When a pressure vessel engineer opens an EN 10222-2 grade table, the choice between P245GH and P265GH can appear deceptively simple: one grade has a higher minimum yield strength. In practice, that choice ripples into welding procedure qualifications, heat treatment scope, procurement lead times, EN 10204 MTC type, and long-term creep behaviour under PED 2014/68/EU requirements. This guide works through every layer of the decision.
Data covers open die forgings and seamless rolled rings under EN 10222-2:2017. Plate and pipe product forms may carry different section-thickness rules, delivery conditions, and available sub-grades. All mechanical property values reference the standard's tables and are not guaranteed as actual test results for any specific heat.
1. What the Grade Names Mean
Both grades use the same EN pressure steel naming convention, defined in EN 10027-1:
- P — Steels for pressure purposes
- 245 / 265 — Minimum specified yield strength in MPa at room temperature, reference thickness ≤ 16 mm
- GH — Suitable for elevated temperature service (geeignet für höhere Temperaturen)
Critically, the number denotes the yield floor, not the tensile strength. Both grades are classified as non-alloy steels — distinguishable from alloy pressure grades (e.g. 13CrMo4-5, 10CrMo9-10) by the absence of a chemical symbol in the designation.
The critical observation: both grades share an identical tensile strength band (410–570 MPa). The differentiation lives entirely in the minimum yield strength and in the manganese-driven chemistry that achieves it.
2. Chemical Composition — Where the Difference Originates
| Element | P245GH (1.0352) | P265GH (1.0425) | Engineering Significance |
|---|---|---|---|
| C — Carbon | 0.08 – 0.20% | 0.08 – 0.20% | Identical — no carbon boost used |
| Si — Silicon | max. 0.40% | max. 0.40% | Identical deoxidation limit |
| Mn — Manganese | 0.50 – 1.30% | 0.80 – 1.40% | Floor +60% in P265GH — primary strength driver |
| P — Phosphorus | max. 0.025% | max. 0.025% | Identical toughness control limit |
| S — Sulfur | max. 0.015% | max. 0.015% | Identical MnS inclusion control |
| Al — Aluminium | min. 0.020% | min. 0.020% | Grain refinement — both grades |
| Nb + V + Ti (sum) | max. 0.05% | max. 0.05% | Microalloying control — both grades |
P265GH achieves its 20 MPa yield advantage through a higher minimum manganese specification, not through carbon addition. This is deliberate: adding carbon to chase strength would raise the carbon equivalent (CE), worsen weldability, and reduce the suitability for the pressure equipment welding environments both grades are designed to serve.
Using the IIW formula CE = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15: a typical P245GH heat (1.10% Mn, 0.16% C) gives CE ≈ 0.34. A typical P265GH heat (1.35% Mn, 0.19% C) gives CE ≈ 0.42. Per EN ISO 13916, sections above 25 mm in P265GH may require preheat to 75–100°C depending on heat input and restraint — while equivalent P245GH sections frequently do not. This difference directly affects weld procedure qualification, fabrication throughput, and labour cost.
3. Mechanical Properties by Thickness
EN 10222-2 provides stepped minimum yield values for increasing thickness bands. Engineers must verify the correct row for their forging's governing section thickness.
| Thickness Range (mm) | P245GH Re min. (MPa) | P265GH Re min. (MPa) | Advantage |
|---|---|---|---|
| ≤ 16 | 245 | 265 | +20 MPa |
| 16 – 40 | 235 | 255 | +20 MPa |
| 40 – 60 | 220 | 240 | +20 MPa |
| 60 – 100 | 210 | 230 | +20 MPa |
| 100 – 160 | 195 | 215 | +20 MPa |
| 160 – 250 | 185 | 200 | +15 MPa |
The 20 MPa advantage is consistent across all practical forging thicknesses. The gap narrows slightly above 160 mm — a function of reduced through-section hardenability in both non-alloy grades following normalizing heat treatment. Jiangsu Liangyi supplies P245GH forgings across the full range from 30 kg to 30,000 kg per piece, covering all thickness bands in the table above.
Elevated Temperature Yield Strength
At 300°C, both P245GH and P265GH lose approximately 25–30% of their room-temperature yield. At 350°C, the reduction is 35–40%. Above this temperature, neither grade is appropriate for creep-controlled design; low-alloy grades such as 13CrMo4-5 or 10CrMo9-10 are required.
