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Stainless Tubing Versus Stainless Pipe Guide

Pipe: 

The purpose with a pipe is the transport of a fluid like water, oil or similar, and the most import property is the capacity or the inside diameter.


nps dn pipes


Pipe rated to ANSI B 36.10 ASME (both welded and seamless) follow that the inside diameter (ID) of a NPS 2 inches pipe with 

  • Schedule 40 is 2.067"
  • Schedule 80 is 1.939"

The IDs are close to 2" and the nominal diameter relates to this inside diameter. Outside diameter (OD) are 2-3/8" for both schedules 40 and 80 (most commonly manufactured schedules in industry)


Since the outside diameter of a single nominal pipe size is kept constant the inside diameter of a pipe will depend on the "schedule" or the thickness of the pipe. The schedule and the actual thickness of a pipe varies with the size of the pipe.


It is common to identify pipes in inches by using NPS or "Nominal Pipe Size". The metric equivalent is called DN or "diametre nominel". The metric designations conform to International Standards Organization (ISO) usage and apply to all plumbing, natural gas, heating oil, and miscellaneous piping used in buildings. The use of NPS does not conform to American Standard pipe designations where the term NPS means "National Pipe Thread Straight".


Nominal Bore (NB) may be specified under British standards classifications along with schedule (wall thickness).  The tolerances are looser to pipes compared with tubes and  they are often less expensive to produce.


Tube

The nominal dimensions of tubes are based on the outside diameter. If we look at Copper Tubes - ASTM B88 the outside diameter of a 2" pipe is 2.125", relatively close to 2".


nps dn tubes


The inside diameter of a tube will depend on the thickness of the tube. The thickness is often specified as a gauge. If we look at Copper Tubes - ASTM B88 the wall thickness of 0.083"of a 2" pipe is gauge 14.


The tolerances are higher with tubes compared to pipes and tubes are often more expensive to produce than pipes.





Nominal wall thickness for seamless and welded steel pipes according ANSI B36.10 are indicated in the table below:


Nominal Pipe Size
(in)
Outside Diameter
(in)
Schedule
102030STD4060XS80100120140160XXS
Wall Thickness (in)
1/80.405   0.0680.068 0.0950.095     
1/40.540   0.0880.088 0.1190.119     
3/80.675   0.0910.091 0.1260.126     
1/20.840   0.1090.109 0.1470.147   0.1880.294
3/41.050   0.1130.113 0.1540.154   0.2190.308
11.315   0.1330.133 0.1790.179   0.2500.358
1 1/41.660   0.1400.140 0.1910.191   0.2500.382
1 1/21.900   0.1450.145 0.2000.200   0.2810.400
22.375   0.1540.154 0.2180.218   0.3440.436
2 1/22.875   0.2030.203 0.2760.276   0.3750.552
33.500   0.2160.216 0.3000.300   0.4380.600
3 1/24.000   0.2260.226 0.3180.318     
44.500   0.2370.237 0.3370.337 0.438 0.5310.674
55.563   0.2580.258 0.3750.375 0.500 0.6250.750
66.625   0.2800.280 0.4320.432 0.562 0.7190.864
88.625 0.2500.2770.3220.3220.4060.5000.5000.5940.7190.8120.9060.875
1010.750 0.2500.3070.3650.3650.5000.5000.5940.7190.8441.0001.1251.000
1212.750 0.2500.3300.3750.4060.5620.5000.6880.8441.0001.1251.3121.000
1414.0000.2500.3120.3750.3750.4380.5940.5000.7500.9381.0941.2501.406 
1616.0000.2500.3120.3750.3750.5000.6560.5000.8441.0311.2191.4381.594 
1818.0000.2500.3120.4380.3750.5620.7500.5000.9381.1561.3751.5621.781 
2020.0000.2500.3750.5000.3750.5940.8120.5001.0311.2801.5001.7501.968
2222.0000.2500.3750.5000.3750.8750.5001.1251.3751.6251.8752.125
2424.0000.2500.3750.5620.3750.6880.9890.5001.2191.5311.8122.0622.344
3030.0000.3120.5000.6250.3750.500
3232.0000.3120.5000.6250.3750.688
3434.0000.3120.5000.6250.3750.688
3636.0000.3120.5000.6250.3750.750
4242.0000.5000.6250.3750.750

  • STD - Standard
  • XS - Extra Strong
  • XXS - Double Extra Strong