基于DNVGL-ST-F101-2017规范的要求，结合海底管线U型坡口焊缝的特点，选择直径为168 mm，壁厚为18.6 mm及管径为508 mm，壁厚为31.8 mm的两种规格管线，制作一系列焊接缺陷，焊接缺陷分布于焊缝根部、热焊、填充及表面区域，缺陷类型包括未熔合、气孔及层间未熔合等。使用TOFD （超声衍射时差法）和PAUT （相控阵超声检测）工艺对试验焊缝进行扫查，评定不同位置缺陷的尺寸，对所有评定的缺陷进行金相试验，通过对比TOFD和PAUT测量结果与金相试验结果的偏差，确定TOFD和PAUT检测的准确性及可靠性。

Based on the requirements of DNVGL-ST-F101-2017 and in combination with the characteristics of U-groove welds of submarine pipelines, two types of pipeline were selected for the test, in which the diameter of one pipeline is 168 mm with its wall thickness being 18.6 mm, and the diameter of the other one is 508 mm with its wall thickness being 31.8 mm. A series of defects including non-fusion, porosity and inter-run etc were made for the two types of pipeline, and the locations of welding defects were distributed in the root, hot pass, filling and surface of the weld. TOFD(time of flight diffraction) and PAUT(phased array ultrasonic testing) technique were used to scan the test welds, and furthermore evaluation of the defects, sizing and metallographic test for all the defects were carried out in order to determine the sizing result deviation. By comparing the differences between TOFD and PAUT measurement results and metallographic test results, the accuracy and reliability of TOFD and PAUT testing can thus be determined.