All accessories except welded pup joints are manufactured from solid modified alloy steel bars similar to drill collars which are fully heat treated to the required chemistry and mechanical properties. The internal bore is trepanned with precision and machined to size with comprehensive quality control.
At request, connections can be cold rolled after machining and phosphate to reduce galling and corrosion.
In addition, pup joint fatigue strength can be improved by incorporating stress relief features on API pin and box connections.