Steel plate for boilermakers and structural fabricators
P265GH and P355GH with 3.1 certificate for projects under PED. S355 J2+N for steel construction EXC2 and EXC3. Permanent stock in Spain: the right material, with the right documentation, when you need it.
Two sectors, one same demand
The right material and flawless documentation. Whether you manufacture under PED or execute structures under EN 1090, your supplier cannot fail.
Manufacturing under PED: documentation is not optional
- Needs P265GH or P355GH according to EN 10028-2, not substitutions with S355
- The 3.1 certificate with heat traceability is what the notified body requires during the final inspection of the equipment
- An incorrect certificate halts the CE declaration and blocks the equipment's marketing in the EU
- Also needs S355 for non-pressurized parts: supports, bases, auxiliary structures
Execute: the construction schedule doesn't wait
- Needs S275 JR and S355 J2+N with correct 3.1 certificate for EXC2 and EXC3
- A delay in material delivery can stop the assembly crew and generate penalties on site
- Needs a variety of thicknesses in a single order to avoid managing multiple suppliers
- For EXC3 in thick plate: ultrasonic testing EN 10160 and 3.2 certificate available on request
What do boilermakers and structural fabricators need from their supplier?
Six real requirements that we solve with stock, certification and specialized technical advice.
Full 3.1 certificate as standard
Not as an additional service. Heat chemical analysis, mechanical properties of the actual batch, regulatory compliance and physical traceability of the material in every supply, without having to request it expressly.
Correct grades for each application
P265GH and P355GH for pressure parts under PED. S355 J2+N for structures. No substitutions, no approximations. The right grade with the right standard.
Real stock with no factory waiting times
The difference between "available" and "in stock" is weeks of delay. Mayor Steel has physical plate in Spain in every grade of the portfolio, without depending on Central European production.
Full range from a single supplier
From structural S235 to P355GH for pressure and S690 QL for high-strength structures. One order, one point of contact, one delivery note with all documentation consolidated.
Thick plate available without waiting
Anchor plates, base plates, truss nodes, thick boilermaking walls. S355 J2+N from 60 mm to 300 mm in permanent stock. Ultrasonic testing EN 10160 available for EXC3.
Specialized technical advice
Guidance on the correct grade before ordering: when to use P355GH instead of S355, which grade corresponds to which thickness, what documentation EXC3 requires for each component.
Mayor Steel products for boilermaking and steel construction
Certified plate from stock with a specific application in each process: PED, EN 1090, heavy boilermaking and steel construction.
Pressure vessel plate P265 GH / P355 GH
Application: Shells, heads and bodies of pressure vessels. Heat exchanger shells. Industrial tanks under PED. Pressure equipment, autoclaves and reactors. Boiler headers and bodies.
Technical advantage: P265GH and P355GH are harmonized materials under the PED Directive: automatically approved without requiring specific approval from the notified body. S355 J2+N cannot replace them in regulated pressure parts without that additional procedure. The 3.1 certificate supplied by Mayor Steel includes heat number, full chemical composition, mechanical properties of the actual batch and traceable physical marking. This is what the notified body needs to issue the final inspection.
Structural plate S275 JR / S355 J2+N
Application in boilermaking: Non-pressurized parts of equipment, structural supports of vessels, bases and auxiliary frames of the equipment.
Application in steel construction: Columns, beams, purlins, gussets, stiffeners, node plates, base plates and secondary elements of industrial buildings, walkways and mezzanines.
Technical advantage: S355 J2+N with CEV generally <0.45%: good weldability without preheating up to 30 mm under normal conditions. Charpy J2: 27 J at -20°C. For EXC2 the 3.1 certificate is mandatory; Mayor Steel includes it as standard.
Thick structural plate S355 J2+N
Application: Large-section anchor plates, column stiffeners, truss nodes, industrial flanges. In boilermaking: thick walls, supports for large-tonnage vessels and heavy boilermaking components.
Technical advantage: The thickness effect reduces yield strength according to EN 10025: at 100 mm, S355 has 315 MPa, not 355 MPa. Critical data for the design engineer. S355 for low temperature: Charpy 27 J at -50°C. UT testing EN 10160 S1/S2 available, essential for EXC3.
High-strength plate S690 QL
Application: Large-span structures with weight reduction, workshop cranes, small-span industrial bridges, structures with high loads where section reduction is decisive.
Technical advantage: Weight reduction of up to 40% compared to S355 with equal load capacity. Tensile strength 770-940 MPa. PWHT prohibited (post-weld heat treatment). Mandatory consumables: E11018-G (MMA) / ER110S-G (MIG/MAG). Heat input: 0.5-2.0 kJ/mm.
Corten plate S355J2WN
Application: Industrial facades, exterior cladding, urban walkways, signage and street furniture structures, architectural cladding and landscape integration elements.
Technical advantage: The surface oxide patina acts as a passivating protective barrier. No paint maintenance throughout the service life. Mechanical strength equivalent to S355. Distinctive aesthetics for steel construction projects with an architectural component.
Why boilermakers and structural fabricators choose Mayor Steel
Five differential value arguments for workshops that cannot afford errors in material or documentation.
📋 Correct 3.1 certificates as standard, without asking
It's not a premium service. Every supply includes an EN 10204 3.1 certificate with heat traceability, chemical composition and mechanical properties of the actual batch supplied. The quality coordinator or notified body will have no objections.
