ISMC & ISMB — Hot-Rolled Structural Steel Sections to IS 2062
Hot-rolled structural sections are the fundamental language of fabricated steel construction. The ISMC (Indian Standard Medium-weight Channel) and ISMB (Indian Standard Medium-weight Beam) produced to IS 2062 and IS 808 appear on virtually every industrial, infrastructure, and commercial project in India — from mezzanine floors and gantry girders to pedestrian bridges and building columns.
Specifying the right section is a function of loading, span, and connection geometry. This page covers the full range we stock, the grades available, and the applications where each section performs best.
All sections are stocked in Grade E250 as standard. Grade E350 and E410 are available on order with 5–7 working day lead time from the mill. Contact us with your BOM for stock availability and current pricing.
ISMC — Indian Standard Medium-Weight Channel
The ISMC is a C-shaped hot-rolled section with tapered flanges (5 % slope on the inner face). Its open profile gives it versatility in connections and mounting that closed hollow sections cannot match.
Dimensions and Properties
| Section | Depth (mm) | Flange (mm) | Web (mm) | Mass (kg/m) | |:--------|:----------:|:-----------:|:--------:|:-----------:| | ISMC 75 | 75 | 40 | 4.4 | 6.8 | | ISMC 100 | 100 | 50 | 4.7 | 9.2 | | ISMC 125 | 125 | 65 | 5.0 | 13.1 | | ISMC 150 | 150 | 75 | 5.7 | 16.4 | | ISMC 175 | 175 | 75 | 6.0 | 19.1 | | ISMC 200 | 200 | 75 | 6.2 | 22.1 | | ISMC 250 | 250 | 82 | 7.2 | 30.6 | | ISMC 300 | 300 | 90 | 7.8 | 36.3 | | ISMC 350 | 350 | 100 | 8.1 | 42.7 | | ISMC 400 | 400 | 100 | 8.6 | 49.4 |
Applications of ISMC Sections
Purlins and girts in heavy-duty structures — when cold-formed sections are under-specified for the applied load, ISMC 125 to ISMC 200 are the robust alternative. They are particularly suitable for industrial buildings with high internal crane activity, where vibration and impact loads exceed normal design assumptions.
Lintels — over door and window openings in composite brick-and-steel construction, the ISMC's parallel top and bottom surfaces make it straightforward to bed in mortar and support the masonry above. ISMC 100 and ISMC 125 are the workhorses for openings up to 1.8 m; ISMC 150 and 175 span to 2.4 m under typical masonry loads.
Back-to-back box columns — two ISMC sections placed web-to-web and bolted through the web at regular intervals form a closed box column with excellent biaxial bending resistance. This arrangement is common in industrial shed columns, machinery support frames, and staircase stringers.
Crane runway beams for light cranes — ISMC 200 to ISMC 300, used as runway beams for under-hung cranes up to 2-tonne capacity, are a cost-effective alternative to fabricated plate girders in light-duty applications.
Mezzanine edge beams and kerb channels — the channel lip provides a natural fixing surface for checker plate or open steel flooring, eliminating the need for welded cleats.
ISMC sections have a 5 % taper on the inner flange face. Standard flat washers will bear on the flange at an angle. Use taper washers (also called bevelled washers) on all bolted connections to the flange face, particularly on crane runway joints and high-tension connections.
ISMB — Indian Standard Medium-Weight Beam
The I-beam (internationally referred to as universal beam or wide-flange section) concentrates material in the flanges where flexural stress is highest, while the web carries shear. This geometry makes the ISMB the most material-efficient section for beams under transverse loading.
Dimensions and Properties
| Section | Depth (mm) | Flange (mm) | Web (mm) | Mass (kg/m) | |:--------|:----------:|:-----------:|:--------:|:-----------:| | ISMB 100 | 100 | 75 | 4.0 | 11.5 | | ISMB 150 | 150 | 80 | 4.8 | 14.9 | | ISMB 200 | 200 | 100 | 5.7 | 25.4 | | ISMB 250 | 250 | 125 | 6.9 | 37.3 | | ISMB 300 | 300 | 140 | 7.7 | 46.1 | | ISMB 350 | 350 | 140 | 8.1 | 52.4 | | ISMB 400 | 400 | 140 | 8.9 | 61.5 | | ISMB 450 | 450 | 150 | 9.4 | 72.4 | | ISMB 500 | 500 | 180 | 10.2 | 86.9 | | ISMB 550 | 550 | 190 | 11.2 | 103.7 | | ISMB 600 | 600 | 210 | 12.0 | 122.6 |
Applications of ISMB Sections
Floor beams in multi-storey steel frames — ISMB 200 to ISMB 350 are the standard secondary beam sizes for floor systems in commercial and industrial buildings. When composite action with a concrete deck is designed, the same section carries 30–40 % more load than the non-composite case, allowing one size reduction on the schedule.
