10.10.2019 Author: VT-METALL
Issues discussed in the material:
- What are the advantages of bending pipes along a radius?
- What happens to the pipe material during this operation?
- What methods exist for bending pipes along a radius?
- What equipment is used for this?
Pipes are widely used in various industrial fields. Before proceeding with the installation work of pipeline systems, it is necessary to perform such a fundamental process as bending the pipe along the radius. Thanks to such processing, the number of required welds is significantly reduced, which has a positive effect on the overall quality of work.
Possible complications during work
The actual bending of such a pipe is the process of giving the element a curved-smooth configuration. This can only be done under pressure, since the part has high strength. To reduce the pressure force required for bending, you can use heating of the bent fragment.
Despite the apparent simplicity of the operation, bending does not always result in elements of the desired configuration. Problems arise quite often. The most common complications include three.
The first is that the inner side of the profile folds in peculiar folds that resemble corrugation. In the correct version, it contracts evenly.
The industry produces many types of profile pipes. They differ in cross-sectional shape, profile height, wall thickness
The second difficulty is the rupture of the outer wall of the profile pipe. During bending it stretches. Sometimes the metal cannot withstand the force and bursts. The third problem is that the pipe, changing its shape, can lose the alignment of the elements.
This means that its fragments in a bent state will lie in different planes. And this is unacceptable. Practice shows that all difficulties occur due to the wrong choice of bending method.
To choose it correctly, you need to take into account the plastic capabilities of the profile pipe. They are determined by the size and shape of the section, as well as the thickness of the walls of the product. Based on these values, you can calculate the minimum possible radius of curvature. Trying to make a round with a smaller radius is strongly discouraged.
To determine the minimum radius, we need the height of the section. It is calculated as follows. The height of the profile is measured, and twice the wall thickness of the product is subtracted from it.
The resulting number will be the desired height, let's denote it h. For pipes with a cross-section in the shape of a rectangle and square, the following rule applies. If the profile height is above 20 mm, the part can withstand bending in a section whose minimum length is hx3.5.
Products with a profile below 20 mm can be bent over a length of hx2.5 or more. This rule applies to all pipes. However, the wall thickness of the part also affects bending limitations.
The thinner it is, the higher the likelihood of a rupture or crushing of the part. Experts strongly do not recommend trying to bend wide products with wall thickness less than 2 mm. In this case, it is optimal to use a welding machine.
When bending a profile pipe, it is very important to perform all actions correctly and carefully, otherwise the part may lose alignment or become wrinkled. This pipe cannot be used
One more thing to be aware of. Pipes made of low-alloy and carbon alloys are very elastic and, after bending, can seem to “spring”, trying to take their previous shape.
This involves additional work with the product, since it will have to be adjusted again according to a pre-made template. Therefore, it is recommended to find out the value of the plastic moment of resistance of a given profile pipe and carry out bending taking this indicator into account. The smaller it is, the less the part will “spring”.
Metal-plastic pipes
Such pipes cope much more effectively with temperature changes, are excellent for hot water supply, heating and are not subject to frost. The pipes consist of two materials; when combined, they provide the products with strength and durability.
The manufacturing method involves a layer of plastic and thin sheets of metal. Despite the ability to withstand high temperatures, pipes are fragile and can be damaged under strong physical stress.
It should be noted that according to their composition, plastic pipes are divided into two main types: polyethylene and polyvinyl chloride.
The former contain various types of polyethylene and can withstand pressure and high temperatures.
The second ones are made of polyvinyl chloride, due to this they are durable and resistant to temperature changes, but are not used for water, since chloride tends to be washed out of pipes and enter the substance, therefore, into the human body.
Features of different profile bending methods
There are two main methods of bending profile pipes: cold and hot. The first assumes that the bending process is carried out without preliminary temperature exposure to the part.
While the second is carried out only with a preheated pipe. It must be admitted that heating the part significantly increases its ductility and facilitates the bending process.
There are no standards strictly regulating the use of cold and hot bending methods for profile products. They are only available for pipes with a round cross-section. According to these standards, hot bending is used for parts whose diameter is 100 mm or more. For rectangular and square pipes, slightly different rules apply.
If you have a one-time job of bending a pipe, you can buy, but it is better to rent a hydraulic pipe bender with a manual drive:
Image gallery
Photo from
Manual hydraulic pipe bender
Replaceable bending segment
Devices for fixing a bent pipe
Bending steel pipes with high force
Plumbers recommend cold bending only all pipes with a profile height of less than 10 mm. Products with a profile height of 40 mm and above are hot bent.
How to bend parts with a profile height from 10 to 40 mm is up to the performer to decide. To avoid mistakes, you can perform a trial bending. In general, if you have a pipe bender, you can use it to bend the pipe without any heat.
