This MS pipe size chart lists the complete dimensional data for mild steel pipes manufactured to IS 1239 (Part 1) and IS 3589, from 15 mm NB (½ inch) to 600 mm NB (24 inches). Every size includes outside diameter (OD), wall thickness for Light, Medium and Heavy classes, and nominal bore in both mm and inches. Sachiya Steel International stocks these sizes in ERW and seamless construction for pan-India and export supply.
Key Terms: NB, DN, NPS, OD, ID, and Wall Thickness
A quick look at the six short codes used in the chart will make the rest of the page easier to understand. These are standard terms commonly used in the industry.
| Term | Short Form | What It Means |
|---|---|---|
| Nominal Bore | NB | The size name of the pipe in millimetres, used in the Indian system. A 50 mm NB pipe is not 50 mm on the inside. It is simply the standard reference number for that size. |
| Nominal Diameter | DN | The European version of NB, also in millimetres. 50 NB and DN 50 are the same pipe. |
| Nominal Pipe Size | NPS | The American version, written in inches. 2-inch NPS, 50 NB, and DN 50 all describe the same size. |
| Outer Diameter | OD | The actual measured outside diameter of the pipe in millimetres. The OD stays the same across Class A, B, and C for any given size. |
| Inner Diameter | ID | The actual inside diameter. It is calculated as OD minus twice the wall thickness, so it changes with the class or the schedule. |
| Wall Thickness | WT | The thickness of the pipe wall in millimetres. This is what decides the class (A, B, or C) under IS 1239, or the schedule (40, 80, 160) under ASME. |
Mild Steel Pipe Size Chart as per IS 1239 Part 1 (15 mm to 150 mm NB)
IS 1239 (Part 1) 2004 is the Indian standard that covers welded and seamless mild steel pipes from 6 mm NB up to 150 mm NB. These pipes are used for water, non-hazardous gas, compressed air, and low-pressure steam. The standard is the Indian equivalent of BS 1387:1985 and is broadly comparable to ASTM A53 Schedule 40.
Under IS 1239, pipes are available in three classes: Light (A), Medium (B), and Heavy (C), where only wall thickness varies while OD remains the same.
The combined chart below lists every standard size from ½ inch (15 mm) up to 6 inch (150 mm) across all three classes.
| NB (mm) | Size (in) | OD (mm) | Light WT | Light kg/m | Medium WT | Medium kg/m | Heavy WT | Heavy kg/m |
|---|---|---|---|---|---|---|---|---|
| 15 | ½" | 21.3 | 2.00 | 0.947 | 2.60 | 1.210 | 3.20 | 1.440 |
| 20 | ¾" | 26.9 | 2.30 | 1.380 | 2.60 | 1.560 | 3.20 | 1.870 |
| 25 | 1" | 33.7 | 2.60 | 1.980 | 3.20 | 2.410 | 4.00 | 2.930 |
| 32 | 1¼" | 42.4 | 2.60 | 2.540 | 3.20 | 3.100 | 4.00 | 3.790 |
| 40 | 1½" | 48.3 | 2.90 | 3.230 | 3.20 | 3.560 | 4.00 | 4.370 |
| 50 | 2" | 60.3 | 2.90 | 4.080 | 3.60 | 5.030 | 4.50 | 6.190 |
| 65 | 2½" | 76.1 | 3.20 | 5.710 | 3.60 | 6.420 | 4.50 | 7.930 |
| 80 | 3" | 88.9 | 3.20 | 6.720 | 4.00 | 8.360 | 4.80 | 9.900 |
| 100 | 4" | 114.3 | 3.60 | 9.750 | 4.50 | 12.100 | 5.40 | 14.400 |
| 125 | 5" | 139.7 | 4.50 | 14.980 | 4.80 | 15.900 | 5.40 | 17.800 |
| 150 | 6" | 165.1 | 4.50 | 17.800 | 4.80 | 19.000 | 5.40 | 21.200 |
Values are based on IS 1239 (Part 1) 2004. All weights shown are theoretical per-metre weights at a steel density of 7.85 g/cm³. The standard allows a weight tolerance of minus 8 per cent on Class A (Light) and minus 10 per cent on Class B (Medium) and Class C (Heavy). Standard supply length is 6 metres unless you specify otherwise.
Class A (Light) MS Pipe Sizes and Weights
Class A is the lightest wall option in IS 1239. It is used when weight and cost matter more than pressure rating, which is why it is used for low-pressure water lines, electrical conduits, light structural jobs, and general fabrication work. Per-metre cost is the lowest of the three classes, but Class A is not meant for gas or any pressurised system; avoid using it in a pipe that carries real pressure.
