Steel plate for wind turbine towers and onshore wind farm structures
S690 QL to reduce tower section thickness and optimize logistics. S355 J2+N for flanges, platforms and load-bearing structures. 450 HB wear-resistant steel for wear areas on maintenance equipment. CORTEN S355 J2W+N for outdoor structures with no paint maintenance. Permanent stock in Spain for wind projects with tight installation windows.
The tower material determines transport cost and installation schedule
In onshore wind turbine towers, the plate thickness determines the weight of each section, the logistics of transport to the site, and the available installation window. The choice of steel is not just structural: it's logistical and economic.
S690 QL versus S355
By switching to S690 QL in the lower sections of the tower, where stresses are highest, it is possible to reduce plate thickness by 25-35% while maintaining structural capacity. In a tower section of 4-5 meters in diameter, this saving reduces the weight per section and facilitates transport on roads with clearance and tonnage restrictions.
CORTEN S355 J2W+N versus painted S355
The outdoor auxiliary structures of a wind farm —fencing, cable supports, substation structures— manufactured in CORTEN develop a stable oxide layer that acts as permanent protection. No repainting cycles throughout the entire service life of the wind farm (20-25 years), compared to repainting every 5-7 years for conventional steel.
No delays in tight installation windows
An onshore wind project has installation windows conditioned by weather conditions and construction permits. Delaying material supply by one week can push the start of installation to the next favorable period. Physical stock in Zierbena (Bizkaia) with fast deliveries throughout the peninsula eliminates this risk.
What does a manufacturer or builder of onshore wind farms need?
Six real needs of onshore wind sector players: tower manufacturers, wind farm builders and auxiliary structure suppliers working with strict technical specifications and weather-conditioned schedules.
Low-temperature toughness for high-altitude and cold-climate sites
Onshore wind farms on the Meseta, the Pre-Pyrenees, the Cantabrian Mountain Range or the mountain systems of northern Portugal operate at temperatures that can drop below -20°C. The Charpy impact quality at low temperature of structural steel is not optional in these applications: it is a design requirement.
Full traceability for wind turbine certification
Wind turbines and their towers are subject to certification by notified bodies (GL, DNV, Bureau Veritas). Technical documentation requires 3.1 certificates with traceable heat numbers for each batch of structural material. Without that traceability, equipment certification gets blocked.
Thick plate for flanges and connecting elements between sections
Connecting flanges between tower sections and between tower and foundation require thick plates of 60 to 150 mm with guaranteed mechanical properties throughout the thickness. Z35 quality (through-thickness properties) may be required to prevent lamellar tearing at critical joints.
Controlled weldability for large-thickness production
Manufacturing tower sections involves large-thickness shop welds (40-80 mm) and field welds under variable temperature and humidity conditions. Controlled CEV and the 3.1 certificate with chemical analysis ensure consistency of preheating parameters and the approved WPS.
Supply capacity for multi-turbine projects
An onshore wind farm of 20-50 turbines represents a structural plate volume of several hundred tonnes with a need for staggered delivery according to the installation plan. Supply capacity and reserved stock management are as important as the price per tonne.
Material for auxiliary structures with minimal maintenance over 25 years
A wind farm's auxiliary structures —control building, transformer supports, substation, perimeter fencing— must have the lowest possible maintenance cost throughout the wind farm's service life. CORTEN eliminates the recurring cost of repainting outdoor structures.
Mayor Steel products for onshore wind turbine towers and wind farms
Each grade has its role in the tower, the foundation or the wind farm's auxiliary structures. The correct steel choice by zone and application determines structural weight, on-site weldability and maintenance cost over 25 years.
S690 QL High Yield Strength Plate — For tower sections where weight and thickness matter
Application: Lower sections of tall wind turbine towers where bending loads are highest and thickness reduction facilitates transport logistics, internal tower reinforcement rings in stress concentration zones, nacelle load-bearing structures where weight reduction is decisive for the lifting system design, auxiliary crane arms integrated into the tower for drivetrain maintenance.
