Oil Drill Pipe Technology and Process

Inertial friction welding has been studied for decades and is a solid-state bonding process without melting. Due to its unique technical and economic advantages, coupled with modern monitoring technology and the use of microcomputers, this process has been widely adopted abroad.

The quality of oil drill pipe largely depends on the welding quality. In the early 1970s, pressurized gas welding and flash butt welding were used for the repair of old drill pipes and the production of new ones. However, the welding process parameters of these two methods were difficult to control, and granular or blocky oxides and silicate non-metallic inclusions easily remained in the weld, forming fatal shallow, flat, micro-pitted welding ash spots. Butt-welded drill pipes with ash spot defects are prone to early brittle fracture during use, far from meeting drilling requirements. Therefore, these two welding methods were gradually phased out.

Later, to meet the requirements of drilling technology for drill pipes, a new drill pipe production technology—friction welding—was developed. This welding method, due to its short heating time and small heat-affected zone (no more than 20mm at both ends of the weld), allows for the removal of harmful inclusions and particles generated in the weld by the pressure applied at the welding tip, significantly improving the weld quality of drill pipes and avoiding various harmful welding defects easily produced by methods such as flash welding. With continuous improvement and refinement of friction welding technology, as well as the programming and automation of welding parameter control, weld quality has become even more stable and improved, while maintaining high production efficiency and low cost. Friction welding technology currently dominates the drill pipe manufacturing process.

Among drill pipe components, the drill pipe body has a complex and highly technical processing capability. Its production process flow is as follows: converter or electric furnace steelmaking → ladle refining → continuous casting of tube blanks → tube blank acceptance → tube blank heating in annular furnace → tube blank piercing → sizing → continuous rolling → reheating → tension reduction → straightening → external surface inspection → head cutting and length cutting → internal surface and dimensional inspection → tube end thickening → tube end grinding and inspection → tempering heat treatment → hot straightening → sampling and mechanical property analysis → longitudinal and transverse non-destructive testing and inspection of internal and external surface defects.

The quality of domestic drill pipe joints has reached the level of foreign countries. Through the application of inertial friction welding technology and welding process, the performance of the weld has been stabilized. If high-quality drill pipe bodies are used, the overall performance of domestically produced drill pipes can reach that of imported drill pipes.

Read more: S135 Drill Pipe Material and Specification or Casing Pipe vs. Drill Pipe

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