The higher the stress triaxiality is,the higher the constraint level is.It is truly possible that the influence of structural stress concentration effect is underestimated in structural integrity assessment.Therefore,it is necessary to select the standard specimen matching the constraint of the actual crack tip for fracture assessment,which can greatly increase the accuracy of the assessment results.

关 键 词：管道 环焊缝 应力集中效应 应力三轴度 拘束 完整性评估 

分 类 号：TH49[机械工程—机械制造及自动化] TQ055.8[化学工程] O343.4[理学—固体力学]