Push-fit systems · Basics

How a push-fit joint works

A push-fit joint has no pressing, no soldered seam and no thread – and still stays permanently tight. That works with five building blocks that belong together: a cleanly prepared pipe end, O-rings that seal, pull-out protection that holds the pipe, a visible insertion depth as a check – and the leak test before wall or floor is closed. This page explains each building block and shows why preparing the pipe end is the whole trick.

1. The prepared pipe end

Everything starts with the cut: square, with the pipe shears or the pipe cutter – not with a saw, not at an angle, not crushed. Then the pipe end is chamfered: a bevelled edge all round ensures that the pipe glides over the O-rings on insertion instead of cutting into them. In the same operation the pipe is calibrated, that is, made round again – the shears press every pipe slightly oval when cutting, and an out-of-round pipe does not seal around the whole circumference. In the GF iFIT system one tool does both in one to two turns; the chamfer must be at least 1 mm (manufacturer information).

2. The sealing element

Sealing is done by elastomer O-rings that sit in place from the factory – in iFIT, two of them in the adapter. From the factory means: nobody has to insert, grease or align a sealing ring on site, and nobody can forget it. The O-rings seal on the smooth pipe surface – that is why the chamfer is so important, and why scratches and chips must be removed before pushing.

3. The pull-out protection

Water pressure pushes joints apart – a little with every pressure surge. A push-fit joint therefore needs an element that holds the pipe mechanically: a grip ring (also called a gripping collet), whose teeth bed into the pipe surface and bite under pull. In iFIT the grip ring sits in the adapter that is pushed onto the pipe; the module clicks audibly onto the adapter. That a freshly pushed joint gives a few millimetres under pull before it holds is normal with this principle – for iFIT, GF allows up to 5 mm.

4. The visible insertion depth

The most common source of error when pushing is a pipe not pushed in far enough: it looks connected but sits only on the first O-ring. Modern systems therefore make the insertion depth visible – in iFIT through an inspection window in the adapter, which must be completely filled by the pipe, in other systems through a mark drawn on the pipe before pushing. In a push-fit system this visual check replaces the press contour: every joint shows whether it is complete.

5. The leak test

Before wall, duct or screed is closed, the pipe is filled, vented and tested for leaks – with test values as specified by the planner; the result belongs in the test report. That applies equally to every joining method; in a push-fit system it is at the same time the final check that every module has engaged. That the pipe moves back a few millimetres during the pressure test is normal according to GF.

The lessons from the early days of push-fit systems

Push-fit joints had failures in their early days, and their causes are well understood: a pipe end that is not chamfered cuts into the O-ring on insertion; a pipe that is not calibrated is out of round and does not seal all round; too shallow an insertion depth lets the pipe move under pressure surges; pipes with too wide a tolerance sit loose; fittings without pull-out protection do not hold tensile forces. Each of these causes has been answered by design in today’s systems: chamfering and calibrating are mandatory steps with the system tool, the sealing rings sit in place from the factory, the grip ring holds against pull, the insertion depth is visible, and the system is always approved for pipe and fitting together. What remains is the care at the pipe end: whoever chamfers, calibrates, pushes up to the stop and does the visual check gets a joint that is tested by the same rules as a press joint. Whoever skips a step has the same source of error as in the past.

On video

GF shows the principle and the installation at a glance – the video loads only after a click.

iFIT System – GF Piping Systems – English · Video: GF Piping Systems (YouTube). The video loads only after your click – your browser then connects to YouTube (Google).

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Technical basis: GF practice guide for installation and repair instructions (08/2026), GF iFIT installation instructions 762 100 469 (09/2020), GF iFIT brochure gfps-39052 (12/2023) – authorised-dealer material, use approved. Information without guarantee – the binding approval remains with the manufacturer.