January 2018

How to take care of your o-rings: what to check before pressing

The o-ring on pressfittings is an essential part of the system. In fact, it is an essential part of the hydraulic seal. Before pressing, we must check the integrity of the o-ring, its proper positioning, and make sure there are no foreign bodies in its seat.
The Pressfitting system combines the practicality of a mechanical seal performed with simple pressing equipment and the guarantee of a hydraulic seal provided by the synthetic rubber o-ring.


Pressfitting system for plumbing connections


Checks before the pressing phase

The o-ring is a very important pressfitting element. It requires a quick but fundamental check before proceeding with the joint.
In fact, the highest percentage of system installation errors are due to failure to check the o-ring before the pressing phase.

It may seem preposterous, but one of the biggest errors is the complete lack of an o-ring inside the pressed fitting!
Frequently, there is damage to the o-ring during insertion in the pipe due to burrs.

The presence of construction site debris or metal burs near the o-ring is an "illness" caused by lack of a preliminary check. These "foreign bodies" are deposited between the pipe and the gasket, causing leaks.

Problems due to o-ring damage:

Error description

Image of the defect

Omitted procedures

missing O-ring

missing oring

Failure to check for presence of o-ring.

O-ring torn during insertion of a pipe that was not properly trimmed.

damaged o-ring by a non deburred pipe

Failure to trim pipe or inefficient pipe trimming procedure.

Presence of sand and other construction site debris inside the o-ring chamber.

 dirt in the fitting

Failure to check the cleanliness of the o-ring chamber.

Presence of metal burrs or debris between the o-ring and its seat or between the o-ring and the pipe.

metal debris in the fitting

Failure to check for burrs / cleanliness of pipe and fitting.



The right o-ring for every application

The standard o-ring in the Eurotubi pressfitting is in black EPDM, equipped with the exclusive "LBP" system that makes the fitting drip if not pressed.


O-rings for the pressfitting system - different colors for different applications


The yellow o-rings are in HBNR and are only for Gas applications.
For special and specific applications, green and red FKM o-rings may be used.

The table below summarizes the choice of o-rings for the most common applications.


Compatibility table oring pressfitting

Click on the image to zoom in


Special applications: you can see the list of chemical compatibilities with pressfittings systems in chapter 14 of the Eurotubi Technical Manual.
For other applications, you should consult the Eurotubi Technical Office.


pressfitting and oring - how to deal with compressed air and pressure tests with air

Pressure and compressed air tests

For compressed air applications, the o-ring must be dampened with water before installation so the "micro-passages" are sealed.
This procedure must also be used when testing the system with air or inert gas.

O-ring storage

In order to ensure the longevity of the o-rings, the storage phase is also important. In fact, warehouse conditions must meet certain parameters such as temperature, humidity, and light exposure.

You can learn more about the topic in this previous article:

Questions about o-rings or pressfittings? Contact our Technical Office.

Other news:
1. MCE 2018: Eurotubi Pressfittings in the starting blocks with a major new development
2. Pressfitting for solar thermal systems: stainless steel or carbon steel?
3. How to take care of your o-rings: what to check before pressing
4. Pressfitting school project: free fittings and equipment for a Slovenian plumbing school
5. Reusing wastewater for industrial processes - a green idea thanks also to pressfittings
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