Class B (Medium) MS Pipe Sizes and Weights
Class B is the standard choice in Indian construction. If a drawing mentions "MS pipe 50 NB" without specifying a class, it usually refers to Class B. Typical uses include general water supply, scaffolding, fencing, low-pressure gas lines, and everyday fabrication work. Most stockists keep Class B on the shelf by default, so it is safe to use when you are raising a purchase order, and the drawing is not specific.
Class C (Heavy) MS Pipe Sizes and Weights
Class C has the thickest wall in the IS 1239 family. It is chosen wherever the pipe has to carry real pressure or act as a structural member. Common applications include fire-fighting lines in high-rise buildings, high-pressure water mains, structural columns, and any job where the pipe doubles as a load-bearing piece.
MS Pipe Size Chart in mm and Inches: Conversion Table
This table gives you a straight conversion between the Indian NB system, the European DN system, and the American NPS (inches) system. It covers every standard pipe size from 6 mm right up to 600 mm, so you can match a drawing in one system against stock in another.
| NB (mm) | DN | NPS (inches) | OD (mm) | OD (inches) |
|---|---|---|---|---|
| 6 | 6 | ⅛" | 10.3 | 0.405 |
| 8 | 8 | ¼" | 13.7 | 0.540 |
| 10 | 10 | ⅜" | 17.1 | 0.675 |
| 15 | 15 | ½" | 21.3 | 0.840 |
| 20 | 20 | ¾" | 26.9 | 1.050 |
| 25 | 25 | 1" | 33.4 | 1.315 |
| 32 | 32 | 1¼" | 42.2 | 1.660 |
| 40 | 40 | 1½" | 48.3 | 1.900 |
| 50 | 50 | 2" | 60.3 | 2.375 |
| 65 | 65 | 2½" | 73.0 | 2.875 |
| 80 | 80 | 3" | 88.9 | 3.500 |
| 100 | 100 | 4" | 114.3 | 4.500 |
| 125 | 125 | 5" | 141.3 | 5.563 |
| 150 | 150 | 6" | 168.3 | 6.625 |
| 200 | 200 | 8" | 219.1 | 8.625 |
| 250 | 250 | 10" | 273.0 | 10.750 |
| 300 | 300 | 12" | 323.9 | 12.750 |
| 350 | 350 | 14" | 355.6 | 14.000 |
| 400 | 400 | 16" | 406.4 | 16.000 |
| 450 | 450 | 18" | 457.2 | 18.000 |
| 500 | 500 | 20" | 508.0 | 20.000 |
| 600 | 600 | 24" | 609.6 | 24.000 |
MS Pipe Standard Size for Large Diameter (IS 3589)
For pipes above 150 mm NB, the governing standard is IS 3589. These are the sizes used for major water supply mains, sewage trunk lines, gas transmission, and large infrastructure projects. Where IS 1239 sorts pipes by Class A, B, or C, IS 3589 simply specifies the outer diameter and the wall thickness directly.
The material grades under IS 3589 are Fe 330, Fe 410, and Fe 450, each with a different yield strength. Your consultant will specify which grade is needed based on the design pressure, depth of burial, and service conditions.
| NB (mm) | Size (in) | OD (mm) | Typical WT Range (mm) | Typical Use |
|---|---|---|---|---|
| 200 | 8" | 219.1 | 4.0 – 8.0 | Water mains, industrial cooling lines |
| 250 | 10" | 273.0 | 4.5 – 8.0 | Pumping mains, fire service lines |
| 300 | 12" | 323.9 | 5.0 – 10.0 | Municipal water, sewage rising mains |
| 350 | 14" | 355.6 | 5.6 – 10.0 | Transmission mains, process piping |
| 400 | 16" | 406.4 | 5.6 – 12.5 | Water supply trunk, industrial effluent |
| 450 | 18" | 457.2 | 6.3 – 12.5 | Major trunk mains |
| 500 | 20" | 508.0 | 6.3 – 12.5 | Irrigation and water distribution |
| 600 | 24" | 609.6 | 6.3 – 14.2 | Large municipal mains, canal crossings |
For sizes above 200 NB, wall thickness is chosen based on the design pressure and the installation depth rather than a fixed class. On pressurised lines, consultants normally work out the thickness using Barlow's formula and then add a corrosion allowance of at least 12.5 per cent.
