Green pipes, raw steel tubes, are processed through a number of steps to make them into drill pipes. First, the walls of green pipes are thickened by a process called "upsetting" through which a pipe's exterior surface is pushed inward. Next, the pipes are threaded and receive a strength-enhancing copper plating. Nondestructive quality control inspection then takes place, after which the pipes are welded to tool joints. Pipes then undergo weld heat treatments and a weld finishing processes that removes welding stress. More tests, including hardness, pressure and non-destructive inspection are carried out on the finished drill pipes before final coating and packaging.
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No. | Outside diameter | Grade | |
inch | mm | ||
1 | 2 3/8 | 60.3 | G105,S135 |
2 | 2 7/8 | 73.0 | G105,S135 |
3 | 3 1/2 | 88.9 | G105,S135 |
4 | 4 | 101.6 | G105,S135 |
5 | 4 1/2 | 114.3 | G105,S135 |
6 | 5 | 127.0 | G105,S135 |