Sealing of threaded connections. Which material is better?

In terms of your home’s insulation and heating efficiency, the little things can add up to a lot. The sealing of your heating system’s threaded connections is one such detail. Proper sealing of connections, be it pipes, fittings, or valves, is essential to avoid leaks and guarantee maximum efficiency. However, selecting the best sealing material can be difficult given the range of options available.

In heating systems, where pipes and components must be joined securely, threaded connections are frequently used. If not adequately sealed, these connections are vulnerable to leaks. At that point, selecting the right sealing material becomes crucial. Varying degrees of toughness, pressure and temperature resistance, and application simplicity are provided by different materials. Making an informed choice for your house can be facilitated by being aware of the benefits and drawbacks of each.

Teflon tape, sometimes referred to as thread seal tape, is a common choice for sealing threaded connections. This thin, flexible tape offers a dependable leak-proof seal and is simple to apply. It is a flexible option for numerous heating systems because it can withstand a broad range of pressures and temperatures. To guarantee adequate sealing, it’s crucial to use the appropriate kind of tape for the given application.

Pipe dope, sometimes referred to as thread sealant or pipe joint compound, is another often utilized sealing substance. Pipe dope, which comes in paste or liquid form, is put to the connection’s threads prior to assembly. When it solidifies, it creates a tight seal that offers exceptional resistance to leaks, even in high-pressure situations. Pipe dope is especially useful for sealing connections between metals.

Considerations including the kind of piping material, operating temperature, and pressure should be made when deciding between thread seal tape and pipe dope. To guarantee the efficacy of the seal, it’s also critical to adhere to the manufacturer’s application and curing time recommendations. The effectiveness and dependability of your home’s heating system can be preserved by choosing the proper sealing material for your threaded connections.

Material Advantages
PTFE tape Easy to apply, good for small leaks, inexpensive
Thread sealant compound Durable, suitable for high-pressure systems, seals larger gaps

Main varieties of pipe sealants

Out of the whole toolbox, the following should be highlighted:

  • Flax
  • Glue sealant
  • Silicone
  • Thread
  • FUM-tape

"Which sealant is better for pipes, and which is worse?" Incorrect. This question needs to be phrased slightly differently in order to make sense: "What type of thread sealant is worth using in specific conditions?"

First, let’s discuss the type of sealant that is inappropriate for use on threaded joints:

  • Silicone (good for flange connections);
  • Ship"s dryer;
  • Whitewash, various kinds of paints.

Thus, four categories of content remain:

  • Len;
  • Thread;
  • Glue sealant;
  • FUM tape.

Sealing tape

Flax for joints with threads

Use flax to wind pipes; it works well on steel, cast iron, and brass components as well. Flax can be used, but only in limited situations where plastic threads are soldered onto metal threads. Applying tape to all-plastic components would be a bad idea. A high tightening torque is necessary when sealing threaded joints where the sealant is flax. Occasionally, this torque may be greater than the plastic components’ capacity, which could lead to the thread breaking off.

In the realm of home heating and insulation, one critical aspect often overlooked is the sealing of threaded connections. These connections play a vital role in ensuring the efficiency and safety of various heating systems, yet the choice of sealing material is frequently underestimated. When it comes to selecting the right material for sealing threaded connections, it"s essential to consider factors like durability, compatibility with different substances, and resistance to temperature fluctuations. While options like Teflon tape and thread sealant compounds are commonly used, each has its advantages and limitations. Teflon tape, known for its ease of use and affordability, provides a reliable seal but may require careful application to prevent leaks. On the other hand, thread sealant compounds offer excellent resistance to high temperatures and pressures but demand proper curing time and application techniques. Ultimately, the choice between these materials depends on the specific requirements of the application, emphasizing the need for informed decision-making to ensure optimal performance and longevity of heating systems.

Plumbing thread

Plumbing floss for thread sealing

Plumber’s thread is an excellent pipe winding, but it has one drawback: it’s expensive. It is ideal for sealing all threaded joints, even those with a ripped surface from a defective threading tool, and it cannot be torn by hand. The torque needed to tighten yarns is different for plastic parts than it is for linen. You can use plumbing thread for any part.

