P355GH is a high-quality, low-alloy carbon steel designed for pressure vessel and boiler applications, defined under EN 10028-2, the European standard for flat products made of steels for pressure purposes. The grade offers excellent mechanical strength, heat resistance, and weldability, which ensure safe and durable operation in high-pressure and high-temperature environments. It is one of the most widely specified pressure vessel grades in Europe and is available as plates, hot-rolled sheets, tubes, and forgings.
P355GH Steel
The designation P355GH follows the EN system for pressure steels: P indicates pressure application, 355 is the minimum yield strength in megapascals for the thinner thickness range, G indicates a fine-grain structure, and H indicates high-temperature suitability. The grade gives optimum performance for pressurized products that must support a creep limit greater than 180 newtons per square millimeter at 400 degrees Celsius, and it is used above all for manufacturing boilers, pressure vessels, and pipes for the transportation of hot liquids.
The steel combines a minimum yield strength of 355 MPa for plates up to 16 mm with high tensile strength and excellent toughness, and it is supplied in plates, hot-rolled sheets, tubes, and forgings to suit a wide range of industrial equipment.
Chemical Composition
The chemical composition of P355GH is controlled within tight limits. Typical maximum or range values include:
Carbon: 0.10 to 0.22 percent, with the exact limit depending on thickness.
Silicon: maximum 0.60 percent.
Manganese: 1.10 to 1.70 percent.
Phosphorus: maximum 0.025 percent.
Sulfur: maximum 0.015 percent.
Copper: maximum 0.30 percent.
Chromium: maximum 0.30 percent.
Nickel: maximum 0.30 percent.
Molybdenum: maximum 0.08 percent.
Niobium, titanium, and vanadium: each limited to small residual maximum values.
The low carbon content and controlled alloy composition reduce welding defects and give the steel good ductility and toughness, with a fine-grain structure supporting impact resistance at low temperature.
Mechanical Properties
The mechanical properties of P355GH vary with plate thickness. Typical values are:
Up to 16 mm: minimum yield strength 355 MPa, tensile strength 510 to 650 MPa.
16 to 40 mm: minimum yield strength 345 MPa, tensile strength 510 to 650 MPa.
40 to 60 mm: minimum yield strength 335 MPa, tensile strength 510 to 650 MPa.
60 to 100 mm: minimum yield strength 315 MPa, tensile strength 490 to 630 MPa.
100 to 150 mm: minimum yield strength 295 MPa, tensile strength 480 to 630 MPa.
150 to 250 mm: minimum yield strength 280 MPa, tensile strength 470 to 630 MPa.
Minimum elongation is typically 20 percent or higher, and the Charpy V-notch impact requirement is defined by the standard, with values commonly in the range of 27 to 40 joules depending on the test temperature specified for the product.
Available Forms and Dimensions
P355GH is available in a wide range of product forms and sizes:
Thickness: 1 mm to 250 mm.
Width: 1500 mm to 3500 mm.
Length: 3000 mm to 27000 mm.
Delivery forms: plates, hot-rolled sheets, tubes, and forgings.
The material is normally delivered with EN 10204 3.1 or 3.2 mill test certificates, and dual certification with comparable ASTM grades such as A516 is available where required by the project.
Applications
P355GH steel plates and sheets are widely used in industrial pressure vessels and high-temperature applications:
Boilers and boiler drums: shells, water walls, superheater tubes, and economizer tubes.
Heat exchangers and steam generators: shell-and-tube exchangers, industrial heaters, and process coolers.
High-pressure storage tanks: petroleum and gas storage, LPG tanks, and pressurized fluid containment.
Chemical and petrochemical processing: reactors, distillation columns, fractionators, and high-temperature piping.
Power generation equipment: pressure vessels, feed-water heaters, condensers, and steam generators.
Tubes and forgings: seamless and welded tubes and forged components for assembling pressure vessels.
The grade provides long-term stability and safety for critical equipment, with high strength and thermal resistance, excellent weldability, good ductility and toughness, and consistent quality assurance.
Frequently Asked Questions
What is P355GH material? P355GH is a pressure vessel steel that gives optimum performance for pressurized products that must support a creep limit greater than 180 newtons per square millimeter at 400 degrees Celsius. It is characterized by good weldability and is used mainly for boilers, pressure vessels, and pipes for hot liquids.
What is EN 10028-2 P355GH equivalent to? P355GH pressure vessel steel is commonly considered equivalent to ASTM A516 Grade 70 and ASME SA516 Grade 70 for many applications, although the two standards differ in composition limits and testing rules, so equivalence should be confirmed against the design code.
What is the difference between P355GH and P355NH? P355GH is designed for high-temperature applications and is characterized by high strength at temperatures up to about 500 degrees Celsius, while P355NH is designed for low-temperature applications and is characterized by high toughness at low temperatures.
What is the yield strength of P355GH? The yield strength ranges from about 280 to 355 MPa depending on thickness, with a minimum of 355 MPa for plates up to 16 mm, and the tensile strength ranges from about 470 to 650 MPa.
Is P355GH weldable? Yes. The low carbon content and controlled alloy composition give P355GH excellent weldability, and it can be welded by standard arc welding processes with qualified procedures.
What is P235GH pipe equivalent to in ASTM terms? P235GH is a European pressure vessel grade under EN 10028-2, and its approximate American equivalent is often considered to be ASTM A285 Grade C, although a direct substitution should always be verified against the design specification.