This is the simplest and most common type of compression fitting. Typically short in length, couplers are used to create a straightforward connection between two lengths of tube or pipe in a straight line.

Compression elbow fittings are angled connectors used to change the direction of pipework, most commonly by 45° or 90°. They are designed to join two pipes at an angle, allowing installers to create corners and reroute pipework within plumbing and HVAC systems. 

Tee compression fittings are three-way pipe connectors shaped like the letter “T” that join pipes mechanically without the need for heat or soldering. They allow a single pipeline to be split into two separate directions, or alternatively combine two flows into one, making them highly versatile for both domestic and commercial plumbing systems.

Compression male and female adaptor fittings are used to join pipework to threaded components such as valves, taps or other fittings without the need for soldering. The compression end uses a nut and compression ring to grip and seal around the pipe, while the male or female threaded end connects to corresponding threaded components. These adaptors provide a reliable, watertight connection and are commonly used in water supply systems, heating installations and irrigation applications. 

Compression end cap fittings, also known as stop-ends, are used to create a watertight mechanical seal on the open end of a pipe, either permanently or temporarily.

Compression fittings can be installed using basic hand tools, typically just an adjustable wrench or spanner to tighten the nut. This helps save both installation time and labour costs, as no soldering, welding or specialist hot-work equipment is required.

Compression fittings are suitable for use with a wide range of pipe and tube materials, including copper, brass, steel, stainless steel and plastic. This versatility makes them suitable for domestic applications.

When installed correctly, high-quality compression fittings can provide a service life of between 20 and 50 years. They are widely used in plumbing, HVAC and gas applications due to their resistance to pressure, temperature fluctuations and corrosion. 

As compression fittings can be installed safely in damp, confined or sensitive environments where the use of naked flames is prohibited, they can help to reduce labour costs and avoid the additional expense associated with hot works permits. 

Although compression fittings can bring benefits to pipework systems, they need to be carefully installed or complications can result. 

The compression nut needs to be turned just enough to compress the olive around the pipe and create a good seal. If the nut is over-tightened, the wall of the pipe can be crushed or the olive distorted. This will result in a joint that will continually weep. 

In the UK, compression fittings should not be installed in inaccessible or concealed locations where they cannot be readily inspected, maintained or, if necessary, tightened. This includes positions such as beneath floorboards, within closed wall cavities or behind permanent fixtures where access cannot be provided. 

The requirements are particularly stringent for gas pipework. Under the details within the IGEM/UP series and BS 68911, compression fittings should not be used in locations that are inaccessible for future inspection and maintenance. Pipe joints should either remain accessible throughout the life of the installation or be formed using permanent jointing methods where concealed installations are unavoidable. 

Correctly installing compression fittings to achieve a secure, reliable and leak-free joint requires appropriate knowledge, training and practical experience. Following the manufacturer's installation instructions is essential to ensure that the fitting is assembled correctly and tightened to the specified torque without over- or under-tightening. 

Where clear installation guidance is unavailable or not readily accessible on site, the likelihood of incorrect installation increases. Poorly assembled joints may not perform as intended, potentially leading to leaks, reduced system reliability or premature joint failure. Providing installers with clear, readily available installation instructions and ensuring they are familiar with the correct installation procedures helps minimise these risks and contributes to the long-term integrity of the pipework system.

Compression fittings are manufactured to suit precise outside pipe diameters. Pipes that are undersized may not seal correctly, while oversized pipes may not fit properly within the fitting body. If the wall thickness of the pipe is too thin, tightening the compression nut can deform or collapse the pipe. Different types of pipe material, such as MLCP, may be better suited to a different type of fitting, such as a press fitting. The manufacturer should be contacted if there is any doubt about the best way to join pipes of a particular material together.

Jointing compound should not be applied unless specified by the manufacturer. Incorrect installation could cause a failure and invalidate any warranty and claims that may result from failed connections where sealant was used. 

If used it should be applied to the olive and not to the threads to ensure effective performance. A small amount is sufficient as excessive compound can be forced into the pipework or interfere with the metal-to-metal sealing surfaces, potentially compromising the integrity of the joint. This adds an extra dimension of human error when sealant is used with compression fittings.