Crane girders — this is where ISMB sections earn their specification in heavy industry. The wide flanges of ISMB 400, 450, 500, and 600 provide a stable running surface for crane wheels, resist lateral forces from crabbing, and are deep enough to keep deflection within the 1/600 span limit that most crane manufacturers require.
Columns under concentric axial load — the biaxial symmetry of the I-section gives it equal radius of gyration about both axes, making it efficient as a column when buckling length is similar in both directions. For unequal buckling lengths, a universal column (UC) section is better — but ISMB columns are a practical alternative when both sections are already on-site.
Transfer beams over large openings — ISMB 450, 500, and 600 carry point loads from columns or walls above wide openings (loading bays, plant access hatches) where a fabricated plate girder is not justified.
ISMB 300 and ISMB 350 are our fastest-moving sections — maintained in ready stock for next-day dispatch. Larger sizes (ISMB 450 and above) typically require 2–4 working days from our regional warehouse network.
Material Standard and Certification
IS 2062:2011 — Hot Rolled Medium and High Tensile Structural Steel
| Grade | Yield Strength (MPa) | Tensile Strength (MPa) | Elongation (%) | Charpy Impact | |:------|:--------------------:|:----------------------:|:--------------:|:--------------| | E250 A | ≥ 250 | 410 – 530 | ≥ 23 | Not required | | E250 B | ≥ 250 | 410 – 530 | ≥ 23 | 27 J at 0 °C | | E250 C | ≥ 250 | 410 – 530 | ≥ 23 | 27 J at −20 °C | | E350 | ≥ 350 | 490 – 630 | ≥ 22 | 35 J at 0 °C | | E410 | ≥ 410 | 540 – 670 | ≥ 20 | 35 J at 0 °C |
Mill Test Certificates covering chemical composition (C, Mn, Si, P, S, Al) and mechanical properties are supplied with every consignment. Third-party inspection by TPIA agencies is available on request.
IS 808:1989 — Section Dimensions
All sections conform to dimensional tolerances specified in IS 808 for depth, flange width, web thickness, mass per metre, and straightness. Out-of-tolerance sections are rejected at source.
Cut-to-Length and Value-Added Processing
| Service | Tolerance | Lead Time | |:--------|:---------:|:---------:| | Standard mill lengths (6 m, 9 m, 12 m) | IS 808 rolling tolerance | Ex-stock | | Cut-to-length (any dimension) | ±3 mm | 1–2 days | | Shot blasting to Sa 2.5 | IS 9954 | 2–3 days | | Red oxide primer painting | 35–50 µm DFT | 2–3 days | | Hole drilling / punching | ±0.5 mm position | 2–4 days |
For project procurement, share your section schedule (size, quantity, length, grade, and delivery date) and we return a itemised quote within 4 working hours.
Frequently Asked Questions
What is the difference between ISMB and ISHB? Both are I-shaped hot-rolled sections. ISMB (Medium-weight Beam) has narrower flanges relative to the web depth — it is optimised for bending. ISHB (Heavy-weight Column) has wider, heavier flanges relative to the depth — it is optimised for axial compression and combined loading in columns. For pure beam applications, ISMB is the correct choice.
Can ISMC be used as a column? Yes, but with awareness of its asymmetry. A single ISMC column bends unsymmetrically under axial load because the centroid and the shear centre do not coincide. Back-to-back channels (box column) eliminate this eccentricity and are the standard arrangement for ISMC columns. Single-channel columns are only acceptable for very light, braced conditions.
Are ISMC and ISMB sections available in weathering steel? Corten A (IS 11587) weathering steel sections are available on indent from the mill. Lead time is 3–5 weeks. Contact our technical team for pricing on minimum order quantities.
What primer is applied in the standard primer painting service? Red oxide alkyd primer to IS 2074, applied at 35–50 µm dry film thickness by airless spray after shot blasting to Sa 2.5. This is a shop primer providing temporary corrosion protection during transport and erection — it is not a final coating system.
