... 9-4-1/2 Threads:NU, EU Coupling Manufacturer of Tubing and Casing coupling according to API SPEC 5CT AND 5BAPI ... 13-3/8" 4.Type: NU, EU(tubing coupling), STC,LC,BTC(casing coupling). 5.Surface treatment: Whole phosphating, or inside phosphating ... pup joints, tool joints, adapter pup-joints, adapter couplings, stabilizers, air-liquid separators, anchors of oil pumps and revolving sand gravitated ...