IS 1239 Part 1:2004 is the BIS specification for welded steel tubes used for water, sewage and gas. Kanpur contractors and PWD/JJM tender teams order Light, Medium or Heavy class on nominal bore from 6 mm to 150 mm NB; RP Sales stocks 15 to 150 mm. At 25 NB, Medium (Class B) wall is 3.2 mm on the site class chart. This is utility tube, not IBR boiler steam material.
Overview
IS 1239 Part 1 (formally IS 1239-1:2004) is the Bureau of Indian Standards specification for steel tubes used for water, sewage and gas, plus related conveyance duties. It defines Light, Medium and Heavy wall classes by nominal bore and covers black and galvanized supply. It is not a boiler-material selection rule. For any steam or boiler-boundary item, use the product specification, material line, design calculation, and component classification approved for that project. Where an IBR form applies, the official forms index distinguishes Form III-A for steam pipes, Form III-B for tubes, and Form III-C for boiler mountings and fittings.
What IS 1239 Part 1 is, and what it is not
IS 1239 Part 1 is a conveyance-tube specification. It governs welded steel tubes ordered by nominal bore and wall class for water, sewage and gas distribution on Indian jobs.
The BIS e-sale listing retrieved on 2026-09-03 records IS 1239 : Part 1 : 2004, reaffirmed 2019, as Steel Tubes, Tubulars and Other Wrought Steel Fittings, Part 1 Steel Tubes. Status is Active, and the technical committee is MTD 19.
Part 2 is a different document: IS 1239 : Part 2 : 2011 (reaffirmed 2021) covers steel pipe fittings, not the tube itself. Do not write "IS 1239" on a fittings line without Part 2.
The standard is not a boiler material specification, and it is not IS 3589 large-diameter water pipe, IS 1161 circular structural tube, or an ASME schedule pipe.
Grade and class are separate fields. YST 210, YST 240 and YST 310 come from IS 1161, while Light, Medium and Heavy describe wall only. An RFQ that names one and omits the other is incomplete.
Who should buy IS 1239 for Kanpur water and JJM work
Use IS 1239 when the approved water, sewage, gas, fire-service, or utility specification names it. Kanpur contractors and PWD/JJM bidders should copy the class, grade or material basis, size, finish, joint details, and test requirements from the design rather than assigning a class from a website application label.
Jal Jeevan Mission, PWD, plumbing, fire-service, and sugar-mill utility packages may cite this standard, but the tender and drawing remain controlling. State black or galvanized finish explicitly and use the coating requirement adopted by the project. Do not infer finish from market habit.
Do not buy IS 1239 for a boiler or steam duty when the approved drawing names another material. For an IBR scope, classify the component and request the prescribed form: III-A for steam pipes, III-B for tubes, or III-C for mountings and fittings.
Do not substitute IS 1239 into oil-and-gas line pipe, large-diameter water pipe, structural tube, or boiler work because an outside diameter appears similar. Use the product standard, range, wall basis, and acceptance route named by the approved design.
Do not assign Medium or Heavy solely from diameter, burial, fluid, or a familiar trade practice. Confirm the class and wall against the governing design pressure, surge or test basis, corrosion allowance, jointing method, installation condition, and approved specification.
Light, medium, and heavy: what the classes mean
IS 1239 class is a wall-thickness designation relative to nominal bore. Light is thinner than Medium, and Medium is thinner than Heavy at the same nominal size, but a class name is not a universal working-pressure or application rating. The designer must select the permitted class and wall for the actual fluid, pressure, temperature, corrosion, joint, installation and test conditions, and both class and grade must be verified against the applicable standard and purchase specification.
Class is wall. Grade is YST. Write both. YST 210 (210 MPa minimum yield) is the most common, with YST 240 and YST 310 available for higher-strength requirements. Specify class and grade explicitly on the RFQ.
Chemical composition (as per IS 1239)
- Carbon: 0.20% max (Grade YST 210), 0.25% max (YST 240), 0.30% max (YST 310)
- Manganese: 0.40-0.60% typical
- Phosphorus: 0.040% max
- Sulphur: 0.040% max
- The chemistry limits are aligned with IS 1161, which permits the three YST yield-strength grades.
Mechanical properties (as per IS 1239)
- Yield strength: YST 210 = 210 MPa min, YST 240 = 240 MPa min, YST 310 = 310 MPa min
- Tensile strength: 330-430 MPa (YST 210), 360-480 MPa (YST 240), 410-530 MPa (YST 310)
- Elongation: 20% min (YST 210), 15% min (YST 240/310)
- All tubes undergo hydrotest at a test pressure calculated per the standard.
IS 1239 vs IS 3589: what changes
IS 1239 covers tubes up to 150 mm NB (approximately 165 mm OD). For larger diameters (168.3-2540 mm OD) used in municipal water transmission, IS 3589:2001 applies instead. IS 3589 also uses the light/medium/heavy class model, but with different wall-thickness tables optimized for large-diameter service.
Both standards are ERW-governed. For larger diameters where ERW is impractical, seamless alternatives per IS 6286 or ASTM A106 become relevant.
