Special Thread for API Casing Pipe

 　　API casing threads are not suitable for the development of high-pressure gas fields, so many manufacturers have developed special joints with their own characteristics. Among them, the gas-sealed special joint thread types suitable for the development of gas fields are:

　　1. NS-CC thread (developed by Nippon Steel), its main features are:

　　1.1 The thread adopts improved API partial trapezoidal thread. High tensile strength of the joint;

　　1.2 Cone surface and cone surface metal main seal and inner shoulder metal secondary seal, so that the joint has good air tightness;

　　1.3 The stepped double straight shoulder structure makes the joint have good anti-torsion and bending ability, and is beneficial to protect the main seal;

　　1.4 The circumferential stress on the joint is lower, which helps prevent stress corrosion cracking.

　　2. Fox thread (co-developed by Kawasaki Steel in Japan and Hunting in the UK).

　　3. TM thread (Japan Sumitomo Metal's improved design based on VAM thread)

　　4. SEC thread (designed and produced by Siderca, Argentina)

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