Impact Toughness
EN 10222-2 requires minimum Charpy V-notch impact energy of typically 27 J longitudinal at +20°C for both grades in the standard delivery condition. Lower test temperatures (–10°C, –20°C) can be specified by agreement. For pressure equipment designed for service below –10°C, fine-grain weldable steels such as P355NL or P460NL should be selected.
4. Weldability — The Most Decisive Practical Factor
In pressure equipment fabrication under EN 13445 or PED 2014/68/EU, weldability constraints frequently outweigh yield strength advantage in final grade selection. A 20 MPa yield benefit becomes counterproductive if it triggers mandatory preheat, additional qualification testing, or PWHT-induced strength recovery that erases the original advantage.
Preheat Requirements
Using the IIW carbon equivalent formula, the higher manganese floor of P265GH produces CE values that, on sections above 25 mm with moderate heat input, enter the preheat-required zone per EN ISO 13916. P245GH's typical CE of ~0.34 generally allows preheat-free welding on sections up to 35–40 mm at comparable heat inputs. The practical impact:
- P265GH on 40 mm tube sheets may require preheat to 75–100°C on all welds
- Preheat on large tube sheet areas increases welding time by approximately 15–20%
- Hydrogen bake-out cycles add further cost on restrained assemblies
For a shell-and-tube heat exchanger with three 42 mm thick P265GH tube sheets, mandatory preheat during tube-to-tube-sheet and flange welding can represent a 10–18% increase in total welding labour cost compared with an equivalent P245GH specification — often exceeding the raw material price difference between grades on a completed vessel.
Post-Weld Heat Treatment (PWHT)
EN 13445-4 governs PWHT requirements based on section thickness and carbon equivalent — not grade designation alone. For both P245GH and P265GH, PWHT is typically mandatory for butt joints above 35 mm. The additional consideration for P265GH: its higher manganese content produces a slightly more pronounced tempering response during PWHT soaking cycles, which can reduce the as-welded yield advantage back toward P245GH levels, partially negating the original reason for the upward grade change.
5. Application Selection Matrix
The following matrix reflects engineering practice across oil and gas, power generation, chemical processing, and petrochemical industries where both grades are routinely specified for forged components.
6. Procurement, MTC Verification, and Grade Substitution Risk
P245GH is significantly more common in forging inventories globally. Its wider manganese specification range (0.50–1.30%) gives steelmakers more flexibility in achieving target chemistry without special-order billets, producing faster availability from standard stock. P265GH billets require a minimum manganese of 0.80%, which narrows the melt window and can add 1–2 weeks to lead time on non-standard dimensions.
EN 10204 MTC Requirements
Whether you specify P245GH or P265GH, the Mill Test Certificate — Type 3.1 or 3.2 — must include:
- Grade designation and material number (1.0352 for P245GH; 1.0425 for P265GH)
- Ladle analysis and product analysis where required by EN 10222-2
- Delivery condition: N (normalised) or N+T (normalised and tempered)
- Mechanical test results: Re, Rm, A%, and Charpy impact energy with test temperature
- Heat (cast) number traceable to forging serial numbers and dimensional records
- Inspector signature and accredited body stamp for Type 3.2 documents
P245GH and P265GH are occasionally treated as interchangeable because they share the same 410–570 MPa tensile strength band. They are not interchangeable without a formal design authority drawing revision. Installing a P245GH forging in a pressure vessel calculated to P265GH allowable stresses constitutes a non-conformance under PED 2014/68/EU, EN 13445-2, and applicable notified body inspection protocols. Verify the material number (1.0352 vs 1.0425) on every MTC against the purchase specification before accepting any forging.
7. Cost, Lead Time, and Availability
P265GH carries a typical material premium of 3–8% over equivalent P245GH forgings in the same geometry and weight class. This reflects the tighter minimum manganese specification and reduced flexibility in melt chemistry. Across a multi-item heat exchanger or pressure vessel kit (tube sheets, nozzle forgings, flanges, connecting rings), the premium compounds: a vessel with €40,000 of forging content might carry an additional €1,200–€3,200 in material cost for the P265GH specification — before accounting for additional welding labour, potential new PQR costs, and extended procurement lead time.
8. Grade Selection Decision Workflow
Apply the following six-step sequence when preparing a forging specification for pressure service in carbon steel. Document each decision with reference to the applicable code clause.
Jiangsu Liangyi manufactures open die forgings and seamless rolled rings in both grades, 30 kg to 30,000 kg per piece. EN 10204 3.1 / 3.2 MTC with full heat and dimensional traceability. ISO 9001:2015 certified, 27 years of experience, global supply to 50+ countries.
