There are several common methods for describing stainless steel pipe and tube dimensions used in tubular piping systems, we should calculate exact sizes without confusion, usually tube and pipe sizes are defined by outside diameter, wall thickness, and length, inside diameter is also mentioned for tube sizes, these parameters are basic to dimensions concept. Welded pipe and seamless pipe are two pipe manufacturing processes.
Nominal Pipe Size
The North American ANSI system is widely applied in pipe systems, Nominal Pipe Size (NPS) is defined standard size for pipes used for different pressures and temperatures, the outside diameter is used in inches, NPS and OD values are not always equal, from NPS ⅛ to 12 inch, the NPS and OD values are different, over 14 inch, the NPS and OD values are equal, the size is actual dimensions, not nominal.
NB
NB (Nominal Bore) is also another method to refer to pipe sizes and dimensions, it is the same value between NB and NPS.
Pipe Schedule
Wall thickness is referred to as the Schedule (Sch.), nowadays, there is a large selection of wall thicknesses to meet all applications under different pressures, standard weight (STD), extra-strong (XS), and double extra-strong (XXS) are three main number for thickness, 5S and 10S are thinner wall thickness for stainless steel pipe.
DN Size
The European ISO system is also OD-based, Diameter Nominal (DN) is also frequently referred to as pipe dimensions, it provides almost the same OD as the ANSI system, but measured in millimeters, and with a lot more choices for different wall thicknesses.
Nominal Pipe Size, Diameter Nominal and pipe Schedule Chart
ASME B36.19 indicates Stainless Steel Pipe dimensions including the outside diameter and the Schedule wall thickness, the Schedule Number has an “S” suffix for wall thickness, having SCH 5S, SCH 10S, SCH 40S, SCH 80S.
ASME B36.10 standard determines carbon steel pipe dimensions, without an “S” suffix for pipe schedule.
| Nominal Size | OD | Wall Thickness, SCH | |||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| NPS | DN | mm | 5S | 10S | 10 | 20 | 30 | 40S | STh | 40 | 60 | 80S | XS | 80 | 100 | 120 | 140 | 160 | XXS |
| 1∕8 | 6 | 10.3 | – | 1.24 | – | – | – | 1.73 | 1.73 | 1.73 | – | 2.41 | 2.41 | 2.41 | – | – | – | – | – |
| 1∕4 | 8 | 13.7 | – | 1.65 | – | – | – | 2.24 | 2.24 | 2.24 | – | 3.02 | 3.02 | 3.02 | – | – | – | – | – |
| 3∕8 | 10 | 17.2 | – | 1.65 | – | – | – | 2.31 | 2.31 | 2.31 | – | 3.2 | 3.2 | 3.2 | – | – | – | – | – |
| 1∕2 | 15 | 21.3 | 1.65 | 2.11 | – | – | – | 2.77 | 2.77 | 2.77 | – | 3.73 | 3.73 | 3.73 | – | – | – | 4.78 | 7.47 |
| 3∕4 | 20 | 26.7 | 1.65 | 2.11 | – | – | – | 2.87 | 2.87 | 2.87 | – | 3.91 | 3.91 | 3.91 | – | – | – | 5.56 | 7.82 |
| 1 | 25 | 33.4 | 1.65 | 2.77 | – | – | – | 3.38 | 3.38 | 3.38 | – | 4.55 | 4.55 | 4.55 | – | – | – | 6.35 | 9.09 |
| 1 1∕4 | 32 | 42.2 | 1.65 | 2.77 | – | – | – | 3.56 | 3.56 | 3.56 | – | 4.85 | 4.85 | 4.85 | – | – | – | 6.35 | 9.7 |
| 1 1∕2 | 40 | 48.3 | 1.65 | 2.77 | – | – | – | 3.68 | 3.68 | 3.68 | – | 5.08 | 5.08 | 5.08 | – | – | – | 7.14 | 10.15 |
