According to API 5CT, Grade: K55/J55 N80 L80 P110
Series of API casing couplings:
API CASING COUPLINGS - SHORT THREAD (STC)
API CASING COUPLINGS - LONG THREAD (LTC)
API CASING COUPLINGS - BUTTRESS THREAD (BTC)
API TUBING COUPLINGS - EXTERNAL UPSET END (EUE)
API TUBING COUPLINGS - NON UPSET END (NUE)
COUPLING PIPE GRADE IDENTIFICATION BY PAINT COLOR