common mistakes when installing flexible springs
Why Does the Pipe Bend and Not the Spring? Analysis of Common Technical Mistakes
In practice, installers who specialize in professional installation of heating systems often encounter a situation that appears to be a simple operation – bending copper or plastic pipes. On paper, it looks like a matter of strength and the right tools. In reality, it is a precise technical task, where a small deviation in the procedure can lead to devaluation of the entire piping system, damage to walls, and subsequent costly repairs. Bending springs are indispensable in this area, yet it is precisely in their use that the most common mistakes occur, which experienced technicians recognize only after the first unsuccessful attempt.
The goal of this article is not only to list errors but to thoroughly explain the physical principles behind why they occur and to offer proven solutions directly from the installers' workshop. We will examine typical scenarios, from the incorrect selection of the spring to the technique of its application and removal, so that you can avoid unnecessary complications on jobs.
Incorrect Ratio of Diameter and Thickness of the Spring
The most fundamental and at the same time most common mistake is the selection of a bending spring without careful consideration of the pipe dimensions. Many installers assume that "a spring is a spring" and that it is sufficient if it fits into the pipe. This is, however, a fatal misconception. If you choose a spring that is too thin in relation to the internal diameter of the pipe, it will not be able to provide sufficient support against the collapse (buckling) of the pipe wall at the bend. Conversely, if the spring is too thick, it will not be able to pass through the curve or will jam already during insertion.
Practical example: During the installation of heating in older apartment buildings, we had customers who used a standard 18x2 spring on a pipe with an internal diameter of 20 mm, where the wall was thin. The result was that the pipe completely collapsed at the end of the first bend, forming a "wave" that made it impossible to connect to the radiator. The correct procedure requires maintaining an exact difference between the external diameter of the pipe and the internal diameter of the spring. For copper pipes, it is critical that the spring fills at least 70-80% of the internal space, which ensures an even distribution of stress.
When selecting a specific type, you must always consider whether you are working with an external or internal diameter. For example, Bending Spring - 20x2; External is specifically designed for pipes with an external diameter of 20 mm, where a smooth bend without deformation of the outer shell is required. On the other hand, Bending Spring - 32x3; Internal is intended for larger diameters, where a higher core stiffness is needed to prevent wall wrinkling at larger bend angles.
Forgetting the Difference Between Internal and External Springs
The second common mistake is ignoring the difference between internal and external bending springs. This difference is not just marketing, but has a direct impact on the mechanical function and safety of the installation. External springs are designed to be inserted into the pipe and support the inner wall from the inside, with their construction allowing them to be easily pulled out after the bend is completed. Internal springs, on the other hand, have a different thread shape or surface treatment that allows them to hold better in the bend area when working with heavier materials or special types of plastic pipes.
Many installers use universal springs that are not optimized for a specific type of material. For example, using Bending Spring - 26x3; Internal on a pipe that requires external support can lead to the problem that the spring "rolls over" during the bend and does not provide the necessary stability. Conversely, using an internal spring where external support is needed can result in the spring getting completely stuck after the bend and not being extractable without damaging the pipe.
It is key to understand that external springs are often designed with a smooth surface for faster sliding, while internal ones may have fine grooves to increase friction. When selecting, always check the product's technical documentation. Bending Spring - 18x2; External is ideal for gentle bends in tight spaces, where minimizing friction is necessary. However, if you are working with thick-walled pipes, a more suitable option might be Bending Spring - 16x2; External, which provides greater stiffness and resistance to torsional forces.
Incorrect Bending and Insertion Technique
Even if you have the correct spring, the technique of its insertion and bending is crucial. One of the most common mistakes is trying to bend the pipe immediately after inserting the spring without placing it precisely at the future bend point. If the spring ends just before the bend point, the pipe will twist and deform in this area because the spring cannot act on this section. The correct procedure requires the spring to extend at least 10 to 15 cm beyond the bend point to ensure an even distribution of forces.
