EN 10028: Pressure Vessel Steel Plates — All Parts & Grades

Quick Answer

EN 10028 is the European standard for flat products (plates and strips) of steel for pressure equipment. It covers six parts: non-alloy and alloy steels for elevated temperatures (Parts 2 and 3), quenched and tempered steels (Part 4), steels for simple pressure vessels (Part 5), austenitic stainless (Part 7, not covered here), and the 9% nickel cryogenic grade X8Ni9 (Part 6). Grades are designated by service condition — temperature, impact energy level, and delivery condition.

EN 10028 is the primary European standard for flat steel products intended for pressure equipment. Published by CEN (European Committee for Standardisation), it defines chemical composition, mechanical properties, and test requirements for pressure vessel plates used in boilers, heat exchangers, storage tanks, and process vessels. The standard is referenced under the Pressure Equipment Directive (PED 2014/68/EU) and provides the technical basis for CE marking of pressure-retaining components manufactured in Europe.

Scope and Applicability

EN 10028 specifies requirements for flat products (plates, strips, and wide flats) of steels intended for pressure equipment such as pressure vessels, boilers, and heat exchangers. The standard is published by CEN and is referenced in the Pressure Equipment Directive (PED 2014/68/EU). Parts 2 through 6 cover carbon, low-alloy, and high-alloy steels for service temperatures ranging from cryogenic (−196°C for X8Ni9) to elevated temperatures (up to ~500°C). CE marking under PED is applicable. Part 7 covers stainless steels (not covered in this article).

Grade Coverage

Part 2: Weldable Fine Grain Steels for Elevated Temperature Service

Grade	Delivery Condition	Typical Service Temp (°C)
P235GH	N	−10 to +400
P265GH	N	−10 to +400
P295GH	N	−10 to +450
P355GH	N	−10 to +450

Part 3: Normalized or Normalized Rolled Weldable Fine Grain Steels

Grade	Sub-grades	Delivery Condition
P275NH	NH, NL1, NL2	N
P355NH	NH, NL1, NL2	N
P460NH	NH, NL1, NL2	N

Part 4: Quenched and Tempered Steels

Grade	Sub-grades	Delivery Condition
P275QH	QH, QL1, QL2	Q+T
P355QH	QH, QL1, QL2	Q+T

Part 5: Steels for Simple Pressure Vessels

Grade	Notes
P265S	Non-alloy, weldable
P355S	Non-alloy, weldable

Part 6: Nickel Alloy Steel for Low-Temperature Service

Grade	Notes
X8Ni9	9% Ni, for cryogenic service down to −196°C (LNG)

Designation key: P = pressure service; number = minimum yield strength (MPa); G = general; H = elevated temperature; N = normalized; Q = quenched; L = low temperature; 1 = −40°C, 2 = −50°C; S = simple pressure vessel.

Chemical Composition Requirements

Heat (ladle) analysis. All values wt% maximum unless stated.

Part 2 Grades

Grade	C max	Si max	Mn max	P max	S max	Al min	Cr max	Mo max	Ni max	N max
P235GH	0.16	0.35	0.60–1.20	0.025	0.015	0.020	0.30	0.08	0.30	0.012
P265GH	0.20	0.40	0.80–1.40	0.025	0.015	0.020	0.30	0.08	0.30	0.012
P295GH	0.18	0.40	0.90–1.50	0.025	0.015	0.020	0.30	0.08	0.30	0.012
P355GH	0.20	0.60	1.10–1.70	0.025	0.015	0.020	0.30	0.08	0.30	0.012

Part 3 Grades

Grade	C max	Si max	Mn max	P max	S max	Al min	Nb max	V max	Ti max	N max	CEV max
P275NH	0.16	0.50	0.80–1.50	0.025	0.015	0.020	0.04	0.06	0.03	0.012	0.40
P275NL1	0.16	0.50	0.80–1.50	0.020	0.010	0.020	0.04	0.06	0.03	0.012	0.40
P275NL2	0.16	0.50	0.80–1.50	0.020	0.010	0.020	0.04	0.06	0.03	0.012	0.40
P355NH	0.18	0.50	1.00–1.70	0.025	0.015	0.020	0.05	0.10	0.03	0.012	0.43
P355NL1	0.18	0.50	1.00–1.70	0.020	0.010	0.020	0.05	0.10	0.03	0.012	0.43
P355NL2	0.18	0.50	1.00–1.70	0.020	0.010	0.020	0.05	0.10	0.03	0.012	0.43
P460NH	0.20	0.60	1.30–1.70	0.025	0.015	0.020	0.05	0.12	0.05	0.015	0.46
P460NL1	0.20	0.60	1.30–1.70	0.020	0.010	0.020	0.05	0.12	0.05	0.015	0.46
P460NL2	0.20	0.60	1.30–1.70	0.020	0.010	0.020	0.05	0.12	0.05	0.015	0.46

