A compression fitting is a type of connector used to join tubes or thin-walled pipes by compressing them together. It provides a reliable, leak-free connection without the need for soldering, flaring, or welding. A compression fitting typically consists of three components:
The Basics of Compression Fittings
Master compression fittings with confidence. Learn how they work, how to install them, and the differences between elbows, tees, and unions.
- Nut: Tightens the assembly
- Body: Main fitting structure
- Ferrule(s): Metal ring(s) that deform to grip the tubing and form a tight seal
How Do Compression Fittings Work?
Users only need to insert the tubing into the fitting and tighten the nut. When the nut is tightened, the ferrule compresses between the nut and the fitting body, creating a leak-proof seal. The benefit of using compression fittings is that it does not require special tubing preparations, allowing for less repair time and ultimately less maintenance costs.
Installation Tips
Make sure your fitting material is compatible with the tubing and fluid/gas type to avoid corrosion or leaks.
Cut tubing squarely and deburr before inserting it into compression fittings.
Insert the tubing fully into the fitting body.
Do not overtighten, as it will deform the ferrule and weaken the seal. Follow the manufacturer's torque recommendations.
Avoid reusing ferrules; they may not reseal properly.
Perform a pressure test after assembling compression fittings to ensure proper installation.
Types of Compression Fittings
Compression fittings are available in a range of sizes and designs. Below are the most common types:
Compression Elbow Fittings
Elbow fittings join two pipes at a 45 or 90-degree angle, changing the direction of flow. Compression elbows are ideal in tight spaces or applications where piping must bend, such as behind walls or in plumbing fixtures like showerheads.
Compression Tee Fittings
Tee fittings have a “T” shape with three connection points: two in-line and one at a 90-degree angle. They can be used for branching off from a main supply line or combining flows from two lines into one.
Compression Union and Coupler Fittings
These straight fittings connect two pieces of tube or pipe in a line. Couplers are typically permanent, while unions allow for disassembly and can be repositioned or moved when required.
Compression Fittings Applications
Compression tube fittings find uses across numerous industries, including:
Plumbing systems
Gas and water lines
Instrumentation
Pneumatic and hydraulic controls
HVAC systems
Medical equipment