MS Plate — Hot-Rolled Structural Steel Plates to IS 2062
Mild steel plate is the most specification-critical product in structural steel fabrication. A beam can often be swapped for the adjacent size in a standard table if the exact section is unavailable. A plate specified on an engineering drawing — base plate thickness, gusset dimension, crane girder web height — cannot be substituted without the structural engineer's sign-off.
This is why plate procurement demands material traceability, dimensional consistency, and a supplier with a service centre capable of delivering accurately cut pieces rather than standard mill sheets that require further processing on-site.
E250 Grade A is stocked in thicknesses from 5 mm to 50 mm for immediate dispatch. E350 and thicknesses above 50 mm are available on 2–4 working day lead time from our mill network. E410 is an indent item — contact us with your project schedule.
Grade Selection — Which IS 2062 Grade Do You Need?
IS 2062:2011 defines five structural plate grades, differentiated by yield strength, tensile strength, and impact toughness. Choosing the correct grade is a structural engineering decision — but understanding the practical differences prevents over-specification (paying for properties you will never use) and under-specification (a compliance failure).
| Grade | Min Yield (MPa) | Tensile Range (MPa) | Charpy Impact | When to Specify | |:------|:--------------:|:-------------------:|:-------------:|:----------------| | E250 A | 250 | 410 – 530 | None required | General fabrication, base plates, gussets, platforms | | E250 B | 250 | 410 – 530 | 27 J at 0 °C | Welded structures in moderate temperature environments | | E250 C | 250 | 410 – 530 | 27 J at −20 °C | Sub-zero environments, refrigeration structures | | E350 | 350 | 490 – 630 | 35 J at 0 °C | High-load fabrication, crane girder flanges, transfer beams | | E410 | 410 | 540 – 670 | 35 J at 0 °C | Heavy-duty structures, pressure vessel applications |
E250 A is the most economical grade but carries no impact toughness requirement. For any structure where dynamic loading, vibration, or low-temperature operation is a design consideration, specify E250 B or E350 minimum. Using E250 A in a crane girder flange plate is a common specification error that becomes visible only after fatigue cracking begins.
The Practical Case for E350
Using E350 instead of E250 in a base plate or stiffener application adds approximately 8–12 % to the material cost. In exchange, the fabricator can use a plate that is 25–30 % thinner for the same load capacity — reducing weight, weld volume, welding time, and distortion control effort. On large fabrication packages, the net cost of E350 is often lower than E250 after fabrication savings are included.
Thickness Range and Dimensional Availability
Standard mill plates are produced in thicknesses from 5 mm to 100 mm. The practical availability of specific thicknesses changes with market conditions — thicknesses in the 8 mm to 32 mm range are held in stock; others are available with short lead times.
Standard Mill Thickness Steps
Thin plates (5 mm to 12 mm): 5, 6, 8, 10, 12 mm — fastest moving stock; used for gussets, stiffeners, packing plates, shim plates, and floor chequered plate applications.
Medium plates (14 mm to 32 mm): 14, 16, 20, 22, 25, 28, 32 mm — the working range for base plates, splice plates, connection end-plates, and web plates in fabricated plate girders.
Heavy plates (36 mm to 100 mm): 36, 40, 50, 60, 75, 100 mm — specified for heavily loaded base plates under major columns, flange plates in bridge girders, and pressure vessel shells.
Cutting Options — Shear, Flame, and Plasma
The cutting method affects edge quality, dimensional accuracy, and heat-affected zone depth. Selecting the right process for each component prevents rework and ensures the plate arrives ready to weld.
Shear Cutting — Up to 20 mm
A mechanical shear blade cuts through the plate in a single stroke. The process is fast, quiet, and produces straight cuts with minimal waste. Shear-cut edges have a slight burnish zone (approximately 30 % of thickness) and a fracture zone below. For non-fatigue-critical structural plates such as base plates, gussets, and cleats, shear cutting is adequate and economical.
Dimensional tolerance: ±1 mm on cut length and width.
Flame Cutting (Oxy-Fuel) — 10 mm to 100 mm
An oxy-fuel torch melts and oxidises the steel along the cut line. Flame cutting is the standard method for thicknesses above 20 mm, complex profiles, and circular holes. The process creates a heat-affected zone (HAZ) of 2–4 mm on each side of the cut — a region where the steel microstructure has been altered by rapid heating and cooling.
For fatigue-critical applications (crane girder webs, bridge plate girder flanges, cyclically loaded connections), the HAZ must be removed by grinding to a depth of at least 3 mm before welding.
