Press-fit pipework is designed to make installation faster and more straightforward. But getting a reliable connection isn't just about having the right fitting and a pressing machine. You also need the correct pressing jaws or chains for the pipe diameter and fitting system.
Using the wrong pressing terminal can affect the quality of the connection, even if the tool appears to complete the pressing cycle.
So, what's the difference between pressing jaws and chains, and when should each be used?
What Is the Difference Between Pressing Jaws and Chains?
Pressing jaws and chains are the components fitted to a compatible pressing tool to form the mechanical connection between the pipe and fitting.
Both are designed to apply the force required to deform the fitting in a controlled way. The resulting connection provides mechanical retention and compresses the seal to create a tight joint.
However, jaws and chains have different designs and are not automatically interchangeable.
Pressing Jaws
Pressing jaws generally consist of two main sections that close around the fitting. For compatible Europress configurations, they create a defined pressing profile and are typically used for smaller pipe diameters.
Jaws are generally compact and convenient to handle, making them practical for installations where access is restricted or there are many smaller connections to complete.
The important point is that the jaw must match the required pressing profile, fitting size and approved tool configuration.
Pressing Chains
Pressing chains use multiple articulated segments that wrap around the fitting. They are generally used for larger pipe diameters where the specified pressing system requires them.
The chain surrounds the fitting and applies the pressing force across the required profile. A compatible adapter and pressing machine may also be necessary.
Chains are not simply larger versions of jaws. Their design and the way they apply force differ, which is why the manufacturer's requirements for each pipe diameter must be followed.
Why Pipe Diameter Matters
One of the most common questions when selecting press-fit equipment concerns the larger diameters, particularly 42 mm and 54 mm.
Depending on the press-fit system, both jaws and chains may be available commercially for these sizes. That doesn't mean both options are approved for every fitting.
Europress i's technical guidance for its press-fit system identifies chains as the required pressing terminals for 42 mm and 54 mm fittings. Its testing found that chains provided a higher pull-out resistance at these sizes, despite both methods meeting the stated pressure test requirements.
The guidance also highlights the importance of keeping pressing equipment clean and properly maintained. Dirt, construction debris and wear on the contact surfaces can interfere with the pressing operation.
The practical takeaway is simple: don't choose a pressing terminal based on diameter alone or because it fits the machine. Check the requirements for the specific Europress system and fitting size.
Always refer to the current technical guide to confirm the approved equipment for your application.
Can You Use Jaws Instead of Chains?
Not unless the specific press-fit system and fitting configuration permit it.
A pressing terminal might physically fit around a fitting and appear to complete the cycle, but that doesn't establish that the connection has been made correctly or that the tool combination is approved.
The pressing profile must match the fitting. The equipment must also apply the correct force and form the connection as intended.
For Europress' specified 42 mm and 54 mm fittings, chains are required. Substituting jaws for these sizes is not an acceptable alternative under the manufacturer's stated requirements.
Using an unapproved combination may compromise the connection and affect the manufacturer's warranty or acceptance of a claim.
Before starting work, confirm:
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The pipe diameter and fitting series.
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The required pressing profile.
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Whether jaws or chains are specified.
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The compatible pressing machine and any required adapter.
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The manufacturer's current installation and maintenance instructions.
This is particularly important when equipment from different manufacturers is being used on the same project.
Why Equipment Condition Matters
Even the correct pressing terminal can produce an unreliable result if it is dirty, damaged or worn.
Pressing jaws and chains operate under significant mechanical loads. Over time, contact surfaces, pins and moving parts can wear, affecting how accurately the tool forms the connection.
Construction sites also expose equipment to dust, metal particles and other debris. Contamination in the pressing profile or between moving components can interfere with correct operation.
Before use, inspect the pressing equipment for visible damage, dirt and signs of wear. Clean it according to the manufacturer's instructions, and don't use equipment that is damaged or outside its required inspection interval.
Routine cleaning is important, but it doesn't replace scheduled servicing.
Follow the pressing tool manufacturer's requirements for lubrication, inspection and maintenance. Where periodic inspection or certification is specified, keep the relevant records up to date.
Get the Pressing Process Right
Selecting the correct jaws or chains is only one part of producing a reliable press-fit connection.
The complete installation process matters, from pipe preparation through to final inspection and testing.
Before pressing a joint:
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Prepare the pipe. Cut it to the required length and remove burrs and debris in accordance with the installation instructions.
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Check the fitting. Confirm the correct fitting, seal and pipe combination for the intended application.
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Mark the insertion depth. Ensure the pipe is inserted fully to the required depth.
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Select the correct pressing terminal. Use the approved jaw or chain, profile, adapter and pressing machine for the fitting size.
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Position the tool correctly. Make sure the terminal is seated in the designated pressing area.
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Complete the pressing cycle. Follow the equipment manufacturer's instructions and do not interrupt or repeat the cycle unless the system instructions specifically permit the action.
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Inspect and test. Check the completed installation and carry out the required testing before commissioning.
Never assume that a joint is acceptable simply because the pressing machine has completed its cycle. Correct equipment selection, installation practice and the prescribed testing procedure all play a role.
Avoid Problems Before They Reach Commissioning
A pressing terminal is a small part of the overall pipework system, but selecting the wrong one can have consequences well beyond the individual joint.
A connection that doesn't meet the system requirements may need to be removed and replaced. If the problem is discovered late, after insulation or other building work has been completed, the repair can involve additional labour and delays.
Checking the correct tooling before installation starts is a straightforward way to reduce avoidable problems.
For contractors working across different pipe diameters or using multiple press-fit systems, it is worth making approved tooling part of the project preparation process. Confirm the equipment requirements before work begins, rather than discovering a compatibility issue on site.
Choosing the Right Pressing Equipment for Europress
Europress press-fit systems rely on compatible fittings, pressing terminals and tools to produce the intended connection.
The correct combination depends on the fitting series, pipe diameter and applicable technical requirements. Jaws and chains should never be treated as interchangeable simply because they appear to fit.
Before installing a Europress system, consult the relevant technical documentation and confirm the approved pressing equipment for the specific application.
Need to check the tooling requirements for your next project? Refer to the Europress technical documentation or contact the Europress team for guidance on selecting the appropriate components for your system.
