Difference between Steel Pipe and Tube

View the common Differences between Stainless Steel Pipes and tubes, check diameter, manufacturing process and applications

What is the difference between pipe and tube?

It is almost always that both pipes and tube components are interchangeably used. While they both are hollow, their main function is to form a system to ferry across various gaseous or liquid media, there are several distinct differences that separate the two.

Pipe - The construction of a pipe is round, which means the cross section of the component is round and hollow in the center. These components are used in a piping system to distribute media, including pellets, powder, gases, and fluids, or even steam. A pipe will be designated by either NPS or DN, which is the nominal pipe size. In the North American system, NPS is a standard set of sizes for pipes that could be used for applications that involve both high or low pressures and temperature requirements. The term Nominal for pipes is in reference to pipe in non-specific terms, which could also aid in identifying the diameter of the hollow in a non-dimensional number. In simple terms, the NPS is a value that helps in understanding the conveyance capacity of the pipe in a rough estimate, although this value does not match the true diameter of the pipe. One of the most important defining characteristics of pipes is their dimensions. These dimensions include the inner diameter or ID, outer diameter or OD, and the wall thickness or WT. The wall thickness is also known as the pipe schedule. Dimensions of a pipe help to the liquid capacity of the pipe. This can be determined by calculating the OD outer diameter minus 2 times WT or wall thickness (or schedule). Since the designated wall thickness is referred to as a schedule, most stainless steel pipes are available in values such as Sch. STD., Sch. XS, Sch. XXS or Sch. 40. It is possible to manufacture separate pipes of varying NPS in combination with the same schedule, and yet, have different wall thicknesses in either inches or millimeters.

Tube - While the configuration of a pipe is always round, the production of tubes is possible in various shapes including round, rectangular, squared, or oval. Similar to pipes, these components have dimensions such as OD and WT, which makes them easier to be ordered. The hollow section of tube components is estimated by outside diameter or the OD, in combination with the wall thickness or WT. The only difference here is that for tubes these dimensions are expressed in inches or millimeters. The dimensions of the tube will often denote the accurate dimensional value of its hollow section.

Different types of Tubes

  • Seamless steel tubes
  • Welded Tubes
  • Cold drawn tubes
  • Precision tubes
  • Hydraulics and pneumatics tubes
  • Heat Exchanger Tubes
  • Coiled Tubes
  • Capillary tube

The main difference is the shape like Stainless Steel Pipe comes always in round shape but you can buy SS Tube in shape of round, rectangular, square, and cylindrical.

Difference between pipe and tube diameter

During placement of the order, it is possible to order a tube with dimensions such as outside diameter and wall thickness. However, in some instances, the order may also be placed with dimensions like OD & ID or ID and Wall Thickness. Usually, the ID or the inner diameter is theoretical, but the wall thickness of a given tube has been defined by a gauge number. Smaller gauge numbers are associated with having larger outside diameters. On the other hand, the pipe is ordered with the NPS standard, wherein both the schedule number and nominal diameter, or the pipe size must be specified.

Pipe and tube manufacturing process

Similar to pipes, tubes can be produced with either seamless or welded construction. Yet, it is more challenging to produce a tube because the tolerances for tubes are tighter. And so the manufacturer needs to meet all to meet the tolerances set by the standards or specifications. And because the manufacturing process of tubes entails a finished product, there are several parameters that need to be looked into, including the testing procedures and quality checks as well as inspections.

Pipe and tube applications

While pipes are conventionally a part of systems that ferry across media, the use of tubes is more specific towards structural applications, such as Scaffolding or staging. Although a temporary structure, tubes may be used to support a work crew and materials to assist the construction, maintenance, or even repair of various structures including - bridges, buildings, as well as other man-made structures.

