... ", 13 3/8", 16", 18 5/8", 20", 30" Grade J55, K55, N We supply all sizes and grades of casing ... 7/8", 3 1/2", 4", 4 1/2" Grade J55, K55, N80, L80-1, L80-9Cr, L80-13Cr, C90, T95 ... , L80-1, L80-9Cr, L80-13Cr , C90, T95, P110, Q125 API Connections Round thread(8tpi, STC and LTC), Buttress thread (5tpi ... nitriding coating; Vacuum insulated; HDPE liner Casing and Tubing in API Spec 5CT