Overview of ASTM A516 and A285
ASTM A516 is a standard specification for carbon steel plates operating under lower or moderate temperature and high-pressure environment services. It is commonly used to manufacture heat exchangers and boilers where excellent toughness, strength, and weldability are required. It is available in different material grades such as 55, 60, 65, and 70, and each grade represents a different level of tensile strength. It can be supplied in normalized or as-rolled delivery conditions to achieve the required mechanical properties according to the operating environment.
On the other hand, ASTM A285 applies to carbon steel plates designed for pressure vessels operating under low to moderate stress conditions. It offers excellent weldability, is suitable for forming, and provides low to intermediate tensile strength. This makes it ideal for non-critical applications such as storage tanks or simple pressure vessels. It is available in different material grades such as A, B, and C, and generally supplied in the as-rolled condition.
Chemical Composition Comparison Table
The chemical composition, especially for carbon, is changing for different grades. ASTM A285 generally consists of a lower amount of alloying elements. On the other hand, ASTM A516 generally consists of a higher amount of manganese and silicon, which enhances the toughness, strength, and ductility of the material. The side-by-side chemical composition comparison of ASTM A285 and A516 is shown in Table 01:
Table 01: Chemical composition comparison of ASTM A285 and A516
Element | ASTM A285 | ASTM A516 |
Carbon (C) | A: 0.17% max | 55: 0.18–0.23% |
Manganese (Mn) | 0.6-1.0% | 0.60–1.20% |
Phosphorus (P) | ≤0.035% | ≤0.025% |
Sulfur (S) | ≤0.035% | ≤0.025% |
Silicon (Si) | – | 0.15–0.40% |
Mechanical Properties (Tensile, Yield, Elongation)
The choice of material grade from the ASTM A516 and A285 is dependent on the service environment. The values of yield strength, tensile strength, and elongation increase with the grade of the material. As you can see, the values from Table 02 in ASTM A285, Grade A, have a tensile strength range of 345–485 MPa, while Grade C reaches up to 415–550 MPa. Similarly, in ASTM A516, the tensile strength rises from 380–515 MPa in Grade 55 to 485–620 MPa in Grade 70, showing a direct relation.
The ASTM A516 offers higher strength across all grades as compared to A285. The yield strength of A516 is also higher, which makes it suitable for higher-pressure and low-temperature service applications. On the other hand, ASTM A285 offers lower yield and tensile strength, which makes it suitable for use in low to moderate-pressure vessels. The elongation and toughness values are almost similar for both ASTM A285 and A516, which helps them to improve the resistance to cracking during fabrication.
Table 02: Comparison of the key mechanical properties of ASTM A516 and A285:
Property | ASTM A285 | ASTM A516 |
Tensile Strength (MPa) | Grade A: 345–485 | Grade 55: 380–515 |
Yield Strength (MPa) | Grade A: 165 | Grade 55: 205 |
Elongation (%) | Grade A: 27 | Grade 55: 27 |
Working Temperature and Pressure Suitability
The selection of ASTM A285 and A516 depends on the working temperature and pressure. If there is high working temperature and pressure, then the material should have high yield and tensile strength. These mechanical properties ensure that the material withstands deformation, internal stresses, and avoids potential failures during service.
In ASTM A516, this generally consists of higher yield strength, higher toughness, and higher tensile strength. Due to its exceptional toughness and strength, it is suitable for applications where there are higher pressures and low or moderate temperatures, such as pressure vessels, oil & gas equipment, boilers, and separators. For thinner plates, it can be supplied in as-rolled condition, and thicker plates can be supplied in normalized condition.
In ASTM A285, it consists of relatively lower to moderate yield and tensile strengths. Due to lower strength, ASTM A285 usage is restricted to lower or moderate pressure applications. It is best used for non-critical vessels and low-pressure storage tanks. Under extreme service conditions, its higher elongation values help it to avoid the sudden fracture of the structure. It is generally supplied in an as-rolled condition.
Table 03: Working temperature, pressure, and applications comparison of ASTM A285 and A516
Property / Condition | ASTM A285 | ASTM A516 |
Service Type | Low to intermediate tensile strength pressure vessels | Moderate and low temperature pressure vessels |
Typical Working Pressure | Low to moderate (≤1.5 MPa or ~220 psi typical) | Moderate to high (up to 5–10 MPa or higher, depending on design) |
Operating Temperature Range | Up to ~400°C (750°F) | Up to ~600°C (1100°F) depending on grade and condition |
Lower temperature | It is not recommended to use it and may cause sudden rapture. | It performs excellent, especially under normalized conditions. |
Typical applications of each grade
The ASTM A285 and ASTM A516 steels are widely used in the manufacturing of pressure vessels, boilers, and storage tanks. But each grade has different mechanical properties. The selection of a specific grade is dependent on the working pressure and temperature. Below is a detailed overview of the typical applications of each grade:
ASTM A285:
It offers a lower to moderate yield strength, which makes it suitable for the non-critical pressure-containing components.
