Therefore, when installing and repairing heating, special attention is paid to ensuring the sealing of joints and connections.
One of the most commonly used methods of joining parts of heating networks is a threaded joint. Consider the materials and methods by which their sealing is provided.
Sealing with end gaskets.
The most technologically advanced and fastest method of assembly, which, however, is rarely used for heating systems. In this method, the part with external threads during assembly compresses the gasket located on the contraction of the mating part. To ensure a tight joint, simply install a gasket (paronite, fluoroplastic, rubber) and screw the parts to the stop. However, this method requires precise machining of the profile of the part with internal threads and it is difficult to ensure a transition without contraction. Therefore, this method of sealing threaded joints is more often used for installation of measuring devices and sensors, where the increase in hydraulic resistance is not important.
It may still be noted that even in this case, experienced locksmiths still additionally use sealant.
Sealing by winding FUM tape
In this case, fluoroplastic tape is used. This method allows you to quickly make the assembly of threaded joints and reduces the make-up effort (due to the low friction coefficient of fluoroplastic). Another advantage is its high chemical resistance and durability.
Sealing of threaded joints with FUM tape
But it also has some disadvantages:
when assembling connections with very smooth or rough threads, the tape can tear or squeeze out;
not suitable for connections that are subject to temperature deformations, as the tape does not have adhesion to the materials and the "game" of joints can squeeze out (of course, you can additionally use sealant, but then the question arises why else the tape);
does not provide reliable sealing of threaded joints with a diameter greater than 25 mm (not suitable for the assembly of batteries heating systems).
Thread for sealing.
Also made of Teflon (fluoroplastic) or nylon, sealing with it has all the same advantages as sealing the threaded joints with FUM tape and the same drawbacks, except tendency to squeeze or break. It is also unsuitable for the assembly of heating system batteries.
Sometimes produced thread is impregnated with non-drying sealant, which improves its adhesion.
Linen heel.
The most well-known and used for a long time sealant. It is used in conjunction with impregnation with oil paint or surik. Although there are more modern materials, linen heel is still the most common material for the assembly of threaded joints of heating system batteries. But still has a lot of disadvantages:
Requires some skill to properly wrap and caulk;
Has a limited durability;
Prone to drying out.
As an option to improve the quality of this method of sealing, a liquid or paste silicone sealant is used for impregnation.
Drying and non-drying liquid and paste sealants
Most often made on the basis of silicone. They have sufficient heat resistance for the assembly of batteries and other elements of the heating system. Makes it easier to assemble threaded joints due to its lubricating effect. If you apply non-drying sealant, the details of the heating system will be easy to dismantle. The disadvantage is that non-drying pastes can squeeze out at high system pressure. A hardening sealant can have shrinkage and such a connection can leak over time.
The most proper approach for sealing threaded joints in heating systems would be a combination of undercoating material and sealant. See the video on how to do this correctly:
How to seal joints in heating and water pipes
On sale, you can find many different materials that are designed to seal the joints of pipelines. The question arises - which of the materials in which cases should be applied? And also - how to use this or that sealant correctly? It is often possible to apply two or more gaskets for the thread, then you need to specify - what to prefer. These recommendations should help to understand these issues and find a solution that will provide sufficient reliability of the connection of pipes and fittings for the entire period of operation. Flax is a cheap material for threaded joints that creates a very good seal. The only thing - it can not be used in all cases.It is designed for connections of metal parts, as it creates a significant density. It is very strong, the effort required by the wrenches, the two parts to be connected, significant. Therefore, linen is not sealed:
plastic parts - the tightening torque exceeds the strength of the material, the parts will be crushed, destroyed, at least the threads.
parts in which the metal coupling with threads is terminated in a plastic (polypropylene) shell, due to the risk of turning (undoing).
For all metal products, tape is the No. 1 material for threaded joints. Next, let's see how to apply it correctly.
