Heavy plate: what changes above 25 mm
Above about 25 mm the plate is rolled from a slab on a reversing mill, and three things change: mechanical properties drop with thickness (S355J2 yield 355 MPa at ≤ 16 mm, 315 MPa at 80–100 mm), internal soundness must be checked by ultrasonic testing because of possible centre segregation, and through-thickness ductility (Z-quality) matters for heavily welded T-joints. Normalized delivery (+N) is standard from 40 mm because it refines the grain and stabilises the impact values. Weight becomes the practical limit: a 100 × 2 500 × 12 000 mm plate weighs 23.5 t and must ship as a single breakbulk piece.
Weight chart
| Thickness | kg/m² | 2 000 × 6 000 (kg) | 2 500 × 6 000 (kg) | 2 500 × 12 000 (kg) | 3 000 × 12 000 (kg) |
|---|---|---|---|---|---|
| 25 mm | 196 | 2 355 | 2 944 | 5 888 | 7 065 |
| 30 mm | 236 | 2 826 | 3 533 | 7 065 | 8 478 |
| 40 mm | 314 | 3 768 | 4 710 | 9 420 | 11 304 |
| 50 mm | 393 | 4 710 | 5 888 | 11 775 | 14 130 |
| 60 mm | 471 | 5 652 | 7 065 | 14 130 | 16 956 |
| 80 mm | 628 | 7 536 | 9 420 | 18 840 | 22 608 |
| 100 mm | 785 | 9 420 | 11 775 | 23 550 | 28 260 |
| 120 mm | 942 | 11 304 | 14 130 | 28 260 | — |
| 150 mm | 1 178 | 14 130 | 17 663 | — | — |
| 200 mm | 1 570 | 18 840 | 23 550 | — | — |
Mill lengths up to 12 m (18 m on request); pieces over 25 t by breakbulk only.
Grades for heavy plate
For die and mould plates the industry often uses S355J2+N with a stress-relieving heat treatment and milled faces; for hardness-critical dies see the wear-resistant / Q&T page.
| Grade | Yield (40–63 mm) | Delivery | Use |
|---|---|---|---|
| S235JR | 215 MPa | As rolled | Counterweights, non-structural bases, slab |
| S275JR | 255 MPa | As rolled | Bases, frames |
| S355J2+N | 335 MPa | Normalized | Machine bases, press frames, structural base plates, cranes (standard) |
| S355K2+N | 335 MPa | Normalized | Heavy welded structures, offshore, wind flanges |
| S355J2+N Z35 | 335 MPa | Normalized, Z-tested | Heavily welded T-joints, box columns |
| P265GH / P355GH | — | Normalized | Pressure vessels — see pressure vessel plate page |
| A36 / A572 Gr. 50 | 250 / 345 MPa | As rolled / N | US-spec projects |
Ultrasonic testing and Z-quality
UT to EN 10160 is offered per plate: class S1/E1 for general structural, S2/E2 for machine and crane bases, S3/E3 for critical lifting and pressure parts (100% scan, no indications over 20 mm). Through-thickness tensile testing to EN 10164 (Z15/Z25/Z35, reduction of area) is specified when welds pull the plate in the thickness direction — base plates with welded columns, box sections, offshore nodes. Both are recorded on the 3.1 or 3.2 certificate.
Cutting, milling and machining
Plasma to 80 mm, oxy-fuel to 200 mm (multi-torch for stacks of base plates), tolerance ±2 mm; bevels and chamfers; drilling and tapping (to M64); face milling on request for base and mould plates (flatness 0.1 mm/m); stress relieving in partner furnaces. Base-plate kits for steel buildings — cut, drilled, milled — ship labelled with the beams.
Tolerances (EN 10029)
| Thickness | Class A (lower / upper) | Class B (lower / upper) |
|---|---|---|
| 25 – 40 mm | −0.8 / +1.4 | −0.3 / +1.9 |
| 40 – 80 mm | −1.0 / +1.8 | −0.3 / +2.5 |
| 80 – 150 mm | −1.0 / +2.2 | −0.3 / +2.9 |
| 150 – 250 mm | −1.2 / +2.4 | −0.3 / +3.3 |
Flatness class N (S on request); cut edges ±2 mm by flame, ±1 mm by plasma.