Nickel Alloy Pipe vs Tube American standards

Pipe   Tube  
ASTM Standards Trade Name ASTM Standards Trade Name
ASTM B167 UNS N06600 Inconel 600 Pipe ASTM B163 UNS N06600 Inconel 600 Tubing
ASTM B444 UNS N06625 Inconel 625 Pipe ASTM B444 UNS N06625 Inconel 625 Tube

DN (Diameter Nominal) Pipe Sizes

Nominal Pipe Size Diameter Nominal Nominal Pipe Size Diameter Nominal
NPS (inches) DN (mm) NPS (inches) DN (mm)
1/8 6 20 500
1/4 8 22 550
3/8 10 24 600
1/2 15 26 650
3/4 20 28 700
1 25 30 750
1 ¼ 32 32 800
1 ½ 40 36 900
2 50 40 1000
2 ½ 65 42 1050
3 80 44 1100
3 ½ 90 48 1200
4 100 52 1300
5 125 56 1400
6 150 60 1500
8 200 64 1600
10 250 68 1700
12 300 72 1800
14 350 76 1900
16 400 80 2000
18 450 Based on ASME B36.10

Pipe Schedule as per ASME B36.10 and ASME B36.19 Standard

For Carbon Steel and Wrought iron Pipe as per ASME B36.10 5, 10, 20, 30, 40, 60, 80, 100, 120, 140, 160, STD, XS, XXS
For Stainless Steel Pipe as per ASME B36.19 5S, 10S, 40S, 80S

Pipe Size Chart in NPS (inche)

Nominal Pipe Size Chart (NPS) - In Inches
Sizes in Inch OD 5 5s 10 10s 20 30 40 40s Std 60 80 80s XS 100 120 140 160 XXS Size in Inch
1/8 0.405 0.049 0.049 0.068 0.068 0.068 0.095 0.095 0.095 1/8
1/4 0.54 0.065 0.065 0.088 0.088 0.088 0.119 0.119 0.119 1/4
3/8 0.675 0.065 0.065 0.073 0.091 0.091 0.091 0.126 0.126 0.126 3/8
1/2 0.84 0.065 0.065 0.083 0.083 0.095 0.109 0.109 0.109 0.147 0.147 0.147 0.188 0.294 1/2
3/4 1.05 0.065 0.065 0.083 0.083 0.095 0.113 0.113 0.113 0.154 0.154 0.154 0.219 0.308 3/4
1 1.315 0.065 0.065 0.109 0.109 0.114 0.133 0.133 0.133 0.179 0.179 0.179 0.25 0.358 1
1 1/4 1.66 0.065 0.065 0.109 0.109 0.117 0.14 0.14 0.14 0.191 0.191 0.191 0.25 0.382 1 1/4
1 1/2 1.9 0.065 0.065 0.109 0.109 0.125 0.145 0.145 0.145 0.2 0.2 0.2 0.281 0.4 1 1/2
2 2.375 0.065 0.065 0.109 0.109 0.125 0.154 0.154 0.154 0.218 0.218 0.218 0.344 0.436 2
2 1/2 2.875 0.083 0.083 0.12 0.12 0.188 0.203 0.203 0.203 0.276 0.276 0.276 0.375 0.552 2 1/2
3 3.5 0.083 0.083 0.12 0.12 0.188 0.216 0.216 0.216 0.3 0.3 0.3 0.438 0.6 3
3 1/2 4 0.083 0.083 0.12 0.12 0.188 0.226 0.226 0.226 0.318 0.318 0.318 0.636 3 1/2
4 4.5 0.083 0.083 0.12 0.12 0.188 0.237 0.237 0.237 0.337 0.337 0.337 0.438 0.531 0.674 4
5 5.563 0.109 0.109 0.134 0.134 0.258 0.258 0.258 0.375 0.375 0.375 0.5 0.625 0.75 5
6 6.625 0.109 0.109 0.134 0.134 0.28 0.28 0.28 0.432 0.432 0.432 0.562 0.719 0.864 6
8 8.625 0.109 0.109 0.148 0.148 0.25 0.277 0.322 0.322 0.322 0.406 0.5 0.5 0.5 0.594 0.719 0.812 0.906 0.875 8
10 10.75 0.134 0.134 0.165 0.165 0.25 0.307 0.365 0.365 0.365 0.5 0.594 0.5 0.5 0.719 0.844 1 1.125 1 10
12 12.75 0.156 0.156 0.18 0.18 0.25 0.33 0.406 0.375 0.375 0.562 0.688 0.5 0.5 0.844 1 1.125 1.312 1 12
14 14 0.156 0.156 0.25 0.188 0.312 0.375 0.438 0.375 0.375 0.594 0.75 0.5 0.5 0.938 1.094 1.25 1.406 14
16 16 0.165 0.165 0.25 0.188 0.312 0.375 0.5 0.375 0.375 0.656 0.844 0.5 0.5 1.031 1.219 1.438 1.594 16
18 18 0.165 0.165 0.25 0.188 0.312 0.438 0.562 0.375 0.375 0.75 0.938 0.5 0.5 1.156 1.375 1.562 1.781 18
20 20 0.188 0.188 0.25 0.218 0.375 0.5 0.594 0.375 0.375 0.812 1.031 0.5 0.5 1.281 1.5 1.75 1.969 20
22 22 0.188 0.188 0.25 0.218 0.375 0.5 0.375 0.875 1.125 0.5 1.375 1.625 1.875 2.125 22
24 24 0.218 0.218 0.25 0.25 0.375 0.562 0.688 0.375 0.375 0.969 1.219 0.5 0.5 1.531 1.812 2.062 2.344 24
26 26 0.312 0.5 0.375 0.5
28 28 0.312 0.5 0.625 0.375 0.5
30 30 0.25 0.25 0.312 0.312 0.5 0.625 0.375 0.5
32 32 0.312 0.5 0.625 0.688 0.375 0.5
34 34 0.312 0.5 0.625 0.688 0.375 0.5
36 36 0.312 0.5 0.625 0.75 0.375 0.5
38 38 0.375 0.5
40 40 0.375 0.5
42 42 0.375 0.5
44 44 0.375 0.5
46 46 0.375 0.5
48 48 0.375 0.5
Size in Inch OD 5 5s 10 10s 20 30 40 40s Std 60 80 80s XS 100 120 140 160 XXS Size in Inch