If there is no special tool, it is worth performing a trial bending of the profile pipe. To do this, one edge of the part is firmly clamped in a vice. A pipe with a diameter larger than that of the product being bent is put on the other end.
The resulting “shoulder” should be pulled strongly, bending the product. If the part bends, you can use the cold bending method. If not, bending with preheating is used.
Plastic pipes
Currently, the market is flooded with plastic products, and pipes are no exception. But it is worth paying attention that the wear resistance of such metal pipes is much less.
They are unlikely to be suitable for operating hot liquids, and they will not last long in an open space exposed to sunlight. However, they are actively used for sewage and cold water supply.
Subtleties of hot bending
Bending of a fragment of a profile pipe occurs after it is heated. It is advisable to perform the operation in one approach, since repeated heating of the metal is undesirable. A product that has cooled to a light cherry color may rupture.
Therefore, this method is ideal for performing a single corner bend. To bend a profile into a rounded arch, it must be used with caution, since repeated heating in this case is inevitable.
It is good to use sifted and calcined sand as a filler for pipes during hot bending. It is poured inside the part using a funnel
To correctly bend a profile pipe using a hot method, you should use a filler. This will prevent possible crushing of the part. Sand is usually used as a filler.
The best option is medium-grained construction sand. If this is not available, material from a children's sandbox will do. First, you need to clean it of unnecessary impurities.
To do this, sand is sifted through a sieve with cells measuring 2-2.5 mm. This will help you get rid of large pebbles and debris. If during the bending process such an inclusion ends up directly next to the pipe wall, it will form a relief that is completely unnecessary.
Too small grains of sand are also not needed. During the heating process, they can sinter, which is undesirable. Therefore, the sand will have to be sifted again, this time through a fine sieve. Its cell size should be about 0.7 mm. We calcinate the sifted sand.
The filler is ready. Now you can work on the detail. First you need to anneal the pipe in the area where bending will be done. Then you can start making the plugs.
You will need two parts of the same size that will cover both ends of the profile pipe so that the sand in it does not spill out. The plugs are made only from wood; no other material can be used.
Let's decide on the size and shape of the parts. These must be pyramids, each ten times longer than the width of the base. The dimensions of the base itself should be almost twice the size of the hole that will be closed with this plug. The prepared products need to be tried on the pipe.
The profile pipe is closed with wooden plugs. In one of them, recesses must be made to allow the release of gases formed inside the heated part.
If everything is fine, we make a longitudinal groove on each side of one of the plugs. The gas accumulated during heating will escape from the workpiece through these grooves. You can start filling the pipe.
To do this, take a plug without grooves and install it in place. A regular funnel is inserted into the opposite end of the part. If the pipe is long, it is placed at an angle to the ground, if it is short, it is placed perpendicularly.
Sand is poured in small portions through the funnel. After each portion, take a rubber or wooden mallet and thoroughly tap the part from below, helping the sand to be distributed as evenly as possible and compacted. Once a dull sound is heard when tapping along the entire length of the pipe, work must be stopped. This means that the part is completely filled with sand.
The sand-filled workpiece is closed with a second plug. Now you need to chalk out the boundaries of the area that will be heated. Its length must be equal to at least six workpiece diameters.
The part is securely fastened in a clamp or vice. If the pipe is welded, it must be secured so that the seam is outside the bend. If it is inside, the part may burst.
Now you should heat the pipe fragment to a red-cherry color. This can be done with a blowtorch or a gas soldering torch. Important point. The entire area should be heated evenly.
Do not allow individual fragments to overheat. If this does happen, such areas should be cooled. An indicator of a sufficiently heated pipe will be scale bouncing off it.
Experts strongly recommend performing hot bending of a profile pipe in one step. Repeated heating of a part can lead to its rupture
After the workpiece is heated, a piece of pipe with a larger cross-section is put on its end. So that the edge of the part does not reach the future bend a little. After which the pipe is carefully bent to the desired shape.
This must be done in one step with a smooth translational movement in a vertical or horizontal plane. The resulting bend is checked against the template.
The bent pipe must cool, after which it should be compared again with the template and make sure that the given shape is correct. If so, the plugs are knocked out. This is often difficult to do, then you can simply burn out the wooden plugs and pour out the sand.
To ensure a clear bend, without folds or tears, you need to pack sand into the pipe as tightly as possible and heat the part evenly.
Metal pipes
These pipes are widely used in the laying of pipelines, oil pipelines and gas pipelines. Today, there is no stronger and more durable material for large-scale pipeline networks.
Characteristics
Without heating, using the cold plastic deformation method, it is recommended to bend profile pipes with a square side of no more than 80 mm .
