What material grade is specified by IS 6912?

The standard specifies DHP (Deoxidized High Phosphorus) grade copper with a minimum of 99.90% Copper and 0.015-0.040% Phosphorus (Table 1).

What are the standard tempers available for these copper tubes?

The standard covers three tempers: Soft annealed (O), Light-drawn (H55), and Hard-drawn (H80) (Clause 5).

Does this standard apply to tubes for plumbing water?

No, this standard is specifically for refrigeration and air-conditioning. Copper tubes for plumbing are covered under IS 12444.

What is the purpose of the Mercurous Nitrate Test?

The Mercurous Nitrate Test (as per IS 2305) is conducted to detect the presence of residual internal stress, which could lead to stress corrosion cracking, especially in hard-drawn or light-drawn tubes (Clause 11.4).

IS 6912

: 1985

Copper Tubes for Refrigeration Purposes - Specification

CurrentFrequently UsedSpecificationBIMMEP · Aluminium and Non-Ferrous Metals

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This standard specifies the requirements for solid drawn (seamless) copper tubes intended for use in refrigeration and air-conditioning systems. It covers the chemical composition, tempers, mechanical properties, dimensions, tolerances, and testing procedures for tubes supplied in straight lengths or coils.

Lays down the requirements for seamless copper tubes specifically intended for refrigeration and air conditioning applications.

Quick Reference Values

Minimum Copper (Cu) Content99.90%

Phosphorus (P) Content Range0.015 to 0.040%

Tensile Strength (Hard-drawn, H80 Temper)275 MPa, Min

Tensile Strength (Annealed, O Temper)205 MPa, Min

Elongation (Annealed, O Temper)40%, Min

Maximum Internal Residue Limit0.038 g/m²

Practical Notes

The internal cleanliness of these tubes is critical to prevent contamination of the refrigerant circuit and potential damage to compressors. Ensure tubes are supplied capped and are handled carefully on-site.

Always specify the correct temper for the application: 'O' (Soft Annealed) for applications requiring significant bending, and 'H80' (Hard-drawn) for straight runs requiring rigidity.

Verify that the material is Deoxidized High Phosphorus (DHP) copper as per Table 1, which is essential for its brazeability and resistance to hydrogen embrittlement.