During recent years, Henan Dongfanglong Machine Manufacture Co., Ltd has developed a variety of products to meet the demand of domestic and overseas markets.

Dongfanglong(Eastlong)'s product line includes tubing and casing couplings, pup joints, crossovers, centralizer, packer and any other downhole tool.

The couplings and pup joints  are produced according to the standards of the American Petroleum Institute (API) and is widely used in offshore and inland gas and petroleum prospecting and recovery.

To be simple, it is the internally threaded cylinder for joining two lengths of threaded pipe.

With this purpose, API 5CT standard coupling plays an important feature in connecting casing and tubing line pipes. On the contrary, the biggest different with general steel pipe coupling is: API coupling manufacturing processes is more rigorous, requires a precisely control in the different processes as blew listed.

Raw material selection
Mechanical test including tensile strength
Impact test
Chemical properties control
Sulfide stress cracking test (for Material grades in C90 or T95)
Size tolerances, OD, Wall Thickness, Length and Straightness
Threads control, threads quantity per inch, threads angle etc (Premium threads option will be more rigorous)
Heat treatment
Additional markings
Material certification
Product Specification Level (PSL-2 or PSL-3)