What Is Soft Copper Pipe (Annealed Copper Tube)?
Soft copper pipe, also known as annealed copper tube, is a copper pipe that has been heated and slowly cooled to increase ductility. This annealing process removes internal stresses from the copper, making the pipe flexible and easy to bend without cracking.
Unlike hard copper pipe (drawn temper), soft copper pipe is supplied in coils, allowing for continuous piping runs with very few joints. This reduces potential leak points and lowers installation labor costs.
Key manufacturing steps for soft copper pipe:
Extrusion of copper billet into a tube
Annealing (heating to 400-650°C, then controlled cooling)
Cleaning and drying
Coiling
Pressure testing and quality inspection
What ASTM Standards Apply to Soft Copper Pipe for HVAC, Gas, and Plumbing?
| ASTM Standard | Application | Typical Grades |
|---|---|---|
| ASTM B280 | Air conditioning and refrigeration systems | C12200 |
| ASTM B88 | Potable water plumbing (Types K, L, M) | C12200 |
| ASTM B819 | Medical gas systems | C12200 |
| EN 12735 | European refrigeration tubing | Cu-DHP |
| IS 2501 | Indian HVAC systems | C12200 |
What Copper Grade Is Used for Soft Copper Pipe (C12200)?
Soft copper pipe is almost always manufactured from C12200 – phosphorus-deoxidized copper. This grade contains 0.015%-0.040% phosphorus, which:
Eliminates hydrogen embrittlement during welding
Provides excellent corrosion resistance
Ensures compatibility with refrigerants (R410A, R32, R134a) and gases
Maintains high thermal conductivity (approx. 385-398 W/m·K)
International equivalents of C12200:
Chinese grade: TP2
European grade: CW024A (Cu-DHP)
Japanese grade: C1220
What Are the Common Sizes of Soft Copper Pipe (in Coils)?
Soft copper pipe is typically supplied in coils of 15m, 30m, or 50m lengths. Below is the standard size range for HVAC and plumbing applications.
| Nominal Size (inch) | Outer Diameter (mm) | Wall Thickness (mm) | Typical Application |
|---|---|---|---|
| 1/4" | 6.35 | 0.76 | Small AC systems, refrigeration |
| 3/8" | 9.52 | 0.81 | Split AC units, gas lines |
| 1/2" | 12.70 | 0.81 | Gas distribution, plumbing |
| 5/8" | 15.88 | 1.02 | Commercial refrigeration |
| 3/4" | 19.05 | 1.07 | Industrial HVAC, main gas lines |
| 7/8" | 22.22 | 1.14 | Large AC systems, chillers |
| 1-1/8" | 28.58 | 1.27 | Industrial refrigeration |
Wall thickness varies by ASTM type (Type K = thickest, Type L = medium, Type M = thinnest). For HVAC applications, Type L is most common.
What Are the Main Applications of Soft Copper Pipe?
HVAC and Refrigeration Systems
Soft copper pipe is the industry standard for connecting indoor and outdoor AC units, refrigerant lines, and heat pumps. Its flexibility allows easy
routing through walls and ceilings.
Gas Distribution (LPG, Natural Gas)
Soft copper pipe is widely used for LPG and natural gas lines in residential and commercial buildings. Fewer joints reduce leakage risk, a critical safety advantage.
Potable Water Plumbing
In confined spaces (e.g., under sinks, behind walls), soft copper pipe allows continuous bending without fittings, reducing potential leak points.
Medical Gas Systems
ASTM B819 soft copper pipe is used for oxygen, nitrous oxide, and medical air in hospitals. The pipe must be cleaned for medical oxygen service.
Marine and Offshore Applications
Soft copper pipe's corrosion resistance to seawater makes it suitable for boat plumbing, cooling systems, and marine HVAC.
Industrial Fluid Transport
Used in refineries, chemical plants, and food processing for transporting non-corrosive fluids and gases.
