Pipe Schedule Dimensions Chart
ASME B36.10M wall thickness, OD, ID and weight per metre for NPS 1/8" to 24" across Schedule 10, 20, 40, 80, 160 and XXS.
A pipe schedule is a dimensionless designation used with nominal pipe size (NPS) to identify a listed wall thickness in ASME B36.10M. This reference shows selected Schedule 10, 20, 40, 80 and 160 dimensions plus XXS. Compare the exact wall and theoretical mass at the required NPS. Do not read the schedule number as a pressure rating or a service approval.
NPS vs Actual OD: For sizes NPS 1/8" through 12", the nominal size does not equal the outside diameter. A "2-inch pipe" actually has an OD of 60.3 mm. From NPS 14" upward the NPS equals the OD in inches. The metric equivalent is DN (Diamètre Nominal). NPS 2" = DN 50.
Why schedules matter for procurement: A schedule and NPS identify a nominal wall in the dimensional table and support a theoretical weight calculation. If the RFQ misquotes the schedule, the supplied wall and mass can differ from the approved material line. Service suitability still requires your project's governing code calculation. That calculation uses the material grade, the design conditions, dimensional tolerance, corrosion allowance, joints and the inspection plan.
Note: For NPS ≤ 10", Schedule 40 = STD (Standard wall). For NPS ≤ 8", Schedule 80 = XS (Extra Strong). Above these sizes, STD and XS have fixed wall thicknesses that differ from Schedule 40/80. XXS (Double Extra Strong) is a separate designation and is not equal to any numbered schedule.
Check the dimensional line on this chart before you raise a purchase order. A 2 inch Schedule 40 line with 60.3 mm OD and 3.91 mm wall has a theoretical mass of 5.44 kg per metre, so 60 lengths at 6 m total about 1,957 kg on the same basis. Send us NPS, schedule, grade, quantity, document scope and delivery PIN with the BOQ, so the Kanpur quotation can state rate, billing basis, freight and proposed timing.
Pipe Schedule Wall Thickness & Weight Chart
Each cell shows Wall Thickness (mm) / Weight (kg/m). A dash (-) indicates the schedule is not defined for that NPS. Weight is calculated using the formula: W = (OD − WT) × WT × 0.02466.
| NPS | DN (mm) | OD (mm) | Sch 10 WT / kg/m | Sch 20 WT / kg/m | Sch 40 WT / kg/m | Sch 80 WT / kg/m | Sch 160 WT / kg/m | XXS WT / kg/m |
|---|---|---|---|---|---|---|---|---|
| 1/8" | 6 | 10.3 | - | - | 1.73 / 0.37 | 2.41 / 0.47 | - | - |
| 1/4" | 8 | 13.7 | - | - | 2.24 / 0.63 | 3.02 / 0.80 | - | - |
| 3/8" | 10 | 17.1 | - | - | 2.31 / 0.84 | 3.2 / 1.10 | - | - |
| 1/2" | 15 | 21.3 | 1.65 / 0.80 | - | 2.77 / 1.27 | 3.73 / 1.62 | 4.78 / 1.95 | 7.47 / 2.55 |
| 3/4" | 20 | 26.7 | 1.65 / 1.02 | - | 2.87 / 1.69 | 3.91 / 2.20 | 5.56 / 2.90 | 7.82 / 3.64 |
| 1" | 25 | 33.4 | 1.65 / 1.29 | - | 3.38 / 2.50 | 4.55 / 3.24 | 6.35 / 4.24 | 9.09 / 5.45 |
| 1-1/4" | 32 | 42.2 | 1.65 / 1.65 | - | 3.56 / 3.39 | 4.85 / 4.47 | 6.35 / 5.61 | 9.7 / 7.77 |
