P355GH

1.0473

Non-alloy carbon-manganese pressure-vessel steel with specified elevated-temperature properties · EN 10028-2:2017 — grade-specific requirements for flat products · EN 10028-1:2017 — general requirements for flat products for pressure purposes

P355GH is the highest-strength non-alloy pressure-purpose flat-product grade in EN 10028-2. It combines a minimum room-temperature yield strength of 355 MPa in thicknesses up to 16 mm with specified 0.2% proof strength through 400 °C. It is normally supplied normalized or normalized rolled and is widely used for welded pressure vessels, boilers, drums and heat-exchanger components. Thickness, delivery condition, impact requirements, fabrication heat treatment and the applicable pressure-equipment design code must all be considered when specifying it.

1.0473Material number · The numerical designation identifies the same EN grade as P355GH.
+NUsual delivery condition · Normalizing rolling may replace separate normalizing at the manufacturer's discretion.
355 MPa minimum at t ≤ 16 mmRoom-temperature yield strength · The minimum decreases progressively to 280 MPa for 150 < t ≤ 250 mm.
510–650 MPa at t ≤ 60 mmTensile strength · The specified range decreases for thicker products.
Minimum Rp0.2 specified from 50 to 400 °CElevated-temperature data · Values depend on nominal product thickness.
Up to 250 mmStandard thickness range · The mechanical-property tables in EN 10028-2 cover P355GH through 250 mm.

Overview

Designation system: EN steel name and EN 10027-2 material number
Product forms: Hot-rolled plate, Hot-rolled sheet, Wide flat and strip within the applicable dimensional standards
Condition: Normalized (+N), the usual delivery condition, Normalized rolled, permitted as a replacement for normalizing at the manufacturer's discretion, Untreated condition only by agreement, with testing performed on test pieces in the usual specified condition
Density: 7.85 g/cm³ (Nominal engineering value for carbon steel; not a grade acceptance requirement in EN 10028-2.)

What the designation covers

P355GH is classified by EN 10020 as a non-alloy quality steel. It is a weldable carbon-manganese steel intended for pressure equipment where strength must be defined both at room temperature and at elevated temperature. In the designation, P identifies steel for pressure purposes and 355 refers to the minimum room-temperature yield strength, in MPa, for the lowest thickness range. The complete suffix GH identifies the elevated-temperature pressure-purpose grade; it should not be shortened or treated as an S355 structural grade.

EN 10028-2 applies specifically to flat products. Although P355GH and material number 1.0473 also appear in standards for pressure-purpose tubes or bars, requirements from those product standards must not be transferred to plate. A purchase order and material certificate should identify the product standard, grade, dimensions and delivery condition—not merely the steel name.

Standard chemical composition

Cast analysis limits in EN 10028-2:2017

Element	Requirement, mass %
C	0.10–0.22
Si	≤ 0.60
Mn	1.10–1.70
P	≤ 0.025
S	≤ 0.010
Al total	≥ 0.020
N	≤ 0.012
Cr	≤ 0.30
Cu	≤ 0.30
Mo	≤ 0.08
Nb	≤ 0.040
Ni	≤ 0.30
Ti	≤ 0.03
V	≤ 0.02
Cr + Cu + Mo + Ni	≤ 0.70

For the aluminium and nitrogen limits, Al/N ≥ 2 also applies. Elements not listed are not to be intentionally added without purchaser agreement, except as needed to finish the heat. Product analysis is subject to the separate permissible deviations in EN 10028-2.

The relatively broad carbon range means that weldability cannot be judged from the grade name alone. EN 10028-2 permits the purchaser and manufacturer to agree a maximum carbon-equivalent value for P355GH. This is particularly relevant for thick plate, highly restrained joints, low heat input, low fabrication temperature or demanding hydrogen-control requirements.

Carbon-equivalent formula specified by EN 10028-2

CEV = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15

Use the actual heat analysis when evaluating a certificate. The standard provides the formula but does not impose a universal maximum CEV unless one is agreed at enquiry and order.

Delivery condition and heat treatment

The usual condition is normalized, designated +N. Normalizing rolling may replace a separate normalizing treatment at the manufacturer's discretion. If the purchaser needs verification that normalized-rolled material will retain compliance after a later normalization cycle, tests in a simulated normalized condition and their frequency can be agreed when ordering.