| 2 | 50 | 60.3 | 1.65 | 2.77 | – | – | – | 3.91 | 3.91 | 3.91 | – | 5.54 | 5.54 | 5.54 | – | – | – | 8.74 | 11.07 |
| 2 1∕2 | 65 | 73 | 2.11 | 3.05 | – | – | – | 5.16 | 5.16 | 5.16 | – | 7.01 | 7.01 | 7.01 | – | – | – | 9.53 | 14.02 |
| 3 | 80 | 88.9 | 2.11 | 3.05 | – | – | – | 5.49 | 5.49 | 5.49 | – | 7.62 | 7.62 | 7.62 | – | – | – | 11.13 | 15.24 |
| 3 1∕2 | 90 | 101.6 | 2.11 | 3.05 | – | – | – | 5.74 | 5.74 | 5.74 | – | 8.08 | 8.08 | 8.08 | – | – | – | – | – |
| 4 | 100 | 114.3 | 2.11 | 3.05 | – | – | – | 6.02 | 6.02 | 6.02 | – | 8.56 | 8.56 | 8.56 | – | 11.13 | – | 13.49 | 17.12 |
| 5 | 125 | 141.3 | 2.77 | 3.4 | – | – | – – | 6.55 | 6.55 | 6.55 | – | 9.53 | 9.53 | 9.53 | – | 12.7 | – | 15.88 | 19.05 |
| 6 | 150 | 168.3 | 2.77 | 3.4 | – | – | – | 7.11 | 7.11 | 7.11 | – | 10.97 | 10.97 | 10.97 | – | 14.27 | – | 18.26 | 21.95 |
| 8 | 200 | 219.1 | 2.77 | 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 |
| 10 | 250 | 273.1 | 3.4 | 4.19 | – | 6.35 | 7.8 | 9.27 | 9.27 | 9.27 | 12.7 | 12.7 | 12.7 | 15.09 | 18.26 | 21.44 | 25.4 | 28.58 | 25.4 |
| 12 | 300 | 323.9 | 3.96 | 4.57 | – | 6.35 | 8.38 | 9.53 | 9.53 | 10.31 | 14.27 | 12.7 | 12.7 | 17.48 | 21.44 | 25.4 | 28.58 | 33.32 | 25.4 |
| 14 | 350 | 355.6 | 3.96 | 4.78 | 6.35 | 7.92 | 9.53 | – | 9.53 | 11.13 | 15.09 | – | 12.7 | 19.05 | 23.83 | 27.79 | 31.75 | 35.71 | – |
| 16 | 400 | 406.4 | 4.19 | 4.78 | 6.35 | 7.92 | 9.53 | – | 9.53 | 12.7 | 16.66 | – | 12.7 | 21.44 | 26.19 | 30.96 | 36.53 | 40.49 | – |
| 18 | 450 | 457.2 | 4.19 | 4.78 | 6.35 | 7.92 | 11.13 | – | 9.53 | 14.27 | 19.05 | – | 12.7 | 23.83 | 29.36 | 34.93 | 39.67 | 45.24 | – |
| 20 | 500 | 508 | 4.78 | 5.54 | 6.35 | 9.53 | 12.7 | – | 9.53 | 15.09 | 20.62 | – | 12.7 | 26.19 | 32.54 | 38.1 | 44.45 | 50.01 | – |
| 22 | 550 | 558.8 | 4.78 | 5.54 | 6.35 | 9.53 | 12.7 | – | 9.53 | – | 22.23 | – | 12.7 | 28.58 | 34.93 | 41.28 | 47.63 | 53.98 | – |
| 24 | 600 | 609.6 | 5.54 | 6.35 | 6.35 | 9.53 | 14.27 | – | 9.53 | 17.48 | 24.61 | – | 12.7 | 30.96 | 38.89 | 46.02 | 52.37 | 59.54 | – |
| 26 | 650 | 660.4 | – | – | 7.92 | 12.7 | – | – | 9.53 | – | – | – | 12.7 | – | – | – | – | – | – |
| 28 | 700 | 711.2 | – | – | 7.92 | 12.7 | 15.88 | – | 9.53 | – | – | – | 12.7 | – | – | – | – | – | – |
| 30 | 750 | 762 | 6.35 | 7.92 | 7.92 | 12.7 | 15.88 | – | 9.53 | – | – | – | 12.7 | – | – | – | – | – | – |
| 32 | 800 | 812.8 | – | – | 7.92 | 12.7 | 15.88 | 17.48 | 9.53 | 17.48 | – | – | 12.7 | – | – | – | – | – | – |
| 34 | 850 | 863.6 | – | – | 7.92 | 12.7 | 15.88 | 17.48 | 9.53 | 17.48 | – | – | 12.7 | – | – | – | – | – | – |
| 36 | 900 | 914.4 | – | – | 7.92 | 12.7 | 15.88 | 19.05 | 9.53 | 19.05 | – | – | 12.7 | – | – | – | – | – | – |
| 38 | 950 | 965.2 | – | – | – | – | – | – | 9.53 | – | – | – | 12.7 | – | – | – | – | – | – |
| 40 | 1000 | 1016 | – | – | – | – | – | – | 9.53 | – | – | – | |||||||
SUMMARY: from the above table, we can see that:
- NPS and DN values are different, they have a corresponding value for outside diameter in millimeters, when NPS ≥ 4, the related DN = 25 multiplied by the NPS number.
