Overview of modern materials for sealing pipes

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This review will help a novice plumber decide on a method for sealing pipes. The article contains a detailed analysis of all materials used for this purpose: flax, FUM tape, plumbing thread and various sealants.

Overview of modern materials for sealing pipes

Despite the emergence of plastic pipes, plumbing and heating systems have still not gotten rid of threaded connections. This means that you still cannot do without winding or another method of compaction. And then the novice plumber faces the question: what to choose for this – good old grandfather’s linen or more technological materials? The question is really important, since the sealing of pipes is the main factor that determines the reliability of any pipeline..

Overview of modern materials for sealing pipes

The modern industry offers a variety of synthetic sealants and sealants. But are they all as good as they might seem at first glance? At the same time, the use of organic materials is not always appropriate, and in some cases it is simply unacceptable. Different packing methods have their pros and cons, which are better to be familiar with before starting work than in the process of eliminating leaks..


Packing with dry linen is not the best option. Organic fibers are hygroscopic, so that compaction is mainly due to their swelling. This can lead to rupture of thin-walled pipe elements, especially if they are made of brittle material. Fibers soaked in water decompose quickly, so this method of sealing is very unreliable. Dry strand packing is not acceptable in high pressure systems as it will not eliminate continuous seepage. It is also not recommended to use flax on steel pipes, even galvanized ones, as the moisture absorbed by it causes corrosion of the joint. As a consequence, in the case of repairs, water taps and fittings are often loosened together with the thread, or it turns out to be unsuitable for reassembly..

Overview of modern materials for sealing pipes

Sealing pipes with flax in combination with paint is more reliable than for a dry strand. At the same time, the fibers are protected from moisture, and the threads are protected from rust, but only partially. The paint, as a rule, does not completely saturate the flax, which means that corrosion and other unpleasant consequences are a matter of time. This method also has one more serious drawback: the connection will be extremely difficult to disassemble, especially with a large pipe diameter. It is also undesirable to use it in heating systems..

Overview of modern materials for sealing pipes

It is much better to use silicone sealant instead of paint. When applied abundantly, it impregnates linen well, reducing its hygroscopicity, and also plays the role of a lubricant, facilitating assembly. The disadvantage of this method, as in the previous case, is low manufacturability and the need for additional components. Nevertheless, it is an excellent option for a seal for a locknut and for installing elements that need positioning (taps, eccentrics, etc.), since the linen winding can be adjusted and remains tight, even if the connection is not tightened to the stop.


Fluoroplastic sealing material (FUM) is a military development. And although a thin polymer tape has long and firmly rooted in the arsenal of plumbers, it was not created at all for use in plumbing and heating systems. Due to its chemical inertness and exceptional thermal stability (up to 300 ° C), pipe sealing with FUM tape is used in pipelines with a chemically active, explosive and high-temperature internal environment, including pure oxygen.

Overview of modern materials for sealing pipes

FUM tape protects threads from corrosion, does not rot or dry out, it is technologically advanced and easy to use. Smooth belt surface reduces friction, which makes assembly and disassembly easier – some of the turns can be done by hand.

Overview of modern materials for sealing pipes

Unfortunately, it is precisely the high antifriction characteristics that are both an advantage and a disadvantage: the joints on the FUM do not withstand vibration and mechanical loads poorly. The second drawback is depressurization after the reverse thread. For these reasons, repair and installation work on pipeline systems assembled entirely at the FUM becomes like a sapper: one careless movement – and some of the connections will have to be rewound. In addition, in order for the pipes to be sealed reliably, it is necessary to tighten or counter the thread. The listed disadvantages make the FUM tape unsuitable for positioning installation, especially for taps and valves..

Plumbing thread

A thread reel for water pipes is a dense cord made of thin synthetic fibers, impregnated with a non-drying water-repellent compound. It has all the advantages of flax in combination with a sealant, but unlike it does not decompose, successfully resists chemical attack and better protects against corrosion..

Overview of modern materials for sealing pipes

The sanitary thread allows adjustment with a reverse stroke up to 180 ° (linen – only up to 90 °) and incomplete tightening, while maintaining the tightness and resistance of the connection to mechanical stress in all directions. In addition, this method is more technological and convenient: the reel is completely ready for use, which does not require unnecessary actions and the use of additional materials. Its only drawback can be considered a relatively high cost..

Plumbing Sealants

The general advantages of materials in this class are ease of use, corrosion prevention and lubrication. Silicone sealant is rarely used without a combination with various kinds of fibrous materials, and non-drying compounds can be used in pure form only in non-pressure systems, otherwise they will simply be forced out of the thread. Drying sealants withstand pressure well, but with a large gap, they shrink significantly as they harden.

Anaerobic sealant is devoid of these disadvantages, which hardens without air access, but only on contact with metal. Obviously, both conditions are met within the threaded connection. At the same time, the volume of the sealant does not change – there is no shrinkage or swelling. The material has sufficient chemical and thermal resistance, and is also able to withstand no less pressure than the pipe itself. The gel is adhesive to metal, making the joint stiff and strong, even when not fully tightened. On an open surface, the anaerobic sealant does not harden – the excess can be simply wiped off with a cloth or washed off with water.

Overview of modern materials for sealing pipes

The main disadvantage of this material is some difficulty in use: the thread must be clean and grease-free, and at temperatures below room temperature, you will have to heat the pipe for the gel to set. It is also not always possible to disassemble the connection without heating, especially if the diameter is more than an inch..


The least technologically advanced option of all considered is flax in any combination. And although impregnation with a sealant brings it closer in properties to a synthetic thread, it is seriously inferior to it in terms of service life, and the low price hardly compensates for this.

The rest of the materials are technologically advanced and approximately equal in durability. The cheapest of them is FUM, but it also has the most disadvantages. Against this background, sealing pipes with plumbing thread looks preferable, despite the relatively high price.

Overview of modern materials for sealing pipes

In turn, it is inferior to anaerobic sealant in terms of reliability: its use requires a certain skill, without which complete tightness cannot be guaranteed. However, skill is a gain, and plumbing thread is easier to use and costs less..

Non-drying silicone sealants are best used as an impregnation for flax. Drying pastes and anaerobic gels are quite self-sufficient, but the former demonstrate low reliability with a large thread gap, and the latter are the most expensive material of all. Nevertheless, their price is adequate to the quality, and in most important indicators these materials are superior to all others..

Thus, the most versatile, technological and reliable seals are plumbing thread and anaerobic sealants. Their use reduces assembly time, increases the reliability of the system under any operating conditions, which fully pays for their cost.

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