The document discusses common welding defects identified by Engr Muhammad Hussain, an inspection engineer at Global NDE Services Pvt. Ltd in Karachi. It lists undercut, porosity, incomplete fusion, overlap, underfill, spatter, excessive convexity, excessive concavity, excessive weld reinforcement, incomplete penetration, excessive penetration, and unacceptable weld profiles as defects addressed by Engr Hussain in his role.