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There are various applications of stainless steel bars in industries like construction, food processing, energy, manufacturing, etc. When you want to buy stainless steel bars, you may find that there are two types of grades available in the market, namely ASTM A276 and ASTM A479. Though both standards have similar grades of stainless steel bars, the applications are different for each standard. ASTM A276 is a specification for stainless steel bars and shapes used for various industrial purposes. ASTM A479 is a specification for stainless steel bars used in pressure vessel service. There are a number of common grades used in both standards. However, both standards have different requirements for use, testing, and inspection.
Figure: Stainless steel round bars used for machining and industrial components.
Why Buyers Confuse ASTM A276 and ASTM A479
ASTM A276 and ASTM A479 are frequently confused due to similar grades of stainless steels in their standards. It is quite likely that the materials may look identical in appearance. In reality, each standard was developed for a specific purpose, with different requirements according to its application. Knowing the difference between the two will help prepare proper purchasing documents.
Similar grades
The common reason for the confusion is that both standards have many common grades of stainless steel. Table 01 below presents some of the frequently requested grades that can be delivered according to either ASTM A276 or ASTM A479 because the grade nomenclature is the same. In most cases, the chemical composition is almost the same.
Table 01: Common Stainless Steel Grades Covered by ASTM A276 and ASTM A479
| Stainless Steel Grade | Typical Applications | ASTM A276 | ASTM A479 |
|---|---|---|---|
| 316 | Marine and chemical processing equipment | Yes | Yes |
| 316L | Pressure equipment and corrosive environments | Yes | Yes |
| 304 | General fabrication, food processing equipment | Yes | Yes |
| 321 | Elevated-temperature service | Yes | Yes |
| 304L | Welded structures and corrosion-resistant equipment | Yes | Yes |
| 347 | High-temperature and pressure applications | Yes | Yes |
Similar product forms
The two standards both apply to stainless steel bars in the forms of round, square, hexagon, and flat bars. The bars in these forms come in the same dimensions and from the same manufacturers. It may be hard to differentiate one from the other based on appearance. The best way to go about this is to refer to the requirements of the project.
Different service requirements
ASTM A276 and ASTM A479 differ in terms of use. ASTM A276 is a general standard applied in various industries. In contrast, ASTM A479 is meant to be used in equipment operated under pressure or heat, such as boilers, heat exchangers, and pressure vessels. ASTM A479 may require additional testing and inspection.
What ASTM A276 Covers
ASTM A276 is a standard that applies to stainless steel bars and shapes. It is frequently used in engineering, manufacturing industries, and other industrial uses. The standard gives specifications in terms of material properties, sizes, tolerances, and finish surfaces.
General-purpose stainless steel bars
ASTM A276 is the standard that deals with stainless steel bars for various applications. Such stainless steel bars are widely used in fabrication and machining operations, as well as for the manufacturing of shafts, fasteners, and machinery parts. There are a lot of types of stainless steel included in this standard.
Stainless steel shapes
Figure 01: Common Stainless steel shapes under the ASTM A276
From Figure 01, it is clear that ASTM A276 also includes stainless steel products in various shapes such as angles, channels, and rolled shapes. These products have their uses in supports, machinery, building structures, and other structures. These products offer sufficient strength and corrosion resistance in tough conditions.
Hot-finished and cold-finished products
This standard applies to hot-rolled and cold-rolled stainless steels alike. It enables the purchasers to have more flexibility to choose according to the requirements of their applications. Hot-rolled bars are produced by heating them up to very high temperatures and can be used when dimensional accuracy is not of much importance.
What ASTM A479 Covers
ASTM A479 is the standard that provides requirements for stainless steel bars that are to be used in high-pressure and temperature environments. ASTM A479 is commonly applied when there is a need to ensure the safety of people. The standard provides requirements for the chemical composition and mechanical properties of materials.
Bars for pressure applications
Standard ASTM A479 deals with stainless steel bars for pressure applications. Such bars find application in the manufacturing of pressure vessels, boilers, heat exchangers, and pipelines. The standard is useful for maintaining strength and resisting corrosion of the material.
High-temperature service
ASTM A479 finds applications at high temperatures. It consists of stainless steel, which maintain their strength under high temperatures. They also have anti-corrosive properties. Because of these properties, ASTM A479 finds widespread application in power plants, petrochemical industries, and industrial heating units.
Valve, fitting, flange, and machined parts
ASTM A479 is used in the fabrication of valves, fittings, flanges, and machined components that are used in vital systems. Material quality is essential in such situations.
ASTM A276 vs A479 Comparison Table
Even though there are many similarities between the two standards (ASTM A276 and ASTM A479) in terms of types of steel covered, the usage of each of the standards is quite different. While the ASTM A276 is a general standard, the application of the ASTM A479 standard is mainly for pressure and high-temperature service.
Table 02: Comparison of ASTM A276 and ASTM A479 stainless steel bar standards
| Feature | ASTM A479 | ASTM A276 |
|---|---|---|
| Scope | Stainless steel bars for pressure-containing and high-temperature applications | General-purpose stainless steel bars and shapes |
| Product Forms | Primarily bars used for pressure-related components | Bars, angles, channels, and other shapes |
| Documentation | Often requires stricter documentation and traceability | Material certification as specified by the order |
| Service Conditions | Critical pressure and elevated-temperature service | General industrial service |
| Common Applications | Pressure vessels, boilers, valves, flanges, fittings, and heat exchangers | Machinery parts, structural components, fasteners, shafts, and fabrication work |
| Testing Requirements | Additional emphasis on requirements for pressure-service materials | Standard testing based on product requirements |
Scope comparison
The ASTM A276 specification is a general industrial specification that includes many kinds of stainless steel bars and sections. The ASTM A479 specification has a more limited scope and applies to bars used in pressure vessel service. The different purpose of the specifications is the main difference between them.
