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The international standards for brass tubes cover aspects such as chemical composition, mechanical properties, manufacturing processes, and application areas. The following are the main international standards along with relevant details: 1. ASTM standards – ASTM B111/B111M-24: Scope of application: Seamless copper and copper alloy condenser tubes and tube blanks with an outer diameter of ≤80 mm, used in heat exchange equipment such as condensers and evaporators. ASTM International. Brass alloys: This category includes copper-nickel alloys such as UNS C70400, C70600, C71000, C71500, etc. The minimum tensile strength of the C71500 alloy in the annealed state (O61) is 360 MPa, while it can reach 495 MPa in the stress-relieved state (HR50). Testing requirements: Expansion testing is required (e.g., C71500 must withstand a 30% increase in outer diameter), residual stress testing, and ammonia fumigation testing (per ISO 6957 method). Update: The 2024 version adds requirements for the grain size of ferritic steel pipes, and revises the welding composition limits for alloys such as C71520. Scope of application of ASTM B150/B150M: A general standard for seamless copper tubes, covering requirements for chemical composition, physical properties, and surface treatment; some brass alloys (such as C70600) may refer to this standard. Scope of ASTM B188: Technical specifications for brass tubes, including requirements regarding composition, dimensional tolerances, and corrosion resistance, suitable for general industrial use. II. International Organization for Standardization (ISO) standard ISO 6957:1988 – Test method: Ammonia fumigation test for stress corrosion resistance of copper alloys. This method is used to determine the sensitivity of materials to stress corrosion cracking in an ammonia atmosphere, and it is suitable for assessing the quality of brass pipes. Applications: It is often used as a referenced testing method in standards such as ASTM B111. III. European Standard (EN) EN 12449:2019-12 Scope of application: General-purpose seamless round copper and copper alloy tubes with an outer diameter of 3–450 mm; it covers chemical composition, mechanical properties, and dimensional tolerances. Brass alloys: include copper-nickel alloys (such as C70600, C71500), but the specific standard details should be consulted based on the particular alloy designation. Substitution relationship: Replaces EN 12449:2016+A1:2019; it was further updated in 2023 to EN 12449:2023-08 – attention should be paid to the applicable version. Scope of application of EN 12451: Seamless copper and copper alloy tubes for heat exchangers; brass materials may be included, but this must be confirmed specifically. IV. Japanese Industrial Standards (JIS) JIS H3300 Scope of application: Seamless copper and copper alloy tubes, covering various alloys such as pure copper C10200 and brass C7150. Brass alloys: C71500 (with 29–33% nickel content) is specifically designated as brass tubing, suitable for corrosion-resistant structural components. Performance requirements: C71500 must meet the chemical composition specifications (such as Fe 0.4–1.0%, Mn 0.2–1.0%) as well as the mechanical property requirements. V. Other relevant standards: ASME BPVC Section II Part B – Specification for non-ferrous metal materials for pressure vessels. It references standards such as ASTM B111, and is applicable to brass tubes used in high-temperature and high-pressure environments. AMS (Aerospace Materials Specifications) related standards: such as AMS 4664 (brass tubes) and AMS 5-1 (ordinary brass tubes), which establish strict requirements regarding chemical composition and manufacturing processes for high-demand industries such as aerospace. VI. Recommendations for standard selection: For heat exchange equipment, prioritize ASTM B111/B111M-24 or EN 12451, as they specify more detailed requirements regarding the corrosion resistance and mechanical properties of the condenser tubes. General industrial use: ASTM B188 or EN 12449 can be referred to, offering a broader range of applications. Aerospace industry: Compliance with AMS standards, such as AMS 4664, is required to meet the reliability demands in extreme environments. Japanese market: JIS H3300 is the main standard, especially for specific brass alloys such as C71500. VII. Precautions Version updates: Standards may be revised periodically (for example, ASTM B111/B111M-24 was updated in 2024), so it is necessary to verify the latest version. Alloy correspondence: Alloy designations under different standards may vary (for example, the equivalent of C70600 in ASTM and EN); it is necessary to refer to ASTM International using the UNS number or by comparing the chemical composition. Testing methods: Some standards refer to external testing methods such as ISO 6957, and these must be applied in accordance with the specific requirements. It is recommended that, in practical applications, the appropriate standards be selected based on project requirements such as industry, region, and environmental conditions, and that compliance verification be carried out through material suppliers or third-party agencies.