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IS 6912:1985 is the Indian Standard (BIS) for copper tubes for refrigeration purposes - specification. 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.
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
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.
Consolidated list per BIS. For the text of each amendment, refer to the BIS portal link above.
coppercopper tubesseamless tubesrefrigerant lines
International Equivalents
Similar International Standards
ASTM B280-20ASTM International, USA
HighCurrent
Standard Specification for Seamless Copper Tube for Air Conditioning and Refrigeration Field Service
Specifies requirements for seamless copper tube (UNS C12200) for air conditioning and refrigeration, including cleanliness.
EN 12735-1:2020CEN (European Committee for Standardization), Europe
HighCurrent
Copper and copper alloys — Seamless, round tubes for air conditioning and refrigeration — Part 1: Tubes for piping systems
Specifies requirements for seamless copper tubes for air conditioning and refrigeration piping systems, focusing on material, temper, and cleanliness.
JIS H 3300:2022JSA (Japanese Standards Association), Japan
MediumCurrent
Copper and copper alloy seamless pipes and tubes
Covers the material grade (C1220) and dimensions but is a general standard not specific to refrigeration cleanliness requirements.
BS 2871-2:1972BSI (British Standards Institution), UK
MediumWithdrawn
Specification for copper and copper alloys. Tubes. Part 2: Tubes for general purposes
Specified the C106 material (DHP copper) but was a general-purpose standard, now superseded by more specific European norms.
Key Differences
≠The internal cleanliness requirement in IS 6912 (max 0.038 g/m² residue) is identical to ASTM B280, but significantly less strict than the modern EN 12735-1 standard (max 0.020 g/m² residue).
≠IS 6912:1985 is significantly older than its current international counterparts (e.g., ASTM B280-20, EN 12735-1:2020), and may not address compatibility with newer refrigerants or modern manufacturing controls.
≠Temper designations vary. IS 6912 uses 'Annealed (O)' and 'Light-Drawn (H55)', whereas ASTM B280 uses 'O60' (annealed coils) and EN 12735-1 uses 'R220' (annealed).
≠While IS 6912 specifies dimensional tolerances, modern standards like EN 12735-1 have more detailed specifications and tighter tolerances for parameters like wall thickness eccentricity.
Key Similarities
≈All standards (IS 6912, ASTM B280, EN 12735-1) mandate the use of Deoxidized High-Phosphorus (DHP) copper, equivalent to UNS C12200 or CW024A, for its excellent formability and brazing characteristics.
≈The requirement for tubes to be of seamless construction is a fundamental similarity, ensuring high pressure integrity and preventing leaks common in welded tubes.
≈All key refrigeration-specific standards (IS 6912, ASTM B280, EN 12735-1) require the tube ends to be capped or plugged after cleaning to maintain internal cleanliness during shipping and storage.
≈The provision of a soft annealed temper is common across all standards to allow for easy on-site bending and flaring without cracking.
≈The drift expansion test requirement, a key measure of ductility, is highly similar. Both IS 6912 and ASTM B280 require the tube to withstand a 40% expansion of the outside diameter without cracking.
Parameter Comparison
Parameter
IS Value
International
Source
Material Grade
DHP Copper
UNS C12200
ASTM B280
Phosphorus Content (P %)
0.015 - 0.040
0.015 - 0.040
ASTM B280
Copper + Silver Content (min %)
99.90
99.9
ASTM B280
Internal Cleanliness (Max Residue)
0.038 g/m²
0.038 g/m² (converted from 0.0035 g/ft²)
ASTM B280-20
Internal Cleanliness (Max Residue)
0.038 g/m²
0.020 g/m² (converted from 0.20 mg/dm²)
EN 12735-1:2020
Tensile Strength (Annealed)
205 - 294 MPa (21-30 kgf/mm²)
≥ 205 MPa (30 ksi)
ASTM B280-20
Elongation (Annealed)
≥ 40%
≥ 40%
ASTM B280-20
Drift Expansion Test
40% of OD
40% of OD
ASTM B280-20
⚠ Verify details from original standards before use
Key Values6
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
Tables & Referenced Sections
Key Tables
Table 1 - Chemical Composition
Table 2 - Mechanical Properties of Copper Tubes
Table 3 - Preferred Outside Diameters and Thicknesses of Copper Tubes in Straight Lengths
Table 4 - Preferred Outside Diameters and Thicknesses of Copper Tubes in Coils
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).