Heat-treatment guidance

Operation	Guidance for P355GH	Status
Normalizing	890–950 °C	Informative guidance in EN 10028-2 Annex A
Quenching	Not specified for the grade	P355GH is not normally ordered as a quenched-and-tempered plate
Tempering	Not specified for the grade	Not part of the usual +N condition

Once the normalizing temperature has been attained through the cross-section, the standard advises that further holding is generally unnecessary and should be avoided.

Untreated delivery is possible only by agreement. In that case, acceptance testing is performed on test pieces in the usual specified delivery condition. Untreated plate therefore must not be interpreted as having certified as-rolled mechanical properties suitable for direct use.

Room-temperature mechanical requirements

Transverse tensile properties in the usual +N condition

Nominal thickness t, mm	Minimum ReH, MPa	Rm, MPa	Minimum elongation A, %
t ≤ 16	355	510–650	20
16 < t ≤ 40	345	510–650	20
40 < t ≤ 60	335	510–650	20
60 < t ≤ 100	315	490–630	20
100 < t ≤ 150	295	480–630	20
150 < t ≤ 250	280	470–630	20

EN 10028-2 states that Table 3 properties apply to the transverse direction. ReH is the upper yield strength.

Charpy V-notch impact energy, transverse test pieces

Test temperature	Minimum KV2
−20 °C	27 J
0 °C	34 J
+20 °C	40 J

These values apply to standard-size Charpy specimens under the standard's sampling and test provisions. Rules for sub-size specimens and product thickness limitations must be taken from EN 10028-1 and the referenced impact-test standard.

The impact table should not be mistaken for a universal minimum design temperature. Suitability at low temperature depends on the pressure-equipment design code, governing material group, stress level, thickness, weld condition, heat treatment and required test temperature. P355GH is an elevated-temperature grade, not a fine-grain low-temperature grade.

Specified strength at elevated temperature

Minimum 0.2% proof strength Rp0.2, MPa

Nominal thickness t, mm	50 °C	100 °C	150 °C	200 °C	250 °C	300 °C	350 °C	400 °C
t ≤ 16	343	323	299	275	252	232	214	202
16 < t ≤ 40	334	314	291	267	245	225	208	196
40 < t ≤ 60	324	305	282	259	238	219	202	190
60 < t ≤ 100	305	287	265	244	224	206	190	179
100 < t ≤ 150	285	268	249	228	209	192	178	167
150 < t ≤ 250	271	255	236	217	199	183	169	159

These are grade requirements from EN 10028-2, not allowable design stresses. No Rp0.2 value is specified for P355GH at 450 or 500 °C in this table.

The elevated-temperature proof-strength table is a principal reason to select P355GH instead of an ordinary structural steel. Pressure-equipment design must nevertheless use the allowable stresses and rules of the applicable construction code. The temperature of the metal, not simply the fluid or design temperature, determines which material data are relevant.

Annex C of EN 10028-2 gives informative reference data for creep strain and creep rupture for P295GH and P355GH. These are mean values with stated scatter and do not establish a permissible continuous-use temperature. Long-duration service must be assessed using the governing pressure design code, total stress history, oxidation environment and required design life.

Welding, forming and fabrication heat treatment

P355GH is intended to be weldable, but the welding procedure must reflect the actual heat analysis, plate thickness, joint restraint, consumable hydrogen level, heat input, interpass temperature and required toughness. EN 10028-2 refers welding practice to EN 1011-1 and EN 1011-2. An agreed maximum CEV is more useful for fabrication control than relying only on the grade's broad composition limits.

Cold forming, hot forming and welding thermal cycles can modify the normalized microstructure and mechanical properties. Severe hot forming or heating into the transformation range may require renormalizing. The fabricator should qualify the complete manufacturing sequence—including forming, welding and post-weld heat treatment—against the equipment code and the certified product condition.

Time-temperature parameter used for stress-relieving guidance

P = Ts × (20 + log10 t) × 10^-3

Ts is the stress-relieving temperature in kelvin and t is the holding time in hours. EN 10028-2 gives Pcrit = 17.3 for C and C-Mn steels, with illustrative combinations of 590 °C for 1 h or 580 °C for 2 h. These are guidance values, not universal PWHT instructions.

Excessive PWHT temperature or accumulated holding time can reduce strength. If the intended time-temperature parameter exceeds the Annex B critical value, the purchaser should inform the plate manufacturer and consider testing samples subjected to the simulated fabrication heat treatment.

