Steel plate for energy, petrochemical and capital equipment

The choice between P265GH and P355GH depends mainly on the design pressure, service temperature and the wall thickness resulting from calculations per EN 13445 or ASME VIII. P265GH is optimal when the design pressure is moderate (generally up to 16-20 bar in standard-volume vessels), material cost is a determining factor, or better weldability is required at very heavy thicknesses. P355GH becomes preferable when pressure is high and you need to minimize wall thickness to reduce weight and material cost, or when the service temperature is elevated and P355GH's higher yield strength allows working with a thinner section while maintaining safety factors. For applications above 375-400°C, other grades outside the scope of EN 10028-2 may be necessary. Mayor Steel can advise on the optimal selection for your specific process conditions.

This is the most frequent question and the most dangerous confusion in the sector. S355 J2+N and P265GH have similar yield strengths at room temperature, but they are not equivalent for several critical reasons. First, EN 10028-2 guarantees the mechanical properties of P265GH at elevated service temperature: we know that at 300°C the yield strength does not fall below a specified minimum value. S355 has no such guarantee. Second, EN 10028-2 strictly controls the residual elements that affect toughness and fatigue resistance at high temperature. Third, P265GH is a material harmonized under PED: its use in regulated pressure parts does not require a particular appraisal from the notified body. S355 is not: it would need that appraisal, which involves additional testing and a process that lengthens and increases project cost considerably more than the price difference between the two materials. Mayor Steel does not accept this substitution in order to protect the customer.

Yes. For high-criticality projects that specify material inspection by a third-party body such as DNV, Lloyd's Register, Bureau Veritas or similar, Mayor Steel can coordinate the inspector's visit to the warehouse in Zierbena prior to shipment. The inspector verifies on-site the dimensions, material marking, documentation (3.1 or 3.2 certificates), and conformity of the material with the project's purchase specification. After the inspection, the body issues its own inspection certificate that complements the steel manufacturer's 3.1 certificate. This service must be arranged with sufficient notice to coordinate the inspector's availability. Mention it in the order or in the prior technical inquiry.

Yes. For heavy structural plate in thicknesses above 60 mm intended for reactor supports, compressor skids or critical structural components in plant, Mayor Steel offers ultrasonic testing per EN 10160 in classes S1 (full surface inspection) and S2 (edge strip) on request. This test detects internal discontinuities such as laminations, inclusions or segregations that are not visible in visual inspection but can compromise the integrity of a support under static or dynamic load. In petrochemical and process plants, where a structural failure can have serious consequences, UT testing on heavy plate is a justified investment. Mention it when requesting the quote so it can be included in the budget from the outset.

Mayor Steel maintains stock of P265GH and P355GH in the most in-demand thicknesses for manufacturing pressure vessels and process equipment. For thicknesses from 20 to 60 mm, availability from stock allows deliveries of 24 to 72 hours throughout the peninsula. For thicknesses out of stock or special dimensions, the lead time is 1 to 3 weeks on mill order, depending on thickness and volume. If you have a project schedule with defined delivery windows, let us know when requesting the quote: we can plan the supply in phases to fit the equipment manufacturing schedule and avoid documentation bottlenecks with the notified body.