MS Pipe Schedule Chart as per ASME B36.10 (Schedule 40 and 80)
ASME B36.10M is the American standard for welded and seamless carbon steel pipe and is the reference used in most international project drawings, oil and gas documentation, and export purchase orders. Instead of Class A, B, or C, ASME defines wall thickness using schedule numbers. The most common being Schedule 40 and Schedule 80. A Schedule 40 mild steel pipe and a Class B IS 1239 pipe are similar but not identical, so always mention the standard in the purchase order.
| NPS (in) | DN (mm) | OD (mm) | Sch 40 WT (mm) | Sch 40 kg/m | Sch 80 WT (mm) |
|---|---|---|---|---|---|
| ½" | 15 | 21.3 | 2.77 | 1.269 | 3.73 |
| ¾" | 20 | 26.7 | 2.87 | 1.684 | 3.91 |
| 1" | 25 | 33.4 | 3.38 | 2.503 | 4.55 |
| 1¼" | 32 | 42.2 | 3.56 | 3.390 | 4.85 |
| 1½" | 40 | 48.3 | 3.68 | 4.050 | 5.08 |
| 2" | 50 | 60.3 | 3.91 | 5.440 | 5.54 |
| 2½" | 65 | 73.0 | 5.16 | 8.630 | 7.01 |
| 3" | 80 | 88.9 | 5.49 | 11.290 | 7.62 |
| 4" | 100 | 114.3 | 6.02 | 16.070 | 8.56 |
| 5" | 125 | 141.3 | 6.55 | 21.770 | 9.52 |
| 6" | 150 | 168.3 | 7.11 | 28.260 | 10.97 |
| 8" | 200 | 219.1 | 8.18 | 42.550 | 12.70 |
| 10" | 250 | 273.0 | 9.27 | 60.310 | 15.09 |
| 12" | 300 | 323.9 | 10.31 | 79.730 | 17.48 |
| 14" | 350 | 355.6 | 11.13 | 94.550 | 19.05 |
| 16" | 400 | 406.4 | 12.70 | 123.300 | 21.44 |
Schedule 40 is generally used for North American plumbing, general process piping, and most low-to-medium pressure fluid lines. Schedule 80 is specified where pressure or mechanical stress is higher, typical for chemical plants, steam lines, and fuel systems. For thicker walls than Sch 80, the schedule ladder continues: Sch 120, Sch 160, and XXS (double extra strong).
MS Pipe Size Chart by Manufacturing Type
Mild steel pipe is made by two routes, ERW (electric resistance welded) and seamless. Each type has its own standard size range.
ERW MS Pipe Size Chart
ERW is the dominant route in India. A flat steel strip (skelp) is rolled into a cylinder, and the longitudinal seam is fused by high-frequency electric current without filler. The process is fast and economical, and ERW pipes offer excellent dimensional consistency.
| Attribute | IS 1239 (Part 1) | IS 3589 |
|---|---|---|
| Size range | 15 mm – 150 mm NB | 168 mm OD – 2032 mm OD |
| Typical class / grade | Class A / B / C | Fe 330 / 410 / 450 |
| Standard length | 6 metres | 6 – 12 metres |
| Common use | Water, gas, scaffolding, general | Water mains, sewage, transmission |
Seamless MS Pipe Size Chart
Seamless MS pipe is hot-pierced from a solid billet, so it has no weld seam. It is the preferred choice for high-pressure, high-temperature, and critical-service lines, and is typically specified under ASTM A106 Grade B, API 5L, or the Indian IS 1239 seamless variant. It is stronger than ERW pipe but also more expensive.
| NPS / NB | Common OD (mm) | Typical Wall Thickness Options |
|---|---|---|
| ½" / 15 NB to 2" / 50 NB | 21.3 – 60.3 | Sch 40, Sch 80, Sch 160 |
| 2½" / 65 NB to 6" / 150 NB | 73.0 – 168.3 | Sch 40, Sch 80, Sch 120, Sch 160 |
| 8" / 200 NB to 12" / 300 NB | 219.1 – 323.9 | Sch 40, Sch 80, Sch XXS |
| 14" / 350 NB to 24" / 600 NB | 355.6 – 609.6 | Sch 20, 30, 40, 60, 80, 100, 120 |
MS Square and Rectangular Hollow Section Size Chart
Mild Steel hollow sections are specified under IS 4923 and are sold by outside side-length rather than nominal bore. They are the default choice for steel frames, gates, awnings, trolley chassis, racking, and light structural work.
| Profile | Side Dimensions (mm) | Common WT (mm) | Common Use |
|---|---|---|---|
| SHS – Square | 20×20, 25×25, 40×40, 50×50, 75×75, 100×100, 150×150 | 1.6, 2.0, 2.5, 3.2, 4.0, 5.0, 6.0 | Frames, posts, furniture, railings |
| RHS – Rectangular | 40×20, 60×40, 80×40, 100×50, 120×60, 150×100, 200×100 | 1.6, 2.0, 2.5, 3.2, 4.0, 5.0, 6.0 | Mezzanines, chassis, greenhouse frames, racks |
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MS Pipe Wall Thickness Chart (mm)
This single table lets you compare wall thickness side by side across IS 1239 Class A, B, and C, plus ASME Schedule 40 and Schedule 80, for the same nominal size.
