In the United States, the state or region you reside dictates the residential and commercial building codes. Advancements in technology and building materials triggered changes in the building codes. The recent changes include permitting copper tube sizing (CTS) piping in residential plumbing solutions.
Summary
Copper pipes & tubes are the most popular throughout the United States, which is why you need a size chart to be sure you get the right one. We’ve included one below to help you out.
In this article, we also look at the following:
- Its uses
- The types
- Connectors
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This red metal has served many advancements in civilization. Several tools for agriculture and handicraft, articles for household items and decoratives, and hunting weapons utilize this metal.
We recognize it in modern technology because there is no other superior material for transporting water. Several years of proven durability that serves its purpose backs it up.
We use it nowadays in several home applications, such as heating, air-conditioning, and plumbing. Copper pipe is available in different sizes, types, and thicknesses. Fittings are available for almost all design applications.
The allowance of these copper water lines will surely interest some people. We are walking you through everything you need to know about CTS tubing.
Copper pipe & tube size chart
The table below is a detailed explanation of its sizes. You can determine the nominal size using the outer diameter (OD). On the other hand, wall thicknesses and inner diameter (ID) vary per type.
For example, a Type K has an internal diameter of 0.305 and a wall thickness of 0.035. A type L has an internal diameter of 0.315 and a wall thickness of 0.030. However, both share the same outer diameter of 0.375 and a nominal size of 1/4.
| Nominal Pipe Size inches | O.D. | K*, I.D. | K, Wall Thickness | L**, I.D. | L, Wall Thickness | M***, I.D. | M, Wall Thickness | DWV****, I.D. | DWV, Wall Thickness |
| 1/4 | 0.375 | 0.305 | 0.035 | 0.315 | 0.03 | – | – | – | – |
| 3/8 | 0.5 | 0.402 | 0.049 | 0.43 | 0.035 | 0.45 | 0.025 | – | – |
| 1/2 | 0.625 | 0.527 | 0.049 | 0.545 | 0.04 | 0.569 | 0.028 | – | – |
| 5/8 | 0.75 | 0.652 | 0.049 | 0.666 | 0.042 | – | – | – | – |
| 3/4 | 0.875 | 0.745 | 0.065 | 0.785 | 0.045 | 0.811 | 0.032 | – | – |
| 1 | 1.125 | 0.995 | 0.065 | 1.025 | 0.05 | 1.055 | 0.035 | – | – |
| 1-1/4 | 1.375 | 1.245 | 0.065 | 1.265 | 0.055 | 1.291 | 0.042 | 1.295 | 0.04 |
| 1-1/2 | 1.625 | 1.481 | 0.072 | 1.505 | 0.06 | 1.527 | 0.049 | 1.541 | 0.042 |
| 2 | 2.125 | 1.959 | 0.083 | 1.985 | 0.07 | 2.009 | 0.058 | 2.041 | 0.042 |
| 2-1/2 | 2.625 | 2.435 | 0.095 | 2.465 | 0.08 | 2.495 | 0.065 | – | – |
| 3 | 3.125 | 2.907 | 0.109 | 2.945 | 0.09 | 2.981 | 0.072 | 3.03 | 0.045 |
| 3.5 | 3.625 | 3.385 | 0.12 | 3.425 | 0.1 | 3.459 | 0.083 | – | – |
| 4 | 4.125 | 3.857 | 0.134 | 3.897 | 0.114 | 3.935 | 0.095 | 4.009 | 0.058 |
| 5 | 5.125 | 4.805 | 0.16 | 4.875 | 0.125 | 4.907 | 0.109 | 4.981 | 0.072 |
| 6 | 6.125 | 5.741 | 0.192 | 5.845 | 0.14 | 5.881 | 0.122 | 5.959 | 0.083 |
| 8 | 8.125 | 7.583 | 0.271 | 7.725 | 0.2 | 7.785 | 0.17 | – | – |
The wall thickness determines the inside diameter, while the nominal size determines the outside diameter of a rigid copper. The OD is always 1/8 inch larger than the nominal size.
What is CTS?
We use copper tube sizing (CTS) in heating, water supply, and HVAC applications. These are available in two types – rigid and soft. Mechanics use a flare connection, solder, compression connection, or pressed connection to join two tubes.
Rigid Type
Water lines are the main application for rigid copper. Mechanics join pipes together using compression, roll grooved, or solder.
These are rigid because of the hardening it goes through during the drawing process. You cannot bend it, so you need to use elbow fittings to go around obstacles. Alternatively, annealing softens it. It allows you to bend or form the material without cracking.
Soft Type
Ductile or soft copper tubing easily bends to go over obstacles in its path. The hardening process makes it rigid, but careful annealing makes it soft again.
As a result, it becomes more expensive than the rigid type. You can join two tubes by roll grooved, solder, or compression. It is the preferred option for heat pumps and split-type air conditioner systems.
What are the connection types?
There are a few ways to connect two tubes. The following are the most common methods of doing it.
Brazing Connection
Brazing is a joining process involving two or more metal items. We join these by melting and pouring a filler metal into the joint. The filler metal should have a lower boiling point so they will not melt together.
Welding is different from brazing because the former involves melting the work pieces. On the other hand, soldering does not require closely fitted parts.
Capillary action allows the filler to flow through the gaps. The filler metal slightly goes over its melting temperature while getting protection from a flux.
It goes through a wetting process before allowing it to cool down. An advantage of brazing is allowing you to join different or the same metals. The filling material should have a melting point above 427 Celcius.
Soldered Connection
Solder fittings slip into the end of the other tube without issues. A mechanic heats the joint using a torch to melt the connection. It forms a strong bond after the cooldown, lasting several decades.
Most modern buildings use a solder connection for their supply lines. Soldering is more cost-effective than flaring, which is more evident in large-scale applications.
We also use the term sweating when referring to soldering. You can interchangeably use these two terms. The filling material should have a melting point below 427 C.
Flare Connection
A flare connection will require an outward spreading of one end of the tubing to a bell shape using a flare tool. We use a flare nut to fit the end onto a male fitting. The flare connection is the most work-intensive type but pays off because of its reliability.
Compression Connection
Compression fittings utilize a thermoplastic ring or a soft metal. It squeezes onto the pipe and into the fitting using a compression nut. The thermoplastic ring or soft metal shapes onto the tube’s surface and creates a sealing effect.
The disadvantage of a compression fitting is its longevity, which has a shorter lifespan than a sweat connection. Its advantage is the easy installation using standard tools. Maintenance is also more frequent with this connection.
Pressed or Crippled Connection
The last type is the crippled connection, which utilizes special copper fittings permanently attached to copper tubing. These already have a sealant inside.
Deforming the fittings takes thousands of pounds-force per sq. inch of pressure. Compressing it pushes the bond against the inner tubing, creating a tight seal.
The following are the advantages of the crippled connection.
- It is long-lasting
- It takes less time than other methods
- The final appearance looks clean
- It does not need open-flame during the installation process
However, the disadvantage is the availability of the parts. It impacts the cost in the long run.
