How to choose a sealant for threaded connections

Until recently, only plant materials were used to seal various plumbing compounds, most often flax thread. Now there are polymers on sale that can be applied under thread and used in various fields of activity. Threaded sealant is a liquid or paste-like retainer for joints, assemblies, reinforcing strength and protecting against corrosion.

Content:

• Why seal a threaded connection
• Use of anaerobic pipe joint sealants
• Properties and composition
• Varieties of sealants
• Flax thread
• Teflon or plumbing thread
• FUM tape
• Non-hardening sealant
• Hardening sealant
• Anaerobic Sealant
• Sealing Gel
• Sealant Colors
• Advantages and disadvantages
• Criterias of choice
• Instructions for use
• Drying time
• DIY removal of anaerobic sealant
• Popular manufacturers

Why seal a threaded connection

The presence of a thread in itself is a guarantee of a strong joining of two parts. But in some cases, without additional sealing, the unit will not serve reliably. An example is plumbing equipment, sewer pipes, radiator connection points: without a good seal, joints can leak. The reason is the regularly occurring temperature differences at which metal and metal-plastic pipes expand and contract.

Similar phenomena occur with constant vibration experienced by water pipes. In addition, with prolonged contact with water, even the highest quality metal begins to rust. As a result, the connection loosens, the thread loosens, leaks occur. It is possible to deal with such problems by tightly tightening the bolts and washers, as well as by applying a special polymer composition.

Sealant for threaded connections will minimize the risk of leakage, reduce the negative effects of vibration, contact with moisture, temperature extremes. Anaerobic sealant is best suited for this purpose, although some plumbers still use FUM tapes or other types of seals.

Use of anaerobic pipe joint sealants

The so-called airless sealants have been used for a long time, but earlier the scope of their operation was limited to mechanical engineering, military industry, and the aerospace industry. Now anaerobic compounds are popular in plumbing, repairing water and gas supply systems. Sealants are relevant in the construction of multi-apartment buildings and private houses. Gel compositions everywhere replace various tapes and cords-seals, since they have a lot of advantages.

Anaerobic fixators work well in aggressive environments, at high pressure (up to 50–100 atmospheres), are heat-resistant. This allows them to be used in the repair of heating pipes, gas boilers. Most sealants can come in contact with drinking water because they do not emit toxic compounds and are harmless to humans. They are also indispensable for the arrangement of underfloor heating in residential buildings, water supply and irrigation systems, are equally well suited for metal and plastic.

Properties and composition

The thread sealant is made on the basis of acrylic polymers or oligomers, which give it the desired viscosity and thixotropic properties. The initiators of curing are hydroperoxide or peroxide. Also, any sealant contains additional substances:

• stabilizers (phenol, quinone);
• plasticizers;
• thickeners;
• pigments.

The sealant is designed to seal and protect various joints and joints. Its structure allows you to penetrate into the smallest cracks, cracks, holes, after which the tool hardens and reliably seals the site. Threaded sealants have a high degree of adhesion to metal and other materials, fixing parts no worse than the thread itself.

Their main properties are:

1. Fluidity. The viscosity of the sealants is optimal for application and introduction into defects and gaps. The smaller the hole to be closed, the more liquid the composition should be.
2. Temperature. Most latches work in the range of –50 ... + 150 degrees. This is enough to seal water supply and heating systems. For pipes and assemblies that heat more strongly, there are specialized heat-resistant compounds.
3. Strength. To break the connection, it is not enough to apply the usual force by hand. The strong hold means gives such a strong seam that it can be disconnected after heating or using special keys.

Some sealants have only technical purpose, others are suitable for fixing pipes for drinking water, which is always noted on the packaging.

Varieties of sealants

Depending on the strength, sealants for threaded connections are divided into several groups:

• easy fixation - are used to close knots exposed to moderate loads, but suggesting the possibility of dismantling; tensile strength is 3–10 Nm;
• medium fixation - strengthen joints that can be removed after heating or using a key; tensile strength - up to 25 Nm;
• strong fixation - it is difficult to disassemble such joints, therefore sealants are usually used to form long-serving nodes; strength is up to 50 Nm.

Sealants from the last group are most resistant to shock and temperature loads, they are indispensable in the arrangement and repair of high pressure systems, pneumatics.

