P355GH and P355NH are both steel grades for pressure vessel applications, but they have some key differences:
1. P355GH
- P355GH is a non-alloy quality steel with specified elevated temperature properties, typically used in high-temperature industrial applications.
- It is primarily used for pressure vessels and boilers operating at moderate to high temperatures.
- P355GH is normalized fine-grain steel with good weldability and excellent toughness.
2. P355NH
- P355NH is a normalized fine-grain steel with specified low-temperature properties, designed for use in low-temperature pressure vessel applications.
- It offers good impact toughness at low temperatures, making it suitable for cryogenic applications.
- P355NH has enhanced strength compared to P355GH due to its normalized condition.
P355GH steel vs P355NH steel in chemical analysis
P355GH steel chemical analysis
Grade |
C. % |
Mn.% |
S. |
N |
Cu |
Nb |
Ti. |
Si. |
P. |
AL |
Cr. |
Mo. |
Ni |
Vi |
|
P355GH |
0.10-0.22 |
0.10-1.70 |
0.015 |
0.012 |
0.30 |
0.020 |
0.03 |
0.60 |
0.025 |
0.020 |
0.30 |
0.08 |
0.30 |
0.02 |
P355NH steel chemical analysis
| Element |
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 |
P355GH steel vs P355NH steel in mechanical properties
P355GH steel mechanical properties
Grade |
Type |
Thickness mm |
Yield strength Mpa(min) |
Tensile Strength MPa |
Elongation % (min) |
Impact Energy (KVJ) (min) |
||
|
-20° |
0° |
+20 |
||||||
|
P355GH |
Normalized |
≤16 16>to≤40 40>to≤60 60>to≤100 100>to≤150 150>to≤250 |
355 |
510-650 |
20 |
27 |
34 |
40 |
|
345 |
510-650 |
20 |
27 |
34 |
40 |
|||
|
335 |
460-580 |
20 |
27 |
34 |
40 |
|||
|
315 |
490-630 |
20 |
27 |
34 |
40 |
|||
|
295 |
480-630 |
20 |
27 |
34 |
40 |
|||
|
280 |
470-630 |
20 |
27 |
34 |
40 |
|||
P355 NH steel mechanical properties
|
Grade |
Type |
Thickness (mm) |
Yield Strength |
Tensile Strength |
Elongation |
|
P355 NH |
Normalized |
≤ 16 |
355 |
490 - 630 |
21 |
|
16> to ≤40 |
345 |
490 - 630 |
21 |
||
|
40> to ≤60 |
335 |
490 - 630 |
21 |
||
|
60> to ≤100 |
315 |
470 - 610 |
21 |
||
|
100> to ≤150 |
305 |
460 - 600 |
21 |
||
|
150> to ≤250 |
295 |
450 - 590 |
21 |
Impact Testing
P355GH: Not typically required to undergo low-temperature impact testing, as it is designed for high-temperature pressure containment.
S355J2: Undergoes low-temperature impact testing (Charpy V-notch test) at -20°C to ensure toughness in structural applications under potentially low temperatures.
Temperature Focus: High Heat vs. Toughness
High-Temperature Strength (P355GH's advantage): P355GH retains higher strength at elevated temperatures. At 300°C, its minimum proof strength (Rp0.2) is ≥ 260 MPa, compared to only ≥ 240 MPa for P355NH. This makes P355GH the clear choice for continuous high-temperature operations.
Low-Temperature Toughness (P355NH's advantage): P355NH is specifically treated to resist brittle fracture in cold environments. This is why related sub-grades exist, such as P355NL1 (tested at -40°C) and P355NL2 (tested at -50°C), for increasingly demanding low-temperature applications.
Typical Applications
For P355GH: Industrial boilers and heat exchangers, high-temperature steam pipelines, petrochemical reactors, and equipment for storing hot liquids.
For P355NH: LPG and cryogenic storage tanks, nuclear reactor pressure shells, welding-intensive chemical equipment, and critical structures in earthquake-prone areas
Domestic Chinese Equivalents
P355GH is similar to Q345R (GB 713), but P355GH offers superior verified high-temperature performance.
P355NH is similar to 16MnDR, a low-temperature container steel, though adjustments in composition and normalizing are needed for equivalence.
Summary and Recommendations
The choice depends entirely on your application's temperature profile:
- Choose P355GH if your primary requirement is strength and stability under high-temperature service conditions.
- Choose P355NH if your application demands superior overall toughness, weldability, and resistance to brittle fracture, especially at low temperatures.
Choosing between them will depend on whether the primary requirements are high-temperature resistance for pressure containment (P355GH) or toughness in low-temperature structural applications (S355J2).
For more information, please contact me freely.
What is the difference between P355GH and P355NH?
P355GH steel is used worldwide by fabricators of welded pressure vessels, industrial boilers and heat exchangers and is engineered to work well in elevated temperature service. P355NH steel is normalized weldable fine grain steel flats under EN 10028-3: 2009 standard.
What 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.
What is P355GH material?
Steel for heat-resistant pressure vessels. P355GH steel gives optimum performance for pressurised products that must support a creep limit greater than 180N/mm2 at 400ºC. These types of steel are characterised by good weldability.
What is the yield strength of P355GH?
between 315 and 355 MPa
Carbon steels that are characterised by a greater resistance to pressure, capable of bearing significant pressure both at high and low temperatures. The yield strength ranges between 315 and 355 MPa, according to the range of thicknesses and its tensile strength goes from 510 to 650 MPa.
What is the yield strength of P355NH?
Material Description. 1) Remark: Steel P355NH is a weldable fine grained steel with a yield strength of max. 355 N/mm².
What is the difference between p355 and S355?
P355GH: Has a minimum yield strength of 355 MPa and is optimized for high-temperature environments in pressure vessels, but has lower toughness in cold conditions. S355J2: Also has a yield strength of 355 MPa but is optimized for structural applications requiring impact toughness.
What is en 10028 2 P355GH equivalent to?
P355GH, a steel grade defined in the EN 10028-2 standard, is equivalent to several other steel grades used for pressure vessel and boiler applications. Key equivalents include ASTM A516 Grade 70, ASME SA516 Grade 70, and 19Mn6 (DIN standard).
