Pressure vessel steel grades
6 pressure vessel steel grades from 2 designation systems, each with a full data sheet. Sorted by system; the yield and tensile values are the first line of each grade's mechanical table.
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EN (European)
| Grade | No. | Type | C % | Yield MPa | Tensile MPa | Equivalents |
|---|---|---|---|---|---|---|
| 16Mo3 | 1.5415 | Molybdenum-alloyed steel for pressure purposes at elevated temperature | 0.12 – 0.2 | 275 | 440–590 | A204 Gr. A, A204 Gr. B, A335 P1 |
| P235GH | 1.0345 | Non-alloy steel for pressure purposes with elevated-temperature properties | ≤ 0.16 | 235 | 360–480 | p265gh, a516-70, s235jr |
| P265GH | 1.0425 | Non-alloy steel for pressure purposes with elevated-temperature properties | ≤ 0.2 | 265 | 410–530 | A516 Gr. 60, A516 Gr. 65, A285 Gr. C |
| P355GH | 1.0473 | Non-alloy steel for pressure purposes with elevated-temperature properties | ≤ 0.22 | 355 | 490–630 | A516 Gr. 70, A537 Cl. 1, SPV355 |
| P355NH | 1.0565 | Weldable fine-grain normalized steel for pressure purposes, elevated temperature | ≤ 0.2 | 355 | 490–630 | A516 Gr. 70, A537 Cl. 1, A737 Gr. B |
ASTM / ASME
| Grade | No. | Type | C % | Yield MPa | Tensile MPa | Equivalents |
|---|---|---|---|---|---|---|
| A516 Grade 70 | K02700 | Carbon steel plate for pressure vessels, moderate and lower temperature | ≤ 0.27 | 260 | 485–620 | P295GH, P265GH, P355GH / P355NH |
Designed for temperature, not just for load
A pressure-vessel grade differs from a structural grade in one decisive way: its properties are guaranteed at elevated temperature, not only at room temperature. EN 10028-2 publishes a yield strength for P265GH at 200, 300 and 400 °C, and the vessel is designed on those numbers.
The GH suffix says so directly — G for guaranteed elevated-temperature properties, H for high temperature. A structural plate with the same room-temperature yield has no such guarantee and cannot be substituted into a code vessel, however similar the analysis looks.
The NH and NL series and why cold matters
Where GH grades answer heat, the NH and NL grades answer cold. P355NL1 and P355NL2 are normalised fine-grain steels with guaranteed impact energy down to −40 and −50 °C, for vessels that run cold or sit outdoors in cold climates.
Brittle fracture is the risk these grades exist to remove. It is not a gradual failure mode — a vessel that is tough at +10 °C can be brittle at −30 °C, which is why the design temperature and not the operating temperature sets the grade.
Documentation is part of the product
Pressure-vessel plate is sold with its paperwork. EN 10204 3.1 is the minimum — chemistry, mechanicals, delivery condition, all certified by the mill's own inspection department. 3.2 adds an independent inspector and is required by many codes and clients.
Ultrasonic testing to EN 10160 for internal soundness, PED 2014/68/EU conformity and AD 2000 W1 statements are ordered per lot. None of this is optional extra: for a code vessel, plate without the right certificate is not the right plate.
faq.h
What does GH mean in P265GH?
Guaranteed elevated-temperature properties. The standard publishes a yield strength for the grade at 200, 300 and 400 °C, and the vessel is designed against those values rather than the room-temperature figure.
Can I use S355 instead of P355GH?
No, not in a code vessel. S355 carries no guaranteed elevated-temperature properties and no pressure-equipment conformity, even where the room-temperature analysis and yield look similar.
What is the difference between P355NH and P355NL1?
The impact test temperature. NH is guaranteed at −20 °C, NL1 at −40 °C and NL2 at −50 °C. All three are normalised fine-grain steels with the same nominal yield.
What certificate does pressure-vessel plate need?
EN 10204 3.1 as a minimum, issued by the mill's inspection department. Many codes and clients require 3.2 with an independent inspector attending, and ultrasonic testing to EN 10160 is commonly added for thicker plate.
Is ASTM A516 Grade 70 the same as P355GH?
They are close counterparts for moderate-temperature vessels and are often accepted interchangeably by agreement, but the standards differ in chemistry limits, impact requirements and test temperatures. The code governing the vessel decides which one is acceptable.