超声波检验SA335P91主蒸汽管道焊缝根部未焊透误判原因分析  

Analysis of Misjudgment of Lack of Root Fusion in Weld of SA335P91 Main Stream Pipe

作　　者：李泽峰[1] 孙常明[1] 鲁玉龙[2] 

机构地区：[1]内蒙古电力科学研究院,内蒙古呼和浩特010020 [2]北方联合电力有限责任公司达拉特发电厂,内蒙古达拉特014300

出　　处：《内蒙古电力技术》2013年第5期90-93,共4页Inner Mongolia Electric Power

摘　　要：对某火力发电厂200 MW机组SA335P91主蒸汽管道对接焊缝进行超声波检验时发生的根部未焊透误判进行了原因分析。结果表明误判主要源于以下2个因素:一是焊接坡口异常,存在焊缝根部沿壁厚方向向内车进5 mm的V形坡口,而管道设计壁厚为27 mm,因此焊缝中心处实际壁厚为22 mm;二是没有严格按规程要求采用SA335P91对比试块,而采用20钢试块制作DAC曲线,二者声速不同而最终导致定位存在误差。该案例分析可为超声波探伤提供实践经验。In this paper, the main reasons for misjudgment of lack of root fusion in the butt weld of SA335P91 main stream pipe by means of ultrasonic examination was investigated. The reasons for the misjudgment were concluded as follows： On the one hand, the root of the weld was V gloove with the maximum depth of 5 mm by turning, thus the thickness in the weld center could be caculated as 22 mm depending on the design thickness（which is 27 mm）. On the other hand, the DAC curve was established by 20 reference block rather than SA335P91 one, thus due to different sound velocities of two materials the position error could not be ignored. The case in this paper could provide practical experiences for ultrasonic examination.

关 键 词：SA335P91焊缝 超声波检验 DAC曲线 误判 声速差异 

分 类 号：TG115[金属学及工艺—物理冶金]