Part 4 Grades

Grade	C max	Si max	Mn max	P max	S max	Al min	Cr max	Mo max	Ni max	CEV max
P275QH	0.18	0.50	1.50	0.025	0.015	0.015	0.30	0.10	0.50	0.40
P275QL1	0.18	0.50	1.50	0.020	0.010	0.015	0.30	0.10	0.50	0.40
P275QL2	0.18	0.50	1.50	0.020	0.010	0.015	0.30	0.10	0.50	0.40
P355QH	0.20	0.60	1.60	0.025	0.015	0.015	0.30	0.10	0.50	0.43
P355QL1	0.20	0.60	1.60	0.020	0.010	0.015	0.30	0.10	0.50	0.43
P355QL2	0.20	0.60	1.60	0.020	0.010	0.015	0.30	0.10	0.50	0.43

Part 5 Grades

Grade	C max	Si max	Mn max	P max	S max
P265S	0.20	0.40	0.80–1.20	0.025	0.015
P355S	0.22	0.55	1.00–1.50	0.025	0.015

Part 6 Grade

Grade	C max	Si max	Mn max	P max	S max	Ni range	Al max
X8Ni9	0.10	0.35	0.30–0.80	0.010	0.005	8.50–10.00	0.10

Mechanical Properties

ReH = minimum upper yield strength (MPa); Rm = tensile strength range (MPa); A = minimum elongation %.

Part 2 — by Nominal Thickness

Grade	t ≤ 16mm ReH	t 16–40mm ReH	t 40–60mm ReH	t 60–100mm ReH	t 100–150mm ReH	Rm (t ≤ 16mm)	A min%
P235GH	235	225	215	215	195	360–500	25
P265GH	265	255	245	235	215	410–530	23
P295GH	295	285	275	265	245	460–580	22
P355GH	355	345	335	325	305	490–630	20

Part 3 — Normalized Fine Grain

Grade	t ≤ 16mm ReH	t 16–40mm ReH	t 40–60mm ReH	t 60–100mm ReH	t 100–150mm ReH	Rm (≤16mm)	A min%
P275NH/NL1/NL2	275	265	255	245	235	370–500	24
P355NH/NL1/NL2	355	345	335	325	305	490–630	22
P460NH/NL1/NL2	460	440	430	410	390	570–720	18

Part 4 — Quenched and Tempered

Grade	t ≤ 16mm ReH	t 16–40mm ReH	t 40–60mm ReH	t 60–100mm ReH	Rm (≤16mm)	A min%
P275QH/QL1/QL2	275	265	255	245	370–530	24
P355QH/QL1/QL2	355	345	335	325	470–630	22

Part 5 — Simple Pressure Vessels

Grade	ReH min (MPa)	Rm (MPa)	A min %
P265S	265	410–530	23
P355S	355	490–630	20

Part 6 — X8Ni9 (Cryogenic 9% Ni)

Condition	t range (mm)	ReH min (MPa)	Rm (MPa)	A min %
QT (quenched+tempered) or QLT	≤ 30	585	690–840	18
QT or QLT	30–50	560	670–820	18
QT or QLT	50–100	540	650–800	18

Impact Test Requirements

Charpy V-notch per EN ISO 148-1.

Part 2 (P235GH–P355GH)

Grade	Standard Temperature	Energy min
P235GH to P355GH	0°C	27 J

Part 3 Sub-grade Impact Classification

Sub-suffix	Temperature	Energy min
NH	−20°C	34 J
NL1	−40°C	34 J
NL2	−50°C	34 J

Part 4 Sub-grade Impact Classification

Sub-suffix	Temperature	Energy min
QH	−20°C	27 J
QL1	−40°C	27 J
QL2	−50°C	27 J

Part 6 — X8Ni9

Test Temperature	Minimum Energy (longitudinal)	Test on
−196°C	41 J average, 34 J individual min	Charpy V, transverse

The X8Ni9 grade requires transverse Charpy tests at −196°C (liquid nitrogen temperature), reflecting its use in LNG storage tanks and cryogenic vessels.

