What is the difference between P355GH and S355j2?

2026-01-23 10:09:37

In the world of steel plate procurement, engineers and buyers frequently encounter two important grades: P355GH and S355J2. While their numerical designations may appear similar, these steels serve fundamentally different purposes and are governed by distinct standards. Selecting the correct material is crucial for project safety, compliance, and cost-effectiveness. This article clarifies the key differences to guide your material selection process.

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GNEE is a leading manufacturer and global supplier of high-quality steel plates, with deep expertise in both pressure vessel steel and structural steel grades. We understand the nuanced specifications of standards like EN 10028-2 and EN 10025-2. Our role is to provide certified materials and technical guidance, ensuring you select the optimal grade—whether it’s P355GH for critical pressure containment or S355J2 for robust structural frameworks.

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Fundamental Standards and Intended Use

The core difference originates from their governing standards and primary design intent. P355GH steel is specified under EN 10028-2, which covers flat products for pressure purposes. Its primary application is in the fabrication of boilers, pressure vessels, and heat exchangers. Conversely, S355J2 steel falls under EN 10025-2, the standard for hot-rolled structural steels. It is designed for general construction, including buildings, bridges, and mechanical components where high load-bearing capacity is required.

Chemical Composition and Property Analysis

The chemical composition of P355GH pressure vessel steel is tightly controlled to ensure excellent weldability, notch toughness, and high-temperature performance. It has defined limits for elements like carbon, manganese, and silicon, and often includes micro-alloying additions. S355J2 structural steel, while also weldable, has a compositional focus on delivering a minimum yield strength of 355 MPa. The "J2" designation specifically indicates its toughness at -20°C, making it suitable for non-pressure applications in colder environments.

P355GH Chemical Composition

P355GH Chemical Composition
Grade	The Element Max (%)
Grade	C	Si	Mn	P	S	Al(min)	N
P355GH	0.10-0.22	0.60	1.10-1.70	0.025	0.015	0.020	0.012
	Cr	Cu	Mo	Nb	Ni	Ti	V
	0.30	0.30	0.08	0.040	0.30	0.03	0.02

S355J2 Chemical composition % of the Product analysis of grade

C	Si	Mn	Ni	P	S	Cr	Mo
max 0.24	0.60	1.70		Max 0.035	Max 0.035
V	Nb	Ti	N	Cu
				0.60

Key Mechanical Properties and Testing

Mechanically, both grades share a minimum yield strength of 355 MPa. However, the required tests differ significantly. P355GH plates undergo rigorous testing for elevated temperature properties (hence the "GH" designation) and often require more stringent impact (Charpy) tests to verify toughness for pressurized service. For S355J2 steel plates, the mandatory tests are focused on ambient temperature tensile strength and Charpy impact at -20°C, sufficient for its structural role.

P355GH Mechanical Property

Grade		P355GH Mechanical Property
Grade	Thickness	Yield	Tensilmie	Elongation	Impact Energy(KV J) min
P355GH	mm	Min Mpa	Mpa	Min %	-20°	0°	+20°
	≤ 16	355	510-650	20	27	34	40
	16> to ≤40	345	510-650	20	27	34	40
	40> to ≤60	335	510-650	20	27	34	40
	60> to ≤100	315	490-630	20	27	34	40
	100> to ≤150	295	480-630	20	27	34	40
	150> to ≤250	280	470-630	20	27	34	40

S355J2 Mechanical Property

		-150				150-250				250-400
Minimum energy nominal thicknessTemperature(-20)		27				27				27
Nominal thickness (mm)		to 16	16 - 40	40 - 63		63 - 80	80 - 100		100 - 150		150 - 200		200-250		250-400
ReH - Minimum yield strength (MPa)		355	345	335		325	315		295		285		275		265
Nominal thickness (mm)	-3				3-100			100-150				150-250		250-400
Rm -Tensile strength (MPa)	510-680				470-630			450-600				450-600		450-600

Choosing the Right Grade: Application Scenarios

Your application dictates the correct choice. Use P355GH material for any component that will contain pressure—such as reactor vessels, storage tanks, or boiler drums—especially those operating at elevated temperatures.
Opt for S355J2 structural steel for beams, columns, crane runways, and other load-bearing elements in construction and machinery.
Misapplication, such as using S355J2 in a pressure vessel, violates design codes and poses serious safety risks.

Conclusion: Source Your Steel from Industry Experts

In summary, while P355GH and S355J2 may have similar strength ratings, they are engineered for different worlds: pressure containment versus structural integrity. Understanding these differences in standards, properties, and applications is key to a successful and safe project. For certified P355GH steel plates or reliable S355J2 steel plates, partner with a knowledgeable supplier like GNEE. We ensure material traceability and compliance.

Request a free quotation for P355GH or S355J2 steel today and let our experts support your next project.

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