Another mistake is applying too much pressure in one movement. Copper pipes are ductile, but they have their yield limit. If you try to make a 90-degree bend in one go, you risk cracking the material or causing permanent deformation that the spring cannot remove. The correct procedure is to bend the pipes gradually without damaging the walls, which means bending the pipe in small steps, slightly adjusting the spring every few centimeters and continuing the bending. This is a process that requires patience and sensitivity to the material.
It often happens that installers use too rigid tools for bending instead of utilizing the properties of the spring. During bending, the spring should be stabilized by hand at the bend point to prevent it from shifting. If the spring shifts during bending, the resulting shape will be irregular and may lead to pipe blockage. Therefore, it is important to remember the Bending Spring - 32x3; internal, which is suitable for larger diameters where greater control over the spring movement is needed.
Ignoring the Length of the Spring and Its Impact on Installation
Very often, installers do not pay attention to the length of the spring. If the spring is too short, it may not cover the entire section that needs to be bent, especially if it is a long pipe with multiple bends. Conversely, if the spring is too long, it may tangle inside the pipe or be difficult to handle in tight spaces. It is important to know what length of spring is needed for pipe installation, which depends on the length of the section to be bent and the number of bends.
Practical example: When installing floor heating, where the pipe needs to be bent into a snake-like shape, it is necessary to use a spring that is long enough to cover the entire length, but also flexible enough to be rotated. If the spring is too long, it may tangle inside the pipe and cause problems when pulling it out. Therefore, it is important to choose the correct length according to the specific project requirements.
Neglecting Maintenance and Storage of Springs
The last, but very important mistake is neglecting the maintenance and proper storage of bending tools. Springs are made of quality steel, but if they are exposed to moisture, corrosion, or mechanical stress outside of operation, they lose their properties. A common mistake is leaving the springs inside the pipes after the work is completed, which can lead to them getting stuck and being difficult to extract. In addition, if the springs are stored in disarray, they may bend or lose their elasticity.
Maintenance and storage of bending tools for long service life requires that the springs be cleaned of dirt, oil, and water after each use and then stored in a dry and protected place. It is recommended to store them in a coiled shape or in special packaging to prevent deformation. Proper maintenance not only extends the life of the springs but also reduces the risk of them getting stuck and damaging the pipes during further use.
Why Does the Spring Get Stuck and How to Remove It?
One of the most common and frustrating situations is when the spring gets stuck in the pipe. This usually happens as a result of incorrect spring selection, excessive bending, or damage to the inner wall of the pipe. If the spring gets stuck, do not try to pull it out forcefully, as this can damage the pipe even more. Instead, try using the methods described in the section on why the spring gets stuck in the pipe and how to remove it.
A common cause of jamming is the use of a spring that is too long for the given pipe, or one that has become tangled inside the pipe. In such a case, it is advisable to use special extraction tools available in our range. If the spring gets stuck due to pipe deformation, it may be necessary to replace the pipe. Therefore, it is important to follow all recommendations regarding the selection and use of springs.
Comparison of Spring Steel Quality from Different Manufacturers
There are many manufacturers of bending springs on the market, but not all are equal. The quality of the spring steel is a key factor that affects the durability and effectiveness of the spring. Cheaper springs may be made from lower quality steel that deforms quickly or loses elasticity. On the contrary, high-quality springs are made from highly alloyed steel that is resistant to corrosion and mechanical stress.
When purchasing a bending spring, always check what kind of steel it is made of. High-quality springs usually have a higher price, but the investment pays off in longer life and reliability. Comparing the quality of spring steel from different manufacturers is therefore important for achieving the best results during installation.