Additional Tests and Requirements

Mandatory test per heat: Ladle chemical analysis, one tensile test per test unit, Charpy impact tests (three specimens per set), and visual inspection.
Ultrasonic testing: Mandatory for plates t ≥ 30 mm per EN 10160, Class S1 as a minimum; Class S2/S3 by agreement.
Through-thickness properties: Z-quality (Z25 or Z35) per EN 10164 can be specified for plates subject to lamellar tearing risk.
Elevated temperature tensile properties: Part 2 grades have mandatory minimum yield strength at elevated temperature (e.g., P355GH: ReT ≥ 186 MPa at 400°C). These values must appear on the MTC for elevated-temperature pressure vessel applications.
Post Weld Heat Treatment (PWHT): Parts 2 and 3 grades are suitable for PWHT. The standard specifies that mechanical properties shall be verified after simulated PWHT if required by PED or the purchaser.
Marking: Each plate marked with standard, grade, heat number, dimensions, inspection mark, and CE mark if applicable.
Inspection documents: EN 10204 Type 3.1 minimum; Type 3.2 for PED-category III and IV vessels.

Cross-Standard Equivalents

EN 10028 Grade	ASME/ASTM Equivalent	IS Equivalent	Notes
P235GH	SA-516 Grade 55 (approx)	IS 2002 Grade 1	Weldable, elevated temp
P265GH	SA-516 Grade 60 / SA-285 Grade C	IS 2002 Grade 2	Very common boiler plate
P295GH	SA-516 Grade 65	—	Intermediate grade
P355GH	SA-516 Grade 70	IS 2002 Grade 3	Most used pressure vessel grade
P275NH	SA-537 Class 1	—	Fine grain, normalized
P355NH	SA-537 Class 2	—	Fine grain, normalized
P355NL1	SA-537 Class 2 (low temp)	—	−40°C impact
P275QH	SA-537 Class 3 (approx)	—	Q+T, pressure
X8Ni9	SA-553 Type I (9% Ni)	—	Cryogenic LNG service

SA-516 Gr.70 and P355GH are both widely used as the workhorse pressure vessel plate grade, but composition and impact requirements differ in detail. Verify before substitution. SA-553 Type I is the direct ASME equivalent of X8Ni9 for cryogenic applications.

MTC Verification Checklist

When verifying an EN 10028 Mill Test Certificate, confirm:

Frequently Asked Questions

What is the difference between P355GH and P355NH?

Both have minimum yield strength 355 MPa and similar tensile strength, but they differ in delivery condition and service intent. P355GH (Part 2) is intended for elevated-temperature service (up to ~450°C) in a normalized condition and has guaranteed elevated-temperature strength values. P355NH (Part 3) is a normalized fine grain steel optimized for cryogenic toughness (NH = Charpy 34 J at −20°C; NL1 = −40°C; NL2 = −50°C). For ambient-temperature pressure vessels with low-temperature design conditions, P355NH is preferred; for boilers and heat exchangers operating hot, P355GH is specified.

Is SA-516 Grade 70 the same as P355GH?

They are functionally similar — both are widely used carbon steel pressure vessel plates with minimum yield around 260–355 MPa and tensile strength 485–620 MPa — but are not identical. SA-516 Gr.70 has different chemistry limits (no CEV requirement), different impact test requirements (ASME supplements vs EN 10028), and different MTC documentation rules. Direct substitution requires engineering review and approval from the vessel code authority (ASME BPVC vs. PED). For EN 10028 certified material, the MTC must state EN 10028-2 P355GH.

What grades are used for LNG storage tanks under EN 10028?

LNG storage tanks operate at −162°C (boiling point of liquefied natural gas). EN 10028-6 grade X8Ni9 (9% nickel steel) is the standard choice in European practice, with mandatory Charpy V-notch testing at −196°C showing at least 41 J average. The ASME equivalent is SA-553 Type I. Some LNG inner vessels also use 304L or 316L stainless steel (EN 10028-7), but X8Ni9 is preferred for large flat-bottomed tanks due to its higher strength and lower material cost.

Does EN 10028 require ultrasonic testing of all plates?

Ultrasonic testing (UT) per EN 10160 is not mandatory for all EN 10028 plates by default, but it is required for plates with thickness ≥ 30 mm in most pressure vessel applications, and the PED specifies UT as mandatory for category III and IV vessels. Class S1 (100% scanning with individual flaw limits) is the standard minimum. The purchase order should explicitly invoke EN 10160 and the required class (S1, S2, or S3) when UT is needed.

What is the significance of the NL1 and NL2 sub-suffixes in Part 3?

In EN 10028-3, the suffix after N indicates the temperature at which Charpy impact tests are performed. NH = −20°C (34 J min); NL1 = −40°C (34 J min); NL2 = −50°C (34 J min). The designation is analogous to the J/K sub-grade system in EN 10025. Specify NL1 or NL2 for pressure vessels designed for cold climates, low-temperature processes, or cryogenic services above −50°C. For temperatures below −50°C, consider Part 6 X8Ni9 or austenitic stainless (Part 7).

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EN 10028: Pressure Vessel Steel Plates — Complete Specification Guide