... the pressure loss completely interchangeable with the API drill pipe oil steel casing1) OD: 2 7/8", 3 1/2", 4 ... tons.Items: Elbow,Tee,Cross,Socket,Union,Bushing,Backnut, Nipple,Crossover, Caps,Plug etc.We will always establish or develop good ... home and abroad contact with us and promote business relations. oil steel casing