Circular Hollow Section (CHS) is round structural tubing specified in India under IS 4923 and in other projects under standards such as EN 10219 or JIS G3444. Its symmetric section can suit trusses, columns, towers, handrails and architectural framing when the engineer has checked axial load, bending, connections and corrosion protection. RP Sales helps Kanpur buyers translate that design schedule into a mill, grade, dimension, certificate and delivery enquiry without treating one YST grade as a universal default.
Fabricators in Kanpur, Unnao, Panki, Dada Nagar and Fazalganj can ask RP Sales to quote CHS against a structural BOQ. The offer should identify the proposed mill, grade, dimensions, GST, certificate scope and delivery basis for that load. PEB contractors, warehouse builders, tower fabricators and solar-structure installers often have different length, marking and inspection needs, so availability and commercial terms are confirmed per schedule rather than inferred from a broad stock claim.
What CHS is and where it fits
CHS is one of three structural hollow-section families covered under IS 4923 (the other two are SHS and RHS — square and rectangular). All three are cold-formed from coiled hot-rolled strip on ERW mills, then sized to the specified OD and wall, ISI-marked, and tested. The circular form has the highest section-modulus-per-kilogram for biaxial bending and the lowest drag coefficient for wind-loaded structures, which is why it dominates lattice towers and outdoor architectural applications.
The competing global standards — EN 10219 (cold-formed welded structural hollow sections) and JIS G3444 (Japanese general structural tube) — overlap heavily with IS 4923 on dimensions, but specify yield differently (EN uses S235JRH / S275J0H / S355J2H; JIS uses STK 400 / STK 500). When a fabricator drawing cites one of these foreign standards, we book the load on the mill that runs the cross-certified production line.
OD and wall reference — IS 4923 dimensional table
| OD (mm) | NB (approx.) | Wall thickness (mm) | kg/m (typ.) |
|---|---|---|---|
| 26.9 | 20 | 2.6 – 3.2 | 1.56 – 1.87 |
| 33.7 | 25 | 2.6 – 4.0 | 1.99 – 2.93 |
| 42.4 | 32 | 2.6 – 4.0 | 2.55 – 3.79 |
| 48.3 | 40 | 2.9 – 4.0 | 3.25 – 4.37 |
| 60.3 | 50 | 3.2 – 5.0 | 4.51 – 6.82 |
| 76.1 | 65 | 3.2 – 5.0 | 5.75 – 8.77 |
| 88.9 | 80 | 3.2 – 5.4 | 6.76 – 11.10 |
| 114.3 | 100 | 3.6 – 6.0 | 9.83 – 16.00 |
| 139.7 | 125 | 4.0 – 6.0 | 13.40 – 19.80 |
| 165.1 | 150 | 4.5 – 6.3 | 17.80 – 24.70 |
| 219.1 | 200 | 4.5 – 8.0 | 23.80 – 41.60 |
Yield grades — YST 210 / 240 / 310 / 355
- YST 210 — verify the mechanical-property table and permitted use in the purchased edition and approved structural design.
- YST 240 — verify the mechanical-property table and use only where the approved member schedule specifies this grade.
- YST 310 — a higher yield-grade designation; member capacity still depends on the exact section and approved calculation.
- YST 355 — use only where the adopted standard edition, project specification and approved member design permit it.
Applications — where CHS lands
- Warehouse & PEB trusses — top and bottom chords, web members, purlin posts.
- Communication & transmission towers — lattice members for cellular, microwave, and 33/66 kV transmission lines.
- Port-handling & bulk-material equipment — conveyor support frames, stackers, ship-loader booms.
- Handrails, balustrades, architectural framing — IS 4923 YST 210 / 240, hot-dip galvanised when specified.
- Solar mounting structures — module table chords, axis support trusses for tracker plants.
Mill brands we coordinate
RP Sales is a wholesale distributor, not a mill. We coordinate CHS supply from the ISI-licensed structural-tube mills active in the Indian market — and we are transparent about which mill brand is on the load before we quote:
- Tata Structura — where this brand is approved, request current availability and confirm the product against the drawing.
- APL Apollo — request current availability against the required OD, wall, grade and delivery programme.
- Jindal Hollow Sections — verify the quoted grade, dimensions, marking and certificate basis for the named load.
- Other approved mills — compare only offers that meet the project's grade, marking, licence and document requirements.
Buying CHS structural pipe in Kanpur
Kanpur's steel trade supports fabricators in Panki, Fazalganj, Jajmau, Chakeri and nearby Unnao. RP Sales uses the buyer's BOQ to separate structural grade, wall, length, coating and mill-brand requirements before requesting availability. That is more reliable than choosing a section from a generic city stock list, especially when the drawing fixes a particular mill approval or YST grade.
Delivery is quoted from the consignee PIN code, bundle length, lifting constraints, total weight and the carrier option available after the load is ready. A mixed load with ERW or GI pipe may be considered when bundle geometry and release timing are compatible, but freight and transit are order-specific. The quotation states its validity, freight responsibility and any inspection-release condition so the buyer can compare commercial offers on the same basis.
Read the Kanpur steel market guide for freight logic, check the steel pipes Kanpur page and the Lucknow delivery page, then send the BOQ through the RFQ form.
Who should use CHS and who should not
CHS can be considered for truss chords and webs, lattice members, support frames, handrails and other structural work when the engineer checks axial load, bending, buckling, connections, fatigue, fire strategy and corrosion protection. The approved member schedule must select the YST grade, OD, wall, length and finish; grade numbers do not map automatically to building types or load bands.