⚡ Real stock = lead times in days, not weeks
The difference between "available" and "in stock" is weeks of waiting. Warehouse in Zierbena (Bizkaia) with fast delivery throughout the peninsula. Your PED inspection and your assembly schedule don't wait for Central European factory production.
🎯 Full range from a single supplier
From structural S235 to P355GH for pressure, S690 QL and thick plate up to 300 mm. The boilermaker who needs P355GH for the body and S355 for the supports manages it in a single order, with a single delivery note and all documentation consolidated.
📦 Thick plate available without waiting for the factory
Few distributors in Spain have real S355 stock in 100, 120 or 150 mm. Mayor Steel has it. For large-section anchor plates, critical nodes or heavy boilermaking walls, we eliminate weeks of waiting for the hardest part to source.
👨🔧 Specialized technical advice before the mistake happens
The Mayor Steel team knows the difference between PED and EN 1090, knows when to recommend 3.2 instead of 3.1, and can advise on which grade to use for each application before a specification error becomes a certification problem or a site non-conformity. You talk to technicians, not order administrators.
Real applications in boilermaking and steel construction
Fourteen specific applications where our plate is in active production at boilermaking workshops and structural fabricators in Spain.
Shells and heads of pressure vessels
P265GH / P355GH, PED
Heat exchanger shells
P355GH, EN 10028-2
Industrial pressure tanks
P265GH, harmonized material
Industrial reactors and autoclaves
P355GH, 3.1 certificate
Columns and beams for industrial buildings
S355J2+N, 10-40 mm
Anchor plates and base plates
S355, 60-150 mm
Stiffeners and truss nodes
S355J2+N, EXC2/EXC3
Industrial walkways and platforms
S355, EN 1090 EXC2
Mezzanines and distribution structures
S355J2+N
Small-span industrial bridges
S355 / S690QL, EXC3
Industrial facades and cladding
Corten plate S355J2WN
Supports and bases for process equipment
S355J2+N, 20-60 mm
Boiler headers and bodies
P265GH / P355GH
Support structures for heavy machinery
Thick S355, 80-200 mm
Related sectors that also work with us
Our boilermaking and steel construction clients regularly refer their clients to us in these sectors.
Heavy Machinery
Cutting and Processing
Oil & Gas / Petrochemical
Mining and Infrastructure
Trailers and Semi-trailers
Request a quote for your boilermaking workshop or steel structure
Tell us the grade, thickness, quantity and whether you need specific certification. We will try to respond within 24 hours with price, availability and documentation from stock. No surprises.
Frequently asked questions from boilermakers and structural fabricators
Concrete answers to the real questions of purchasing managers, technical directors and quality coordinators.
Not without specific approval from the notified body. S355 J2+N is not a harmonized material under the PED Directive 2014/68/EU. Its use in regulated pressure parts requires a specific approval that lengthens and increases the cost of the project more than the price difference between the two grades. P265GH and P355GH are harmonized materials: they can be used directly without additional procedures. Mayor Steel does not accept this substitution and we warn you before the order, not after.
The EN 10204 type 3.1 certificate includes: heat number identified and traceable to the physical material, full chemical composition of the batch supplied, mechanical properties measured from the actual batch (yield strength, tensile strength, elongation, Charpy), declared conformity with EN 10028-2 and verification by inspection personnel independent of the manufacturer. The physical marking of the material is traceable to the heat number. This documentation is what the notified body needs to issue the final inspection of the equipment under PED.
For EXC2 according to EN 1090-2: a 3.1 inspection certificate according to EN 10204 is mandatory. Mayor Steel includes it as standard in all supplies. For EXC3: in addition to the 3.1, on critical elements and thick plate, a 3.2 certificate with third-party inspection is recommended, along with ultrasonic testing EN 10160 on thick plate to detect internal discontinuities. Mayor Steel can arrange both options on request without needing to change supplier.
It depends on the thickness and ambient temperature. With a temperature ≥5°C and thicknesses up to 30 mm, it is generally not necessary, given that the CEV of S355 J2+N is usually below 0.45%. Below 5°C or for thicknesses of 30-60 mm, preheating of 50-100°C is recommended. For thicknesses of 60-100 mm: 100-125°C. These temperatures must be recorded in the workshop's WPS. We can advise you on the requirements according to the thickness and conditions of your site.
Yes. Mayor Steel offers ultrasonic testing according to EN 10160 in classes S1 and S2 for thick structural plate, on request. This test detects internal discontinuities (laminations, inclusions, segregations) and is mandatory or highly recommended in EXC3/EXC4 structures and plates over 100 mm for primary structural applications. If your project requires it, indicate this when requesting the quote so it can be included in the documentation from the start.
Yes. Mayor Steel manages split shipments with fast deliveries throughout the peninsula from stock in Zierbena (Bizkaia). For projects with a defined schedule, we can agree on planned periodic deliveries with a fixed price during the supply period. Tell us the schedule and we'll structure it with you.
Mayor Steel maintains permanent stock of steel plate in Spain and Portugal, with a warehouse in Zierbena (Bizkaia), which allows fast delivery times to boilermaking workshops and structural fabricators throughout the peninsula. For industrial boilermakers, this means that the material delivery time does not affect the notified body's inspection date. For structural fabricators, it means that the assembly schedule is not subordinated to production at a Central European steelworks with 4-6 weeks of waiting. From the Basque Country we cover the northern industrial corridor with daily deliveries, and the rest of Spain —Madrid, Barcelona, Valencia, Seville, Zaragoza— with consolidated national transport.