Compression fitting
In plumbing
A joint on water pipework made by tightening a nut over a ring called an olive, which squeezes onto the pipe and seals it. It needs no heat, which makes it useful where soldering would bring a fire risk, and it can be taken apart later. Too little tightening leaves it weeping, and too much can distort the olive.
Using Compression fitting in a plumbing system
Updated
A distinction worth remembering
A compression fitting seals through the specified parts working together. Pipe material, dimensions and manufacturer requirements matter, including supports or inserts where required. Tightening harder is not a reliable remedy for an incompatible or damaged joint.
Questions to take further
- Does a joint that looks dry immediately prove the work is finished?
- No. Appropriate testing, inspection and checking the system under its intended conditions are part of the work. Access for maintenance and suitable support matter too.
Sources
- Skills England: plumbing and domestic heating technician — The systems, materials, planning and customer responsibilities in the England occupational standard.
Where Compression fitting fits in the learning path
The Pipework & Jointing section covers these topics:
- Pipe Materials
- Pipe Joints and Fixings
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- Pipe Joints and FixingsPipework & Jointing
- Pipe MaterialsPipework & Jointing
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A small valve on the pipe to a single tap, cistern or appliance, so that one outlet can be turned off without shutting off the whole house. Many are quarter-turn: the slot or lever lines up with the pipe when the valve is open and sits across it when closed. Turning one off and then opening the outlet shows whether it has worked.
Service valve
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Service valve — Isolating valve
A small valve on the pipe to a single tap, cistern or appliance, so that one outlet can be turned off without shutting off the whole house. Many are quarter-turn: the slot or lever lines up with the pipe when the valve is open and sits across it when closed. Turning one off and then opening the outlet shows whether it has worked.
Read the Service valve entryBefore you start: some plumbing work is regulated or notifiable
Some water fittings work needs notice to, and consent from, the water supplier before it starts. Check the rules where you live.
Gas work is for competent workers covered by a Gas Safe registered business in Great Britain. Northern Ireland has separate gas regulations. Do not work on gas pipes or appliances yourself.
In England, installing an unvented hot-water system over 15 litres is notifiable building work: use a competent installer registered with a competent-person scheme, or tell building control before work starts. Leave this work to a suitably skilled person.
Wales, Scotland and Northern Ireland have their own water and building rules; check which apply before work starts. Electrical connections belong with an electrician.
This guide does not qualify you or make you competent, approved or registered for plumbing, gas or unvented work.
A definition is a start. Using it in a real question is where it sticks.