| NB (mm) | OD (mm) | Class A | Class B | Class C | Sch 40 | Sch 80 |
|---|---|---|---|---|---|---|
| 15 | 21.3 | 2.00 | 2.60 | 3.20 | 2.77 | 3.73 |
| 20 | 26.9 | 2.30 | 2.60 | 3.20 | 2.87 | 3.91 |
| 25 | 33.7 | 2.60 | 3.20 | 4.00 | 3.38 | 4.55 |
| 32 | 42.4 | 2.60 | 3.20 | 4.00 | 3.56 | 4.85 |
| 40 | 48.3 | 2.90 | 3.20 | 4.00 | 3.68 | 5.08 |
| 50 | 60.3 | 2.90 | 3.60 | 4.50 | 3.91 | 5.54 |
| 65 | 76.1 | 3.20 | 3.60 | 4.50 | 5.16 | 7.01 |
| 80 | 88.9 | 3.20 | 4.00 | 4.80 | 5.49 | 7.62 |
| 100 | 114.3 | 3.60 | 4.50 | 5.40 | 6.02 | 8.56 |
| 125 | 139.7 | 4.50 | 4.80 | 5.40 | 6.55 | 9.52 |
| 150 | 165.1 | 4.50 | 4.80 | 5.40 | 7.11 | 10.97 |
How to Choose the Right MS Pipe Size
To specify a pipe, first choose the required NB, then select the class or schedule for pressure and load, and finally confirm the standard that aligns with the project drawing and practice.
Plumbing and Water Supply
Domestic and commercial water lines use ½–3 inch (15–80 mm) IS 1239 Class B pipes. High-rise rising mains shift to 4-inch / 100 mm Class B or C, while underground municipal mains usually adopt IS 3589 pipes from 150 mm NB upward.
Structural and Construction Use
Use 40–50 mm NB Medium ERW pipe for site scaffolding and railings. Choose Class C or Sch 80 for structural members. For light fabrication, prefer IS 4923 MS square or rectangular sections over round pipe.
Gas, Steam, and Fluid Transfer
Use IS 1239 Medium or Heavy pipes for non-hazardous gas, air, and low-pressure steam. Hazardous gas, high-pressure steam, and refinery fluids require seamless ASTM A106 Gr B or API 5L pipes as per project specifications.
Fire-Fighting and High-Pressure Lines
For Indian buildings, wet riser, hydrant, and sprinkler lines typically use IS 1239 Class C or IS 3589 pipes. Sachiya Steel provides Class C pipes with hydrostatic test certificates for consultant approvals.
MS Pipe Tolerance, Length, and Supply Conditions
The values published in any size chart are nominal. The actual pipe will be within standard tolerances, so checking these helps at the goods receipt stage.
| Parameter | IS 1239 (Part 1) | ASME B36.10 / ASTM A53 |
|---|---|---|
| Weight tolerance | −8% on Class A (Light); −10% on Class B and C | −10% typical |
| Wall thickness tolerance | −10% on the specified value | −12.5% on specified value |
| OD tolerance (up to 48.3 mm) | +0.4 mm / −0.8 mm | ±0.4 mm |
| OD tolerance (above 48.3 mm) | ±1% of OD | ±1% of OD |
| Standard length | 6 metres (random or fixed) | 6 m, 12 m, or double-random |
| End finish | Plain end, bevelled, or screwed-and-socketed | Plain, bevelled, or threaded NPT |
Sachiya Steel MS Pipe Stock Range
Sachiya Steel International Pvt. Ltd. is a Mumbai-based manufacturer and exporter of mild steel pipes, with an ISO 9001:2015 quality management system. Our ready stock covers every size listed in the charts above.
| Product | Size and Specification |
|---|---|
| ERW MS pipe | 15 mm to 350 mm NB (½" to 14") in IS 1239 Class A/B/C and IS 3589 Fe 410 |
| Seamless MS pipe | 15 mm to 600 mm NB (½" to 24") in ASTM A106 Gr B, ASTM A53 Gr B, API 5L Gr B, Sch 20 to Sch XXS |
| MS square and rectangular hollow sections | 20×20 to 200×200 SHS; 40×20 to 200×100 RHS; wall 1.6 mm to 6.0 mm |
| End finish | Plain end, bevelled end, threaded (NPT or BSPT) |
| Standard length | 6 metres ex-stock; 12 metres on order |
| Certification | BIS IS mark, Mill Test Certificate (EN 10204 3.1), hydrostatic test report |
| Export experience | GCC, Southeast Asia, East Africa, Europe, Russia, South America |