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ASTM A270 Standard Specification for Seamless and Welded Austenitic and Ferritic/Austenitic Stainless Steel Sanitary Tubing
1. Introduction
ASTM A270 Standard Specification for Seamless and Welded Austenitic and Ferritic/Austenitic Stainless Steel Sanitary Tubing is a standard developed for the industry by ASTM International that indicates the requirements for seamless and welded stainless steel sanitary tubing. This heat-treatable standard, which is also referred to as the A270, covers both ferritic and austenitic steel grades, which are the two most common types of stainless steels in the world. It is described in detail the requirements for longitudinal submerged arc welded tube, whose wall thickness is equal or greater than 0.004 in (1.0 mm). The specification covers the products fabricated in both cold-working and hot-working processes.
2. Scope
This specification covers multiple grades of seamless and welded austenitic and ferritic/austenitic stainless steel sanitary tubing intended for use in various sanitary, food, and dairy applications. It covers product composition, mechanical property requirements, size limitations, and preparation for shipment. The materials can be classified into two categories – cold-worked stainless steel and hot-worked stainless steel.
3. Product Classifications
A. Seamless Sanitary Tubing
Seamless Sanitary Tubing is designed for use in applications where the highest level of cleanliness is required. It is well-suited for milk and dairy operations. The seamless tubing is produced by cold-working and heat-treating followed by annealing processes. It is available in several grades, including 304L, 316L, and 3163/L.
B. Welded Sanitary Tubing
Welded Sanitary Tubing is manufactured using a submerged arc welding (SAW) process. It is a form of resistance welding that develops heat and pressure in the course of joining the two surfaces. The process is able to produce stainless steel tubular products of superior quality and strength. The welded tubing is available in multiple grades, including 304L, 316L, and 3163/L.
4. Size Limitations
The A270 applies to seamless and welded tubes with a diameter not less than 0.004 in (1.0 mm), but not more than 8 in (203.2 mm). The finished tubes must meet the dimensional and tolerances requirements given in the specification.
5. Mechanical Requirements
The mechanical requirements of the A270 specification include the following tests: tensile strength, yield strength, elongation, hardness, and impact testing. The tensile properties must conform to the specified requirements while the hardness must not exceed 75HV and the impact strength must be sufficient enough as per the requirements stated in the specification.
6. Corrosion Testing
The A270 contains several corrosion tests to ensure that the stainless steel tubing meets the desired cleanliness. These tests include exposure to various aggressive environments, such as salt spray and other corrosive agents. The tests involve exposing the tubing to a variety of exposure conditions for a specific period of time, after which it is tested for any corrosion signs.
7. Quality Assurance
The A270 provides procedures for verifying that the quality of the stainless steel tubing conforms to the requirements of the standard. These requirements include product inspections and tests to ensure that the tubing is manufactured in accordance with the specification. Quality assurance tests are carried out to ensure that all tubes conform to the requirements of the standard and demonstrate a good quality finish.
Conclusion
The ASTM A270 Standard Specification for Seamless and Welded Austenitic and Ferritic/Austenitic Stainless Steel Sanitary Tubing is a necessary standard for all sanitary and food related industry. It provides necessary requirements for the composition, mechanical properties, product dimensions, preparation for shipping, and quality assurance. This standard is essential for the production of hygienic, safe and reliable stainless steel sanitary tubing.