IS 1239 Light vs Medium vs Heavy class: selection table
Wall-thickness class is a commonly confused RFQ variable. Use the table only to distinguish the three relative wall series at the illustrated size: it is not a pressure-rating or end-use selector. The purchase order must copy the class and dimensions selected by the approved design.
| Class | Relative wall in this comparison | OD / wall mass ratio | Mill test reference | Buyer action |
|---|---|---|---|---|
| Light (A) | Thinnest listed series | ~9-13x | Verify adopted IS 1239 test route | Use only when the approved design specifies Light |
| Medium (B) | Intermediate listed series | ~7-10x | Verify adopted IS 1239 test route | Use only when the approved design specifies Medium |
| Heavy (C) | Thickest listed series | ~5-8x | Verify adopted IS 1239 test route | Use only when the approved design specifies Heavy |
Do not use a rule of thumb that assigns Medium below a diameter or Heavy to burial, combustible gas, wet risers, or fire hydrants. Fluid, design and surge pressure, temperature, joint, corrosion allowance, installation, fire code, authority requirements, and the adopted standard must support the selected class and wall.
For any fire-protection installation, the National Building Code of India (NBC 2016, Part 4: Fire & Life Safety) mandates IS 1239 Heavy class galvanised steel pipe for wet-riser and hydrant systems. Light class is explicitly disallowed on fire-fighting service, and using it on a fire-safety tender will fail third-party inspection and put the occupancy certificate at risk.
How to specify IS 1239 on an RFQ
Write the line so a mill or stockist can price one product. Size, class, grade, finish and documents must sit on the same line. A note that only says "MS pipe IS 1239" produces mixed Light and Medium offers.
- Size: NB in mm (15 to 150) and OD if the drawing uses millimetres
- Wall: Light / Medium / Heavy, or Class A / B / C, plus wall in mm if the BOQ shows it
- Grade or material basis: state exactly what the applicable IS 1239 revision, approved design, and tender require, and do not infer it from current stock
- Length: 6 m standard; 4 m or 5 m on request, or cut-to-length if the site cannot handle 6 m
- End finish: plain end (PE) or threaded and coupled (T&C)
- Coating: black, or hot-dip galvanized per IS 4736
- Certificate: MTC 3.1 per IS 1239, heat number, BIS licence number
- Inspection: mill, or named TPI if the tender requires it
- Packing: bundled, tagged, stencil of NB, class, heat
- Delivery: quantity in metres or MT, destination, ex-works Kanpur or delivered
Price is not part of IS 1239 and changes with size, class, grade or material basis, finish, quantity, source, testing and market conditions. Ask for a current proforma that states availability, legally applicable tax, freight, processing, inspection, delivery basis, and committed date for the exact line item.
Worked mass example: 25 NB Medium, 200 lengths of 6 m
Use the site formula W = (OD - t) x t x 0.02466 kg/m. Steel density in that formula is 7850 kg/m3.
From the IS 1239 class thickness chart on this site, 25 NB Medium (Class B) is OD 33.7 mm and wall 3.2 mm. That is the same row as the pipe-weight table: 2.41 kg/m and 14.5 kg per 6 m length.
Check: (33.7 - 3.2) x 3.2 x 0.02466 = 30.5 x 3.2 x 0.02466 = 2.41 kg/m.
Two hundred lengths of 6 m come to 1,200 m. Mass is 1,200 x 2.41 = 2,892 kg, which is 2.89 MT.
Multiply the verified theoretical or certified lot mass by the current quoted rate only after confirming whether the commercial basis is per kilogram or per tonne and whether it uses theoretical or actual mass. Legally applicable tax, freight, packing, processing, inspection and other charges require a current written quotation.
Do not mix this 25 NB row with the 50 NB comparison table on this page. Class wall changes with NB, so always read the chart for the exact bore.
Common mistakes on IS 1239 procurement
In practice, class is written when the buyer meant grade, and grade is written when the buyer meant class. YST 210 Medium is a valid order; "Heavy grade" is not.
Light class on a fire hydrant or wet-riser fails inspection. NBC 2016 Part 4 calls for Heavy class galvanised pipe on that service.
IS 1239 is offered against an IS 3589 trunk main because both say water, but the OD ranges do not overlap in normal use. 150 mm NB is the top of this standard.
Galvanized pipe is assumed when the PO said black, or black is delivered when the BOQ said GI. State IS 4736 when zinc is required.
An MTC without heat number, hydrotest record or BIS licence number is a receipt problem. Match stencil, bundle tag and certificate before the truck leaves.
Standards and compliance for Indian jobs
The governing tube document is IS 1239 Part 1:2004. Yield grades are taken from IS 1161:2014, and galvanizing, when ordered, follows IS 4736:2000.
Hydrostatic testing is part of acceptance. This page's class table records 50 kg/cm2 as the hydrostatic test pressure for Light, Medium and Heavy. The BIS product manual for IS 1239 (Part 1):2004 (PM/1239 (Part 1)/4, Feb 2022) states each steel tube is eddy-current or hydrostatically tested to 5 MPa.
Fire-fighting wet-riser and hydrant pipe follows NBC 2016 Part 4 and Heavy class GI; Light class is not acceptable on that service.
Do not use a form label to convert IS 1239 into an approved boiler material. If the drawing names another specification for steam or boiler duty, follow it and confirm the component-specific IBR route with the competent authority.
BIS product certification (ISI mark) and EN 10204 Type 3.1 answer different questions: the mark is mill licence, and the MTC is heat-wise test data. Tender language often wants both.
Key points
- IS 1239 Part 1:2004 covers welded tubes 15-150 mm NB in Light, Medium and Heavy class.
- Class is wall. YST 210 / 240 / 310 is grade. Specify both on the RFQ.
- 25 NB Medium is 33.7 mm OD x 3.2 mm wall, 2.41 kg/m on the site weight table.
- Fire hydrant and wet-riser work needs Heavy class GI, not Light class.
- Do not use IS 1239 for IBR steam. Move to SA-106, SA-192, SA-210 or SA-213 as drawn.