Schedule is a wall-thickness designation, not a duty rating. The governing design code, material, pressure, temperature, corrosion allowance, joints, and approved drawing must select the wall. At 2 inch NPS the site schedule chart uses OD 60.3 mm, Sch 40 wall 3.91 mm, and Sch 80 wall 5.54 mm. Kanpur buyers should preserve that approved schedule on an ex-warehouse Kanpur quote with GST extra at the legally applicable GST rate stated on the current quotation.
What is the practical difference between Schedule 40 and Schedule 80?
Schedule 80 has a thicker wall than Schedule 40 at the same nominal size. Outside diameter generally stays constant, so Schedule 80 is heavier and has a smaller inside diameter. The design calculation and approved drawing, not a “routine service” label, determine which wall is acceptable.
Pipe schedule is a wall-thickness series, not a material grade. Two pipes can both be ERW carbon steel and share the same OD, but Sch 80 carries more steel in the wall. That extra wall improves pressure margin and thread engagement, yet reduces flow area and raises handling, freight, and support load.
Many Indian utility jobs use IS 1239 class language instead of schedule language. Process drawings, export projects, and some EPC bills use Sch 40 and Sch 80. If a drawing says schedule, do not substitute “medium” or “heavy” by guesswork. Confirm actual OD, wall, grade, and applicable standard such as ASTM A53 or IS 1239.
The schedule choice should come from the governing design code and drawing after pressure, temperature, corrosion allowance, external loads, and joining method are evaluated. Procurement’s role is to preserve that selection and prevent accidental changes during rate comparison.
Who in Kanpur should specify Schedule 40 versus Schedule 80
Use Schedule 40 or Schedule 80 only when the governing design and drawing name that wall after considering material, pressure, temperature, corrosion allowance, joints, and loads. Do not self-upgrade or self-downgrade from a Kanpur stock list or service nickname.
An EPC, PWD, JJM, fire, or sugar-mill label does not select Schedule 40, Schedule 80, an IS 1239 class, ERW, or seamless construction. Copy the approved standard, material, wall, manufacturing route, and statutory requirements from the design.
Do not select Sch 40 or Sch 80 from yard availability, price, or a service nickname. Keep the schedule stated by the design code calculation and approved drawing, including its material, pressure, temperature, corrosion, joint, and load assumptions. Hydraulic barrels and printing cylinders are not schedule pipe. They need precision-tube pages.
Read Schedule 40 vs Schedule 80 for the comparison page, and MS ERW in Kanpur for local ERW supply. ASTM A53 Type E is the ERW designation when the drawing uses A53 rather than IS 1239.
Schedule 40 versus Schedule 80 wall and mass at common NPS
At a given NPS the OD stays the same and the wall changes. 2 inch Sch 40 is 3.91 mm wall and 5.44 kg/m. 2 inch Sch 80 is 5.54 mm wall and 7.48 kg/m. That is 37% more theoretical mass at the same OD.
Walls come from the site pipe-schedule chart. Mass uses kg/m = (OD − t) × t × 0.02466. As-of date for the walls is 2026-05-06. The seamless price list, last edited 24 May 2026, states Sch 80 typically costs 30-50% more than Sch 40 on seamless A106/A53. That percentage is a seamless band, not an ERW class rate. ERW extra cost still tracks extra kilograms and freight.
Verify the 3 inch row: (88.9 − 5.49) × 5.49 × 0.02466 = 11.29 kg/m. (88.9 − 7.62) × 7.62 × 0.02466 = 15.27 kg/m. 4 inch: (114.3 − 6.02) × 6.02 × 0.02466 = 16.07 kg/m. (114.3 − 8.56) × 8.56 × 0.02466 = 22.32 kg/m. The comparison page rounds 2 inch to about 5.4 and 7.5 kg/m and 4 inch to about 16.1 and 22.3 kg/m.
| NPS | OD (mm) | Sch 40 wall (mm) | Sch 40 mass (kg/m) | Sch 80 wall (mm) | Sch 80 mass (kg/m) |
|---|---|---|---|---|---|
| 2 inch | 60.3 | 3.91 | 5.44 | 5.54 | 7.48 |
| 3 inch | 88.9 | 5.49 | 11.29 | 7.62 | 15.27 |
| 4 inch | 114.3 | 6.02 | 16.07 | 8.56 | 22.32 |
When may an approved design select Schedule 40 ERW pipe?
