Cause Analysis on Piercing of a Drilling Pipe at Welding Area

The analysis of piercing hole macro-appearance, microstructure, energy spectrum, chemical compositions and hardness test were carried out to the piercing drilling pipe. The results show that as a certain area of welding grey spot defect existed in welding area of the drilling pipe, the bonding strength, fatigue property and impact toughness of the drilling pipe welding seam were reduced greatly, which led to the piercing of the drilling pipe early at welding area. Finally, the prevention methods and suggestion were put forward.