Developing a Nondestructive Testing Program for Homopolar Welding of API 5L Line Pipe

Developing a Nondestructive Testing Program for Homopolar Welding of API 5L Line Pipe
Robert S. Hudson and Robert W. Carnes, Jr., Center for Electromechanics, The University of Texas at Austin, J.J. Pickle Research Campus · Mail Code R7000, Austin, Texas 78712. (512) 232-1678;
Francis J. Dodd, Automated Inspection Systems, Inc., 4861 Sunrise Drive, Suite 101, Martinez, California 94553. (510)335-9206

Review by NDTnet
The paper was presented by Robert Hudson. The program was developing a NDE program for qualifying the new welding process and for use on the J-Lay pipe laying production. The most importand steps in developing a NDE program consisted of characterizing possible HPW flaws, identifying what will be the best suited NDT method, developing appropriate tests and calibration blocks, applying the method, and correlating the results with weld and real time process parameters, destructive testing results, and microstructural features. Probes used to interrogate the weld line include pulse-echo, TOFD, and tandem. Of these probes, the tandem was considered the best suited to detect any reflectors oriented along the weld plane. Successful test techniques will be applied to twelve inch pipe welds. A follow-on program to the present research program is proposed which will include a fracture mechanics study of HPW and a NDT program. The goal of the NDT program will be a qualified NDT method for HPW. Microstructural characterization for HPW is also proposed.

Robert Hudson with Outline of Presentation

Homopolar Offshore Pipeline Welding Research Program

Introduction

Ultrasonic Testing was demonstrated at the Booth

Table 1: Summary of possible Defects in Solid State Welds. Viewgraph reproduced by NDTnet !:indicates possible occurence
Defect	Method
Defect	Electric Resistance Weld	Flash Butt Weld	Friction Weld	Diffusion Weld	Homopolar Weld
Hook Cracks
Penetrators - Flat Spots	!	!
Decarburization	!	!	!
Cold Welds			!	!	!
Partial Bonding	!	!	!	!	!
Weld Area Crack	!	!	!	!	!
Inclusions	!	!	!	!	!
Porosity	!	!	!	!	!
Hydrogen Entrapment	!	!	!	!	!