How to bend a polypropylene pipe: ways and recommendations
Laying or repairing utilities, the homeowner may be faced with the need to organize the rotation of the pipes. Of course, this can be done with fittings. But many people prefer to bend a polypropylene pipe without the use of additional connecting elements. After all, they are potential places of occurrence, which require constant monitoring and optional costs for their repair or replacement.
There are several ways to bend a polypropylene pipe
A little theory of how to bend a polypropylene pipe
Bending is a technological process, the ultimate goal of which is to change the slope of the geometric axis of the pipe. It is accompanied by the occurrence in the walls of this product elastic and resilient deformations. Compressive stresses occur on the inner side of the bend, and on the outside - stretch.
The bending process causes a change in the shape of the profile. So, the initial annular cross section is transformed into an oval. The greatest ovality is observed in the center of the perished and decreases to its beginning and end. This phenomenon is explained by that, that the central part of the bent pipe has the greatest compressive and tensile stresses. formula, by which you can determine the ovality of the profile as a percentage looks like this:
Q = {(Dmax - Dmin) / Bottom line} * 100.
The parameters present in the formula correspond to the maximum, minimum and nominal outer diameter at the bend.
Bending pipes is a serious process, which requires some knowledge
That the bent element perfectly fit into the pipeline, the workpiece must be of a certain length. The following formula can be used to calculate it:
L = 0,0175 * R *? + L,
where: l is the length of the straight section of the pipe, necessary for its capture,? - bend angle of the pipe in degrees, R is the radius of curvature of the pipe in millimeters.
bending methods
Polypropylene is considered to be quite solid, incapable of bending material. Moreover, most manufacturers do not recommend this procedure over pipes, made on its basis, as they may lose their attractive performance. Therefore, the question may naturally arise, whether it is possible to bend polypropylene pipes? The answer is simple: it is possible. But only with the right approach.
Polypropylene pipes are very solid, therefore it is necessary to bend them accurately
You should know, that the value of the maximum allowable minimum bending radius of polypropylene pipes depends on their outer diameter. You will find this data for the most popular sizes in the table below.
Table 1
| Diameter, millimeters | Bending radius, millimeters |
| 50 | 400 |
| 40 | 320 |
| 32 | 256 |
| 25 | 200 |
| 20 | 160 |
Today, there are several ways to form a bend in such products.
How to bend a polypropylene pipe with a construction blow dryer
You will need it:
- sample, which has the required angle. It must be made of solid material;
- construction hair dryer.
First you need to make a template. It will be needed to fix the pipe in a given position.
Importantly! Particular attention should be paid to the formation of a smooth surface of the template. This will prevent dents from forming, chips or bends. in addition, the surface of the bent pipe will remain smooth.
Then use a pencil or marker to mark the area of the future bend on the pipe. It is recommended to comply with its length to the length of the template.
For, to properly bend the pipe, you will need a ready-made or homemade template
Having done that, set the construction hair dryer so, so that nothing prevents to bring to it a segment of a propylene pipe. For uniform heating it is deformed, gently and gently move a section of pipe along the flow of hot air.
Heating of the pipe should be performed while monitoring its condition. It is necessary to place in a template and to fix there a pipe, when it acquires the ability to bend easily (this will happen at a temperature of about 140 ° C), but will not have time to lose its shape as a result of melting (temperature approx 170 ° C). That the result was not pathetic, you have to fall into this interval. On the template, the pipe will cool and retain the formed angle. After that, you can start installing it.
How to bend a polypropylene pipe with a molding machine
This work is performed in three stages.
- Manufacture from wood-fiber board (Fiberboard) fix it. It will be useful to give the polypropylene pipe the desired shape.
- Creating a silicone shell. A molding machine is required at this stage. Made ??with its help the cover provides at the moment of fixing of a pipe in a frame protection of its surface against potential damages: scratches, dents and chips.
- Bending procedure. Insert the polypropylene pipe into the shell, fasten the product in a frame made of fiberboard, place the structure in the molding machine. Polypropylene will soften under the action of high temperature, will begin to sit on the frame and take the desired shape. The product should be removed after finishing 10 minutes. After removing the tube from the frame, leave it to cool completely.
After removing the pipe from the molding machine, it must be allowed to cool
Keep this in mind when creating a fiberboard frame, that its geometric dimensions must correspond to the length and diameter of the pipe. After, how the dimensions will fit, sand it carefully - smoothness is required for this, so that there are no traces of the use of the frame on the finished pipe.
Flexible polypropylene pipes on high-tech equipment
By this we mean liquids (glycol, glycerin) baths, electric furnaces, as well as gas or steam chambers. They are used to preheat the pipes. Electric furnaces are inferior in performance to vertical liquid glycerin baths.
An air tunnel electric furnace is used to perform local bends on long pipes. Places of passage of the pipe through its end caps must have seals on the outer diameter, and the ends of the pipes are plugged by means of plugs.
Importantly! When heating is carried out in a vertical liquid bath, the workpiece must be immersed as follows, so that its end protrudes above the surface of the liquid by at least two outer diameters.
If the sizes of the heating equipment do not allow to carry out warming up of the bent pipe on all length at once, it is necessary to bend in several receptions. But this process will be more time consuming and complicated, as without skills it is easy to spoil a product.
Flexible pipes with high-tech equipment
The temperature of the liquid should be 165 + 5 ° C. If the heating procedure is carried out in an electric furnace, the air temperature must be maintained at 20-30 ° C is higher than the value of this parameter of the liquid in the bath. Temperature control is performed using thermostats, and if there are none - manually according to the thermometer. It is necessary to carry out warming up evenly on length to bend sites and on wall thickness. Provision, heated to the set temperature, without loss of stability of the form, must be in a highly elastic state.
Importantly! Reheating of an already bent segment is not allowed.
Many household craftsmen have heard of the so-called pipe bender. So they ask questions, how to bend a polypropylene pipe with the help of such units. One of the most common technologies is to roll the heated pipe around the template without the use of filler.. It is used, if it is necessary to create a bending radius, exceeding more than 3,5 times the outer diameter of the workpiece provided, that the value of the ratio of the thickness of its wall to the outer diameter is greater 0,065. Actually, this parameter determines the nomenclature of polypropylene pipes, bending which is allowed without filler.
Different types of pipe benders are used to bend pipes
Basic requirements, put forward by this technology, are formulated as follows:
- the gap between the covering roller and the bending template should be smaller 10 percent of the outer diameter of the pipe is bent;
- the diameter of the covering roller and the streams of the bending template must be equal to the minimum diameter of the workpiece.
Angle control is performed on a circular scale located on the template. To obtain the required value of this parameter, to bend a polypropylene pipe it is necessary taking into account its springing - 10%.
After completing the bending process, the resulting product must be subjected to external inspection. The surface of the bent part must be smooth and even. There may be slight traces of the bending tool. But there should be no dents or cracks.
Importantly! The quality of work performed is determined by the ovality of the profile at the bend. The requirements of regulatory documents in this regard will be met, if the value of this parameter does not exceed eight percent.
Cold flexible polypropylene pipe
This method can also be used. But it must be borne in mind, that here the probability of damaging the pipe increases significantly.
All the above methods of bending polypropylene pipes have proven their viability in practice. But, let's repeat, their implementation requires a careful approach. Only then will the final product be able to operate for a long time.
