P91钢管在焊接过程中,若工艺控制不严，易产生层间微裂纹缺陷。该缺陷长度及高度尺寸均较小，单纯使用射线探伤易漏检。使用超声波检测时反射波高较低，按现有超声波探伤标准判伤，也易造成漏检或误判。通过对P91钢管对接焊缝层间裂纹缺陷的超声波检测及现场解剖实例介绍，提出了此类裂纹缺陷的有效检出方法和判伤建议，即进行射线检测的同时进行超声波检测，对于怀疑位置可进行TOFD检测复核。

If the process of the welding was not controlled strictly in the P91 pressure pipebutt weld, the interlayer cracks would occur easily. The interlayer cracks were too small to be examined out if only using radiographic inspection. The reflected echo of ultrasonic tesing was too low to be examined out, thus causing misjudgement as well. Through introducing the real example of ultrasonic testing of interlayer cracks in P91 pipe butt weld field dissection, the effective method and suggestion on how to exam the P91 pressure pipe’ butt weld of interlayer cracks was proposed, that is to use the ultrasonic testing method and at the same time to use the method of radiographic inspection, and use the TOFD as well, if necessary.