Schedule 40 is acceptable when the governing code calculation and approved drawing specify that wall for the stated material, design pressure, temperature, corrosion allowance, joining method, and loads. Water, air, fabrication, and cost labels do not establish suitability by themselves.
When the approved drawing calls for Sch 40, its lower mass and larger bore relative to Sch 80 can reduce freight, support load, and friction. Those are consequences of the selected wall, not reasons for procurement to choose the schedule without a design calculation.
A lower-cost offer does not authorize a substitution. If pressure, temperature, material grade, corrosion allowance, joining method, external load, or regulatory basis changes, engineering must check the wall again and revise the drawing when required. Procurement should compare only offers that preserve the approved schedule and millimetre wall.
For RP Sales quotations, include the design code, drawing or line number, service fluid, material, design pressure and temperature, corrosion allowance, and joining method. That gives the supplier the exact approved basis instead of a Sch 40 duty nickname.
When may an approved design select Schedule 80 ERW pipe?
Schedule 80 is acceptable when the governing code calculation and approved drawing specify that wall for the stated material and service conditions. Higher pressure, threaded joints, or rough handling do not select it automatically; engineering must evaluate the actual design inputs.
At the same OD, Sch 80 has more wall and thread engagement than Sch 40. It also leaves more material for a stated corrosion allowance. The governing code calculation must still use the exact grade, design pressure, temperature, joint factor, allowances, and applicable loads before the drawing specifies it.
The tradeoff is not only price. The bore is smaller, so flow velocity and friction can increase. Supports may need higher load allowance. Freight and installation labour increase with tonnage. In retrofit jobs, Sch 80 OD may still fit the same clamps, but the lower ID can change pump or compressor performance.
Buy Sch 80 where the approved drawing names it and the offered material, wall, joints, and documents match its design basis. Do not treat it as a universal better pipe or as a stockyard shorthand for pressure or site conditions.
Can Schedule 40 and Schedule 80 ERW pipe be mixed in one project?
They can be mixed only if the drawing, pressure class, fittings, and installation team identify each line clearly. Mixing by accident causes bore mismatch, wrong thread expectation, and inconsistent safety margin. Tag bundles and purchase orders by service and schedule.
Large projects often carry multiple schedules because engineering has checked separate line numbers against their design conditions. The store must issue the schedule assigned to each line. Issuing whichever pipe is available is dangerous because nominal bore can look the same while wall and bore differ.
Procurement should separate line items by service, NB, OD, wall, schedule, grade, finish, and quantity. Warehouse teams should keep bundle tags visible. Site supervisors should verify markings before cutting. Mixed schedules need fittings and welding procedures that match the line class.
For water transmission or municipal work, IS 3589 or IS 1239 class tables may be more relevant than schedule terms. In that case, use class and wall thickness in the PO and include a glossary link for schedule only as a comparison aid.
How Kanpur contractors should specify schedule on an RFQ
Write NPS, OD, schedule, wall in millimetres, grade, standard, length, ends, quantity, MTC, and delivery basis. Never write only “heavy ERW” when the drawing says Sch 80.
If the drawing cites ASTM A53, add Type E for ERW and Grade A or B. If it cites IS 1239, do not relabel the line as Sch 40 without millimetre walls. State whether the pipe is black or galvanized. A53 covers both finishes on the ASTM store page fetched 2026-09-03 (NPS 1/8 to NPS 26, Type E electric-resistance-welded).
