What is the difference between ASME SA 515 and 516?

What is the Difference Between ASME SA 515 and 516?

ASME SA 515 is a coarse-grain carbon steel for high-temperature pressure vessels, while ASME SA 516 is a fine-grain carbon steel for moderate and low-temperature applications, offering better toughness.At Gangsteel, we specialize in manufacturing ASME SA 516 GR 70 plates, which provide superior notch toughness and weldability for critical industries like oil and gas. This article compares the grain structure, chemical composition, mechanical properties, and applications of SA 515 and SA 516 to clarify their differences.

Grain Structure: The Core Difference

The primary distinction between ASME SA 515 and SA 516 lies in their grain structure, which significantly impacts their performance in pressure vessel applications:

• SA 515: Utilizes a coarse-grain practice, suitable for high-temperature environments (up to 538°C). Coarse grains are less prone to creep at elevated temperatures but offer lower notch toughness, making SA 515 less ideal for low-temperature service.
• SA 516: Employs a fine-grain practice, achieved through controlled rolling and normalizing heat treatment. This enhances notch toughness, making SA 516, such as ASME SA 516 GR 65, ideal for moderate and low-temperature applications (down to -46°C) where brittle fracture risks are higher.

Gangsteel’s SA 516 plates, including ASME SA 516 GR 60 and ASME SA 516 GR 55, are fine-grain treated, ensuring superior performance in demanding environments like sour gas processing.

Chemical Composition Comparison

While both SA 515 and SA 516 are carbon steels, SA 516 has stricter controls on phosphorus and sulfur to enhance weldability and toughness, especially for Hydrogen Induced Cracking (HIC) resistance in sour service:

Gangsteel’s SA 516 plates are specifically tested for HIC per NACE TM0284, with sulfur content as low as 0.003% for critical applications, making them superior for modern pressure vessel requirements compared to SA 515.

Mechanical Properties Comparison

The mechanical properties of SA 515 and SA 516 reflect their differing grain structures and temperature applications:

The fine-grain structure of SA 516, as used in ASTM A 516 GR 70, results in better impact resistance at low temperatures, making it the preferred choice for modern pressure vessels. SA 515, with its coarse grain, is better suited for high-temperature applications where creep resistance is prioritized over toughness.

Temperature Service Ranges

• SA 515 GR 70: Designed for intermediate and high temperatures (up to 538°C), as coarse grains maintain stability under prolonged heat exposure. It is commonly used in older boiler designs where high-temperature creep is a concern.
• SA 516 GR 70: Optimized for moderate and low temperatures (down to -46°C), with fine-grain structure reducing the risk of brittle fracture in cold environments. This makes SA 516 ideal for oil and gas applications, especially in sour service where HIC resistance is critical.

Gangsteel recommends SA 516 for most modern pressure vessel applications due to its versatility and superior toughness, particularly for projects requiring compliance with NACE MR0175/ISO 15156 standards.

Applications and Selection Criteria

• SA 515 Applications:

  • High-temperature boilers and steam drums.
  • Older pressure vessel designs where high-temperature stability is key.
  • Applications with less stringent low-temperature requirements.

• SA 516 Applications:

  • Oil and gas pressure vessels and pipelines, especially with sour gas exposure.
  • Petrochemical reactors and heat exchangers requiring HIC resistance.
  • Power generation boilers operating at moderate pressures, such as those using ASTM A 516 GR 65.

Gangsteel’s SA 516 plates are available in thicknesses from 6mm to 200mm (custom up to 300mm), with widths up to 4,500mm and lengths up to 12,000mm, tailored to project specifications. Our plates are normalized or stress-relieved to enhance toughness and weldability, making them a superior choice over SA 515 for most contemporary applications.

Gangsteel’s Commitment to SA 516 Quality

At Gangsteel, we prioritize SA 516 over SA 515 for its enhanced toughness and modern applicability. Our SA 516 plates undergo:

• Ultrasonic Testing: Per ASTM A435 to ensure defect-free material.
• HIC Testing: Per NACE TM0284 for sour service reliability.
• Impact Testing: Charpy V-notch at -46°C to verify low-temperature performance.
• Certifications: Mill Test Certificates (MTCs) per EN 10204 3.1, verified by SGS and BV.

Our global supply chain ensures delivery to over 50 countries, with 3-7 day shipping to Asia, maintaining a zero-defect record. Gangsteel’s SA 516 plates, such as ASTM A 516 GR 60, are designed to integrate seamlessly with other ASME-compliant components

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Why Choose SA 516 Over SA 515?

SA 516’s fine-grain structure offers several advantages:

• Superior Toughness: Better performance in low-temperature and sour gas environments.
• Enhanced Weldability: Lower phosphorus and sulfur content reduce weld imperfections.
• Modern Standards: Aligns with current ASME BPVC requirements for safety and reliability.
• Versatility: Suitable for a broader range of temperatures and applications compared to SA 515.
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Conclusion

ASME SA 515 is designed for high-temperature pressure vessels with coarse-grain steel, while ASME SA 516, such as ASME SA 516 GR 70 and ASME SA 516 GR 60, offers fine-grain steel for moderate and low-temperature applications with superior toughness. Gangsteel’s SA 516 plates are the preferred choice for modern pressure vessels, providing reliability and compliance with global standards. Contact Gangsteel for tailored solutions and competitive quotes for your project needs.

Keywords: ASME SA 515 vs 516, coarse grain vs fine grain steel, pressure vessel plates, Gangsteel SA 516