A Study on the Development of Diagnosing System of Defects on Surface of Inner Overlay Welding of Long Pipes using Liquid Penetrant Test

PT를 이용한 파이프내면 육성용접부 표면결함 진단시스템 개발에 관한 연구

  • Lho, Tae-Jung (School of Mechatronics Engineering, Tongmyong University)
  • 노태정 (동명대학교 메카트로닉스공학부)
  • Received : 2018.07.11
  • Accepted : 2018.10.05
  • Published : 2018.10.31


A system for diagnosing surface defects of long and large pipe inner overlay welds, 1m in diameter and 6m in length, was developed using a Liquid Penetrant Test (PT). First, CATIA was used to model all major units and PT machines in 3-dimensions. They were used for structural strength analysis and strain analysis, and to check the motion interference phenomenon of each unit to produce two-dimensional production drawings. Structural strength analysis and deformation analysis using the ANSYS results in a maximum equivalent stress of 44.901 MPa, which is less than the yield tensile strength of SS400 (200 MPa), a material of the PT Machine. An examination of the performance of the developed equipment revealed a maximum travel speed of 7.2 m/min., maximum rotational speed of 9 rpm, repeatable position accuracy of 1.2 mm, and inspection speed of $1.65m^2/min$. The results of the automatic PT-inspection system developed to check for surface defects, such as cracks, porosity, and undercut, were in accordance with the method of ASME SEC. V&VIII. In addition, the results of corrosion testing of the overlay weld layer in accordance with the ferric chloride fitting test by the method of ASME G48-11 indicated that the weight loss was $0.3g/m^2$, and met the specifications. Furthermore, the chemical composition of the overlay welds was analyzed according to the method described in ASTM A375-14, and all components met the specifications.


Automatic PT inspection system;Deformation analysis;Diagnosing surface defects;Liquid Penetrant Test(PT);Overlay welding;Structural strength analysis;3D modeling


Supported by : 동명대학교


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