Dimensions & weights welded and seamless wrought steel pipes ASME B36.10

Notes:

• The size of all pipe in Table above is identified by the dimensionless designator nominal pipe size (NPS) or diameter nominal (DN).
• Pipe NPS 12 (DN 300) and smaller have outside diameters numerically larger than their corresponding sizes. In contrast, the outside diameters of tubes are numerically identical to the size number for all sizes.
• The manufacture of pipe NPS 1/8 (DN 6) to NPS 12 (DN 300), inclusive, is based on a standardized outside diameter (O.D.).
• This O.D. was originally selected so that pipe with a standard O.D. and having a wall thickness that was typical of the period would have an inside diameter (I.D.) approximately equal to the nominal size. Although there is no such relation between the existing standard thickness - O.D. and nominal size - these nominal sizes and standard O.D.s continue in use as standard.
• The manufacture of pipe NPS 14 (DN 350) and larger proceeds on the basis of an O.D. corresponding to the nominal size.

Outside diameter tolerances for Seamless and Welded Pipes ASTM A530

PIPE NPS/ DN/ OD	Allowed Outside Diameter Tolerance
	Over		Under
	inches	mm	inches	mm
NPS 1/8 to 1.1/2 DN 6 to 40 OD 10.3 to 48.3 mm	1/64	0.4	1/64	0.4
Over 1.1/2 to 4 DN 40 to 100 OD 48.3 to 114.3 mm	1/32	0.8	1/32	0.8
Over 4 to 8 DN 100 to 200 OD 114.3 to 219.1 mm	1/16	1.6	1/32	0.8
Over 8 to 18 DN 200 to 450 OD 219.1 to 457 mm	3/32	2.4	1/32	0.8
Over 18 to 26 DN 450 to 650 OD 457 to 660 mm	1/8	3.2	1/32	0.8

Pipes inside diameter tolerance

• Forged and Bored, and Cast Pipes.
  The inside diameter shall not vary under that specified by more than 1/16 in. (1.6 mm). There shall be no variation over the specified inside diameter.

Pipes wall thickness tolerance

PIPE NPS/ DN/ OD	Tolerance, % from Nominal
	Over	Under
NPS 1/8 to 2.1/2, incl. all t/D ratios DN 6 to 65 OD 10.3 to 73.0, mm	20.0	12.5
NPS 3 to 18, incl. t/D up to 5% DN 80 to 450 OD 88.9 to 457, mm	22.5	12.5
NPS 3 to 18, incl. t/D > 5% DN 80 to 450 OD 88.9 to 457, mm	15.0	12.5
NPS 20 and larger, incl. welded, all t/D ratios DN 500 OD 508, mm	17.5	12.5
NPS 20 and larger, incl. seamless, t/D up to 5% DN 500 OD 508, mm	22.5	12.5
NPS 20 and larger, incl. seamless, t/D > 5% DN 500 OD 508, mm	15.0	12.0

Pipes weight tolerance

The pipes weight tolerance depends on the nominal pipe size.

• Pipes NPS 12 (DN300, 323.8mm) and under, weight tolerance is.. -3.5% / +10%
• Pipes over NPS 12 (DN300, 323.8mm),weight tolerance is.. -5% / +10%
• Pipe of NPS 4 (DN100, 114.3mm) and smaller may be weighed in convenient lots; pipe in sizes larger than NPS 4 shall be weighed separately

Pipes length tolerance

• Seamless and Welded (no filler metal added).
  If definite cut lengths are ordered, no length of pipe shall be under the length specified and not more than 1/4 in. (6.35 mm) over that specified.
• Forged and Bored, Cast, and Cast Cold-Wrought.
  If definite cut lengths are ordered, no length of pipe shall be under the length specified and not more than 1/8 in. (3.2 mm) over that specified.
• For pipe ordered to random lengths, the lengths and variations shall be agreed upon between the manufacturer and purchaser.