P275NH is a normalized, weldable fine-grain steel per EN 10028-3 (Mat. No. 1.0487), with min. yield strength 275MPa. It suits high-temp pressure equipment like boilers and reactors, boasting good formability and reliable quality.
Overview
P275NH is a non-alloy steel with the material number 1.0487. The designation breaks down as follows:
P: Pressure purposes.
275: Minimum yield strength of 275 MPa.
NH: Normalized fine-grain steel with specified elevated temperature properties.
This material is known for its excellent weldability and stable mechanical properties under heat exposure.
P275NH Boiler Quality Steel Chemical Composition:
| C | Si | Mn | Ni | P | S | Cr | Mo | V | N | Nb | Ti | Al | Cu |
| max 0.16 | max 0.4 | 0.8 - 1.5 | max 0.5 | max 0.025 | max 0.015 | max 0.3 | max 0.08 | max 0.05 | max 0.012 | max 0.05 | max 0.03 | max 0.02 | max 0.3 |
P275NH PVQ Steel Plate Mechanical Properties:
| Nominal thickness (mm): | to 60 | 60 - 100 | 100 - 150 | 150 - 250 |
| Rm - Tensile strength (MPa) (+N) | 390-510 | 370-490 | 360-480 | 350-470 |
| Nominal thickness (mm): | to 16 | 16 - 40 | 40 - 60 | 60 - 100 | 100 - 150 | 150 - 250 |
| ReH - Minimum yield strength (MPa) (+N) | 275 | 265 | 255 | 235 | 225 | 215 |
| KV - Impact energy (J) transverse, (+N) | -20° 30 |
0° 40 |
+20° 50 |
| KV - Impact energy (J) longitud., (+N) | -20° 40-45 |
0° 47-65 |
+20° 55-75 |
| Nominal thickness (mm): | to 60 | 60 - 250 |
| A - Min. elongation at fracture (%) (+N) | 24 | 23 |
Main Applications
Boiler and Pressure Vessel Manufacturing：Core application field, used to produce boiler drums, steam headers, heat exchangers, high-pressure storage tanks, and reactor shells. It is the preferred material for equipment bearing high temperature and pressure in thermal power, chemical, and metallurgical industries.
Petrochemical Industry：Applied in oil refining, natural gas processing, and chemical synthesis equipment, including separators, desulfurization towers, pipeline fittings (flanges, valves), and medium storage tanks for crude oil, natural gas, and chemical reagents.
Power Generation Industry：Widely used in thermal power plants (high-pressure water supply pipes, turbine casings, economizers) and hydropower stations (pressure pipelines, surge tanks), as well as auxiliary equipment for nuclear power plants (non-core pressure-bearing components).
Other Fields：Used in marine engineering (pressure cabins, shipborne storage tanks), food processing (high-temperature sterilization pots), and bridge/building structures (load-bearing components requiring high strength and toughness).
Corresponding Application Conditions
Temperature Conditions：Suitable for long-term operation at -20℃ to 400℃. It maintains stable mechanical properties without deformation or failure under continuous high-temperature conditions, and resists low-temperature impact at -20℃, meeting cold and high-temperature working environment requirements.
Pressure Conditions：Adaptable to medium and high-pressure working environments, with a maximum allowable working pressure matching its yield strength (≥275MPa) and tensile strength (390-510MPa), suitable for equipment under combined pressure and thermal loads.
Medium Conditions：Resistant to mild corrosion from neutral and weakly corrosive media (water, steam, crude oil, natural gas). Not suitable for strong acid/alkali environments unless additional anti-corrosion treatment is applied.
Processing and Installation Conditions：Requires standardized forming, welding, and heat treatment processes (preheating 80-150℃, post-weld heat treatment 550-650℃). Must pass ultrasonic inspection to ensure no internal defects before application, ensuring safe operation of key equipment.
Key Processing Technologies
Normalization Treatment：As a normalized steel, P275NH must undergo normalization (heating to 890-950℃, holding adequately, then air cooling). This refines its grain structure, ensures min. yield strength 275MPa, and enhances toughness for high-temp pressure service.
Forming Process：It features good cold and hot formability. Cold forming (bending, stamping) is feasible at room temp without excessive force; hot forming (heating to 700-1050℃) suits complex shapes like boiler drums, with post-forming stress relief if needed.
Welding Operation：Weldability is excellent. Recommended processes include SMAW, GMAW, GTAW. Preheat to 80-150℃ (based on thickness) to avoid cracks; post-weld heat treatment (550-650℃) optimizes joint performance without strength loss.
Finishing & Inspection：Post-processing includes grinding to remove burrs. Strict ultrasonic inspection is mandatory per EN 10028-3 to detect internal defects, ensuring product reliability for pressure vessel and boiler applications.
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What are the minimum yield strength and tensile strength of P275NH?
The minimum yield strength of P275NH is 275 MPa (for thickness ≤16mm), and its tensile strength ranges from 410 MPa to 560 MPa. These values ensure good load-bearing capacity in pressure vessel applications.
Which standard specifies the technical requirements for P275NH?
P275NH is governed by the European standard EN 10028-2, which details its chemical composition, mechanical properties, heat treatment, welding requirements, and inspection methods for pressure vessel steels.
What are the common applications of P275NH?
P275NH is widely used in manufacturing pressure vessels, boilers, storage tanks, heat exchangers, and pipelines for petrochemical, power generation, and chemical industries, suitable for moderate temperature and pressure conditions.
What is the impact test requirement for P275NH?
P275NH requires Charpy V-notch impact tests at -20°C. The minimum average impact energy is 27 J for three specimens, ensuring good low-temperature toughness to resist brittle fracture in cold environments.
Does P275NH have corrosion resistance? Can it be used in corrosive environments?
P275NH has basic atmospheric corrosion resistance but is not suitable for strong corrosive environments (e.g., acidic/alkaline media). It needs anti-corrosion coatings or linings if used in such harsh conditions to extend service life.
What is the delivery condition of P275NH?
P275NH is usually delivered in the normalized condition (symbol: N), as specified in EN 10028-2. The delivery document must include chemical composition, mechanical properties, heat treatment records, and inspection reports.
Can P275NH be used for low-temperature pressure vessels?
It can be used for low-temperature applications down to -20°C, thanks to its qualified impact toughness at that temperature. For lower temperatures (below -20°C), low-temperature-specific steels like P275NL1 are more appropriate.
What is the thickness range of P275NH plates usually supplied?
P275NH plates are commonly supplied with thickness ranging from 5mm to 200mm. For thicknesses above 16mm, the yield strength may decrease slightly, but it still meets the standard requirements.
What is the recommended heat treatment process for P275NH?
P275NH typically undergoes normalizing heat treatment (heating to 890-950°C, holding adequately, then air cooling). This process refines grains, improves toughness and weldability, meeting pressure vessel service demands.
What is the maximum service temperature of P275NH?
The maximum continuous service temperature of P275NH is around 400°C. Beyond this temperature, its mechanical properties may degrade, affecting the safety and durability of pressure-bearing structures.