What are the Thread Connection Requirements Between Drill Pipes (API, GOST, Premium)?

Threaded connections between drill pipes and tool joints must adhere to strict international standards: the American Petroleum Institute (API) standards (such as API 5CT for casing/tubing threads) and the Russian GOST standards are the global mainstream.

Typical API thread types include API round threads (round threads, commonly used for casing) and API buttress threads (trapezoidal threads, with high shear strength, commonly used for casing). The Eurasian GOST specifications are similar. These standards have extremely stringent requirements for thread geometry and tolerances — pitch, thread angle, diameter, and length dimensions must be controlled within very small tolerances to ensure component compatibility and connection sealing.

In addition, premium connections, as proprietary gas-tight threads, surpass API standards and feature optimized profiles, gas-tight metal-to-metal seals, higher torque transmission, and improved sealing and connection surfaces. They are suitable for high-pressure, deep-hole, highly corrosive environments, and scenarios requiring frequent assembly and disassembly. Their contour shapes are more complex, and manufacturing precision requirements are higher.