Gas Metal Arc Welding (GMAW) Flux Cored Arc Welding (FCAW) Metal Cored Arc Welding (MCAW) Practice Test

When assembling a pipe joint, tack welds are used to position and lock the pieces before the full weld. For a circular joint like an 80 mm pipe, you need enough tacks to resist rotation and keep the joint aligned during welding. Placing three tacks evenly around the circumference (about 120 degrees apart) gives three-point stabilization so the halves can’t tilt or shift while you weld the seam. The length should hold the pieces but not create excessive heat or distortion. About 12.7 mm (1/2 inch) is a common tack length for this size, providing sufficient hold without overdoing the heat. Two tacks would allow rotation around the joint; four would be more than necessary and add extra heat; one tack cannot secure the entire circumference. So three tacks at 12.7 mm long is the appropriate approach.