| 1-1/2" | 40 | 48.3 | 1.65 / 1.90 | - | 3.68 / 4.05 | 5.08 / 5.41 | 7.14 / 7.25 | 10.15 / 9.55 |
| 2" | 50 | 60.3 | 1.65 / 2.39 | - | 3.91 / 5.44 | 5.54 / 7.48 | 8.74 / 11.11 | 11.07 / 13.44 |
| 2-1/2" | 65 | 73 | 2.11 / 3.69 | - | 5.16 / 8.63 | 7.01 / 11.41 | 9.53 / 14.92 | 14.02 / 20.39 |
| 3" | 80 | 88.9 | 2.11 / 4.52 | - | 5.49 / 11.29 | 7.62 / 15.27 | 11.13 / 21.35 | 15.24 / 27.68 |
| 3-1/2" | 90 | 101.6 | 2.11 / 5.18 | - | 5.74 / 13.57 | 8.08 / 18.63 | - | - |
| 4" | 100 | 114.3 | 2.11 / 5.84 | - | 6.02 / 16.07 | 8.56 / 22.32 | 13.49 / 33.54 | 17.12 / 41.03 |
| 5" | 125 | 141.3 | 2.77 / 9.46 | - | 6.55 / 21.77 | 9.53 / 30.97 | 15.88 / 49.11 | 19.05 / 57.43 |
| 6" | 150 | 168.3 | 2.77 / 11.31 | - | 7.11 / 28.26 | 10.97 / 42.56 | 18.26 / 67.56 | 21.95 / 79.22 |
| 8" | 200 | 219.1 | 2.77 / 14.78 | 6.35 / 33.31 | 8.18 / 42.55 | 12.7 / 64.64 | 23.01 / 111.27 | 22.23 / 107.92 |
| 10" | 250 | 273.1 | 3.4 / 22.61 | 6.35 / 41.77 | 9.27 / 60.31 | 12.7 / 81.55 | 28.58 / 172.33 | 25.4 / 155.15 |
| 12" | 300 | 323.8 | 3.96 / 31.23 | 6.35 / 49.71 | 10.31 / 79.70 | 12.7 / 97.43 | 33.32 / 238.68 | 25.4 / 186.91 |
| 14" | 350 | 355.6 | 3.96 / 34.34 | 7.92 / 67.90 | 11.13 / 94.55 | 12.7 / 107.39 | 35.71 / 281.70 | - |
| 16" | 400 | 406.4 | 4.19 / 41.56 | 7.92 / 77.83 | 12.7 / 123.30 | 14.27 / 137.99 | 40.49 / 365.36 | - |
| 18" | 450 | 457.2 | 4.19 / 46.81 | 7.92 / 87.75 | 14.27 / 155.87 | 15.88 / 172.82 | 45.24 / 459.59 | - |
| 20" | 500 | 508 | 4.78 / 59.32 | 9.53 / 117.15 | 15.09 / 183.42 | 20.62 / 247.83 | 44.45 / 508.11 | - |
| 24" | 600 | 609.6 | 5.54 / 82.52 | 9.53 / 141.02 | 17.48 / 255.24 | 24.61 / 355.02 | 52.37 / 719.63 | - |
Weight Calculation Formula
- OD = Outer Diameter in millimeters (mm)
- WT = Wall Thickness in millimeters (mm)
- 0.02466 = constant derived from π × ρ / 1,000,000 where ρ = 7850 kg/m³ (carbon steel density)
How Kanpur contractors specify schedule
When you write a Kanpur RFQ, you should copy the schedule, NPS, material grade, design code and exact wall from the approved drawing or tender schedule. Do not infer Schedule 40 from a water or fire-system label, or Schedule 80 from the words "high pressure." Where a line falls under boiler jurisdiction, name the required IBR forms (Form III-A for steam pipes, Form III-B for boiler tubes, Form III-C for boiler mountings and fittings only) and leave the exact document set to the approved inspection plan.
Component drawings may instead call for precision tube. Water-well casing may name IS 4270 or another project-approved product standard. A close OD does not make those products interchangeable with schedule pipe. Name the required MTC type, heat or lot traceability, inspection scope, packing and delivery basis in the enquiry. Then treat the accepted quotation and purchase order as the commercial record. The borewell guide, Kanpur procurement page and dated market reference give separate RFQ context.
