Coupling Tubing and casing couplings are the joining of two short length pipe, mainly used for the connection and repair of oil pipe and downhole tools Tubing and couplings thread types : Non-upset thread(NU), External- upset thread(EU); Casing and couplings thread types: Long-round thread(LC), Short-round thread(SC), buttress thread(BC) Grade: K55,J55,N80-1,N80Q,L80-1,P110,etc. Pup joint Tubing and casing pup joints are machined according to the latest version of API SPEC 5CT. The steel grade includes J55,K55,N80-1,N80Q,L80-1,P110,etc. There are two types of thread widely used in tubing pup joint namely Non-upset thread(NU), External- upset thread(EU); Casing and couplings thread types: Long-round thread(LC), Short-round thread(SC), buttress thread(BC). Our testing and inspection method system is complete, using a whole set of thread instrument to inspect taper, pitch, tooth, height, tooth type,etc. The products have passed the identification of china petroleum pipeline. Quality supervision ,inspection and testing center and gained the unanimous praise from the customers. Crossover Crossover coupling any size ,length ,grade and weight is available on customer request.