ASME SA515 Grade 70 is a carbon-silicon steel plate engineered specifically for intermediate and higher-temperature pressure vessel service. Governed by the ASME SA-515/SA-515M specification (identical to ASTM A515/A515M), it is the highest-strength grade among the three grades in the A515 series (Gr. 60, Gr. 65, and Gr. 70), delivering a minimum tensile strength of 485 MPa (70 ksi).
SA515 Gr. 70 steel plates are produced using silicon-deoxidized practice, exhibiting a coarse-grain austenitic microstructure (typically ASTM grain size 1 to 5). Although this coarse-grain structure inherently limits low-temperature notch toughness, it offers a distinct advantage in elevated-temperature environments: a coarser grain size reduces grain boundary area, thereby imparting superior creep resistance and mitigating strength degradation at elevated operating temperatures. Consequently, SA515 Gr. 70 serves as an ideal material choice for power boiler steam drums, heat exchanger shells, and pressure vessels operating within the 300°C to 500°C (570°F to 930°F) range.
GNEE Steel is a leading global supplier specializing in pressure vessel and boiler steel plates, backed by over 18 years of specialized export experience across more than 60 countries. Our technical department-staffed by 2 senior engineers, 17 project engineers, and 10 associate engineers-provides end-to-end technical support from material selection through final delivery. Maintaining long-term strategic partnerships with major domestic steel mills, we guarantee complete supply chain traceability for every plate, linked directly from the heat number to the Mill Test Certificate (MTC).
Gnee Steel has supplied 50,000+ tons of pressure vessel plates to 60+ countries. Every SA515 Gr.70 plate ships with a full EN 10204 Type 3.1 MTR, traceable from heat number to delivery. Type 3.2 third-party witnessed certification available on request.
ASME SA515 Grade 70 High-Temperature Carbon Steel Plate Specification
| Parameter | Specification & Technical Details |
| Product Name | ASME SA515 Grade 70 Carbon Steel Plate for High-Temperature Boilers and Heat Exchanger |
| Governing Standards | ASTM A515/A515M, ASME SA515/SA515M |
| Metallurgical Features | Fully killed coarse-grain austenitic steel, silicon-deoxidized practice, optimized for elevated-temperature creep resistance. |
| Dimensional Scope |
Thickness: 6–300 mm; Width: 1500–4200 mm; Length: 3000–18000 mm (Custom cut-to-size available). |
| Delivery Condition |
1. Plates ≤50mm (≤ 2 in.): As-Rolled, Normalized, or Quenched & Tempered (Q&T). 2. Plates > 50 mm (> 2 in.): Mandatory Normalizing heat treatment (strict ASME code requirement). |
| Surface Finish & Fabrication | As-Rolled mill scale, shot-blasted rust removal, shop-primed, precision edge beveling, and secondary machining services. |
| Export Packaging | High-tensile steel strapping + moisture-proof plastic film + wooden dunnage/skids, corner protection, engineered for ocean freight. Fumigation certificates (ISPM 15) available upon request. |
ASME SA515 Grade 70 Carbon Steel Plate Chemical Composition
| Element | Ladle Analysis (Max) | Product Analysis (Max) |
| Carbon (C) | 0.30–0.35 | 0.30–0.35 |
| Manganese (Mn) | 1.20 | 1.30 |
| Silicon (Si) | 0.15–0.40 | 0.13–0.45 |
| Phosphorus (P) | 0.035 | 0.035 |
| Sulfur (S) | 0.035 | 0.035 |
Carbon Equivalent Calculation Formula (for welding reference)
Ceq = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15
ASME SA515 Grade 70 Carbon Steel Plate Mechanical Property
| Property / Parameter | Standard Value |
| Yield Strength, min. | 260 MPa (38 ksi) |
| Tensile Strength Range | 485–620 MPa (70–90 ksi) |
| Elongation, min. | ≥ 21% |
| Elongation, min. | ≥ 17% |
| Allowable Stress | 102 MPa (14,800 psi) |
| Creep-Rupture Strength | 161–314 MPa |
| Density | 7.85 g/cm3 |
| Modulus of Elasticity ($E$) | 205 GPa |
ASME SA515 Grade 70 Plate High-Temperature Performance in Boilers and Heat Exchangers
SA515 Gr. 70 is engineered specifically for pressure vessel and boiler applications operating at intermediate and elevated metal temperatures, typically ranging from 300°C to 500°C (570°F to 930°F). Its suitability for these elevated-temperature services is governed by three primary metallurgical factors:
Coarse-Grain Microstructure - Superior Creep Resistance
ASME SA515 steel is intentionally manufactured using a coarse-grain practice. At elevated temperatures, grain boundaries are the primary sites for creep deformation-where grain boundary sliding, migration, and void formation occur under sustained stress. A reduced grain boundary area (i.e., a coarser grain structure) results in lower creep rates and superior dimensional stability under long-term elevated-temperature loads. This is the fundamental metallurgical rationale for specifying A515 for higher-temperature service, whereas ASTM A516 (produced to fine-grain practice) is preferred for lower-temperature and notch-toughness-critical applications.
Silicon Content - Oxidation Resistance
The specified silicon content (0.15%–0.40%) serves a dual function: it acts as a primary deoxidizer during steelmaking and enhances high-temperature oxidation resistance. Silicon promotes the formation of a stable SiO2 sublayer beneath the iron oxide scale, effectively retarding oxidation rates when metal temperatures exceed 400°C (750°F).
