In the past we talked about the dribble of pipe endings that may be obtained through brushing and the use of some utensils. The two techniques already described can be used for pipes of medium or small thickness (0.4 to 3.0 mm), but they cannot be used for thicker or heavier pipes, nor by those who need to do some soldering works or more complex mechanic bevels, perhaps both internal and external, and sometimes also to register the cut ending and/or calibrate the internal part of the pipe.
This article intends to face these manufacturing problems by first introducing the reasons for heavy bevelling of pipes, then discussing the most known systems and the advantages/disadvantages of each system. Afterwards, it will be introduced a new line of ‘static’ machineries, which have satisfactory performances and a practical use, that are more and more widespread in several industrial sectors (some of which are mentioned below).

- Industrial boilers
- Heat exchangers
- Thermochemical plants
- Naval architecture
- Oil piping
- Food sector
- Concrete mixers
- Cereal transportation
- Heavy carpentry
- Heavy pressure oleodynamics
-Elbows and pipes for soldering purposes

Preparation Goal
To prepare a pipe for an orbital soldering is normally the final process of an entire working cycle, and can be run in different ways. The preparation goal is to give the piece an easy soldering, a perfect perpendicularity between the axis and the piece to be soldered, and therefore the correct alignment (in particular for long pipes), and finally to guarantee that the final length of the product meets the project expectations. Furthermore, a pipe that is correctly registered and beveled will acquire a higher aesthetical value and will be easily accepted by the buyer even if it bought yet to solder.
The type of beveled preparation depends on soldering specifics, and it is decided based on the project, according to different norms. Obviously, also the pipe dimensions and materials play an important role; for example the preparation of an inox pre-curved pipe Dia. 25x3 mm to be soldered to TIG may consist only in the registration and an external bevel of 1,5x45°, while a short flange obtained from a hot-rolled pipe Dia. 220x10 mm to be soldered MIG-MAG internally and externally may need, apart from faceting, an external bevel of 30° according to the DIN 2595 norms, and an internal preparation (that has to be specified as well).

Elbow emery machines bevelling
One of the most known and used bevelling systems is the one done with abrasive machineries. They can be electrical or pneumatic and they are suitable to several materials and different sizes, and they are considered rather cheap. On the other hand, however, it is a dirty and dangerous system, because of the sparkles and metallic particles produced with the abrasion. Furthermore, it is quite noisy, it can easily generate fire, the dust produced might be breathed, and it requires a protective equipment that is often uncomfortable for the workers.
Moreover, there are hidden costs and problems that make it less convenient. For example, the cost of the abrasive disks may be high, especially if they are of a good quality suitable to the materials of the pipes to be processed. There may also be a contamination problem: the above mentioned particles might contaminate the internal part of the pipe, and make soldering a difficult task. Because it is a manual manufacture, the end result depends on the ability of the worker that could decrease at the end of the shift, and therefore the geometrical values required might not be satisfied. Furthermore, it is often a long and boring manufacturing process.

Thermal cut and plasma bevelment
This technique can grant acceptable results only in certain kinds of pipe preparations. Like the previous system, also this one is rather cheap as far as machineries and consumer goods, but the accuracy of the cut is influenced by the experience of the worker. A few things have to be taken into account: a patchy cut surface, a certain amount of waste that has to be eliminated, the risk of fire, the need of aspiration and filtration systems for the fumes, etc.
While the thermal cut can be used only on iron pipes, plasma cut can be used also for pipes made in stainless steel and other materials, but never for outlined bevels. These systems cannot execute a faceting and a beveling of the pipe at the same time. The automatic positioning devices improve the accuracy, but cannot solve the other problems mentioned above or the overheating of the material.

Bevelling through boring machine or lathe
Using a conventional machine such as a parallel lathe or a cutter boring machine, an excellent result will be obtained as far as precision and the reiteration of the operation are concerned. It is possible to obtain mould shapes, internal and external bevelments, and preparations for the soldering in a very versatile way, and in an acceptable time.
It is obvious that the machine has to be suitable to the work that has to be done, in particular as far as the dimensions and the outline of the piece. A lathe, for instance, must be of a dimension that is compatible with the work it is supposed to execute. It cannot bevel curved pipes aside from a few exceptions. A cutting boring machine is more suitable for pipes that have big dimensions (but not long ones), or for elbows or curves to be soldered as long as it is provided with a boring bar or an interpolation program and suitable clamps to hold the piece – things which might be rather expensive.
Both these types of machines need specialized workers and enough space for the pipes to be maneuvered, but they are more expensive than the machines described previously as well as the ones that are going to be introduced and analyzed. Furthermore, these conventional machines could often be used for more precise and/or more valuable manufactures.

