Axial or Push-in Fittings: System Overview and Installation Guidelines

Recommendation points

• Disadvantages of common pipelines
• Features of Slide Fitting Systems
• Assortment of leading manufacturers
• Where to get the tool
• Installation rules

The high cost of modern engineering communications is primarily due to their long service life and ease of installation. Our site councils.RU will tell you about pipelines with axial fittings designed to operate for at least 50 years and considered the most modern type of water supply and heating systems.

Disadvantages of common pipelines

For more than two decades in the Russian market, polypropylene and metal-plastic pipes have been leading in popularity. And this at a time when there are more technically advanced systems that have long been considered an established standard in the West. The reasons for this are simple: production in the CIS is not developed, and the high cost and the resulting low demand for imported products do not allow the development of a full-fledged logistics network, which would solve the problem of high cost.

Nevertheless, even the current level of prices for polyethylene pipes with push-in fittings makes their use fully justified, taking into account all the advantages, the main of which is the operational resource. However, before proceeding to consider the advantages of axial fittings, one should consider the disadvantages inherent in other pipelines, but absent in the system we are considering. This is best done using the example of alternative options:

1. Metal pipes require welding or brazing equipment. Steel pipes are prone to corrosion, resulting in poor water quality and reduced system life, and corrosion-resistant materials such as copper are expensive. In view of the above, metal pipes, among other things, are not intended for concealed installation.

2. When soldering polypropylene pipes, it is impossible to control the quality of the connections, which depends not only on the professionalism of the installer, but also on the properties of the material, which has already been said in other articles on the site. A typical disease of such systems is a decrease in the conditional passage to 30-40% of the nominal.

3. Metal-polymer pipes with threaded press fittings are, in fact, a budget analogue of axial systems, but at the same time have a much shorter service life. In addition, the connections of such pipes cannot be walled up..

Most of the disadvantages of a particular pipeline system are not due to the material of the pipes themselves, but to the type of connections. The above examples are characterized by low manufacturability of installation, due to which it is impossible to guarantee the constant quality of the connections, while the reliability of the entire system is determined by its weakest node..

Features of Slide Fitting Systems

One-piece connections are considered the most reliable today, they are allowed to be used when assembling flush-mounted systems. The closest relative of axial fittings are compression fittings for polyethylene pipes, but they have several differences. Firstly, it is important to maintain proper positioning so that the belts formed during the crimp line up with the annular grooves on the fitting. Secondly, compression fittings are not recommended for joining PE-RT pipes, whereas push fittings are suitable for use with all types of XLPE. The third difference is a fundamentally different installation process: from work with crimp connections, only the procedure for preparing pipes and the need to use a special tool have been preserved.

The rest of the axial systems in terms of their operational characteristics are fully consistent with pipelines on compression fittings. The breaking force of the connection exceeds 1 kN, the pipeline is able to operate under pressure up to 12 bar and withstand short-term surges up to 18–20 bar, the temperature of the transported liquid can reach 100 ° С.

The above is true for materials from most manufacturers that provide an official warranty for their products. There is a series of Chinese counterfeits, which are few in number and are well recognized by the quality of stamping and casting. It makes no sense to use such materials in systems with overpressure or operating at high temperatures, just as it makes no sense to combine expensive quality pipes with second-rate fittings..

Assortment of leading manufacturers

In the plumbing market, you can find push-in axial fitting systems made of brass and plastic. Each option has its own installation features and different requirements for operating conditions.

Metal press fittings were the forefather of modern polymer systems. Brass products are more expensive, but they are more difficult to counterfeit due to the high quality requirements of the alloy, which explains the consistently high reliability. At the same time, high-quality plastic fittings have characteristics that are superior to metal: high resistance to alternating loads and corrosive environments. An example of this is REHAU, which are considered the standard of reliability in the world of plumbing..

Most manufacturers focus on metal fittings, including VALTEC, ProAqua, General Fittings and TECE. Also less expensive in comparison with REHAU systems made of polymeric materials are common – UPONOR and KAN-Term. But you need to remember that products from Europe in Russia are not widespread, which is why there is a great risk of running into a Chinese counterfeit instead of an original high-quality product..

The range of most manufacturers is small: straight connectors, tees, angles, transitions to threaded connections, as well as universal ferrules. As a rule, all elements belong to the pipe system of the 16th or 20th diameter, although the oldest representatives of the market offer materials for systems with any nominal size up to 50 mm. In addition, the benefit from buying branded sanitary ware is also that the manufacturer offers special fittings for connecting heating radiators, manifolds with pressure test connections, brackets for mixers, etc..

Where to get the tool

The use of axial fitting systems is considered the prerogative of professional installation teams. This is because in numerous demonstrations of the material’s capabilities, sets of equipment are also presented that an ordinary craftsman cannot afford and which are inappropriate to purchase for a single use..

However, it is not necessary to use an electrically powered professional tool. There are sets of hand tools that are not capable of providing such a high installation performance, but they are quite suitable for assembling small water and heat supply systems for a house or apartment..

An option for those who want to assemble the system on their own is to rent a set of tools. Such an opportunity exists in any city where a representative office of large pipe and fitting manufacturers operates. There is one trick here: it is better to instruct the manager not only to provide the necessary tools, but also materials, providing a diagram of the pipelines. Thus, if the work is delayed due to a lack of fittings or pipes, you can continue to use the tool for free..

The special tool kit consists of only three items:

• Scissors. Most plastic pipe scissors will work. It is impossible to cut polyethylene pipes with a hacksaw or angle grinder: only pipe scissors form a straight cut without burrs.

• Calibrator. After cutting, the pipe may deform, and its inner diameter is initially smaller than necessary for reliable crimping. To process the end before crimping, a special tool is provided – a calibrator, which expands the nominal bore and leveling the profile to the shape of a perfect circle. If, for some reason, the edge is torn, another special tool is used for chamfering – a rimmer.

The difference in speed between manual and professional tools is evident in the work of the calibrator. The electric drive allows the pipe to be calibrated in a few seconds and in one movement, while manual processing requires more time and additional physical effort.

• Crimper. The arrangement is extremely simple and represents a movable clamp in the form of a fork, which allows you to push the slide sleeve onto the fitting, transmitting the pressing force through a special belt. Like the calibrator, the crimper can be lever or electric, the difference is also expressed in speed and convenience..

If the tool is rented, you need to ensure that by the time the work starts, you have all the plumbing equipment and auxiliary tools prepared for installation. You will need a hammer drill or other equipment for direct fastening, clips, valves, keys and sealant for threaded connections, etc. To reduce the rental time of the tool, by the beginning of the pressure test, all pipes should be laid in thermal insulation, leaving a margin for trimming and processing edges.

Installation rules

Sliding fittings have bypassed all existing analogues in terms of manufacturability of making connections. Convenience of work and consistently high quality of work have become the hallmark of these systems, which is clearly demonstrated by a simple pipeline crimping scheme.

1. Trim the pipe edge flush with the stop flange of the fitting.
2. Throw a sleeve on the pipe, turning it with a flared skirt to the cut.
3. Extend the pipe with a calibrator until the deadbolt enters at the mark of the required diameter. In the case of a power tool, wait until the complete cycle of its operation.
4. Insert the fitting into the extended edge of the pipe until it stops.
5. Pull the crimp sleeve with a crimper.

In terms of speed, the process of making the connection is not inferior even to soldering: although it takes only a few seconds to warm up the joint, after mixing it is necessary to wait some time until the plastic cools down, as a rule it takes about a minute. At the same time, the crimping speed of the axial system is about 35-40 seconds when using hand tools and about 15-20 seconds when working with professional electrical equipment..