Tightening the nut compresses an olive between the fitting body and pipe, forming the seal. The pipe must be clean, round and fully inserted.
Mechanical Pipe Joints for Water and Heating Repairs
Compression fittings make a mechanical seal around a pipe using a nut and olive, so no flame is needed. MacBlair stocks a large selection that includes gate valves, isolation valves and connectors in common plumbing sizes.
Measure the pipe by outside diameter and check the fitting’s service rating. Cut copper plumbing tube square, remove burrs and insert it fully before tightening. Misalignment or an oval pipe end can stop the olive sealing evenly.
Tighten the nut enough to compress the olive, then test. Excess force can distort the fitting or pipe and make a leak more likely. Jointing compound should only be used where the fitting manufacturer permits it, never as a substitute for correct assembly.
Compression joints are useful for accessible repairs and valve connections. Concealed locations may have additional restrictions, so check the installation requirements. The wider plumbing fittings range includes alternatives for the rest of the run.
Compression Fittings FAQ's
The fitting body may be reusable if undamaged, but the olive and sometimes the nut should be replaced. Inspect the pipe where the old olive gripped it.
PTFE tape is not normally wrapped around the olive. Use only the jointing method stated by the fitting manufacturer for that connection.
Tighten it to the manufacturer’s guidance, then pressure-test. Overtightening can crush the olive or distort the pipe, while undertightening can leak.
Only when the fitting and pipe manufacturer allow it, with the correct internal pipe insert. Check compatibility and pressure-temperature ratings.