Beveling through portable mandrills
There are a few types of portable pipe cutters; they can be pneumatic, electric or hydraulic, and can have different sizes: from very small, so that they can be adjusted to very narrow spaces, to very big to operate in pipes that are of a few meters in diameter. Normally each machine is studied for a specific diameter range, and a big machine (for pipes up to 5”) cannot be used for small pipes (such as for a pipe of 1”). They can clamp the piece either from the inside or from the outside, or they can be positioned through lifters or hydraulic hoists.
A rather known type of pipe cutter is based on the principle of the boring bar already described above. The machine is normally moved forward by the worker through a mechanic adjuster. The cut is completed with a full turn of the machine around the pipe, and, by changing the type of cutter, it is possible to obtain a perpendicular cut or a cut with an external bevelment. (Picture 6 from C+F catalogue)
Another machine that is quite known (developed by a Swiss company) is based on the principle of a cutter that spins around the pipe penetrating it, while the pipe is clamped and steady. (See picture 4)
With almost any of the machines described so far it is possible to bevel pipes of different materials, with different preparation angles, thicknesses that can reach up to 10 mm, and with a limited cost, but with a few side effects. Working times are normally long: the portability of the systems does not allow to perform large bevelments, and it takes a few minutes to perform them on each end of the pipe. Moreover, it has to be taken into consideration also the time needed to clamp the piece to the machine that is normally done through an external vise. If the clamping is not accurate, there is the risk of injury of the worker or to break the machine.
Since these machines have to be portable, accessible and easy to maneuver, they are not provided with special safety measures, nor with devices to collect the waste, or with automatic lube systems; it’s easy to figure out the consequences of this. For these reasons, these machines should be used for small amounts of pieces and/or variable sizes, or in case a static machine cannot be used because of the particular geometry of the piece that is to be beveled.

Heavy beveling machines for pipes
If the pipes that need to be beveled have large diameters or thickness, and they are geometrically precise, made in different materials (including the super duplex, hastelloy, stainless steels), and if there is a lack of qualified workers, and short working times, ease in loading and unloading the machine, and safety conditions are required, then the heavy beveling machines are the choice to make. These machines have all the aforementioned features, unlike the machines introduced previously, which had these same features, but never altogether in the same machine.
The heavy beveling machines are provided with a manual or semi-automatic cycle; they can have also an automatic cycle on customer’s request. In the simplest and cheapest version, the clamping and unclamping of the pipe are done through a manual screw system, with prismatic clamps (with a “V” shape that grants the suitability to different pipe sizes) to be used when the thickness of the pipe and the desired bevelment are not bigger than 4-5 mm.

In this case, the advancing of the head that holds the instrument is controlled by a lever operated by a worker, and it has a pre-set mechanic clamp that determines the depth of the bevelment, and grants the reiteration of the operation. On this basic version a lubrication-refrigeration system, a safety carter, and a drawer to collect the waste are available. In the more sophisticated versions, always competitive as far as quality/price is concerned, the clamping and unclamping of the vise are automatic, and they operate the advancing and the return of the head. The clamps are easy to change, and outlined according to the diameter of the pipe, so that it is not damaged if the pipe is not very thick, and they can hold a firm grasp on the pipe also when a large bevelment has to be performed.
In order to reduce the cycle times, the machines can be provided with a fast-pace advancing of the head – the work is performed with a slow speed, and the return of the head in the original position is fast. By changing properly the rotation per minute of the mandrill, it is possible to optimize the cutting speed according to the diameter size, the thickness and the material of the pipe, the manufacture type, and the utensil used; all of this can be performed in the same way it is performed on a conventional machine. It is important to point out – according to the manufacture – that it is possible to use three, four, or even six plaques in rough metal that can be adjustable to the diameter of the piece to manufacture, and which are suitable to perform the external and internal bevelment, the faceting, or more than one operation at the same time on the pipe.
The ledge of the pipe from the vises can be determined by a mechanical clamp, micrometrical regulated, on which it can be installed a sensor that detects the piece and activates automatically the cycle. For repetitive manufactures on different pipe sizes, to change the beveling angle and/or to speed up the presetting of the utensils, it is also possible to change the plaque holders, or to change the head that holds the utensils.
These machines are rather moderate as far as encumbrance is concerned; they are quite small in particular in the mandrill and vies areas, and they are open on the upper part to allow the manufacture of curved pipes, as well as visibility, and the control of the entire working cycle. It also grants an easy access for maintenance and cleaning. They 4 diametrical capacity established when they are projected, but they can be built according to the automation rate chosen by the customer and with a capacity up to 2”-4”-6”-8” etc. They represent the natural enhancement of the portable cutters, improving their efficiency.