9. Full Comparison Summary
| Criterion | P245GH (1.0352) | P265GH (1.0425) | Verdict |
|---|---|---|---|
| Min. yield strength ≤ 16 mm | 245 MPa | 265 MPa | P265GH +20 MPa |
| Tensile strength range | 410–570 MPa | 410–570 MPa | Equal |
| Typical CE (IIW formula) | ~0.34 | ~0.42 | P245GH better |
| Weldability / preheat risk | Lower CE — generally preheat-free <35 mm | Higher CE — preheat may be required >25 mm | P245GH better |
| PWHT softening response | Standard | Slightly more pronounced due to Mn | P245GH better |
| NACE MR0175 sour service | Preferred — lower CE, lower HAZ hardness | Requires chemistry control and confirmation | P245GH better |
| Material availability | Wider billet stock — broader CE band | Tighter melt spec — narrower chemistry window | P245GH better |
| Material cost | Baseline | +3–8% premium | P245GH lower |
| Thick-wall >100 mm components | Check calculation — may be marginal | Better design margin — justifies specification | P265GH better |
| ASTM approximate equivalent | A105 / SA-105 | A516 Gr.60 / SA-516 Gr.60 | Context-dependent |
10. Frequently Asked Questions
Is P245GH equivalent to ASTM A105?
P245GH (EN 10222-2) is widely cited as a European functional equivalent to ASTM A105 for forged pressure fittings and flanges. Both are non-alloy carbon-manganese steels with similar room-temperature strength levels. However, they are not specification-identical: chemistry limits, impact testing requirements, and certification formats differ between EN and ASTM systems. A formal drawing revision and design authority approval is required before substituting one for the other on any PED- or ASME-coded vessel.
What is P265GH equivalent to in ASTM standards?
P265GH is generally considered comparable to ASTM A516 Grade 60 / SA-516 Grade 60 in terms of pressure vessel applications and strength level. The yield and tensile strengths are similar, but the standards differ in chemistry, impact test requirements, and quality inspection protocols. For projects requiring EN standards and PED compliance, P265GH is the correct specification; for ASME-coded vessels, A516 Gr.60/70 or A105 is standard depending on the product form.
Can P245GH and P265GH be substituted for each other?
No — not without a formal design authority drawing revision. Although both grades share the 410–570 MPa tensile strength band, their minimum yield strengths differ by 20 MPa. A vessel designed to P265GH allowable stresses cannot legally or safely use P245GH material without recalculating wall thickness. Conversely, P265GH may be used where P245GH is specified, but this represents unnecessary cost and potential weldability complications. Always verify the material number (1.0352 vs 1.0425) on every EN 10204 MTC.
Does P265GH need preheat before welding?
It depends on section thickness, heat input, and the actual carbon equivalent of the specific heat. A typical P265GH heat with CE ~0.42 (IIW formula) may require preheat to 75–100°C on sections above 25 mm under EN ISO 13916 guidance. Actual preheat requirements must be determined via the welding procedure specification (WPS) qualified by procedure qualification testing (PQR). P245GH with CE ~0.34 typically does not require preheat on sections below 35–40 mm at standard heat inputs.
Conclusion
For the vast majority of pressure equipment applications — shell-and-tube heat exchangers, standard pressure vessel shells, mid-pressure valve bodies, and small-to-medium flanges — P245GH (1.0352) delivers sufficient strength while offering clear advantages in weldability, carbon equivalent, material availability, and cost. The grade has been the preferred European pressure steel for forgings precisely because its chemistry balances strength, toughness, and fabricability at a level suited to the vast majority of real-world pressure equipment design conditions.
P265GH earns its specification in a well-defined set of scenarios: thick-wall components where 20 MPa more yield translates to measurable wall reduction, high-pressure boiler drums where the design calculation leaves no margin with P245GH allowable stresses, and large-bore heavy-flange configurations where the extra strength changes the outcome of EN 13445 calculations.
The most common specification error is selecting P265GH conservatively — without running the calculation — and then discovering at the fabrication stage that the higher CE complicates welding procedures, extends lead times, or triggers PWHT requirements that partially cancel the strength advantage. Run the design calculation first. Specify the grade the numbers require.
For custom-forged P245GH forged components — tube sheets, seamless rolled rings, flanges, nozzle forgings and valve bodies — manufactured to EN 10222-2 with full EN 10204 3.1 or 3.2 certification, visit our P245GH forged parts product page for dimensional ranges, available product forms, and technical specifications.