Heavy plate price per ton
Priced per plate and mill lot; as a guide S355J2+N heavy plate sits 10–20% above the 3–20 mm S235JR band, with extras for UT class, Z-quality, thickness over 100 mm and single-plate lots. Cutting is per metre, milling per m². Firm price per plate within one working day.
Bands from our weekly export list (September 2026), FOB Istanbul, full-container quantities, excluding freight and certificates. Firm price per project on RFQ within one working day.
Export: flat-rack and breakbulk
Plates to 5 t and 6 m fit 40' HC containers (max 24–25 t); heavier or longer pieces go on 40' flat-racks (to 40 t) or breakbulk from Derince / Gemlik with lifting lugs or chain slings; trucks carry 24 t to the EU, Balkans and Iraq. HS code 7208.51 (>10 mm, non-alloy) / 7225.40 (alloy).
| Term | Detail |
|---|---|
| MOQ | 1 plate; 20 t for economic freight |
| Incoterms | FOB Derince / Istanbul · CIF / CFR Gulf, Africa · DAP EU, Balkans, Iraq, Caucasus |
| Lead time | 25–60 mm partly stock 5–10 working days; thicker 4–8 weeks; UT/machining +5–10 |
| Packing | Single plates on bearers with lifting lugs or slings; kits strapped on skids |
| Container / truck | 40' HC to 5 t / 6 m per plate · flat-rack to 40 t · breakbulk any size · truck 24 t |
| Documents | Invoice, packing list per plate, EN 10204 3.1/3.2, UT and Z reports, CE, certificate of origin |
| Payment | 30% advance, balance against B/L copy; L/C at sight via London office |
Certificates
EN 10204 3.1 per plate with chemistry, tensile, impact; UT report EN 10160; Z-test EN 10164; 3.2 with Lloyd's, BV, DNV or TÜV witness on request; certificate of origin; CE per EN 10025.
How to order
Send grade, thickness × width × length or the cutting plan, UT/Z requirements, machining, quantity and port. Reply within one working day with price per plate, weight and the shipping method.
Standards
- EN 10025-2 (S235JR, S275JR, S355J2/K2 +N)
- EN 10029 (tolerances, class A–D)
- EN 10160 (ultrasonic testing, S0–S3 / E0–E4)
- EN 10164 (through-thickness Z15/Z25/Z35)
- ASTM A36 / A572 / A516 / A6
Grades
Grade data sheets (chemistry, mechanicals, equivalents) are on our reference site: S235JR · S355J2 · A36 · A516 Grade 70
Frequently asked questions
What is the thickest plate you can supply?
200 mm as rolled plate in S235JR / S355J2+N, and thicker slabs or forged blocks on request; widths to 3 000 mm and lengths to 12 m (18 m from the mill).
Why is +N (normalized) specified for thick plate?
Normalizing refines the coarse as-rolled grain of thick plate, giving reliable impact toughness through the thickness and better flatness after cutting; it is standard from 40 mm for S355J2.
What is UT class S2/E2?
EN 10160 ultrasonic testing: S refers to the plate body, E to the edges; class 2 allows indications up to 1 000 mm² body / 30 mm edge length. Machine bases and crane parts are usually specified S2/E2, critical lifting and pressure parts S3/E3.
What is Z35 steel?
Plate tested for through-thickness ductility (EN 10164) with a minimum 35% reduction of area — used where welds load the plate perpendicular to its surface, to prevent lamellar tearing.
How much does a 100 mm plate weigh?
785 kg/m²: 2 000 × 6 000 mm = 9.4 t; 2 500 × 12 000 mm = 23.5 t — a breakbulk piece.
Can you machine base plates and mould plates?
Yes — flame or plasma cut, drilled and tapped, face-milled to 0.1 mm/m, stress-relieved on request; delivered as kits.
How is heavy plate shipped?
Up to 5 t / 6 m per plate in 40' HC containers; heavier or longer on flat-racks (to 40 t) or breakbulk vessels from Derince; 24 t trucks to the EU, Balkans and Iraq.