What is the temperature range of P355NH?
Its most widespread use is in application environments up to 400 ºC. P355NH steel is supplied in the normalised condition. The normalising temperature is 900 - 950 ºC, and it must be left in the furnace after temperature equalising for approximately 1 minute per millimetre of thickness of the plate.
From a fabrication standpoint, P355NH is a highly reliable "workhorse" plate. It is favored by workshops because its normalized condition makes the material predictable during cutting and welding. It does not suffer from the internal residual stresses that can cause "spring-back" or warping in non-normalized structural plates.
Decoding the Name:
P: Indicates the material requires a Mill Test Certificate (MTC) to 3.1 or 3.2 levels for pressure safety.
355: The strength metric ($355$ MPa).
N: Normalized, which improves the "toughness" of the heat-affected zone (HAZ) after welding.
H: Identifies the plate as heat-resistant.
Key Comparison:
When compared to ASTM A516 Grade 70, P355NH is often seen as more specialized due to the explicit "H" rating for temperature. While A516 Gr 70 is a versatile pressure steel, P355NH is specifically optimized for the European EN 13445 design code for unfired pressure vessels.
Key Characteristics:
Cold Formability: Excellent for rolling into cylindrical shells or pressing into dished ends (heads) for tanks.
Minimal Preheating: Due to the low carbon content, it often requires less preheating during welding compared to other high-strength alloys.
Smooth Surface: The normalization process often results in a cleaner surface scale that is easier to prime and paint.
Common Applications:
Dished ends for pressure vessels, air receivers, compressor cylinders, and welded flanges for high-pressure service.
What is the density of P355NH?
The density of P355NH steel is typically around 7.85 g/cm³ (or 7850 kg/m³), which is standard for many steel grades, with some sources noting values like 7.80 g/cc or 7800 kg/m³, reflecting its composition as a non-alloy elevated temperature quality steel used in pressure applications.
What is P355NH steel Plate Thickness?
P355NH steel plates come in a wide range of thicknesses, commonly from 6mm up to 250mm or even 350mm, depending on the supplier and specific application, used for boilers and pressure vessels, with the thickness affecting mechanical properties like yield strength, as specified by the EN 10028-3 standard.
What is P355NH equivalent?
P355NH (EN 1.0565) is a European steel for pressure vessels, with key equivalents being ASTM A662 Grade C (USA), WStE355 (German DIN), and A510AP (French AFNOR). It's a fine-grain, normalized steel with a minimum yield strength of 355 MPa, suitable for elevated temperatures, offering good weldability and resistance to brittle cracking, often used in tanks for pressurized gases.
Chemical composition
| C % | Si % | Mn % | P % | S % | Cr % | Ni % | Mo % | V % | Ti % | Cu % | Al % | Nb % | N % | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Min | 0.01 | 0.01 | 1.10 | 0.000 | 0.000 | 0.00 | 0.00 | 0.00 | 0.000 | 0.000 | 0.00 | 0.020 | 0.000 | 0.0000 |
| Max | 0.18 | 0.50 | 1.70 | 0.025 | 0.010 | 0.30 | 0.50 | 0.08 | 0.100 | 0.030 | 0.30 | - | 0.050 | 0.0120 |
Mechanical Properties
| Format | Dimension [mm] | Yield strength min [MPa] | Tensile strength [MPa] | Elongation A5 [%] | Impact (ISO-V) strengthmin |
|---|---|---|---|---|---|
| Round bar | 25 < 35 | 355* | 490-630 | 22 | -20 °C 40 J (long) |
| Round bar | 35 < 50 | 345* | 490-630 | 22 | -20 °C 40 J (long) |
| Round bar | 50 < 70 | 325* | 490-630 | 22 | -20 °C 40 J (long) |
| Round bar | 70 < 100 | 315* | 470-610 | 21 | -20 °C 40 J (long) |
| Round bar | 100 < 150 | 295* | 450-590 | 21 | -20 °C 40 J (long) |
1What temperature will damage P355NH?
P355NH steel is designed for elevated temperatures, commonly used up to around 400°C (750°F) for pressure vessels, but significant strength loss starts to occur above 300°C (572°F), with rapid weakening and potential deformation above 400°C (750°F), though its ultimate failure depends on load, duration, and specific service conditions. Damage isn't a sudden event but a gradual loss of strength and stiffness.
2What is the hardness of P355NH?
P355NH steel, used for pressure vessels, doesn't have a single hardness number but is characterized by a minimum yield strength of 355 MPa, with typical tensile strength ranging from 490 to 630 MPa, and often supplied in a normalized condition for good toughness, though hardness values like Brinell can vary by supplier and processing, generally falling in a soft-to-medium range suitable for welding and low-temperature service, often around 170-200 HB.
3What is the temperature range of P355NH?
Its most widespread use is in application environments up to 400 ºC. P355NH steel is supplied in the normalised condition. The normalising temperature is 900 - 950 ºC, and it must be left in the furnace after temperature equalising for approximately 1 minute per millimetre of thickness of the plate.
4What are the advantages of P355NH?
P355NH steel offers advantages like high strength at elevated temperatures, excellent weldability, and good resistance to brittle fracture, making it ideal for pressure vessels, boilers, and gas tanks, especially for storing pressurized gases like propane or butane in environments up to about 400°C. Its normalized, fine-grained structure provides superior cold and hot formability, ensuring structural integrity under demanding conditions.
5What is P355NH material?
A pressure vessel steel grade with good weldability and high resistance to brittle cracking, P355NH is used by the world's fabricators for the manufacture of pressure vessel tanks for the storage of pressurised gases.
6What is P355NH material grade?
P355NH is a normalized, fine-grain, weldable steel grade (according to EN 10028-3) designed for pressure vessels and boilers, offering good high-temperature strength and resistance to brittle cracking, with 'H' indicating its suitability for elevated temperatures, 'N' for normalized, and 'P355' for its minimum yield strength (355 MPa). It's used for components like pressurized gas tanks, steam boilers, and piping, and has variants like P355NL1/NL2 for low-temperature service.
7What is the effective use of P355NH?
P355NH is a high-strength, normalized pressure vessel steel (EN 10028-3) effective for manufacturing boilers, pressure tanks, heat exchangers, and pipelines, especially in the oil & gas, chemical, and energy industries, due to its excellent weldability, toughness, and suitability for operating at elevated temperatures (up to around 400°C) and in low-temperature (cryogenic) conditions. Its "NH" designation means it's normalized for specified elevated-temperature properties, making it ideal for storing pressurized gases like LNG/LPG and for heavy-duty structural applications.
If you have project requirements for P355NH, we welcome your inquiry. GNEE maintains a large inventory of commonly used high strength steel grades for your selection.For detailed mechanical properties, chemical composition, and technical data, as well as free samples, please contact our factory immediately. We offer competitive prices, stable quality, and professional service. Email: info@gneesteels.com