Structural CHS is not a pressure-pipe designation. Water, gas, fire and boiler lines must use the product standard, material, wall, joining and regulatory route on the approved system design; neither IS 1239 Heavy nor a seamless grade is a universal answer for those services. Do not substitute CHS, SHS or RHS shapes without a revised structural calculation and written design approval.
Grade selection table: YST 210 to YST 355
| Grade | Min yield (MPa) | Min tensile (MPa) | Typical use |
|---|---|---|---|
| YST 210 | 210 | 330 | Handrails, light architectural work |
| YST 240 | 240 | 410 | Warehouse trusses, sheds, mezzanines |
| YST 310 | 310 | 450 | Industrial buildings, PEB columns, port equipment |
| YST 355 | 355 | 490 | Telecom towers, weight-critical structures |
Properties per the IS 4923 grade list on this page, reviewed 24 May 2026.
RFQ checklist for CHS structural pipe
A complete CHS line reads: OD and wall (for example 114.3 mm OD x 4.5 mm), yield grade (YST 240), length (6 m random or cut-to-length), finish (black or hot-dip galvanised), quantity in MT or pieces, and the mill brand where the tender names one. Grade and wall both matter; grade sets strength while wall sets buckling and connection capacity.
- Section, grade, length. State OD, wall, YST grade and whether lengths are 6 m random or exact cut-to-length figures.
- Mill brand and marking. Name Tata Structura, Apollo or Jindal where specified, and put the required BIS marking and MTC heat-linkage checks on the purchase order.
- Quantity and delivery. Give the piece count, calculated weight, delivery PIN code and ex-works or delivered basis; the quotation will state any mill or transport minimum that applies.
- Coating and inspection. State galvanising per IS 4736 where needed and whether TPI by SGS, Bureau Veritas or TUV applies before dispatch.
Worked example: sizing a 40-piece truss chord order
Take a truss chord in 114.3 mm OD x 4.5 mm wall, YST 240. Theoretical weight follows W = (OD minus WT) x WT x 0.02466. That gives (114.3 minus 4.5) x 4.5 x 0.02466, which is 109.8 x 4.5 x 0.02466 = 12.184506 kg per metre. One 6 m length is 73.107 kg.
The site planning table rounds that kg/m figure to 12.18, then rounds 12.18 × 6 = 73.08 to 73.1 kg per 6 m. Use 73.1 kg as the planning mass per length. Forty lengths at 73.1 kg weigh 40 × 73.1 = 2,924 kg, or 2.92 MT. Send that calculated quantity for a current availability and minimum-order check rather than padding it to an assumed mill threshold. Check the result on the pipe weight calculator before sending the PO.
Common mistakes and inspection points
In practice, CHS orders fail on four points. First, buyers confuse grade with class: YST 240 is a yield grade while Light, Medium and Heavy are wall-thickness classes, and the RFQ must state both. Second, thin-wall substitution on tower members, where a cheaper 3.2 mm wall replaces a designed 4.5 mm wall and the connection capacity drops. Third, missing ISI marking on bundles, which government tenders reject. Fourth, uncoated sections sent to outdoor duty without a galvanising line in the PO.
At receipt, caliper the OD and wall on one piece per bundle, read the ISI mark and heat number against the MTC, count bundles against the packing list, and confirm galvanised lots show the IS 4736 coating line on the certificate. For YST 355 tower steel, add TPI witnessing of the tensile test to the order.
Standards and compliance
IS 4923 governs the CHS dimensions, YST 210 / 240 / 310 / 355 grades and ISI marking, with yield grades drawn from IS 1161 practice. EN 10219 covers cold-formed welded hollow sections in S235JRH / S275J0H / S355J2H grades, and JIS G3444 covers general structural tube in STK 400 / STK 500 grades; mills cross-certify loads where the drawing cites a foreign code. Galvanising follows IS 4736. Pressure-piping alternatives sit under IS 1239 and IS 3589.
Clause references sit in the Sources list below; the full grade tables live on the IS 4923 reference.
Key points
- CHS covers 21.3 mm to 219.1 mm OD in YST 210, 240, 310 and 355 grades.
- The structural designer selects YST grade, OD and wall together; no grade is a default for sheds, trusses or towers.
- State grade, wall, mill requirement, marking and certificate scope explicitly in the purchase order.
- Availability and delivery depend on the exact OD, wall, grade, mill, quantity and consignee PIN code.
- Do not use structural CHS as a pressure-pipe substitute; the approved water, gas or fire-system design must name its own product standard and wall.
Sources and references
- IS 4923, Hollow steel sections for structural use: dimensions, YST grades, ISI marking (cited by code and clause; no catalogue URL).
- IS 1161, Steel tubes for structural purposes: YST 210 / 240 / 310 chemistry and properties (cited by code; no catalogue URL).
- EN 10219, Cold formed welded structural hollow sections: S235JRH / S275J0H / S355J2H grades (cited by code; no catalogue URL).
- JIS G3444, Carbon steel tubes for general structure: STK 400 / STK 500 grades (cited by code; no catalogue URL).
- Grade tables and marking practice: see the IS 4923 reference and IS 1239.
Related catalogue and reference pages: all products, ERW pipes, IS 1239 standard, IS 3589 large-OD pipe, Kanpur steel market, steel pipes Kanpur, steel pipes Lucknow, MTC & ISI documentation, request a quote.
FAQ — CHS structural pipe procurement
What is the difference between CHS, SHS and RHS?
Which yield grade should I specify — YST 210, 240, 310, or 355?
Do you stock Tata Structura, Apollo, and Jindal CHS?
What OD range does CHS cover in IS 4923?
Are CHS sections covered by ISI marking?
Can you supply to JIS G3444 or EN 10219 specifications?
Updated: