Big size pressfittings: rules and tips for their correct pressing
Two of the winning features of the pressfitting system are the ease and speed with which the joints are made. Strengths that also apply to size fittings, i.e. diameters from 76.1 mm to 108 mm. For these “big size” diameters the pressing procedure is slightly more demanding, in this article we will talk about some aspects to consider to obtain a perfect pressing.
Pressing Big Size fittings is just as simple and intuitive as pressing smaller diameters. There are, however, some passages where greater attention must be paid, mainly as a result of their greater size, size and weight.
Pressing Big Size fittings: where to pay more attention than smaller diameters
In relation to these “increased” characteristics, we will now present some steps of the pressing operations, concerning all diameters, but which – in big size fittings – must be carried out with greater skill, precisely because of their larger dimensions.
Pipe surface free of dirt and deep marks
To carry out the pressings correctly, the first essential factor is the surface quality of the pipe: we must carefully check that the external surface of the pipe is clean and without deep marks. In the event of any obvious imperfections, in fact, the outside of the tube will have to be prepared – where possible – by removing the mark, as explained in this short episode of our pressfitting video course: How to open tube packages without damaging them and the repair of small marks. Pipes with marks that are too deep in the area where the pressing will take place must be discarded, because they could lead to leaks.
O-ring checks for big size fittings
Checking the presence of the o-ring inside the fitting could be an obvious but essential operation, subsequently, we must check that the o-ring is not damaged and that it is perfectly in its seat. With a larger O-ring seat – such in Big-size fittings – it is easier for the O-ring to move from its correct position.
Maintain the correct insertion depth
As with any pressing operation, it is important to mark the correct insertion depth of the pipe into the fitting with a permanent marker. This operation becomes crucial when pressing fittings with big size diameters, as they make it easier for the pipe to move from the insert position.
In big size, in fact, the insertion of the pipe into the fitting is deliberately looser in order to allow the o-ring (which in big size fittings is of the normal type and not toroidal LBP) to be able to take on the leak before press, function in a natural way, when the fitting has not yet been pressed.
Why the insertion of Big size fittings is looser: differences between pressing fittings according to diameters
Unlike diameters 12 to 35, fittings from diameter 42 to 108 have the pressing approximately to a triangular shape, this also applies to Big Size fittings, i.e. 76.1, 88.9 and 108. Thanks to the triangular-shaped pressing and higher tolerances, the LBP function is naturally performed directly by the “standard” shaped O-rings in Big Size fittings.
We can see how, from diameter 42 to 108, the polygonal pressing profile obtained is different, i.e. approximating to a triangular shape, but still homogeneous.
Weight, dimensions and safety issues
Considering their weight and increased footprint, Big Size pipe and fittings must be handled with special care. A fall could cause an injury to the operator. For the pressing of Big Size fittings, where possible, it is preferable to work in two: one operator will dedicate himself to the pressing, while the other will take care of inserting and maintaining the pipe and fitting in the mounting position.
Checks on pressing chains, cleaning and lubrication
Keeping the pressing equipment in complete efficiency is another essential aspect, if we want our pressings to be carried out in a workmanlike manner.
Chains and adapters are more complicated tools than jaws and must be used and inspected with greater care. In addition, construction sites are often dirty and dusty and, we have to be very careful where we place our equipment. The accumulation of dirt and dust can, in fact, easily lead the chain to work badly and, consequently, to decrease its useful life.
We must get into the habit of always checking the state of cleanliness, the possible presence of foreign bodies and the effective lubrication of the equipment, always carrying out checks and lubrications within a certain number of operations.
Eurotubi Pressfitting video course: use and maintenance of press terminals
The quality and good working condition of the pressing equipment are of fundamental importance, in order to be able to create a state-of-the-art pressfitting system. In this video, we’ll look at the differences between jaws, adapters, and chains. We will also explain how they should be visually checked and the periodic actions to be carried out for maintenance and cleaning. Finally, we will talk about the absolute importance of their periodic inspection at the relevant authorized service centers.
Before pressing the big size fittings, we must check that all the sectors of the chains are able to slide freely on themselves.
At the end of the pressing, it is important to carry out a visual inspection of the work we have just done, checking that the insertion depth has been maintained and verifying the absence of pronounced aesthetic defects, such as the “pinch effect“.
How to avoid the pinch effect when pressing big size fittings
The pinch effect is often caused by worn, unmaintained chains and poorly sliding chain sessions. Failure to check the functionality, state of wear and proper routine maintenance of the press chains can lead to the formation of this defect.
There are two different levels of pinch defect, the first level concerns purely aesthetic defects, due to the “physiological” accumulation of material in a single point of the pressing: a type of defect that in any case does not affect the hydraulic seal in any way.
The second level of “pinch” defect is the one that can seriously compromise the hydraulic tightness of the fitting. This type of defect derives from problems inherent in the pressing chains, specifically when the latter are too old, worn or not properly maintained.
Big Size Pressfittings: An Important Asset for HVAC Systems and Process Fluids
We have seen how, although they are as easy to perform as those of smaller diameter fittings, the pressings of Big Size fittings, given their characteristics, need to maintain a greater level of attention during the preparation and construction phases.
The advent of large diameters in pressfittings has led to the possibility of expanding the type of systems that can be made with this interesting joining methodology, passing from residential and medium-sized commercial building systems, to being able to serve even the most “demanding” – in terms of capacity – industrial plants. A “revolution” in the field of plumbing installations that, day after day, helps installers to build more systems, in less time and with less effort.
A special thanks to the Eurotubi Test Room for their valuable cooperation during the writing of this article.