Service limitations and optional testing

P355GH is not corrosion resistant. Corrosion allowance, coating, lining, corrosion monitoring or a different alloy may be required depending on the process medium. The presence of elevated-temperature strength data also does not establish resistance to oxidation, graphitization, hydrogen damage, fatigue, thermal cycling or creep for a particular service.

Hydrogen-induced cracking testing in accordance with EN 10229 can be specified as an option. EN 10028-2 defines HIC acceptance classes using crack length, thickness and sensitivity ratios. HIC testing is not part of the basic P355GH designation and does not by itself constitute complete qualification for sour or wet-H2S service; the applicable project and service standards remain controlling.

Specifying and purchasing P355GH plate

Items that should be settled on the purchase order

Item	Why it matters
Standard and edition	State EN 10028-2 together with the applicable EN 10028-1 requirements; do not order by grade name alone.
Grade identifier	Specify P355GH or 1.0473.
Dimensions and tolerances	Thickness determines the guaranteed strength. Identify the applicable dimensional and flatness tolerance standard and tolerance class.
Delivery condition	The usual condition is +N. Identify any agreed departure, simulated heat treatment or special fabrication cycle.
Inspection document	State the required EN 10204 document type, commonly 3.1 when required by the project or equipment code.
Impact testing	Confirm required temperature, energy, orientation, specimen location and any project requirement beyond the standard minimum.
Weldability controls	Consider an agreed maximum CEV and any tighter chemistry limits needed by the welding procedure.
Through-thickness or ultrasonic quality	Specify any required through-thickness properties, ultrasonic examination level or internal-soundness criteria; these are not created by the grade name.
HIC testing	Specify EN 10229 test solution, acceptance class and any supplementary criteria if hydrogen-induced cracking is a service concern.
Fabrication heat treatment	Tell the manufacturer about severe or repeated heat-treatment cycles and request simulated-condition testing where necessary.

Verify the certificate against the ordered thickness and condition. A certificate showing compliant chemistry but mechanical tests from an inapplicable thickness range, orientation or heat-treatment condition is not sufficient evidence of compliance.

Selection and substitution

P355GH is selected where the strength of P235GH, P265GH or P295GH is insufficient but a non-alloy normalized pressure-vessel steel remains appropriate. For more demanding low-temperature toughness, fine-grain grades under EN 10028-3 may be more suitable. For higher-temperature or creep-dominated service, molybdenum- or chromium-molybdenum-alloy pressure steels may be required.

Cross-standard comparison must address more than nominal strength. Chemistry, heat treatment, impact testing, elevated-temperature data, thickness ranges, product form, inspection, certification and the approved materials list of the construction code all affect substitution. ASTM A516 Grade 70 is frequently compared with P355GH commercially, but it is not an identical or automatically interchangeable grade.

Sources

DIN EN 10028-2:2017-10 — Flat products made of steels for pressure purposes, Part 2DIN Media
SIST EN 10028-2:2017 — Standard previewSlovenian Institute for Standardization
SIST EN 10028-1:2017 — General requirements for pressure-purpose flat productsSlovenian Institute for Standardization
P355GH pressure-vessel steel product dataArcelorMittal Europe
Heat-resistant pressure-vessel steelsSalzgitter Flachstahl GmbH

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Discussing: P355GH / 1.0473

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P295GH / 1.0481	Lower-strength grade in the same EN 10028-2 non-alloy family	Similar purpose and delivery condition, but lower room- and elevated-temperature strength requirements.
P355NH / 1.0565	Related normalized fine-grain pressure steel under EN 10028-3	Shares a 355 MPa nominal strength level but has a different grade definition, chemistry and toughness framework; not equivalent.
16Mo3 / 1.5415	Alloy pressure-purpose steel in EN 10028-2	Lower nominal room-temperature yield than P355GH but molybdenum alloying provides a different elevated-temperature and creep-performance profile.
ASTM/ASME A/SA-516 Grade 70	Approximate commercial counterpart	Not identical. Substitution requires design-code approval and a detailed comparison of specification, condition, chemistry, toughness, testing and certification.
P355GH in EN tube and bar standards	Same steel name used for other product forms	Tube and bar standards impose their own dimensions, manufacturing routes, conditions and property requirements; plate certificates cannot be treated as tube or bar certification.