Carbon Content - Elevated-Temperature Strength Retention
A relatively higher carbon content (0.24%–0.35%) provides solid-solution strengthening, which is maintained far more effectively at elevated temperatures compared to lower-carbon grades. Consequently, within the 400°C to 500°C range, ASME SA515 Gr. 70 retains higher allowable design stress values than many lower-carbon alternatives per ASME BPVC Section II, Part D.
ASME SA515 Grade 70 Steel Plate Welding & Fabrication Performance
Carbon Equivalent & Weldability
SA515 Gr. 70 steel exhibits a moderate Carbon Equivalent (CE), typically ranging from 0.45 to 0.55. This classifies it as a material with moderate weldability. While it can be readily joined using all standard arc welding processes-such as Shielded Metal Arc Welding (SMAW), Gas Metal Arc Welding (GMAW), Submerged Arc Welding (SAW), and Flux-Cored Arc Welding (FCAW)-proper preheating is mandatory, particularly for heavy-gage plates, to prevent hydrogen-induced cold cracking (HICC).
Recommended Preheat Temperatures
| Plate Thickness | Recommended Preheat |
|---|---|
| ≤ 12 mm | Optional (ambient ≥ 10°C); Ensure surface is dry and free of moisture |
| 13-25 mm | 10°C; minimum Light preheat recommended in humid conditions |
| 26-50 mm | 80-120°C; Mandatory preheat; verify interpass temperature |
| > 50 mm | 120-150°C; Mandatory preheat; consider low-hydrogen consumables |
Post-Weld Heat Treatment (PWHT)
| Thickness | PWHT Recommendation |
|---|---|
| ≤ 38 mm (1.5 in.) | Generally not required |
| > 38 mm | Recommended per ASME Section VIII, Div. 1, UCS-56 |
| All thicknesses (severe service) | Recommended regardless of thickness |
Recommended Welding Consumables
| Process | Recommended Consumable | AWS Classification |
|---|---|---|
| SMAW (Shielded Metal Arc) | Low-hydrogen electrode | E7018 |
| GMAW (Gas Metal Arc) | Solid wire + Ar/CO₂ mix | ER70S-6 |
| SAW (Submerged Arc) | Wire + flux combination | F7A2-EM12K |
| FCAW (Flux-Cored Arc) | Low-hydrogen flux-cored wire | E71T-1M |
Not sure about preheat temperature for your plate thickness? Gnee's engineering team provides free welding procedure consultation with every order - send your WPS for technical review and we'll respond within 24 hours.
ASME SA515 Grade 70 High Temp Carbon Steel Plate Typical Application
Power Boiler Equipment Power plant steam drums, water-cooled headers, high-temperature economizer tube sheets, and steam superheater headers/casing.
Petrochemical High-Temperature Heat Exchangers Shell-and-tube high-temperature heat exchangers, catalytic reformer heater shells, high-temperature oil/gas separators, and pressure-retaining sections of distillation columns.
Chemical Pressure Vessels High-temperature reactors operating above 345°C (650°F), thermal fluid/hot oil pressure tanks, and high-temperature surge vessels.
Sour Service / H₂S Environments (With Value-Added Testing) When supplied with supplementary NACE MR0175 compliance and Hydrogen-Induced Cracking (HIC) testing, it is widely used in high-temperature hydroprocessing and sour oil/gas processing units.
Price and Customization
Prices may vary depending on factors such as order quantity, specifications, etc. Sizes can be customized as needed. Common thicknesses range from 6-300mm, and widths range from 1600-4200mm. Additionally, cutting, rolling, ultrasonic testing, and other processing treatments are available.
GNEE has a professional and passionate team. The management team has rich experience and accurately grasps the industry direction; the production department currently has 150 employees, including 2 senior engineers, 17 engineers and 10 assistant engineers; the sales team provides attentive services to meet customer needs. All teams work together to promote the steady development of the company.
FAQ
What is the difference between ASTM A515 and ASME SA515?
ASTM A515/A515M is the original material specification developed by ASTM International. ASME SA515/SA515M is the identical specification adopted into the ASME Boiler and Pressure Vessel Code (BPVC) Section II. The chemical composition and mechanical property requirements are identical. The "SA" prefix indicates ASME adoption. For pressure vessel or boiler applications requiring an ASME code stamp, specify SA515 on your purchase order.
Is SA515 Gr.70 suitable for low-temperature service?
No. SA515 Gr.70 is a semi-killed, coarse-grain steel designed for intermediate and higher-temperature service. It is not recommended for low-temperature applications (below -29°C). The coarse-grain microstructure results in lower impact toughness at sub-zero temperatures compared to fine-grain alternatives. For low-temperature service, specify SA516 Gr.70 (fully killed, fine-grain) or an impact-tested grade per your project specifications.
What is the difference between A515 Gr.70 and A516 Gr.70?
The key differences are:
(1) Deoxidation: A515 is semi-killed; A516 is fully killed (silicon-killed).
(2) Grain structure: A515 is coarse-grain (ASTM 1-5); A516 is fine-grain (ASTM 5-8).
(3) Temperature suitability: A515 for intermediate/higher temperatures (300-500°C); A516 for room to low temperatures (down to -46°C with impact testing).
(4) Low-temperature toughness: A516 is significantly better.
(5) Creep resistance: A515 is better at elevated temperatures due to fewer grain boundaries.
Selection rule: Choose A515 for high-temperature boiler/vessel service; choose A516 when low-temperature toughness is required.
Beyond container plates like SA515 Gr70, we have a diverse range of steel plates, as shown in the table below: high-strength low-alloy plates for equipment lightweighting, wear-resistant plates to reduce maintenance costs, weather-resistant plates to extend outdoor component lifespans, and marine plates for ensuring ship safety. If you're interested in any of these steel plate types, we are happy to discuss your needs with you.
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