Technical advantage: With a yield strength of 690 MPa versus 355 MPa for S355 J2+N, it allows the thickness of tower sections to be reduced while maintaining structural capacity under wind, weight and fatigue loads. In towers of 80-100 meters, reducing the thickness of the lower sections (from 40-50 mm to 25-30 mm) reduces the weight of each section by 15-25%, facilitating transport on restricted roads and reducing the tonnage required by the installation crane.
Critical restriction to communicate to the technical department: S690 QL has PWHT (post-weld heat treatment) prohibited. Welding consumables must be high-strength: E11018-G for MMA, ER110S-G for MIG/MAG. Heat input must be kept between 0.5 and 2.0 kJ/mm. Low-temperature toughness is ≥30 J at -40°C (S690 QL) or -60°C (S690 QL1) for sites in cold climates or at high altitude. Wind turbine certifiers (DNV, GL) may require additional documentation on the qualification of welded joints in S690 QL.
| Tower zone | S355 J2+N thickness | Equiv. S690 QL thickness | Weight saving |
|---|---|---|---|
| Lower section (bending-dominant) | 45 mm | 30 mm | -33% |
| Mid section | 30 mm | 20 mm | -28% |
| Reinforcement ring | 20 mm | 14 mm | -25% |
S355 J2+N Structural Plate — The tower's base material
Application: Mid and upper height tower sections where thickness is not a critical logistics factor, internal tower platforms, internal access stairs and structure, cable tray and safety system supports in the tower, nacelle frames and internal structures, structural housings for auxiliary equipment. S355 J2 guarantees 27 J at -20°C, a common requirement for sites in continental or mountain climates.
Technical advantage: The reference grade for tower manufacturing: optimal balance between strength, weldability and cost. CEV generally <0.45% ensures shop and field weldability without preheating up to 30 mm under normal conditions. The J2 sub-designation (impact at -20°C) is the minimum required by most tower designers' specifications for continental European sites.
S275 JR Structural Plate — Secondary structures and auxiliary buildings
Application: Structure of the wind farm's control and transformation building, metal supports for transformers and medium-voltage cells, support structures for auxiliary electrical equipment skids, access platforms to substation equipment, cable support structures in trenches and ducts, substation fencing and enclosures.
Technical advantage: For secondary structural applications where S355 is over-specified and material cost is relevant. S275 JR reduces material cost in structures that are not directly in the turbine's load path and are designed with more generous safety factors.
S355 J2+N Heavy Plate ≥ 60 mm — Critical flanges and connecting elements
Application: Connecting flanges between tower sections made from rolled heavy plate (an alternative to forging), embedment flange between the tower's lower section and the concrete foundation (foundation flange), base plates for anchor bolts in high-load foundations, structural connecting elements at the tower base requiring Z35 quality to prevent lamellar tearing.
Technical advantage: Tower flanges are critical elements subjected to high-amplitude fatigue cycles over 25 years. Through-thickness property homogeneity (with impact testing at ¼ and ½ thickness) and heat traceability are requirements of the certification process. Stock in 60, 80, 100 and 120 mm thicknesses with immediate availability to avoid delays at critical points in the manufacturing schedule.
CORTEN S355 J2W+N Plate — No paint maintenance for 25 years
Application: Outdoor metal structures of the wind farm's control building and substation, support structures for the wind farm's self-consumption solar panels, perimeter fencing and enclosures, signage and beaconing structures at site access points, supports for meteorological and environmental monitoring equipment, outdoor walkways for accessing equipment outside the tower. Any outdoor wind farm structure where the maintenance-free lifecycle justifies the material cost premium.
Technical advantage: CORTEN develops a stable oxide patina within 2-5 years that acts as a barrier against further corrosion. In a wind farm with a 25-year service life, it eliminates repainting cycles every 5-7 years. The cost premium over painted S355 is recovered before the first avoided repainting cycle. Restriction: Not suitable for high-salinity areas or for tower interiors where condensation prevents the protective patina from developing correctly.
450 HB Wear-Resistant Plate — Maintenance equipment and farm access
Application: Hoppers and bodies of wind farm maintenance vehicles working with gravel and road repair material, linings for access road cleaning and maintenance equipment, loading/unloading platforms for aggregates at the foundation site, compaction equipment for the farm's internal roads. Within the turbine itself: wear-area linings inside the nacelle subject to vibration and friction.