Important Notes:

  • ASME B36.10M-2015: Welded and Seamless Wrought Steel Pipe
  • ASME B36.19M-2004: Stainless Steel Pipe (For 5S,10S,40S and 80S)
  • Don’t get confused between 3 1/2 inch nominal with 3.5 inch OD, 4" nominal with 4.000" OD

NPS pipe size chart metric

Metric Nominal Pipe Size Chart (NPS) / Nominal Pipe Dimension in Millimeter (mm)
DN (mm) OD 5 5s 10 10s 20 30 40 40s Std 60 80 80s XS 100 120 140 160 XXS DN in mm
6 10.3 1.24 1.24 1.73 1.73 1.73 2.41 2.41 2.41
8 13.7 1.65 1.65 2.24 2.24 2.24 3.02 3.02 3.02
10 17.1 1.65 1.65 1.85 2.31 2.31 2.31 3.2 3.2 3.2
15 21.3 1.65 1.65 2.11 2.11 2.41 2.77 2.77 2.77 3.73 3.73 3.73 4.78 7.47
20 26.7 1.65 1.65 2.11 2.11 2.41 2.87 2.87 2.87 3.91 3.91 3.91 5.56 7.82
25 33.4 1.65 1.65 2.77 2.77 2.9 3.38 3.38 3.38 4.55 4.55 4.55 6.35 9.09
32 42.2 1.65 1.65 2.77 2.77 2.97 3.56 3.56 3.56 4.85 4.85 4.85 6.35 9.7
40 48.3 1.65 1.65 2.77 2.77 3.18 3.68 3.68 3.68 5.08 5.08 5.08 7.14 10.16
50 60.3 1.65 1.65 2.77 2.77 3.18 3.91 3.91 3.91 5.54 5.54 5.54 8.74 11.07
65 73 2.11 2.11 3.05 3.05 4.78 5.16 5.16 5.16 7.01 7.01 7.01 9.53 14.02
80 88.9 2.11 2.11 3.05 3.05 4.78 5.49 5.49 5.49 7.62 7.62 7.62 11.13 15.24
90 101.6 2.11 2.11 3.05 3.05 4.78 5.74 5.74 5.74 8.08 8.08 8.08 16.15
100 114.3 2.11 2.11 3.05 3.05 4.78 6.02 6.02 6.02 8.56 8.56 8.56 11.13 13.49 17.12
125 141.3 2.77 2.77 3.4 3.4 6.55 6.55 6.55 9.53 9.53 9.53 12.7 15.88 19.05
150 168.3 2.77 2.77 3.4 3.4 7.11 7.11 7.11 10.97 10.97 10.97 14.27 18.26 21.95
200 219.1 2.77 2.77 3.76 3.76 6.35 7.04 8.18 8.18 8.18 10.31 12.7 12.7 12.7 15.09 18.26 20.62 23.01 22.23
250 273 3.4 3.4 4.19 4.19 6.35 7.8 9.27 9.27 9.27 12.7 15.09 12.7 12.7 18.26 21.44 25.4 28.58 25.4
300 323.8 3.96 3.96 4.57 4.57 6.35 8.38 10.31 9.53 9.53 14.27 17.48 12.7 12.7 21.44 25.4 28.58 33.32 25.4
350 355.6 3.96 3.96 6.35 4.78 7.92 9.53 11.13 9.53 9.53 15.09 19.05 12.7 12.7 23.83 27.79 31.75 35.71
