The welding process used to join the ends of two pipes of uniform cross-section, is
A
Spot welding
B
Seam welding
C
Projection welding
D
Upset butt welding
Correct Answer: Upset butt welding
Upset butt welding is a welding technique that produces coalescence simultaneously over the entire area of abutting surfaces or progressively along a joint, by the heat obtained from resistance to electric current through the area where those surfaces are in contact