IS 4923 is the BIS specification for square and rectangular hollow steel sections used as structural members. The BIS product manual for IS 4923:2017 covers hot-formed and cold-formed SHS and RHS in grades YSt 210, YSt 240, YSt 310, YSt 355, YSt 420 and YSt 460. Kanpur contractors and PEB fabricators order it as SHS or RHS, not as circular water pipe.
Overview
IS 4923 is the Bureau of Indian Standards (BIS) specification for cold-formed square hollow sections (SHS) and rectangular hollow sections (RHS) used in structural steelwork. Specify IS 4923 when the drawing calls for SHS or RHS as a structural member that must carry load, not as water or gas pipe. The 2017 revision is the common commercial reference for size tables, dimensional tolerances, mechanical properties, and routine mill tests. Yield-strength grades commonly stocked and ordered under this family are YSt 210, YSt 240, and YSt 310. Later amendments to IS 4923 also define higher-strength grades (YSt 355 and above) that appear in PEB and industrial projects, but order the higher grades only when the drawing, design note, and mill capability explicitly support them: do not assume every IS 4923 stock line automatically includes them. IS 4923 is not a pipe standard for fluid service. Circular structural tubes fall under IS 1161, and water/gas conveyance tubes fall under IS 1239. A complete purchase line states outside dimensions × wall thickness × grade × length × finish (black or galvanized), plus MTC and inspection requirements.
What IS 4923 is, what governs it, and what it is not
IS 4923:2017 is titled Hollow Steel Sections for Structural Use: Specification (Second Revision). The BIS product manual (HTTP 200 on 3 September 2026) states that the standard covers hot-formed and cold-formed square and rectangular hollow steel sections. Licence grades are YSt 210, YSt 240, YSt 310, YSt 355, YSt 420 and YSt 460. Manufacturing on the licence may be seamless or welded (ERW / HFIW), and coating may be uncoated (black) or galvanized.
An IS 4923 section is square or rectangular. It is a closed structural member. It is not IS 1161 circular structural tube or IS 1239 water or gas pipe, and it is not a pressure-part boiler tube. Ordering MS pipe as per IS 4923 without a SHS or RHS size is the usual RFQ error and delays the quote.
Who should specify IS 4923 on Kanpur structural jobs
Specify IS 4923 only where the approved structural drawing names SHS or RHS to that standard. Kanpur fabricators should write outside dimensions × wall × YSt grade, edition, length, finish, tests and documents rather than "MS pipe as per IS 4923". Availability, price, legally applicable tax, freight, processing, inspection and delivery must be confirmed for that exact current line item.
Do not specify IS 4923 for circular columns; that is IS 1161. Do not specify it for water risers or gas lines; that is IS 1239. Do not specify it for large municipal mains (IS 3589) or IBR boiler tubes (SA210 / SA192). Higher grades YSt 355, 420 and 460 exist on the BIS licence scope, but order them only when the design note and mill licence include them.
What IS 4923 covers, and what it does not
IS 4923 governs cold-formed square and rectangular hollow steel sections for structural applications. It addresses dimensions, mass, tolerances, mechanical properties and testing for sections that designers treat as structural members: columns, beams, purlins, bracings and fabricated frames.
It does not govern circular structural tubes (use IS 1161) or water/gas/sewage conveyance pipes (use IS 1239 for small-bore and IS 3589 for large-diameter mains). Ordering "MS pipe as per IS 4923" without stating SHS/RHS size is a common RFQ error and delays quote turnaround.
Grades: YSt 210, YSt 240, YSt 310 (and YSt 355 practice)
- YSt 210: 210 MPa minimum yield, common for light fabrication, secondary members, and general structural frames
- YSt 240: 240 MPa minimum yield, a frequent mid-range choice for industrial structures and mezzanines
- YSt 310: 310 MPa minimum yield, used where higher design stress or weight reduction is specified
- YSt 355: used on some PEB and high-strength structural scopes; confirm design approval and mill supply before treating it as default IS 4923 stock
- Always write grade explicitly on the PO. "IS 4923 only" is incomplete
Dimensions, tolerances and testing buyers should expect
Commercial RFQs specify SHS as side × side × thickness (for example 50 × 50 × 3.2 mm) and RHS as long side × short side × thickness (for example 100 × 50 × 3.6 mm). Mass per metre should align with the size table for the ordered wall, and a large mass variance is a red flag on receipt inspection.
Expect dimensional checks on outside dimensions, wall thickness, squareness/out-of-square, twist and length. Mechanical testing typically includes tensile properties (yield, tensile strength, elongation). For welded hollow sections, flattening or equivalent formability checks are part of the mill's quality regime under the standard. Call out any extra NDT or third-party hold points in the tender if the structure is critical.
Typical applications in Indian projects
- Pre-engineered building (PEB) columns, rafters, purlins and bracing
- Mezzanine floors, walkways and equipment platforms
- Solar module mounting structures and tracker frames
- Warehouse racking, storage systems, and conveyor supports
- General structural fabrication: trusses, portals and machine frames
How to specify and what MTC should show
Write the order as: size (SHS/RHS) × thickness × grade × length × quantity × finish. Example: "IS 4923 RHS 100 × 50 × 3.6 mm, YSt 310, 6 m, black, MTC 3.1." If zinc-coated supply is required, state the galvanizing route on the PO: hot-dip galvanizing is commonly referenced to IS 4736 for tubes, with zinc coating mass tested per IS 6745.