- From NPS 1/8 to NPS 12 (including) the value is nominal, not actual OD, for example, NPS 6 inch (DN150), pipe outside diameter should be 168.3 mm, not 152.4 mm.
- When NPS over and including 14, pipe OD should actual dimension, for example, NPS20 inch, the diameter should be 508 mm, and it should converted inch to mm by multiplying it by 25.4.
- The pipe’s inside diameter is defined by the outside diameter and Schedule.
Examples Of actual outside diameter
- NPS 1 actual O.D. = 1.5/16″ (33.4 mm)
- NPS 2 actual O.D. = 2.3/8″ (60.3 mm)
- NPS 3 actual O.D. = 3.1/2″ (88.9 mm)
- NPS 4 actual O.D. = 4.1/2″ (114.3 mm)
- NPS 12 actual O.D. = 12.3/4″ (323.9 mm)
- NPS 14 ACTUAL O.D. = 14″(355.6 MM, 14 x 25.4 mm)
Standard Stainless Steel Pipe
Standard Stainless Steel Tube
Difference Between Pipe And Tube Dimension
In general, NPS is a pipe size number that refers to a nominal diameter, not an actual diameter as specified above, the actual physical OD is larger than its nominal OD, and the schedule number is for the pipe thickness mentioned, the pipe can be measured by the inside diameter because pipe is used to transportation fluid, it needs to calculate relevant parameter。
Tube sizes are expressed in inch or millimeter, which is the actual value, the actual physical OD of a tube is just the same as its nominal OD in both outside diameter and wall thickness, tube dimension in wall thickness is not expressed by Schedule Numble, see more tube size chart.
Reading more about pipe and tube differences.
BWG
BWG stands for “Birmingham Wire Gauge”, each BWG number represents a specific steel tubing thickness, BWG number decreases with increasing thickness of the tube, for example, in BWG16, the wall thickness is 1.65 mm.
BWG, SWG and ASWG can be converted in inches and mm.
Shapes and Sizes
We usually mention tube and pipe size is a round shape other shapes of tube and pipe have special sizes to specify, generally used in structure and decorative purposes, these shapes include:
Dimension Tolerance
When measuring tube and pipe sizes, the tolerance is required strictly as standard, which specified dimensions Permissible Variations, including outside diameter tolerance, wall thickness tolerance, length tolerance, straightness and ovality, more details in Tube & Pipe Tolerances.
Stainless Steel Pipe Manufacturer
We produce stainless steel pipe complying with ASTM, DIN, JIS, EN, and ISO standard manufacturing processes, particular tolerance requirements in continuous production and test requirements, our quality pipe products are used in many industries due to excellent corrosion resistance, high-temperature resistance and high strength.
Pipe is manufactured in standard stainless steel, nickel alloys and special alloys in a large range of sizes, outside diameters from 10.3 to 1524 mm and wall thicknesses up to 70 mm, NPS from 1/8 to 60 inch, from DN 15 to DN 1700, pipe schedule for wall thickness covers Sch 5S, Sch 10S, Sch 40S and Sch 80S according to ASME B36.19, beveled ends and plain ends are available.
