⑴ API Round Thread Casing Coupling
★ The dimension classification for the coupling is the same as the size designation for the pipe on which the coupling is used.
★ Groups 1, 2 as well as 3-Tolerance on outdoors diameter W: +_1% however not more than +_3,18mm.
★ Group 4-Tolerance on outside size W: +_1% yet not above +3,18, -1,59mm.
★ Tolerance on diameter of recess, Q for all teams: +0,79, 0mm.
⑵ API Buttress Thread Casing Coupling
★ The dimension classification for the coupling is the same as the size classification for the pipeline on which the coupling is made use of.
★ Groups 1, 2 and also 3: Tolerance on outdoors diameter W: +_1% but not higher than +_3,18mm.
★ Group 4: Tolerance on outdoors size W: +_ 1% yet not more than +3,18 -59mm.
★ Groups 1, 2 and 3: Tolerance on outside diameter Wc: +0,79, -0,40mm.
⑶ The casing coupling is utilized to attach 2 coverings
★ Steel grade: J55, K55, N801, N80Q, L80 1, L80 9Cr, L80 13Cr, C90, T95, P110, Q125, and so on
★ Specification: 4-1/2, 5, 5-1/2, 6-5/8, 7, 7-5/8, 8-5/8, 9-5/8,10 -3/4, 11-3/4, 13-3/8, 16, 18-5/8, 20, etc.
★ Thread type: Long round thread (LC), brief round string (STC), buttress thread (BC), unique string, and so on.