Schedule 40 versus 80: price bands in Kanpur
At the same NPS, the listed Schedule 80 wall carries more theoretical steel mass per metre than Schedule 40. Total commercial cost still depends on the written per-kilogram or per-length rate and its complete scope. The indicative seamless bands below are ex-warehouse Kanpur, reviewed 24 May 2026, and exclude GST at 18 percent as published on the seamless price list on that date. They are dated references, not firm quotes or current tax guidance.
| Size (NPS) | OD (mm) | Sch 40 band (₹/kg) | Sch 80 band (₹/kg) | Bands as of |
|---|---|---|---|---|
| 2 inch | 60.3 | 80 to 98 | 95 to 118 | 24 May 2026 |
| 4 inch | 114.3 | 76 to 94 | 91 to 113 | 24 May 2026 |
For the two sizes shown, the Schedule 80 band endpoints are roughly 19 to 20 percent above the corresponding Schedule 40 endpoints as of 24 May 2026, while the bands themselves can overlap. That gap is per kilogram, not a universal premium, and only for these two sizes on that date. Total cost per length also changes because Schedule 80 carries more kilograms per metre. The full band table is on the seamless pipe price list. The Schedule 40 versus 80 comparison works through weight side by side.
RFQ checklist for schedule pipe
A schedule number on its own leaves the wall, the grade and the freight open. Send us these ten items with every schedule enquiry to Kanpur.
- NPS plus DN: state both, for example 2 inch (DN 50), so the OD is fixed.
- Schedule plus exact wall: write Sch 40 with 3.91 mm, since STD diverges above NPS 10.
- Standard and grade: ASTM A106 Grade B, A53, or API 5L with PSL level where relevant.
- Length: single random 5.8 or 6.0 m, double random 9 to 12 m, or cut-to-length.
- End finish: plain end, beveled for butt weld, or threaded with couplings on small sizes.
- Quantity in lengths and MT: both figures, so we can plan freight and truck fill.
- Test certificate: name the required MTC type and any IBR forms (Form III-A for steam pipes, Form III-B for boiler tubes, Form III-C for boiler mountings and fittings only), subject to the approved inspection plan.
- Inspection: name any agency or approval process, scope, hold points, location, fees and release evidence in the RFQ, and confirm the allocation in the written quotation.
- Coating: bare, epoxy, FBE or 3LPE for buried and cross-country service.
- Delivery basis: destination PIN with ex-warehouse Kanpur versus delivered terms.
Worked example: 2 inch Sch 40 against Sch 80
Take 2 inch NPS with OD 60.3 mm. Schedule 40 uses a 3.91 mm wall: (60.3 minus 3.91) times 3.91 times 0.02466 gives 5.44 kg per metre. One 6 m length weighs about 32.6 kg. Sixty lengths total about 1,957 kg, which is 1.96 MT.
Schedule 80 at the same OD uses a 5.54 mm wall, which computes to 7.48 kg per metre. The listed wall is therefore about 38 percent heavier per metre for this nominal size. Wall thickness changes one term in a pressure-design calculation. The comparison does not assign a design pressure or approval to either schedule. Run the applicable ASME B31.1 or B31.3 calculation with material allowable stress at design temperature, joint factors, dimensional tolerance, corrosion allowance and other code terms before you lock the schedule.
Common mistakes in schedule procurement
The classic error is assuming STD always equals Schedule 40. It does up to NPS 10, then the two diverge and an STD order can arrive thinner than the design assumed. The mirror error hits XS above NPS 8. A second mistake is mixing schedule language with IS 1239 class language on one order. A quotation that names B class is not automatically supplying Schedule 40, even where walls look close at one size. Convert both to OD and wall in mm first.
A third mistake is reading NPS as a measured bore. A 2 inch pipe has a 60.3 mm OD. Fit-up fails when fabricators cut to a 50 mm assumption. A fourth is specifying XXS by default for safety. Double extra strong walls cost far more per metre. Threading and welding procedures take extra work, and the supports carry the added dead load. Let the governing design code and project specification pick the schedule. Do not add XXS as a default safety margin on the purchase order.
Standards and compliance
ASME B36.10M governs the wall and diameter tables behind every schedule number on this page. It covers welded and seamless wrought steel pipe for high or low temperatures and pressures. The catalogue page is linked under References. The thin-wall Barlow relationship, P equals 2 times S times t divided by D, shows how wall and stress basis affect pressure, but it is not a design-pressure result on this page. Substituting a material's yield strength for the code allowable stress would overstate a usable design pressure. ASME B31.1 or B31.3 design also accounts for temperature, joint and quality factors, allowances and dimensional tolerance. Put the schedule, the standard and the grade in their own PO fields, and name the governing design code on its own line.