Mill Test Certificates should identify heat/cast number, chemical composition, mechanical results for the ordered grade, dimensions/size, and reference to IS 4923. For project sites, retain heat-wise traceability so cut lengths still link to the certificate.
RP Sales supplies structural hollow sections for fabrication and project offtake. For current size and grade availability, see Structural Hollow Sections (/products/structural-hollow-sections) and send size × thickness × grade on the RFQ.
IS 4923 vs IS 1161 vs IS 1239: quick distinction
Use IS 4923 when the member is a square or rectangular hollow section for structural load. Use IS 1161 when the member is a circular structural tube graded by yield strength. Use IS 1239 when the tube is for water, gas, or similar conveyance with Light/Medium/Heavy wall classes and hydrostatic testing as the primary pressure proof.
Do not substitute these standards by outside diameter alone. A circular tube ordered for a handrail or column should cite IS 1161. A water riser should cite IS 1239, and a SHS column should cite IS 4923.
RFQ checklist for IS 4923 SHS and RHS
The BIS product manual says each certified consignment needs a test certificate with Standard Mark, cast or control-unit number, and the test results. Write size × thickness × grade so that certificate can be checked at the gate.
- Shape: SHS or RHS
- Size: side × side × thickness, or long side × short side × thickness (example already on this page: 50 × 50 × 3.2 mm or 100 × 50 × 3.6 mm)
- Grade: YSt 210, 240 or 310; name 355 / 420 / 460 only with design cover
- Forming: cold-formed or hot-formed, because the product manual covers both
- Length: 6 m common commercial length; state project cuts
- End finish: plain cut, as fabricated
- Coating: black, or galvanized with zinc mass tested to IS 6745 and coating requirement to IS 4736
- Certificate: MTC 3.1 with heat, chemistry, yield, tensile and elongation
- Inspection: mill, or TPI if the PEB or solar client names an agency
- Delivery basis: ex-works Kanpur, quantity in metres or MT, with legally applicable tax and charges stated in the current quotation
Worked tonnage example using the site circular formula
IS 4923 mass for SHS and RHS comes from Table 1 and Table 2 of the standard, not from the circular-pipe formula. Until those table values sit on the PO, buyers still need a circular check on any companion CHS. The site formula W = (OD − t) × t × 0.02466 kg/m applies to circular tube.
A companion 50 NB circular member at OD 60.3 mm and 3.6 mm wall weighs 5.03 kg/m, or 30.2 kg per 6 m, the same worked numbers used on the IS 1161 page. For the SHS line 50 × 50 × 3.2 mm already cited on this page, take mass from the mill table printed on the MTC and compare it with the ordered size. Large mass shortfall on receipt is the inspection flag, not a circular-formula estimate.
| Item | Size | Mass basis | Result |
|---|---|---|---|
| Companion CHS | 50 NB, OD 60.3 mm, t 3.6 mm | Site formula 0.02466 | 5.03 kg/m; 30.2 kg / 6 m |
| SHS on this page | 50 × 50 × 3.2 mm | IS 4923 Table 1 / MTC | Use mill table; do not invent kg/m |
| RHS on this page | 100 × 50 × 3.6 mm | IS 4923 Table 2 / MTC | Use mill table; do not invent kg/m |
Common IS 4923 procurement mistakes
In practice, PEB and solar lots fail when the PO says IS 4923 without grade or wall, or when circular IS 1161 is delivered against a SHS column mark.
- MS pipe written on a SHS line item
- YSt grade omitted, so YSt 210 arrives against a YSt 310 design
- Hot-formed assumed when the drawing wanted cold-formed, or the reverse
- Galvanizing ordered without IS 4736 / IS 6745, so coating mass is untested
- IS 1239 class tube stood in for a 72 × 72 SHS because the metre rate looked lower
Standards and compliance for IS 4923
The BIS product manual points chemistry of welded sections to strip per IS 2062 or IS 10748. Seamless hollow sections are limited to 0.040 percent sulphur and 0.040 percent phosphorus. Mechanical testing is Clause 15 of IS 4923, run on a UTM to IS 1608 (Part 1). Dimensions are Clause 10. Mass is Clause 9 against Table 1 and Table 2. Galvanizing mass is Annex B / Clause 11.1 with IS 4736 and IS 6745.
Grouping in the manual splits depth D into four bands: up to 38 mm; above 38 mm to 63.5 mm; above 63.5 mm to 100 mm; and above 100 mm. That grouping is a BIS sampling rule, not a design table. Keep the PO on the actual D × B × t and grade.
Key points for IS 4923 buyers
- IS 4923:2017 covers hot-formed and cold-formed SHS and RHS, not circular pipe.
- Licence grades run YSt 210 through YSt 460; stock RFQs still need an explicit grade.
- Galvanizing, when ordered, is checked to IS 4736 with coating mass per IS 6745.
- SHS/RHS mass comes from the standard tables and the MTC, not from the circular 0.02466 formula.
- Do not close an IS 1161 or IS 1239 line with IS 4923 sections.