What are causes and prevention of lack of penetration defect in Welding?

  1. Lack of penetration –

“Improper penetration of weld metal through the thickness of joint or weld metal not extending to the required depth into the joint root”

  • Acts as stress riser from which a crack may propagate


Cause –

  • Root gap too small
  • high welding speed
  • Low heat input
  • Too large electrode dia


  • Proper joint preparation
  • Proper heat input & welding speed
  • Use suitable size of electrode