Abstract: In order to solve the engineering application problem of quantitative detection technology for incomplete welding defects in welded joints of metal pressure pipes, digital radiographic technology and phased array ultrasonic technology were selected to detect the prefabricated incomplete welding defects in carbon steel and stainless steel welded specimens, and the depth and width of defects were quantified, which verified the feasibility of the two methods in quantitative detection of incomplete welding defects in metal pipes. The results show that the accuracy of digital ray technology and phased array ultrasonic technology in quantitative detection of the characteristic size of incomplete welding defects in metal pipes for the quantification of defect width and depth can meet the engineering needs of safety evaluation of welded joints in pressure pipes with defects. Digital ray technology has advantages in determining the nature of defects; Phased array ultrasonic technology has the advantages of high detection efficiency, non radiation and accurate quantification. In practical application, the inspector shall comprehensively select the detection method based on the advantages, disadvantages and application characteristics of the two technologies.Highlights: Digital ray technology and phased array ultrasonic technology are used for quantitative detection of incomplete welding defects in metal pipes. The accuracy and reliability of the two technologies are verified, and the engineering application problem of quantitative detection of incomplete welding defects in metal pressure pipes is solved.