In addition, drill pipes mostly use butt-welded connections between pipe ends and tools, and welds and their heat-affected zones are weak links in strength. In order to improve the strength of the weld zone, the pipe end is generally thickened.
There are three types of pipe end thickening: internal thickening, external thickening and internal and external thickening. In addition, according to production needs, one end of the drill pipe is a male tool joint and the other end is a female tool joint. It is required that the drill pipe body and the male and female tool joints be connected by welding. In order to increase the strength of the weld, both ends of the drill pipe body should be thickened before welding. Drill pipes (pipes) mostly use the welding connection between the pipe end and the tool to the welding zone. The welding and heat affected zone are weak links of strength. In order to improve the strength of the weld zone, the pipe end is generally thickened.