End Finishes
All pipe threads are NPT threads in accordance with the requirements of ANSI B2.1 with a taper of 3/4 inch per foot.
  One coupling is applied handling tight to each length of threaded pipe, unless otherwise specified.
  ASTM pipe — Coupling on 2 inch and smaller standard weight pipe are straight-tapped and without recess. Couplings on 2-1/2 inch through 6 inch standard weight pipe are taper-tapped and without recess. Couplings on 8 inch and larger standard weight pipe and on all sizes of extra strong and heavier pipe are taper-tapped and recessed.
  API pipe — Couplings on all sizes and weights are taper-tapped and recessed.
Plain Ends ASTM A53 pipe of STD, XS or in wall thicknesses less than 0.500 inch, other than XXS, shall be beveled. Wall thicknesses over 0.500 inch and all XXS pipe shall be cut square. Angle of bevel is not specified but normally a 30 degree bevel is furnished.
  ASTM A106 does not stipulate end finish but normal practice is similar to A53.
  API 5L plain end pipe (other than XXS) in sizes 2-3/8 inch OD and larger shall be furnished with ends beveled to an angle of 30 degree (plus 5 degree, minus 0 degree). XXS pipe 2-3/8 inch OD and larger shall be furnished with ends cut square.