Copper tubing is often used for main water lines and refrigerant lines in HVAC systems because of its anti-corrosive properties. The most common types of copper tubing used in residential and commercial construction include Type K, Type L, and Type M. In older homes, you might come across DWV piping (for drain-waste-vent). ACR is sometimes used for air conditioning and with compressed air. There is also medical gas tubing.
Copper Tubing Sizes
The American Society for Testing and Materials has designated standard sizes for copper tubing, with the actual outside diameter always ⅛" larger than the standard size designation. Different types of tubes have different measurements of thickness. Type K tube has thicker walls than Type L tube and Type L walls are thicker than Type M, for any given diameter.
All inside diameters depend on tube size and wall thickness.
The same measurements do not apply to ACR tubing, which uses the actual outside diameter as the size designation.
Soft vs. Hard Copper Tube
Soft copper tubing is more pliable and can be bent by hand, while harder copper tubing is rigid and requires a type of fitting called an “elbow” in order to create a new direction. For this reason, rigid tubing is often used throughout the house, and soft tubing is used where the most flexibility is needed.
The strength and hardness of copper tubing is typically referred to as “temper.” Rigid tubing is considered drawn temper, while softer tubing is referred to as annealed. Both types of tube can be joined with fittings.
How to Bend Copper Tubing
The most common practice for bending pipes is to use a pipe bender. You must match the appropriate size of your tube to the appropriate size of pipe bender. Manual pipe benders are especially popular and probably the most straightforward way to bend most copper pipes, given their relative flexibility. Cut your tube to the appropriate size before bending.
Step 1. Set dial
Move the dial of your manual pipe bender to your desired radius and degree required to make the appropriate bend.
Step 2. Insert pipe
Adjust the arms of the pipe bender so that you are able to insert your pipe.
Step 3. Align
With the reference marks visible, adjust the bender so the center of where you want your bend aligns with the center of the die.
Step 4. Secure
Adjust the arm/latch to secure the pipe in place.
Step 5. Bend
Use the support arm to bend the pipe, according to the dial, then remove your pipe.
Connecting Copper Tubing
There are several different ways to join copper tubes such as soldering, blazing, and electric resistance. Soldered joints with capillary fittings are most common on water lines, while brazing is more popular with refrigerant piping. Electric resistance provides a flameless way to create soldered joints.
Soldered Joints
In this method, solder is heated to a specific temperature to create leak-tight joints by filling gaps between the fitting and the tube with molten solder. The addition of flux enables even spreading.
Brazing
Similar to soldering, this method uses an alloy filler to join pipes and can be done on metals that are dissimilar. Flux is typically still used and the alloy must be brought up to a certain temperature to create the connection.
Flameless
In some cases, using heat may not be an option. Common methods on these occasions include flared joints and roll groove coupling systems. Flared methods require a flared joint, flare nut, and special tools.
More detailed information about copper tube joining methods can be found in the Copper Tube Handbook, developed by the Copper Alliance.
Benefits of Using Copper Tubing
In addition to its anti-corrosive properties, there are a number of other reasons why copper is often used for plumbing and HVAC systems. Here are just a few.
Affordable
Copper is long-lasting and, due to its flexibility, can be more accessible and require fewer tools. It requires less maintenance over time, and also has high mechanical strength, high-temperature resistance, and a lifetime resistance to UV degradation.
Bendable
The bending qualities of copper make it ideal to use in tight ceiling and wall spaces. It also means that fewer elbow fittings are required to make adjustments to paths below the house.
Recyclable
Copper can be reused and recycled without degradation, making it eco-friendly.
Dependable
Copper is manufactured to regulated standards, marked with identification, and acceptable under most plumbing codes.
Copper tubing is standard in many industries and also broadly used for projects that require flexible piping. Bending and connecting piping may require some level of expertise and specific tools, but a general understanding could make your next project go more smoothly.
Product Compliance and Suitability
The product statements contained in this guide are intended for general informational purposes only. Such product statements do not constitute a product recommendation or representation as to the appropriateness, accuracy, completeness, correctness or currentness of the information provided. Information provided in this guide does not replace the use by you of any manufacturer instructions, technical product manual, or other professional resource or adviser available to you. Always read, understand and follow all manufacturer instructions.