The repair technique of lengthening drilling tools by stub welding has been in existence since the 1940s. Over the past sixty years this process has become highly advanced due to modern day technology and the advanced development of welding materials. Today an operator can expect to double the life span of his drilling tools through the use of stub welding technology.
Quality stock used for stubbing
The welding stages are constantly monitored to ensure only the purest weld is applied into the groove. The submerged ARC technique creates a protective slag layer over the weld as it is being applied, which is then removed before that same area returns to the welding head for its next pass. Even large cross sectional welds retain sufficient tensile strength to provide a good safety factor of weld strength over the strength of the pin/box connection. The weld material is also soft enough to provide good resistance against fatigue cracking with a safety factor of 1.25 over the connections when 70,000 PSI weld is used.
Tools to consider for stub-welding