Key points
- Schedule numbers identify wall dimensions by NPS. They do not establish a pressure rating without material, temperature, code, joints and the approved calculation.
- 2 inch Sch 40 weighs 5.44 kg per metre against 7.48 for Sch 80, about 38 percent heavier.
- STD equals Sch 40 only up to NPS 10; XS equals Sch 80 only up to NPS 8.
- For the 2 inch and 4 inch bands shown, Sch 80 endpoints are roughly 19 to 20 percent higher per kg. Total length cost also reflects its greater kg per metre.
- Send us NPS, exact wall, grade, MTC and delivery PIN when you ask us to quote schedule pipe from Kanpur.
References
- ASME B36.10M: Welded and Seamless Wrought Steel Pipe, American Society of Mechanical Engineers. Catalogue page (fetched HTTP 200, 3 Sep 2026): asme.org: B36.10M welded and seamless wrought steel pipe.
- ASTM A106/A106M: Seamless Carbon Steel Pipe for High-Temperature Service, ASTM International. Cited by code for Grades A, B and C.
- ASME B31.1 / B31.3: Power Piping and Process Piping, American Society of Mechanical Engineers. Cited by code for design pressure calculation.
Frequently Asked Questions
Pipe schedule is a dimensionless designation used with NPS (Nominal Pipe Size) to identify a listed wall thickness in ASME B36.10M. For one NPS, you can compare a schedule column by its exact wall and theoretical mass. The designation alone is not a pressure rating or service approval. The governing design code, material, temperature, allowances, joints and the approved calculation control those decisions.
Schedule 80 has a thicker wall than Schedule 40 for the same NPS in the dimensions shown. For example, 2" NPS is 3.91 mm in Schedule 40 and 5.54 mm in Schedule 80, so Schedule 80 is heavier per metre. That comparison does not assign service or pressure rating. Material, temperature, corrosion allowance, joints, the governing code and the approved calculation must select the wall.
NPS stands for Nominal Pipe Size. It is a North American designation system for pipe dimensions that does not directly correspond to any physical measurement of the pipe. For NPS 1/8" through 12", the actual outside diameter (OD) is larger than the nominal size. From NPS 14" upwards, the NPS equals the OD in inches. NPS is used alongside the metric DN (Diamètre Nominal) system. For example, NPS 2" = DN 50.
The original schedule formula is: Schedule Number = 1000 × (P / S), where P is the internal working pressure (psi) and S is the allowable stress (psi) of the pipe material. In practice, ASME B36.10M standardised specific wall thicknesses for each NPS/schedule combination. Two pipes of the same schedule but different NPS will have different wall thicknesses. Write both NPS and schedule (or the exact wall thickness) on the RFQ so the line is not ambiguous.
There is no schedule that this page can assign from the label "water supply." Copy the standard, material, schedule or exact wall from the approved design after you check pressure, temperature, corrosion allowance, joining, supports, testing and authority requirements. If the project instead names an IS 1239 class, compare OD and wall in millimetres rather than treating Class B as Schedule 40.
Dispatch timing, freight and receipt at site depend on size, quantity, finish, documents, destination PIN and current availability. Share the delivery PIN and required-at-site time in the RFQ so the written quotation separates ex-warehouse Kanpur dispatch from transit and arrival. Mill rolling and IBR-stage inspection need their own lead-time confirmation.
Name the required MTC type, heat traceability and any buyer-nominated third-party inspection in the RFQ. If you nominate an agency such as SGS, Bureau Veritas or TUV, obtain written confirmation of scope, location, hold points, charges, document availability and release evidence before the purchase order. This page does not promise standing inspection access.
Related Resources
- Steel Pipe Weight Calculator
- ERW Pipe Supplier in Kanpur
- Seamless Steel Pipes in Kanpur
- IS 1239 Standard: Full Reference
- ASTM A106 Standard: Full Reference
- Steel Pipes Supplier in Kanpur
- Kanpur Steel Market Buyer Guide
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