Quality Welds: The basics of the I-CAR welding qualification test

Part 3 of 3: Butt Joint with Backing

Jan. 1, 2020

Quality WeldsPart 3 of 3: Butt Joint with BackingWelding Qualification Test Q&AThis month we conclude our examination of the requirements of I-CAR’s Welding Qualification Test (WQT) that began in the January issue with the step-by-step procedures to perform a plug weld on a lap joint. Last month we examined the fillet weld on lap joint. In this month’s issue we examine the most challenging weld required during the test: the butt joint with backing.The WQT requires that technicians perform a 1-1 1/2 in. weld (25-38 mm) on a butt joint with backing using Gas Metal Arc (MIG) welding equipment. The butt weld with backing is performed in both the vertical and overhead positions in the same manner as the two previous welds we examined. The butt weld with backing joins three coupons—two positioned along lengthwise with a coupon positioned behind.To perform the butt joint with backing weld in the vertical position:

Proper placement of the assembled coupons for welding in the vertical position. Be careful not to position clamps too close to the weld area.

This weld shows good tearout along its length after destructive testing.

This weld passes visual inspection. Note the reference marks at 1 1

About the Author

Russell Thrall III

Former ABRN Editor-in-Chief Russell Thrall, a second-generation collision repairer, has experienced the shop from the bottom up, starting as a clean up person and working his way to assistant manager by age 17. Thrall joined the staff of Chilton's Automotive Body Repair News in 1991 as technical editor and as senior editor in 1992. From 1993 through 2000, Thrall served as editor of Collision Repair Industry INSIGHT. Thrall returned to the staff of ABRN in June 2000 as editor-in-chief of the industry's largest monthly trade magazine. Thrall was a frequent speaker at industry events including the Collision Industry Conference (CIC), NACE, and numerous other local and regional events. He served as co-chairman of the Collision Industry Conference Electronic Commerce committee and is a member of the Board of Directors of the National Auto Body Council.