Manual bending machine BLACKSMITH M3-G. Photo 220Volt
Pipes with a square side size of up to 30 mm are bent on manual machines. To increase the productivity of machines, group bending of profile pipes stacked next to each other is used. The width of the row depends on the design of the machine and its power.
Adviсe
To make the pipe bend more easily, the bending area must be heated with a hair dryer before work.
Please note that the melting point of polyethylene does not exceed 135 degrees. Heating above this value will lead to irreparable consequences
Many websites recommend checking the temperature using a strip of paper. Charring of the paper indicates that the desired temperature has been reached. But nowhere is it stated that the charring temperature of paper is higher than 150 - 200 degrees. It follows from this that the use of a blowtorch or burner for heating is unacceptable, since the flame temperature is distributed unevenly and exceeds the minimum values several times.
The use of pipe benders allows you to bend pipes with a radius less than permissible, but you must first check the quality on an unnecessary section from one batch. The resulting fold is sawed with a hacksaw and carefully inspected for the presence of delaminations and other defects. If they are absent, you can begin finishing work.
How to bend rebar, sheet metal, etc. without having a special tool
If you have already started a major renovation with your own hands, regardless of where it is carried out: at home or in an apartment, then you need to be prepared for many tests.
Among other things, a number of issues may arise that are very difficult to solve without the proper experience and special equipment. For example, not everyone knows how to bend a sheet of metal, reinforcement, profile, corner, etc. getting a decent result. In this article we will try to answer “inflexible” questions, while making do with a minimum amount of tools.
How to bend a sheet of metal, galvanized sheet, profile
Very often, when installing metal structures, it is necessary not only to cut steel sheets, but also to give them a curved shape.
This can be done at home without spending money on third party services. For example, how to bend a sheet of metal? To do this we need a wooden or rubber hammer, pliers, and a table.
If a 90-degree bend is expected, then this set of tools should be sufficient. The sheet is simply hung over the edge of the table, after which the desired curvature is achieved by uniform tapping in the bending area.
Brands, brands, manufacturers
From the rich variety of foreign and Russian manufacturers, the following companies can be distinguished, based on customer reviews:
- Manual pipe benders:"Stalex" (the main production is in Europe), "Smart&sol >
- Electromechanical pipe benders: “Blacksmith” (a popular Chinese manufacturer of equipment for cold forging in Russia).
Hydraulic pipe bender Stalex HB-60 Premium. Photo VseInstruments.ru
How to bend a sheet of metal evenly
If the workpiece is relatively small, then you can use a vice, in which, using two gripping bars, you can firmly secure a sheet of metal, and only after that bend it with a hammer. If necessary, the bend can be heated with a gas burner, but this method is not applicable to galvanized products!
Bend a sheet of metal
If we are talking about a thin metal sheet, then the bending procedure can be significantly simplified.
To do this, the metal is “scratched” at the bend (we use a rule or a metal ruler, and a pointed piece of a hacksaw blade for metal as a cutter). The metal, cut to half its thickness, subsequently easily bends along the outlined line. We can say that we have almost figured out how to bend a sheet of metal.
We bend galvanized steel
How to bend galvanized steel?
This can be either a galvanized metal sheet or a finished product, for example, a profile. The sheet is bent in the same way as when bending any other metal sheet. How to bend a profile? You'll have to tinker with him. To obtain a large radius of curvature of a square or rectangular profile, you can use the following method: tightly fill the profile with fine sand, plug both holes with wooden stakes, and only then bend it by gently tapping it with a mallet.
To bend a U-shaped profile (this, in principle, also applies to obtaining sheets of curved shape), it is necessary to additionally use a form object, the curvature of which corresponds to the finishing part. To facilitate the bending process, triangular elements can be cut out in the profile.
Then the bent product is “wrapped” around the object by uniform tapping with a hammer.
Important! In order for the bend to be as even and correct as possible, the hammer blows should be light and fall as close to each other as possible. How to bend galvanized sheet easier? Using a grinder, we make one or two cuts in the bend area (thereby temporarily weakening the structure), bend the product, and then weld the bend.
This approach is important to use when bending profiled pipes and products of complex metal shapes. We remember that you cannot heat galvanized steel to simplify bending!
Perhaps one of the most difficult tasks faces people who are thinking about how to bend a corner. To get a solid product, you will have to sweat, evenly and slowly tapping the surface of the corner, gradually bending it.
It is recommended to use a gas burner, which can be used to heat the bend. You can do it easier - use a grinder as in the case described above with a galvanized product. It’s even easier to buy an already curved product, then the question “how to bend a corner” will disappear by itself.
How to bend reinforcement
At home, it is quite possible to bend the reinforcement, however, a lot depends on your physical characteristics and the diameter of the metal rod.