Anaerobic sealant

Anaerobic sealants are unquestionably appropriate for factory-made cast iron, brass, and plastic threaded joints that need to be wound up, but there is a unique situation with steel components.

Various lubricants that adhere to the threads are used when creating threads in steel parts. When glue is applied, it adheres to greasy surfaces and stays there. One may ignore this. A channel may form once the coupling is screwed on, through which the liquid will eventually escape.

Not always accessible on location to clean the thread surface of grease residue. Because there is string and linen, it is not advised to use glue-sealant as a sealant for steel threads and parts.

It’s important to use the right kind of adhesive sealant when applying sealant. Certain types need to be heated in order to separate the joints. Consider a plastic pipe that starts with a metal coupling and ends with a metal connection. It has to be heated (obviously over 100 degrees) before you can disassemble it. It doesn’t matter for the metal portion, but the plastic pipe might get damaged later. Thus, consider the type of threaded joints you’re using sealant on!


Fume-tape is not a reliable pipe sealing material. Nonetheless, since there is no need to worry about anything leaking out, the tape can be used in the vegetable garden on a dacha plot.

How to seal a joint with flax?

Sealing threaded connections requires extreme caution. Being cautious ensures that nothing will leak. It will be necessary to use a specific paste when working; it cannot be done without it. It can be smeared directly onto the thread or left on the wound flax.

Your hands get filthy from the paste. Wiping them off is not a very pleasant task. This explains the existence of a flyhack: the installer sits down, wraps the tape around the threaded connection, and checks the winding quality (it should be uniform). The installer then uses the paste to make twelve connections at once. To enable the coupling to be screwed onto the male thread fearlessly, the connection should be free of protruding hairs for the first two turns. Additionally, a roll or thickening forms by the thread’s end.

The final two threads are sealed entirely. Compared to the other turns, they are finer but not fully threaded. These are the locations where the two parts are sealed together by the sealing material.

How to wind up the thread?

Notches are made with a key if the thread is smooth. Beginning with the third turn, the thread is wound. The thread should then be free for the first two turns, similar to how linen is, and seal for the final two turns. Threaded joint sealing will be flawless if all the procedures are followed correctly.

How to apply adhesive sealant?

Unlike flax, sealant cannot be applied to multiple joints at once. Just prior to the connection, the adhesive is applied to the threads in the shape of a "sausage" and thoroughly spread throughout the threads. This is to ensure that there are no gaps that could eventually allow water to seep in.

Once the connection is sealed, the threads need to be examined. As a result, the sealant is only applied very rarely and only in extreme circumstances. For instance, glue is the best material to use when joining a plastic component to a metal one.

Despite what the manufacturer says, experience suggests that the sealant should only be applied to one part. Apply the adhesive thoroughly with your finger to the coupling and threads if you are sealing a threaded joint that will be challenging to reach. This will ensure that there are no exposed areas of paint. It is clearly visible, and it is either red or blue in color. Before the components can be connected, all of the streams must be filled. It is best to avoid using glue as a pipe sealant for steel parts.

Maintaining the energy efficiency of our houses is essential for sustainability and comfort. An important factor in the overall integrity of insulation and heating systems is threaded connections. The decision regarding which material to use to seal these connections can be complex and influenced by a number of variables.

The kind of system in use is one of the most important factors. For example, materials like Teflon tape or thread sealant are frequently used in plumbing applications where water and other liquids are involved. These materials have good sealing qualities that keep leaks from happening and guarantee that liquids pass through pipes smoothly.

Conversely, materials like pipe dope or thread sealant with PTFE (polytetrafluoroethylene) may be more appropriate in high-temperature environments, such as those found in HVAC systems or industrial settings. These materials are made to endure high temperatures without breaking down, so they will continue to offer a trustworthy seal over time.

It’s also important to consider aspects like application simplicity and compatibility with the materials being linked. While Teflon tape is widely compatible and easy to use, there are some circumstances where pipe dope may have superior adhesion and sealing capabilities.

In the end, application-specific requirements and personal preference will determine which sealing material is best. Finding the best solution for obtaining maximum performance and longevity in heating and insulation systems can be aided by experimentation and consultation with industry experts.

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Sergey Ivanov

I like to help people create comfort and comfort in their homes. I share my experience and knowledge in articles so that you can make the right choice of a heating and insulation system for your home.

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