Technical advantage: Certified Brinell hardness of 425-475 HB, service life 4-6 times longer than S355 under abrasive work. In a wind farm with a gravel access road network and heavy maintenance vehicles over 25 years, the cost premium of wear-resistant steel in work equipment is marginal compared to the cost of replacing hoppers and bodies every 6-12 months.
P265 GH / P355 GH Pressure Vessel Plate — Hydraulic and pneumatic systems
Application: Hydraulic accumulators of the pitch control system in wind turbines, vessels for hydraulic brake and nacelle orientation (yaw system), pneumatic aerodynamic brake system tanks, high-pressure filter housings in nacelle hydraulic systems, pressure vessels of the cooling systems for high-power generators and gearboxes.
Technical advantage: Materials harmonized under PED 2014/68/EU: their use in pressure vessels of regulated equipment does not require special approval from the notified body. The 3.1 certificate with heat traceability is mandatory for the wind turbine's technical documentation. Replacing P265GH or P355GH with S355 in these applications requires processing a particular material appraisal that delays and increases the cost of the equipment's certification process.
Why tower manufacturers and onshore wind farm builders choose Mayor Steel
Five differential value arguments for a sector that works with weather-conditioned schedules, strict certification specifications, and projects involving hundreds of tonnes of structural plate.
⚡ Real stock in Spain = installation windows met
An onshore wind project has installation windows conditioned by weather conditions and construction permits. Delaying material supply by one week can push the start of installation back by weeks or months. Warehouse in Zierbena (Bizkaia) with fast delivery throughout the peninsula. No dependence on 4-6 week Central European lead times.
📋 Complete certification documentation from the first order
Wind turbine certification by DNV, GL or Bureau Veritas requires 3.1 certificates with heat traceability for all structural materials. Mayor Steel supplies complete documentation as standard, with no additional steps. The turbine's technical file is not delayed by missing material documentation.
⚙️ Technical guidance on high-strength steels for towers
The transition to S690 QL in tower sections requires adapting the approved WPS, changing consumables and reviewing preheating parameters. Mayor Steel's technical team guides this process and provides the material's technical documentation needed for requalifying the welding procedure with the notified body.
📦 Full project range from a single supplier
S690 QL for tower sections, S355 J2+N for platforms and flanges, heavy plate for the foundation flange, P265GH for the hydraulic system and CORTEN for the wind farm's auxiliary structures. All in the same order, with a single point of contact, consolidated certification and simplified procurement management for the project.
💰 Material cost is not just the price per tonne
The project manager of a wind developer or the procurement director of a tower manufacturer doesn't just evaluate the price of the plate per tonne. They evaluate the total cost of procurement: material price, the cost of delays due to stock shortages at critical points in the schedule, the cost of additional certification steps due to incomplete material documentation, and the 25-year maintenance cost of auxiliary structures. Mayor Steel helps optimize that total project cost, not just the steel purchase price.
Applications of our plate in onshore wind turbine towers and wind farms
Twelve real applications where choosing the right steel determines structural behavior, weldability in the shop and field, and maintenance cost over the wind farm's service life.
Lower sections of tubular tower
S690 QL or S355 J2+N, 25-50 mm
Tower-to-foundation embedment flange
Heavy S355 J2+N, 80-150 mm
Internal tower platforms and stairs
S355 J2+N, 6-15 mm
Cable supports and electrical trays
S275 JR, 5-12 mm
Control and transformation building structure
S275 JR + outdoor CORTEN
Auxiliary crane arms inside the tower
S690 QL, 10-25 mm
Hydraulic accumulators of the pitch system
P265 GH / P355 GH, PED
Supports and perimeter fencing of the wind farm
CORTEN S355 J2W+N, 5-20 mm
Hoppers for wind farm maintenance vehicles
450 HB wear-resistant, 8-20 mm
Internal tower reinforcement rings
S690 QL or S355 J2+N, 20-40 mm
Wind farm substation structure
S355 J2+N + S275 JR, 8-30 mm
Turbine supports for hillside installations
Heavy S355 J2+N, 60-100 mm
Related sectors that also work with us
Wind turbine tower manufacturers and wind farm builders share procurement needs with these sectors.