Safe Pressure When Bending Copper and Plastic Pipes
It is important to know what pressure is safe when bending copper and plastic pipes. Excessive pressure can lead to pipe cracking or permanent deformation. On the other hand, too little pressure can cause the spring to not function properly. Safe pressure depends on the material and thickness of the pipe. For copper pipes, a recommended pressure is approximately 10-15 kg, while for plastic pipes, this pressure is lower, approximately 5-10 kg.
Always monitor the reaction of the pipe and the spring during bending. If you feel resistance, stop and check whether the spring is correctly positioned. Do not use excessive force, as this can damage the pipe. Safe pressure is key to a successful installation and preventing damage.
Incorrect bending angle and the formation of a "band" at the bend location
The fourth critical mistake is ignoring the geometry of the bend and attempting to create an overly sharp angle (e.g., 90°) at one point without sufficient spring length. When the installer applies force on a short section where the spring cannot evenly distribute the stress, a so-called "band" or flattening area is created, which reduces the pipe cross-section and increases hydraulic resistance in the system. The correct technique requires the angle to be formed gradually along the entire length of the curve that the spring covers.
Neglecting thermal expansion and thermal shocks
Technicians often forget that copper pipes are sensitive to temperature changes and the spring must be designed to allow the natural expansion of the material. If the spring is used to create an overly rigid shape that does not account for expansion at operating temperatures, internal stress can develop. This manifests as cracking of joints or pipe deformation over time. In underfloor heating installations, where temperatures change dynamically, it is necessary to use springs that support a smooth transition between temperature states without creating concentrated stress points.
FAQ: Frequently asked questions about the purchase and use of bending springs
Why does my spring keep getting stuck in the pipe?
Spring jamming is usually caused by incorrect spring selection (too thin or thick), excessive bending in one step, or damage to the inner wall of the pipe. Check whether the spring is suitable for your pipe diameter and whether you followed the gradual bending procedure. If the spring gets stuck, do not use excessive force, but try to remove it using special tools or leave it in the pipe and replace the pipe.
How to choose the right bending spring according to the pipe diameter?
To choose the correct spring, you need to consider the inner diameter of the pipe and the thickness of its wall. For copper pipes with an outer diameter of 20 mm, a 20x2 spring is suitable, for 26 mm diameter pipes a 26x3 spring, and for 32 mm diameter pipes a 32x3 spring. Always check the product's technical documentation and compare it with your needs.
Is there a difference between internal and external bending springs other than the name?
No, the difference is significant. External springs are designed to support the inner wall of the pipe from the inside and have a smooth surface for easier pulling. Internal springs, on the other hand, have a different shape or surface treatment that allows them to hold better at the bend location when working with heavier materials or special types of plastic pipes.
What length of spring do I need for pipe installation?
The length of the spring should be sufficient to cover the entire section you want to bend, plus a few extra centimeters for secure gripping. For long sections with multiple bends, it is advisable to use a spring that is long enough to cover the entire section, yet flexible enough to be rotated.
How to properly store bending springs?
After each use, springs should be cleaned of dirt, oil, and water, and then stored in a dry and protected place. It is recommended to store them in a coiled shape or in special packaging to prevent deformation. Proper maintenance extends the lifespan of the springs and reduces the risk of them getting stuck.
Why do waves appear on the surface of the pipe during bending?
Waves on the surface of the pipe are usually caused by using a spring that is too thin or by excessive bending in one step. The correct procedure requires using a spring of appropriate diameter and gradually bending the pipe in small steps to prevent wall deformation.
Conclusion
Installing bending springs is a technical task that requires precision, knowledge of materials, and adherence to the correct procedure. Common mistakes, such as incorrect spring selection, ignoring the difference between internal and external springs, or neglecting maintenance, can lead to serious problems during installation. By following the recommendations and procedures described in this article, you can avoid these mistakes and ensure a high-quality and reliable installation of heating systems.
Remember that the correct choice of bending spring, such as Bending spring - 20x2; external or Bending spring - 32x3; internal, is key to the success of your installation. Investing in quality tools and following technical procedures always pays off.
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