Dimensional tolerance: ±2 mm on straight cuts, ±3 mm on complex profiles.
Plasma Cutting — 3 mm to 50 mm
A plasma arc at 20 000 °C melts the steel while a high-velocity gas jet removes the molten metal. Plasma cutting is faster than flame cutting for plates up to 25 mm, produces a narrower kerf, and leaves a shallower HAZ of 0.5–1.5 mm — significantly better than oxy-fuel for precision components.
Plasma is the preferred process for tight-tolerance components — connection end-plates, shear tabs, moment plate connections, and architectural steel where the cut edge is exposed in the finished work.
Dimensional tolerance: ±0.5 mm on cut length and width.
We operate plasma cutting in-house. Profiles up to 1 500 mm × 3 000 mm can be nested from a standard mill sheet and cut in a single setup. Provide a DXF file of your component profiles and our service centre returns a quote with cutting time, material yield, and per-piece cost within 4 hours.
What to Specify When Ordering
A complete plate specification prevents the most costly procurement error: receiving material that is chemically correct but mechanically unsuitable, or dimensionally accurate but in the wrong delivery condition.
The minimum information required for a plate order:
- Grade — E250 A, E250 B, E250 C, E350, or E410
- Thickness — nominal in millimetres; state the minus tolerance that is acceptable (IS 2062 standard allows −0.30 mm on plates up to 25 mm thick)
- Width × Length — in millimetres; or "random mill lengths" if you are blanking in-house
- Delivery condition — as-rolled (AR), normalized (N), or thermomechanically rolled (M/TM)
- Quantity — in metric tonnes or number of pieces with dimensions
- Inspection level — standard MTC; or third-party inspection (TPIA); or ultrasonic testing (UT) for pressure vessel applications
Delivery Conditions Explained
As-Rolled (AR): The plate is used in the rolling condition without any further heat treatment. This is the standard for most structural applications.
Normalized (N): The plate is reheated above the austenite transformation temperature and air-cooled, refining the grain structure and improving toughness. Normalized plates are specified for impact-critical and fatigue-critical applications.
Thermomechanically Rolled (M/TM): Rolling is performed within a controlled temperature range that combines controlled rolling and accelerated cooling. TM plates achieve higher strength and toughness than normalized at the same thickness — they are common in high-strength grades and heavy sections.
Fabrication Notes — Welding Thick Plates
Welding MS plate above 25 mm thickness requires attention to hydrogen-induced cracking (HIC) — a delayed cracking phenomenon that can occur in the HAZ 24 to 72 hours after welding without any visible indication during the weld itself.
Preheat temperature requirements by thickness and grade:
| Thickness | E250 | E350 | |:---------:|:----:|:----:| | Up to 25 mm | Not required | 50 °C | | 25 mm to 40 mm | 50 °C | 100 °C | | 40 mm to 63 mm | 100 °C | 150 °C | | Above 63 mm | 150 °C | 200 °C |
These are minimum interpass and preheat temperatures for basic-coated (E7018/E5016 type) electrodes. Welding procedure specifications (WPS) for qualified welding engineers will specify exact values for the base material, consumable, and joint geometry combination.
Under-plate weld cracking is the most common cause of structural fabrication warranty disputes. This is a fabrication procedure responsibility — not a material defect. We flag it here because the plate will test within specification; cracking occurs due to diffusible hydrogen in the weld pool combined with high residual stress in thick sections.
Frequently Asked Questions
Can you supply checker plate (tread plate)? Yes. MS checker plate to IS 3502 is available in thicknesses from 4 mm to 10 mm with a raised diamond or lentil pattern. Standard sizes are 2 500 × 1 250 mm. Used for walkway flooring, stair treads, vehicle loading ramps, and vehicle body floors.
What is the maximum plate size you can supply in a single piece? Standard mill plates are available in widths up to 3 000 mm and lengths up to 12 000 mm. For project requirements exceeding these dimensions, we co-ordinate with the mill on special rolling — add 4–6 weeks to the schedule.
Do you supply Corten / weathering steel plate? IS 11587 (Fe 415 Cu / Cor-Ten equivalent) weathering steel plate is available on indent. Typical lead time is 4–6 weeks from the mill. Please contact our technical team with your project specification, as weathering steel requires specific welding procedure qualification.
Is third-party inspection available? Yes. We facilitate third-party inspection by agencies including Bureau Veritas, Lloyd's Register, SGS, and DNV GL. Inspection scope can cover dimensional checks, hardness testing, tensile and bend testing from heat samples, and ultrasonic testing for internal lamination defects. Add 3–5 working days to dispatch time for TPIA.