Welded Stainless Steel Pipe
Pipes Manufactured from Coil, The fully automated production process from the coil is the most technically sophisticated and economical process for manufacturing longitudinally welded pipes, we produce pipes in standard sizes and customised sizes with outside diameters ranging from 6 to 1219 mm, with wall thicknesses up to 30 mm. The standard lengths are 6 or 12 m. Fixed lengths or lengths up to a maximum of 18 m can be produced in a number of sizes without circumferential welding.
We use all the current welding processes in continuous production, the main ones are the TIG process, plasma process and laser beam welding process.
Pipes Manufactured from Plate, Dongshang produces longitudinally welded pipes with wall thicknesses of up to 70 mm and an outside diameter of up to 2 032 mm (80″) from individual steel plates – in standard dimensions from stock, as well as individually for your projects. We produce manufactured lengths of up to 12 m without circumferential weld, and up to 24 m with circumferential weld.
Seamless Stainless Steel Pipe
Seamless pipe is extruded from a hollow billet and fully annealed, the material is re-drawn through a die, heat-treated in a vacuum furnace and worked, cleaned, and re-worked until reduced to size, annealing is a process that removes the temper, or stiffness from the tubing, resulting in a pipe which can be further processing.
Stainless Steel Pipe Standard Specifications
- A312 – Seamless, Welded Stainless Steel Pipes
- A358 – -Welded Stainless Steel Pipe for High-Temperature Service and General Applications
- A376 – Seamless Stainless Steel Pipe for High-Temperature Central-Station Service
- A409 – Welded Large Diameter Austenitic Steel Pipe for Corrosive or High-Temperature Service
- A778 – Welded, Unannealed Austenitic Stainless Steel Tubular Products
- A790 – Seamless and Welded Ferritic / Austenitic Stainless Steel Pipe
- DIN EN 10217-7
Stainless Steel Materials
Dongshang produces welded pipe and seamless pipe made from stainless steel in different material grades. There are verities of standard and special alloys that can be offered in high-quality materials for specific corrosive applications.
Typical stainless steel grades are:
- 304 Stainless Steel
- 304L Stainless Steel
- 316 Stainless steel
- 316L Stainless Steel
- 316H Stainless Steel
- 316Ti Stainless Steel
- 317L Stainless Steel
- 321 Stainless Steel
- 347 / 347H Stainless Steel
- 904L Stainless Steel
- 254 SMO Stainless Steel (UNS S31254)
- 309/309S Stainless Steel
- 310/310S Stainless Steel
- 409 Stainless Steel
- 409L Stainless Steel
- 430 Stainless Steel
- 439 Stainless Steel
- 2205 Duplex
- S32750 Super Duplex (2507)
- S32760 Super Duplex
Our Capabilities
For many years, we have been manufacturing pipes in various sizes for a large number of applications, including the process industry, apparatus engineering and mechanical engineering. Our combination of modern production technology, technical ability and years of experience allows us to produce high-quality stainless steel pipes, such as size form, tolerances, material, testing requirements and mechanical technological qualities, these technical characteristics can be agreed upon with us and optimized to meet specific needs.
Surface Finishes, depending on the material and the industrial application, Dongshang satisfies a range of requirements for the inner and outer surfaces of the pipe from especially rough to especially smooth surfaces, there are different surface types can be specified, such as chemical pickling, grinding of external and internal surfaces.
Shapes, a wide variety of shapes is available to meet specific applications, such as, Square pipes Hexagonal pipes, Oval pipes, and Elliptical pipes.
Tolerances, Tolerances in manufacturing our pipes are always provided by ASTM and international standards. We meet the demanding requirements of our customers in a targeted way, whether in relation to the inner and outer diameters, wall thicknesses, straightness, or true running accuracy.
We have been producing high-quality pipes with smooth surfaces and complying with high-quality requirements, our quality assurance system throughout the production process guarantees compliance with the selected tolerances for applications.