What is P355QL2?
Four characters carry the entire specification:
P - pressure purposes, the prefix shared across the EN 10028 family.
355 - minimum yield strength, 355 MPa, guaranteed up to 50 mm.
Q - quenched and tempered, the mandatory delivery condition in this part of the standard.
L2 - low-temperature properties, with the guaranteed impact test at −60 °C.
P355QL2 Pressure Vessel Steel Plate Chemical Composition
Ladle analysis, maximum percentages per EN 10028-6:2017:
| Element | Max % | Element | Max % |
|---|---|---|---|
| C | 0.16 | Cr | 0.30 |
| Si | 0.40 | Cu | 0.30 |
| Mn | 1.50 | Mo | 0.25 |
| P | 0.020 | Nb | 0.05 |
| S | 0.005 | Ni | 0.50 |
| N | 0.015 | Ti | 0.03 |
| B | 0.005 | V | 0.06 |
| Zr | 0.05 | - | - |
P355QL2 Boiler Steel Plate Mechanical Properties
| Thickness t (mm) | ReH min (MPa) | Rm (MPa) | A min (%) | Impact test temperature | Min. average KV, transverse (J) |
|---|---|---|---|---|---|
| t ≤ 50 | 355 | 490–630 | 22 | −60 °C | 27 |
| 50 < t ≤ 100 | 335 | 490–630 | 22 | −60 °C | 27 |
| 100 < t ≤ 200 | 315 | 450–590 | 22 | −60 °C | 27 |
Common specification mistakes on QL2 orders
- Quoting Q-grade chemistry - phosphorus 0.025 % and sulphur 0.010 % on a QL2 order defeats the purpose of the branch.
- Stating "impact tested" without a temperature - the temperature is the requirement; energy alone means nothing.
- Asking for elevated-temperature values on an L grade as though they were included; they belong to the H variant.
- Naming a UT requirement without a class - "UT" is a method, not an acceptance criterion; state EN 10160 or ASTM A578 with the quality level.
- Ordering to a superseded edition - EN 10028-6:2009 tabulates mechanical values only to 150 mm, while the 2017 edition goes to 200 mm. Naming the edition avoids an argument about which table applies.
P355QL2 Steel Plate Typical Applications
- Refrigerated storage where the design metal temperature reaches −60 °C
- Low-temperature gas storage and transport equipment in the −40 to −60 °C band
- Cold-climate and arctic process equipment - separators, scrubbers, heat exchangers
- Petrochemical low-temperature separation and gas-treatment vessels
- Vessels with a cold-start or cold-hydrotest case
Equipment-by-equipment detail is on our P355QL2 applications page.
Dimensions, Tolerances and Edge Condition
| Item | Requirement |
|---|---|
| Thickness range in EN 10028-6 | Mechanical values guaranteed to 200 mm |
| Dimensional and shape tolerances | EN 10028-1 |
| Usual edge finish | Sheared or thermally (flame) cut, normally for plate under 40 mm |
| Surface condition | Mill finish; shot blasting, priming or coating on request |
| Marking | Grade, heat number, dimensions, standard - traceable to the certificate |
P355QL2 Pressure Vessel And Boiler Steel Plate Specifications
| Order line | What to write |
|---|---|
| Standard and edition | EN 10028-6:2017 |
| Grade | P355QL2 (1.8869) |
| Dimensions | Thickness × width × length; GNEE range 8–200 mm × 1000–4200 mm × 5000–18000 mm |
| Delivery condition | +QT (quenched and tempered) |
| Impact requirement | −60 °C, 27 J transverse as standard; state 40 J where specified |
| Tolerances | EN 10028-1 unless another standard is named |
| Certification | EN 10204 3.1, or 3.2 with third-party witness |
| Supplementary testing | UT (EN 10160 / ASTM A578) with class stated; Z-direction (EN 10164, Z25/Z35); simulated PWHT |
| Surface and packing | Blasting, priming, coating, export packing as required |
Getting the last three lines right at enquiry stage avoids the most expensive kind of delay: plate already produced that cannot be certified to a requirement discovered later.
FAQ
What is the difference between 1.8868 and 1.8869?
One temperature step: 1.8868 is P355QL1, tested at −40 °C; 1.8869 is P355QL2, tested at −60 °C. At −40 °C a QL2 plate must reach 40 J where QL1 must reach 27 J, and QL2 carries the tighter 0.005 % sulphur limit.
Can P355QL1 be substituted where P355QL2 is specified?
Only with the design engineer's agreement - the substitute is tested 20 °C warmer and holds no −60 °C guarantee.
Do you stock thicknesses above 200 mm?
EN 10028-6 tabulates guaranteed mechanical values up to 200 mm, which is the top of our range. Thicker sections fall outside the standard's guaranteed values and are handled as a special enquiry.
What tolerance standard applies?
EN 10028-1 governs dimensional and shape tolerances unless the order names another standard. Plates under 40 mm are normally supplied sheared or flame cut.
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