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Unformatted text preview: SPECIFICATION FOR WELDED UNS N08020, N08024, AND N08026 ALLOY TUBES SB-468 01 (Identical with ASTM Specification B 468-99 except that certification has been made mandatory.) 1. Scope 4. Ordering Information 1.1 This specification covers welded UNS N08020, N08024, and N08026 alloy boiler, heat exchanger, and condenser tubes for general corrosion-resisting and lowor high-temperature service. 1.2 This specification covers tubes 1⁄8 to 5 in. (3.18 to 127 mm), inclusive, in outside diameter and 0.015 to 0.500 in. (0.38 to 12.70 mm), inclusive, in wall thickness. Table 2 of Specification B 751 lists the dimensional requirements of these sizes. Tubes having other dimensions may be furnished provided such tubing complies with all other requirements of this specification. 1.3 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only. 4.1 It is the responsibility of the purchaser to specify all requirements that are necessary for the safe and satisfactory performance of material ordered under this specification. Examples of such requirements include, but are not limited to, the following: 4.1.1 Quantity (feet or number of lengths), 4.1.2 UNS number, 4.1.3 Size (outside diameter and minimum or average wall thickness), 4.1.4 Length (random or specific), 4.1.5 ASTM designation, 4.1.6 Product Analysis — State if required, 4.1.7 Certification — Certification and a report of test results are required, 2. Referenced Documents 4.1.8 Purchaser Inspection — State which tests or inspections are to be witnessed, if any, and 4.1.9 Supplementary requirements, if any. 2.1 ASTM Standards: A 262 Practices for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels B 751 Specification for General Requirements for Nickel and Nickel-Alloy Welded Tube E 8 Test Methods for Tension Testing of Metallic Materials 5. Materials and Manufacture 3. General Requirement 3.1 Material furnished in accordance with this specification shall conform to the applicable requirements of the current edition of Specification B 751 unless otherwise provided herein. 610 5.1 The tubing shall be made from flat-rolled stock by an automatic welding process with no addition of filler metal. Subsequent to welding and prior to final heat treatment, the material shall be cold-worked in either the weld metal only, or in both the weld and base metal. 5.2 Heat Treatment — Tubing of UNS N08020 alloy shall be furnished in the stabilized-annealed condition. Tubing of UNS N08024 alloy shall be furnished in COPYRIGHT American Society of Mechanical Engineers Licensed by Information Handling Services PART B — NONFERROUS MATERIAL SPECIFICATIONS TABLE 1 CHEMICAL REQUIREMENTS Composition, % UNS N08020 0.07 2.00 0.045 0.035 1.00 32.00–38.00 19.00–21.00 2.00–3.00 3.00–4.00 8× carbon–1.00 ... Remainder SB-468 Element Carbon, max Manganese, max Phosphorus, max Sulfur, max Silicon, max Nickel Chromium Molybdenum Copper Columbium (Nb) + tantalum Nitrogen IronA A UNS N08024 0.03 1.00 0.035 0.035 0.50 35.00–40.00 22.50–25.00 3.50–5.00 0.50–1.50 0.15–0.35 ... Remainder UNS N08026 0.03 1.00 0.03 0.03 0.50 33.00–37.20 22.00–26.00 5.00–6.70 2.00–4.00 0.10–0.16 Remainder By difference. the annealed condition. Tubing of UNS N08026 alloy shall be furnished in the solution-annealed condition. NOTE 1 — The recommended annealing temperatures are 1800 to 1850°F (982 to 1010°C) for UNS N08020, 1925 to 1975°F (1052 to 1079°C) for UNS N08024, and 2050 to 2200°F (1121 to 1204°C) for UNS N08026. A TABLE 2 MECHANICAL PROPERTY REQUIREMENTS Tensile Strength, min, ksi (MPa) 80 (551) Yield Strength,A min, ksi (MPa) 35 (241) Elongation in 2 in. (50.8 mm), min, % 30.0 6. Chemical Composition Yield strength shall be determined by the offset method at 0.2% limiting permanent set in accordance with Test Methods E 8. An alternative method of determining yield strength may be based on total extension under load of 0.5%. 6.1 The material shall conform to the composition limits specified in Table 1. One test is required for each lot as defined in Specification B 751. 6.2 If a product analysis is performed, it shall meet the chemistry limits prescribed in Table 1, subject to the analysis tolerances specified in Table 6 of Specification B 751. fied in Table 2. One test is required for each lot as defined in Specification B 751. 7.2 Flattening Test — A flattening test shall be made on each end of one tube per lot. Superficial ruptures resulting from surface imperfections shall not be cause for rejection. 7.3 Flange Test — A flange test shall be made on each end of one tube per lot. 7. Mechanical Properties and Other Requirements 7.1 Mechanical Properties — The material shall conform to the mechanical property requirements speci- 7.4 Nondestructive Test Requirements — Each tube shall be subjected to either a pressure test or a nondestructive electric test at the manufacturer’s option. The purchaser may specify which test is to be used. 611 COPYRIGHT American Society of Mechanical Engineers Licensed by Information Handling Services SB-468 2001 SECTION II SUPPLEMENTARY REQUIREMENTS The following supplementary requirements shall be applied only when specified by the purchaser in the inquiry, contract, or order: S1. Corrosion Tests S1.1 One intergranular corrosion test per lot shall be performed by the manufacturer on a sensitized specimen and tested in accordance with Practices A 262. When this supplementary requirement is specified, the specific practice (Practice B or Practice E) shall also be specified. If Practice B is specified, the specimen must pass with a rate of less than 0.002 in. (0.05 mm) per month. A lot for intergranular corrosion testing shall be the same as for mechanical testing. S1.1.1 In addition to the anneal recommended in Note 1, the specimen shall be sensitized for 1 h at 1250°F (677°C) before being subjected to corrosion testing. S1.1.2 If any corrosion test specimen fails the test, the material represented by such specimens may be reheat-treated and resubmitted for test. 612 COPYRIGHT American Society of Mechanical Engineers Licensed by Information Handling Services ...
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This note was uploaded on 10/04/2010 for the course ENGINEERS 22453175 taught by Professor Heydari during the Spring '08 term at Miami University.

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