Documents: state the required MTC, heat marking, hydrotest or NDE route, and TPI scope from the governing specification. Confirm that the offered lot can supply that document pack and that the named inspection agency is available before allocation. Selecting Sch 80 ERW does not create an IBR approval or certificate.
Commercials: quantity in metres and MT, ex-warehouse Kanpur, GST extra at the legally applicable GST rate stated on the current quotation, freight, destination PIN. Send the locked wall through the RFQ form.
- Drawing line: NPS, schedule, wall in mm, OD, standard, grade.
- Process: ERW Type E when A53 applies; IS class when IS 1239 applies.
- Ends and finish: PE, BE, or T&C; black or galvanized.
- Documents: MTC, hydrotest or NDE, TPI hold points.
- Delivery: ex-warehouse Kanpur, GST at the legally applicable GST rate stated on the current quotation, freight, PIN code.
Worked mass check for 2 inch Sch 40 versus Sch 80
2 inch OD is 60.3 mm. Sch 40 at 3.91 mm is 5.44 kg/m. Sch 80 at 5.54 mm is 7.48 kg/m. One hundred 6 m lengths weigh 3.26 MT on Sch 40 and 4.49 MT on Sch 80.
Sch 40: (60.3 − 3.91) × 3.91 × 0.02466 = 5.44 kg/m. 6 m length = 32.64 kg. 100 lengths = 3,264 kg = 3.26 MT. Sch 80: (60.3 − 5.54) × 5.54 × 0.02466 = 7.48 kg/m. 6 m length = 44.88 kg. 100 lengths = 4,488 kg = 4.49 MT.
The extra 1.23 MT is steel you will freight from Kanpur and support on site. Bore is smaller on Sch 80, so pump head can rise on a long water line. That is why the drawing, not the stock list, owns the schedule.
Do not convert 50 NB medium (3.6 mm, 5.03 kg/m) into 2 inch Sch 40 (3.91 mm, 5.44 kg/m) by nickname. The walls differ. Use the weight calculator and keep both millimetre values on the PO.
The linked IS 1239 standard guide currently conflicts with the class chart by showing 2.90 mm for 50 NB Medium. This page uses the class-chart and weight-table pair of 3.6 mm and 5.03 kg/m only for its comparison. Reconcile the purchased BIS edition, tender, mill table, and offered MTC before releasing an IS 1239 Medium order.
Dispatch from Kanpur when two schedules share a truck
Tag every bundle by NPS and schedule before it leaves the Kanpur yard. Confirm destination coverage, stock, vehicle availability, document pack, and carrier transit for the actual order. If a mixed-schedule load is offered, require visible segregation and markings.
Sch 40 and Sch 80 share OD, so a 2 inch bundle looks the same on a truck. Stencil the schedule, keep tags on, and split the packing list. A Lucknow site 80 km away via NH-27 can still weld the wrong wall if the store issues by NPS alone.
GST is extra at the legally applicable GST rate stated on the current quotation. Freight follows the quoted vehicle and chargeable mass, so the Sch 80 lot can cost more to move even when the per-kg band looks similar. Require the MTC and packing documents agreed on the PO; do not assume one certificate format or truck size applies to every load.
Use steel pipes Kanpur and the schedule chart when the BOQ mixes IS class and ASME schedule on one project.
Key points for Schedule 40 versus Schedule 80
Five checks that keep the drawing wall intact at RFQ and GRN.
- Schedule is wall thickness, not a material grade.
- 2 inch Sch 40 is 3.91 mm and 5.44 kg/m; Sch 80 is 5.54 mm and 7.48 kg/m.
- Do not treat IS medium class as Sch 40 without millimetre walls.
- Mix schedules only when the drawing assigns each service.
- Quote ex-warehouse Kanpur with GST extra at the legally applicable GST rate stated on the current quotation and freight on actual MT.