1) Grade A: It is typically used in low-pressure storage tanks, air storage vessels, and small-scale pressure vessels for non-corrosive gases or liquids. The reason behind its usage in lower-pressure applications is the lower carbon content among the A285 grades. Due to this, it offers lower strength, good weldability, and excellent elongation.
2) Grade B: It is used to manufacture moderate internal pressure steam vessels, expansion tanks, and moderate pressure storage tanks. The carbon content is higher as compared to grade A, which helps it to slightly higher yield and tensile strength. Its ductility is slightly less compared to grade A, which may lead to formability difficulties.
3) Grade C: It has the highest tensile and yield strength among the ASTM A285 grades. It consists of higher carbon content compared to A, B grades, but still offers good weldability. Due to higher strength and maintained weldability, it is used to manufacture the mild chemical storage units, process tanks, and heat exchangers shells at lower stress.
ASTM A516:
It offers higher yield strength and exceptional toughness, which makes it ideal to usage for use in higher-pressure applications. It is widely used in industries such as petrochemical, oil and gas, and chemical processing.
1) Grade 55: It is used for lower-pressure boilers, storage tanks, and heat exchangers. The reason behind this usage is moderate yield, tensile strength, and the highest elongation among other grades of ASTM A 516.
2) Grade 60: The moderate combination of strength, toughness, and weldability makes it the most common grade to fabricate the pressure vessel. Its other applications include industrial boilers, low-temperature service tanks, heat exchangers, and oil refineries.
3) Grade 65: It offers higher strength than grade 60, which makes it suitable for use for enhanced pressure resistance. It is used to manufacture gas separators, pressure drums, process piping, and autoclaves.
4) Grade 70: It is used to manufacture high-pressure reactors, boilers, and storage tanks, widely used in petrochemical and refinery plants. It is ideal for harsh service environments due to its higher strength and exceptional toughness among all grades of ASTM A516. It offers excellent fracture toughness and resistance to brittle fracture.
Cost and Availability
The cost is dependent on the alloying elements and heat treatment services used to achieve the required properties. The availability of these materials depends on the supply and demand, logistics, and global economic health.
The ASTM A285 is generally cost-effective than A516 due to less usage of alloying elements and lower mechanical strength requirements. It is readily available in standard thickness from the distributors. But its limited usage in high-performance equipment may lead to it not being available in higher thickness. The usage of ASTM A285 is limited to non-critical and replacement applications.
ASTM A516 is slightly more expensive than A285 due to more usage of alloying elements, more heat treatment services, and more requirements for mechanical strength. It offers excellent cost-to-performance value, especially for critical pressure vessels. The grades 60 and 70 can easily be available due to large volume production by steel mills. It is readily available in a wide range of thickness, width, and plate sizes. The widespread production ensures consistent quality and quick procurement.
Recommendation by Use Scenario
The choice between ASTM A285 and ASTM A516 depends on the service pressure, temperature, and criticality of operation. Generally, ASTM A285 is used under low-pressure, low-temperature, and cost-effective applications. ASTM A516 is used for high temperature, high pressure, and critical applications. Table 04, given below, summarizes the most suitable applications for each material under different use scenarios:
Table 04: Recommended material and reason for different service scenarios
Use Scenario | Recommended Material | Reason / Justification |
High-Pressure Service | ASTM A516 (Grades 65 or 70) | Provides higher tensile and yield strength and is capable of withstanding elevated internal pressure without deformation. |
Moderate Pressure and Temperature | ASTM A516 (Grade 60) | Offers balanced mechanical properties, good weldability, and toughness. It is ideal for boilers and process vessels operating at moderate levels. |
Low Pressure and Low Temperature | ASTM A285 (Grade C) | Adequate for simple, low-stress vessels, and cost effectiveness is important. |
High Temperature Operation (up to ~600°C) | ASTM A516 (Grades 65 or 70) | Maintains strength and resistance to creep at elevated temperatures. |
Sub-Zero or Cryogenic Conditions | Normalized ASTM A516 (Grade 70) | Excellent notch toughness and ductility at low temperatures prevent brittle fracture. |
Non-Critical Applications | ASTM A285 (Grades A or B) | It offers a lower cost and sufficient mechanical properties for vessels under minimal stress. |
Critical Pressure Equipment (Reactors, Heat Exchangers, Boilers) | ASTM A516 (Grades 60–70) | Superior strength, toughness, and weldability for safety and long-term service. |
Summary
The ASTM A285 is suitable for low-pressure, low-temperature, and non-critical applications. It is cost-effective, has good weldability, and adequate ductility. On the other hand, ASTM A516 is designed for moderate- to high-pressure and low-temperature service applications. It provides higher tensile and yield strength, superior toughness, and reliable performance in critical applications such as boilers, heat exchangers, and reactors.
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