Metal Construction
Heavy Machinery
Cutting and Processing
Industrial Vehicles
Solar PV Energy
Request a quote for your wind turbine tower or onshore wind farm project
Tell us the grades, thicknesses and estimated project volume. We'll respond within 24 hours with price, availability and technical guidance on the optimal combination of materials for each zone of the tower and the wind farm.
Frequently asked questions from manufacturers and builders of onshore wind farms
Technical answers to real questions from project managers, technical directors and procurement managers in the wind sector.
The most commonly used grade for manufacturing onshore wind turbine towers is S355 J2+N per EN 10025-2. Thickness varies depending on the section's position in the tower and the turbine's total height: the lower sections, which support the maximum bending loads, typically have thicknesses of 35 to 60 mm in standard towers of 80-100 meters, while the upper sections can go down to 10-15 mm. For taller towers, or when weight reduction facilitates transport logistics, some design specifications incorporate S690 QL in the lower sections, allowing wall thickness to be reduced by 25 to 35% with the same structural capacity. The choice between S355 and S690 QL depends on the specific tower design and the approved certification process.
The pressure vessels of a wind turbine's hydraulic systems are subject to the PED Directive 2014/68/EU when they exceed certain pressure and volume thresholds. The PED requires that materials used in pressure-bearing parts be either materials harmonized under the directive or have a particular material appraisal from the notified body. S355 J2+N is not a harmonized material under PED for pressure parts: its use in pressure vessels regulated by PED requires processing a particular appraisal that lengthens and increases the cost of the turbine's certification process. P265GH and P355GH per EN 10028-2 are materials harmonized under PED: they do not require particular approval and simplify the equipment's technical documentation before the notified body.
CORTEN S355 J2W+N is not typically used for manufacturing the wind turbine tower itself for several reasons: wind turbine certification specifications (DNV, GL) are primarily developed for S355 J2+N and S690 QL, the protective patina development process requires wetting and drying cycles that do not always occur inside the tower, and tower manufacturers usually work with epoxy or zinc paint systems documented in the turbine's maintenance plan. CORTEN is especially suitable for the wind farm's outdoor auxiliary structures: control building, transformer supports, perimeter fencing, signage structures and any outdoor element where the maintenance-free lifecycle justifies the cost premium over painted S355.
Yes. For multi-turbine wind farm projects, Mayor Steel designs a supply plan with the total project volume reserved in stock and staggered deliveries according to the manufacturing and installation schedule. Certification documentation (3.1 certificates with heat traceability) is generated on a consolidated basis to simplify management of the technical file. In projects of this scale, we also aim to minimize the number of different heats supplied for each grade, maximizing the homogeneity of mechanical properties throughout the project. Tell us the estimated volume per grade and thickness and we'll plan it together.
For sites with design temperatures below -20°C, S355 J2+N (toughness guaranteed at -20°C) may be insufficient if the site's design temperature is lower. In that case, the designer's specification may require S355 K2 (27 J at -40°C) or S355 NL (27 J at -50°C per EN 10025-3). For structural elements field-welded under winter temperature conditions, controlled CEV and preheating instructions specific to low temperatures are equally important. Mayor Steel can supply S355 in J2, K2 and N/NL sub-grades according to the specific requirements of the site. Let us know your site's design temperature and we'll advise you on the appropriate grade.
Mayor Steel maintains permanent stock of steel plate in Spain and Portugal, with a warehouse in Zierbena (Bizkaia), enabling fast delivery times to wind turbine tower manufacturers and onshore wind farm builders throughout the peninsula. Northern Spain —the Basque Country, Navarre, La Rioja, Aragón and Castilla y León— is home to both the main tower manufacturers and some of the highest-capacity wind farms, and from Zierbena we also serve projects in Extremadura, Castilla-La Mancha, Andalusia and Portugal with consolidated transport. Compared to Central European suppliers with lead times of 4 to 6 weeks, Mayor Steel is the difference between a project schedule that is met and one that waits for the material.