Soft Copper Pipe vs Hard Copper Pipe
| Feature | Soft Copper Pipe (Annealed) | Hard Copper Pipe (Drawn) |
|---|---|---|
| Flexibility | High – can be bent by hand | Low – requires fittings for direction changes |
| Form supplied | Coils (15-50m) | Straight lengths (3-6m) |
| Number of joints | Fewer (continuous runs) | More (requires elbows and couplings) |
| Leak potential | Lower | Higher |
| Installation speed | Faster | Slower |
| Typical applications | HVAC, gas lines, confined spaces | Visible pipe runs, main water lines |
For long, bending runs (e.g., connecting AC outdoor to indoor unit), specify soft copper pipe. For straight, visible pipe runs, specify hard copper pipe.
FAQ
Q1: What is the difference between soft copper pipe (C12200) and hard copper pipe for HVAC applications?
Soft copper pipe (C12200) is annealed and flexible, supplied in coils, and used for bending connections between AC units. Hard copper pipe is drawn and rigid, supplied in straight lengths, and used for visible main lines. For HVAC refrigerant lines that require bending, specify soft copper pipe C12200.
Q2: What is the ASTM equivalent of soft copper pipe C12200 for air conditioning?
Soft copper pipe C12200 with ASTM B280 is the standard for air conditioning and refrigeration systems. For water plumbing, the same grade under ASTM B88 (Type L or K) is used. Always specify both the grade (C12200) and the ASTM standard when ordering.
Q3: Can soft copper pipe be used for LPG gas lines?
Yes, soft copper pipe C12200 is widely used for LPG and natural gas distribution. Its flexibility allows continuous runs with fewer joints, reducing leakage risk. Confirm local gas codes, as some jurisdictions require specific wall thickness or tin-lined copper for certain gas types.
Q4: What wall thickness (Type K, L, or M) is recommended for soft copper pipe in residential plumbing?
For residential potable water, Type L soft copper pipe (medium wall thickness) is the most common choice. Type K (thickest) is used for underground or high-pressure applications. Type M (thinnest) is used only for low-pressure heating systems. Specify Type L soft copper pipe for standard residential plumbing.
Q5: What is the maximum operating pressure for soft copper pipe C12200 in HVAC systems?
Soft copper pipe ASTM B280 is typically rated for 700-800 psi burst pressure and 300-400 psi working pressure for R410A systems.
Q6: Can soft copper pipe be welded or brazed?
Yes, soft copper pipe C12200 is easily brazed or soldered. Due to its phosphorus content (0.015%-0.040%), it resists hydrogen embrittlement. Use 15% silver brazing rods (BCuP-5) for refrigerant lines. Do not use high-temperature welding without proper purge gas.
Q7: What is the annealing temperature for soft copper pipe, and can it be re-annealed?
Soft copper pipe is annealed at 400-650°C during production. If the pipe work-hardens during bending, it can be re-annealed using a torch (heat to dull red, then quench in water). However, repeated annealing may affect dimensions. For critical applications, replace rather than re-anneal.
Q8: How does soft copper pipe C12200 resist corrosion in marine environments?
C12200 offers good corrosion resistance to seawater and marine atmospheres due to its high copper content (≥99.90%) and phosphorus addition. For prolonged marine submersion, consider additional protection or a cupronickel alloy. Soft copper pipe C12200 is suitable for boat freshwater and HVAC systems.
Q9: What is the typical lead time for a production order of soft copper pipe in custom coil lengths?
Standard lead time for soft copper pipe is 7-15 days for common sizes (1/4" to 7/8") after order confirmation. Custom coil lengths or non-standard diameters may require 15-25 days. Request a written lead time confirmation for your specific order.
Packaging for Soft Copper Pipe
Coils wrapped in waterproof plastic with desiccant bags
Steel-reinforced wooden crates or cardboard boxes with steel straps
Plastic end caps on coil ends (if applicable)
Clear labeling with grade (C12200), standard (ASTM B280), size, length, and heat number
Custom packaging available for OEM orders
Factory Equipment for Soft Copper Pipe
Continuous casting furnaces for copper melting
Extrusion presses for tube forming
Annealing furnaces with precise temperature control (400-650°C range)
Coiling machines for 15m, 30m, and 50m coils
Pressure testing equipment (hydrostatic or pneumatic)
Eddy current testers for flaw detection
Cleanliness testing lab (for refrigeration and medical grades)
CNC cutting and end-finishing machines
