压力容器免除焊后热处理的最大厚度

Maximum exemption thickness of post weld heat treatment for pressure vessels

工程实践表明现代钢材质量与焊接技术足以保证结构钢在更大厚度时免除焊后热处理,相关厚度值远高于现行规范源于工程经验的最大焊后热处理(Post weld heat treatment,PWHT)豁免厚度规定。从压力容器防脆断的角度出发,基于断裂力学原理,研究了材料最大PWHT豁免厚度的影响因素,结合Q345R钢性能数据,评价了具体厚度值的工程适用性,分析指出保守的防脆断条款是导致我国压力容器规范最大PWHT豁免厚度小于欧美规范的根本原因。

Engineering practice shows that modern steel quality and welding technology are sufficient to ensure that the structural steel is exempt from post weld heat treatment at larger thicknesses.Relevant thickness is much larger than the provision of maximum exemption thickness of PWHT in the specifications,which originates from engineering experience.In the light of the potential brittle fracture failure of pressure vessel,the method for determining maximum exemption thickness of PWHT was suggested according to the principle of fracture mechanics.Combined with performance data of the Q345R steel,the engineering applicability of the specific thickness values was demonstrated.The results show that the conservative brittle fracture prevention requirements results in the maximum exemption thickness of PWHT in Chinese pressure vessel code being less than that of European and American codes.