How to bend reinforcement? To do this, we need two pieces of steel pipes, the diameter of which is greater than the diameter of the bent rod. The longer the length of such pipes, the easier it will be to bend the reinforcement (gain in strength due to leverage). All you need to do in order to bend the reinforcement is to insert it into two pipes and, securing one of the pipes (pressing it with your foot or resting it between the pillars), using the second as a lever to give the reinforcement the desired curvature.
That's all!
Adviсe
About the intricacies of the hot method
To successfully bend a pipe using a hot method, you should use sand filler. The ideal option is medium-grained sand - construction or river. If it is not possible to use just this one, as a last resort, material from a children's sandbox, but previously cleared of unnecessary contents, will do. To remove unnecessary impurities, it must be sifted through a sieve with holes of about 2 millimeters. After the first sifting, large elements - twigs and stones - will remain on the sieve. Their presence in the filler is extremely undesirable, because when heated they can affect the relief and form bulges. Next, you need to sift the future filler a second time, this time through a fine sieve to get rid of too fine sand. After sifting, the sand is calcined.
The pipe, at the place where bending will occur, is annealed. Before adding the filler, you should take care of the plugs that will prevent it from spilling out. It is recommended to make them from wood so that they fit tightly to the walls. It is necessary to make grooves in one of the plugs through which hot air will escape. Such holes are located on each side, that is, with a square section there should be four of them. After installing the plug without holes through the funnel, you can begin filling the filler. In this case, you should periodically tap the part to compact the sand. After securing the second plug, you can mark the bend location, secure the part and produce uniform heating. If the part is welded, then the seam should be located outside the bend to avoid its divergence. The color of the part ready for bending should be red-cherry, and scale should fly off the pipe.
About the intricacies of the cold method
Subtleties of the cold method:
- Without the use of special tools and heating in the cold season, the bending process can be significantly simplified. For this, as an alternative to the sand method, water is used as a filler. After filling and installing the plugs, the product is exposed to frost for the time necessary for the liquid to completely freeze. In light of the physical properties of frozen water, bending will be easier to implement.
- To avoid hand injuries and to reduce the applied effort, it is proposed to use a profile pipe with a cross-section slightly larger than the bendable one. To do this, the larger profile is placed over the edges of the smaller one, thus increasing the leverage of force.
- Craftsmen advise doing a test bend on an unnecessary part of the product; this will give an idea of its physical properties and prevent mistakes in subsequent attempts.
Summarizing the above, we can draw conclusions about how effective this or that method will be. To obtain better results and save time, it is more advisable to turn to professionals who have equipment specially designed for these purposes. If the work involves multiple bending of products, then why not think about purchasing special equipment, and perhaps also providing bending services to other people. In this case, you can quickly pay for the device.
To learn how to bend a pipe without a pipe bender for a canopy, see the following video.
Aluminum pipes
Despite the fact that this material is very flexible and easily deformable, it can only be used in industries or for the manufacture of structures.
Aluminum is capable of releasing harmful substances into the environment, so it is absolutely not suitable for pipelines.
Pipe benders for profile and round products
Pipe benders for steel and copper pipes are:
- manual,
- mechanical.
Moreover, whether it is a manual or mechanical type determines both the design features of the pipe bender and its performance.
Manual devices
The manual pipe bender consists of:
- beds,
- conveyor,
- clamping element.
The pipe is inserted into a conveyor consisting of rollers connected by a chain transmission, and is pressed by the upper (or lower) roller, which presses on the corresponding edge of the product. By rotating the handle of the feed rollers, you can move a measuring length through the pressure zone, and as a result, bend a profile pipe or a similar round-shaped product.
However, the manual process has its own nuances. Firstly, it is still possible to bend a profile pipe with your own hands, but to achieve the result you need to apply significant effort. Secondly, manual pipe benders are suitable for processing only small batches of products.
Mechanical apparatus
The mechanical apparatus saves us from the need to waste our energy bending the profile pipe to the desired radius. After all, in a mechanical pipe bender, both the conveyor and the clamping element operate not from the muscular strength of the operator, but from an electric motor and a hydraulic drive.
In this case, the operation scheme of the device remains unchanged. That is, as in the first case, we fill the conveyor with a pipe, create a pressing force on the plane of the product being bent (where the profile pipe must be bent even before the measuring segment begins to move along the conveyor) and turn on the device in the network. As a result, the pipe passes the pressure roller zone and changes its curvature. The process of manual and mechanical bending will be discussed in more detail below.
Buying or making forged decor
Decorative elements of cold forging from profile pipes for fences, gates and gates can be made independently or purchased from a large supplier. It will usually cost less to buy if you want to make one set for your home garden.
For these purposes, you do not need to buy equipment for cold forming, but only a welding machine and an angle grinder. All decorative elements are available for sale, so any fence can be made not only based on budget requirements, but also according to your own or selected sketch.