Flax "dry" is not used, it must be lubricated with a special sanitary paste. It is applied either directly to the threads, or on the coiled flax. Folk experience also suggests - instead of paste you can apply sunflower oil, the quality of the jointing is not reduced, at least such information is not available.From the flax is allocated a strand and rolled on the thread on each arm. The winding is done tightly and neatly. There should be no protruding hairs. The first two turns are not filled, and at the end of the thread is made shoulder.Special thread for seals, high strength (you can not tear with your hands) wound on spools, sold in stores. Its main disadvantage is the high price, otherwise it has a lot of advantages.
It can be used on all parts, the tightening torque is lower compared to linen, so you can also wind up plastic.
It seals very well and can even be used on torn threads.
If it were not for the cost of this material, only such plumbing thread would be used for joints.Winding is done in the same way as with linen - the first two turns of thread are left empty so that the parts can be joined, and then there is a winding on each knob of thread, at the end of the winding - a double layer, ie shoulder.Fum-tape is not suitable for creating reliable connections on the pipelines. The material is not very strong, sufficient tightness in the threaded joints of metal products with it does not occur. But for plastic connections that will be dismantled, such as summer pipeline for irrigation, Fum tape - the most suitable sealant. With the rubber tape connected parts can be wrapped by hand. In this case there is a small tightness of the joint on the threads, so that there is no leakage for some time. The slight force when tightening does not provide sufficient tightness, does not guarantee that this joint will not leak. For fixed joints, especially if they will be little available during operation, it is recommended to use other materials.
Heating in the house can be done by yourself - the main issues of installation If there is a twist in the connection with the fum tape, which is already in operation, it is likely that there will be a leak. This is a serious drawback, given that for the rotation does not need a lot of force.At the household level, foum tape can be used, (and is popular due to the cheapness, ease of use, and little effort), for connections that are in plain sight - when connecting the shower, faucets, etc.
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The material is special, not exactly cheap, seals well, cases of leaks after its correct use have not been fixed. But only after the wrong....
The obvious disadvantage of adhesive sealant is that the quality of the joint will depend on the "human factor" more than the winding. The fact is, glue doesn't work well on greasy surfaces.Where will greasy surfaces come from? It could just be carelessness - dropping oil on the threads or rubbing the part with your hands in oil. Parts can be kept greased (especially steel parts). But the main thing is that during thread cutting, grease is applied. That's after such an operation on the steel parts glue sealant is absolutely not suitable.It should be noted that there are samples of glue, with which the undocking of pipes requires heating over 100 degrees. Such heating is often difficult, not safe, plastic can be damaged, etc. Therefore, the adhesive-sealant is still chosen by the circumstances.Apply the adhesive is simple. Applied only immediately before joining, squeezed from a tube on the thread and smeared with a finger over the entire thread without a gap.In what cases should I give preference to glue?
When joining plastic parts to metal parts, glue is preferable. But such a connection is not common.
The second case - when access to the junction will be difficult. Such a connection is better to plant on the glue, and the grease is performed abundantly without economy, on both docked parts.
Read about the problems of soldering polypropylene piping - how to make the installation correctly and reliably Threading requires great accuracy of execution. The thread must be filled with an even layer without any gaps, and there must be a sealing material in each thread. It is placed to the end of the thread, where it forms a shoulder.The main sealing of thread connections occurs on the last two turns of the thread. On parts, more often the last two threads are not penetrated to their full depth. Therefore, at this point, the material is wedged between the two parts very tightly.It is not bad if an additional (cross-check) quality control of the linen underwinding is organized during the performance of the work. This is especially true when several dozens of such joints are made at once.
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For those who are constantly engaged in installation, it is recommended to always have with you tape, plumbing thread and adhesive sealant, in order to quickly and efficiently make any connection. It is recommended to use all of this in accordance with the above tips.
When doing work at home with their own hands, when doing something simple and in plain sight, you can use cheap fum-tape, but you need to wrap more. When installing whole systems with their own hands, on metal, it is better to use tape (with lean oil), and for small amounts of work it is even better to use thread. Maximum attention should be paid to the quality of the winding on the thread.
What should never be used to seal threaded joints:
You do not need to use plain silicone, it is designed for flanged connections.
Do not use paints, whitewash, minerals, which are of little use, but make the connections semi-disassembled - this is long outdated.
