What Is a Compression Fitting?
A ring joint is a compression fitting that uses a ring-shaped gasket to connect pipes. It is also called a ring joint. Ring joints are often used to connect low-pressure copper pipes with small pipe sizes.
One of the unique advantages of compression fitting is that the ring makes contact with the pipe end during fastening, ensuring a tight seal. The ring applies pressure evenly to achieve a sealed connection, thus minimizing leakage of fluids and gases. They are also relatively easy to install and remove, making them suitable for maintenance and repair work.
However, it is important to install compression fittings correctly. Manufacturer’s instructions regarding joint assembly procedures and fastening torques must be followed. Improper installation can adversely affect sealing and joint strength.
Uses for Compression Fittings
Compression fittings are used in a variety of applications. The following are examples of compression fitting applications:
1. Compressed Air
Compression fittings are widely used in industrial compressed air systems. Since compressed air is supplied at high pressure, the joints must be pressure-resistant. Ring joints are ideal for compressed air piping and connections because they withstand high pressures and provide a reliable seal.
Compressed air is used to drive or clean instrumentation. Compressed air produced by compressors and other equipment is often distributed to various locations by piping.
2. Infrastructure
Compression fittings are also widely used in infrastructure. They are often used in plumbing projects, such as water supply, drainage systems, and fire equipment. They are easy and quick to install, allowing for efficient construction.
3. Ships
In marine environments and vessels, they are required to operate in salt water and under harsh conditions. Ring type fittings are used in ship pipelines to minimize seawater leakage and corrosion. They also ensure reliability and durability as they withstand the vibrations and upheavals of ships.
Principle of Compression Fittings
In a compression fitting, a metal ring is inserted between the two pipe ends. The ring then deforms during fastening to establish a joint between the pipes. The ring is pressurized by the fastening device to ensure a tight fit with the pipe ends.
The deformation of the metal ring creates a metal-to-metal seal between the pipes. This seal minimizes leakage even under high pressure and high temperatures.
In a compression fitting, even pressure distribution between the pipes is critical. The even compression of the rings improves the strength and sealing of the joint. This pressure distribution is controlled by the fastening device.
The material is mainly brass, with a free-cutting brass rod used for the body, nut, and metal ring, and forging brass rod often used for the elbow and tee body. Some are nickel-plated to improve corrosion resistance.
Types of Compression Fitting
There are various types of compression fittings. Different types of ring joints should be used for different applications. The following are examples of compression fitting types.
1. Double-Ended Compression Fitting
Double-ended compression fittings are products in which metal rings are inserted at both ends of a pipe. The rings deform at both ends to ensure a tight fit with the pipe. This type of ring fitting is typically used in piping systems and is suitable for high pressure and high temperature environments.
2. Single-Ended Threaded Compression Fitting
Single-end threaded ring joints are products with a male thread on one end. It is possible to connect one end to equipment piping, etc. There is a lineup of various bore diameters for the threaded end, which can be selected according to the diameter of the piping to be connected.
3. Elbow Type Compression Fitting
Elbow-type ring joints are special compression fittings used at pipe bends and elbows. This type of ring joint provides excellent sealing against pressure and heat fluctuations at bends.
4. Cheese-Type Compression Fitting
Cheese-type ring joints are compression fittings that allow three branches of piping. It is used when you want to branch the fluid supply.