PLUMBCRATE
How to choose and fit compression olives
Quick answer: choose an olive that matches the pipe's outside diameter (15mm olive for 15mm pipe), use copper olives for most domestic copper work, slide the nut on before the olive, push the pipe fully home, then tighten hand-tight plus about one turn while holding the fitting body still.
What an olive does
An olive is a soft metal ring that sits between the compression nut and the fitting body. As the nut is tightened, the olive is squeezed onto the pipe and into the fitting, making a watertight seal without solder.
Choosing the right olive
- Size: it must match the pipe's outside diameter: 8mm, 10mm, 15mm, 22mm or 28mm are common UK metric sizes. Imperial pipe may need adaptors or specific olives.
- Copper olives: softer, compress easily, the usual choice for copper pipe.
- Brass olives: harder; used where the fitting maker specifies them.
- Plastic pipe: use the pipe maker's metal pipe insert inside the pipe, and follow their guidance on olive type.
Shop compression brass fittings and olives.
How to fit an olive
- Cut the pipe square with a pipe cutter and remove burrs inside and out.
- Slide the nut onto the pipe, threads facing the fitting.
- Slide the olive on after the nut, so it sits square on the pipe.
- Push the pipe fully into the fitting until it stops.
- Bring the nut up and tighten by hand.
- Hold the fitting body with one spanner and turn the nut about one full turn with another. Check for leaks and nip up slightly only if needed.
Common mistakes
- Fitting the olive before the nut (the nut cannot then go on).
- Not pushing the pipe fully home, so the olive seals on a short length and can leak or pull out.
- Over-tightening, which distorts the olive and the pipe.
- Reusing a damaged olive.
Removing an old olive
A compressed olive grips the pipe. Use an olive puller, or cut the pipe back behind it if there is slack. Avoid hacksawing along the olive, which can score the pipe.
Related
See our guide to fixing a leaking compression fitting, isolating valves and tap connectors.