Product form comparison
ASTM A276 covers both bars and different shapes, thus providing more flexibility for the variety of applications. ASTM A479 primarily covers bars that will be machined to form various parts. So, there is more flexibility in terms of product shape provided by ASTM A276.
Application comparison
The materials covered by ASTM A276 are used in general engineering applications. Materials covered by ASTM A479 find their application in pressure and high-temperature equipment. Reliability is an essential factor here. Typical applications of ASTM A479 are valves, flanges, fittings, and pressure vessel parts. Figure 02 illustrates various service conditions for ASTM A276 and ASTM A479 materials.
Figure 02: Typical end-use applications for ASTM A276 and ASTM A479 stainless steel bars.
Testing and documentation comparison
Both of these grades have requirements on chemical and mechanical aspects. ASTM A479 is more likely to be used in critical applications. Additional inspections and certifications may be needed in such cases. Tracing of the material may also become a necessity. The buyer should make sure of the required tests.
Which Standard Should Buyers Choose?
Selection of either ASTM A276 or ASTM A479 will be determined by the application and service conditions. Either of the two standards could have the same grades of stainless steel. The right standard to adopt depends on how the material will be used. One should consider the pressure, temperature, and industrial needs when purchasing.
For general machining parts
The ASTM A276 material specification is generally used for machining purposes. The material specification covers stainless steel in shafts, fasteners, brackets, couplings, bushings, and many other machine parts that do not normally function under pressure. The material specification allows for many grades and product forms of stainless steel, making it economically useful in industry.
For pressure-containing components
ASTM A479 is employed for materials that operate under high-pressure conditions. Some of the applications are pressure vessels, boilers, heat exchangers, and process piping. This ASTM standard is recommended for use in critical services.
For structural bars and shapes
ASTM A276 is more suitable for cases where there is a need for structural bars and shapes. The standard specification deals with more than just stainless steel bars but also includes structural shapes like angles and channels. This material is extensively used in supporting constructions, equipment frames, platforms, and architectural applications. In contrast, the ASTM A479 deals mostly with bars for pressure applications and not structural ones.
For valves, fittings, and flanges
The ASTM A479 is often utilized for producing valves, fittings, and flanges. Such components can be used in various process systems. Often, they must function under certain stressful conditions such as under pressure, at high temperatures, and in corrosive environment. Such requirements can be met using the ASTM A479 standard.
How to Specify Bar Standards in an RFQ
A good request for quotation will ensure that suppliers give accurate quotations and the right materials. In case one wants to buy stainless steel bars under ASTM A276 or ASTM A479, it is important for him/her to give all details. This ensures accuracy in the procurement process.
Grade and diameter
The stainless steel grades should always be indicated in the RFQ. Buyers should also indicate the desired bar diameter, thickness, width, or any other dimensional specifications based on the form of product to be acquired.
Shape and tolerance
There must be a clear indication of the shape of the bar that will be used. This can be either a round bar, square bar, hexagonal bar, or flat bar. In case there is a need for any special shapes, then the actual shape must be indicated.
Heat treatment condition
The buyer needs to indicate the heat treatment in the RFQ, in order to avoid the wrong supply of material. The heat treatment will influence the strength of the metal. The heat treatment will also influence the corrosion resistance and machinability of the metal.
Certificate and inspection requirements
The RFQ should list all required documents and inspections. Common documents include the mill test certificate (MTC), inspection records, and shipping documents. Critical applications may need third-party inspection. Material traceability may also be required. Extra testing and quality documents may be needed. Including these requirements in the RFQ helps to avoid mistakes and ensures the material meets project needs.
Conclusion
ASTM A276 and ASTM A479 are two stainless steel bar standards that are crucial in different industries. Both standards differ in terms of their applications. ASTM A276 is concerned with stainless steel bars and shapes for machining, fabricating, and construction. On the other hand, ASTM A479 is concerned with bars intended for use in pressure and high-temperature equipment. Service conditions are crucial in such applications.
Buyers have to select one or the other according to the conditions of service. The grade of the stainless steel is not sufficient information. Understanding of their scope, product forms, test requirements, and applications will help buyers choose the right material. A detailed Request for Quotation with detailed requirements will facilitate purchases as well.
FAQ
Can the same stainless grade meet both ASTM A276 and ASTM A479?
A grade name may appear in both standards, but the order and MTC must confirm the exact standard supplied.
Which standard is better for pressure-containing parts?
ASTM A479 is generally used when stainless steel bars will be used for pressure vessel or high-temperature service.
What should buyers send for a stainless steel bar quote?
Send the standard, grade, bar shape, size, tolerance, quantity, heat treatment condition, application, and certificate requirements.
Inquiry Support
Send your stainless steel bar standard, grade, shape, tolerance, quantity, and certificate requirements. Request a quote from Jianglin Steel.