400 406.4 4.19 4.19 6.35 4.78 7.92 9.53 12.7 9.53 9.53 16.66 21.44 12.7 12.7 26.19 30.96 36.53 40.49
450 457 4.19 4.19 6.35 4.78 7.92 11.13 14.27 9.53 9.53 19.05 23.83 12.7 12.7 29.36 34.93 39.67 45.24
500 508 4.78 4.78 6.35 5.54 9.53 12.7 15.09 9.53 9.53 20.62 26.19 12.7 12.7 32.54 38.1 44.45 50.01
550 559 4.78 4.78 6.35 5.54 9.53 12.7 9.53 22.23 28.58 12.7 34.93 41.28 47.63 53.98
600 610 5.54 5.54 6.35 6.35 9.53 14.27 17.48 9.53 9.53 24.61 30.96 12.7 12.7 38.89 46.02 52.37 59.54
650 660 7.92 12.7 9.53 12.7
700 711 7.92 12.7 15.88 9.53 12.7
750 762 6.35 6.35 7.92 7.92 12.7 15.88 9.53 12.7
800 813 7.92 12.7 15.88 17.48 9.53 12.7
850 864 7.92 12.7 15.88 17.48 9.53 12.7
900 914 7.92 12.7 15.88 19.05 9.53 12.7
950 965 9.53 12.7
1000 1016 9.53 12.7
1050 1067 9.53 12.7
1100 1118 9.53 12.7
1150 1168 9.53 12.7
1200 1219 9.53 12.7
DN in mm OD 5 5s 10 10s 20 30 40 40s Std 60 80 80s XS 100 120 140 160 XXS DN in mm

Notes:

  • ASME B36.10M-2015: Seamless & Welded Wrought Steel Pipe
  • ASME B36.19M-2004: Stainless Steel Pipe (For 5S,10S,40S and 80S)

Nominal pipe size od chart (outer diameter)

NPS*
in Inch		 NPS*
OD in Inch		 DN in mm NPS*
OD in mm
1/8 10.3 6 10.3
1/4 13.7 8 13.7
3/8 17.1 10 17.1
1/2 21.3 15 21.3
3/4 26.7 20 26.7
1 33.4 25 33.4
1.25 42.2 32 42.2
1.5 48.3 40 48.3
2 60.3 50 60.3
2.5 73 65 73
3 88.9 80 88.9
3.5 101.6 90 101.6
4 114.3 100 114.3
5 141.3 125 141.3
6 168.3 150 168.3
8 219.1 200 219.1
10 273.1 250 273.1
12 323.8 300 323.8
14 14 350 355.6
16 16 400 406.4
18 18 450 457
20 20 500 508
22 22 550 559
24 24 600 610
26 26 650 660
28 28 700 711
30 30 750 762
32 32 800 813
34 34 850 864
36 36 900 914
38 38 950 965
40 40 1000 1016
42 42 1050 1067
44 44 1100 1118
46 46 1150 1168
48 48 1200 1219

*NPS - Nominal Pipe Size

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