13 3/8" btc casing coupling 1.Grade: J55, K55, N80, ... NU 3.Standard: API 5CT 13 3/8" btc casing coupling--------------------------------------------------------------------------------------------SpecificationAPI Tubing CouplingSize and SpecificationDescriptions and SizeType ... 8”TYPE: NUE, EUE (tubing coupling), STC, LC, BTC (casing coupling).SURFACE TREATMENT: Whole phosphating, or inside phosphating ...