By viscosity, thread sealants are:

• liquid and pasty;
• fluid, medium-flowing and dense (difficult-flowing).

For minimum clearances, liquid sealants with a viscosity of less than 20 MPa are chosen, otherwise they will not be able to penetrate the hole. With a gap of 0.5 mm or more, it is allowed to buy sealants with any viscosity, even the thickest.

For threaded connections, you can use different tools that differ in properties, composition, shape.

Flax thread

The use of flax is the oldest method of imparting tightness to threaded joints. Flaxseed is inexpensive, sold everywhere.

Unfortunately, this “sealant” has a number of disadvantages:

1. The complexity of the application. Without proper experience, it will not work to thread the thread correctly. When applied inaccurately, the thread will unwind quickly and the connection will be leaking.
2. Hydrophilicity. Flax literally absorbs moisture, is impregnated with it, while it swells very much. Weak pipes in the joints can burst, and metal joints are at risk of corrosion. It is best to use flax thread for pipes made of the most durable materials.
3. Low temperature resistance. Flax can not be used for heating seams, radiators, batteries, as it will soon collapse.

Teflon or plumbing thread

By the principle of action, such threads resemble linen, so when working with them, dexterity and correctness of actions are also important. Teflon thread is impregnated with a special composition that gives it strength, improves technical characteristics. It is suitable for water supply, gas pipelines, other pipes, fits snugly to the thread, and serves for a long time without destruction.

The sanitary thread tolerates heating, temperature changes, is safe for humans and can be used on pipes with drinking water.

FUM tape

Such a tape has a low price, is easier to use than threads. It must be wound on the thread in any way, tighten the nut or fitting, and a reliable connection will be ready. The FUM tape does not stick, does not break, after unscrewing the joint, it can simply be removed if necessary. The device is suitable for various pipes, including those in contact with drinking water.

FUM tape also has a minus. She is not able to tightly fix the joint, therefore, with strong vibration or mechanical stress, the knot weakens. After a while, a leak may appear, so you will have to tighten the nuts regularly. Do not use the tape where the pipes undergo high pressure.

Non-hardening sealant

Threads are treated with such compounds, then a nut is screwed, as a result, the seam will be tightly sealed and become an obstacle to the fluid. The sealant in the form of a paste remains somewhat viscous, so you can unscrew the washer at any time. The tool does not stick the pipes, but simply densely fills all the seams and cracks. It does not contain toxic compounds, it is harmless. Non-hardening sealant is not used for pipes under pressure: water will displace it with the inevitable appearance of a leak.

Hardening sealant

Sealants from this group are the most durable, they serve for a long time, because they tightly fix the compounds and are not washed with water. After applying the product to the thread, put a nut on it, wait a while until it dries completely, and start operating the pipeline. If water is supplied under pressure, sealants with the highest strengths should be purchased.

Anaerobic Sealant

It is such sealants that are the most modern and are rapidly gaining popularity. They are suitable for home and professional use, are sold in convenient tubes of different sizes. In the open air, anaerobic retainers retain a liquid texture; they can be applied to any thread without any problems.

Only after tightening the fitting or nut, the product will begin to polymerize and turn into a kind of plastic. The total hardening time is up to 3-4 hours, and then the connection can be put into operation. The dismantling of the joint is usually carried out after heating.

Sealing Gel

Such tools are used where increased resistance to vibration is required. They have high elasticity, tolerate mechanical loads, are durable and reliably seal joints. As a rule, all gel fixers are anaerobic in principle.

Sealant Colors

Sealants for threaded joints are available in a variety of color options. Depending on the manufacturer, you can find blue, yellow, green, white, black and other means. For most brands, color determines the strength and other properties of the sealant.

Examples of shades of sealants:

1. Green. It gives a weak degree of fastening of the joints, so you can unscrew the nut manually or using a standard wrench. Has a limited spectrum of action, usually used for pipes with a diameter of less than 1.5 inches.
2. Red. It is characterized by enhanced setting, completely hardens in a few hours, is excellent for pipes made of ferrous metals, withstands significant temperature extremes.
3. Blue. Universal sealant, suitable for metal, plastic, polymerizes in 15–20 minutes. It has an average degree of fixation, works at temperatures up to + 100 ... 150 degrees.
4. White. Typically, such sealants are used for plastic joints, as well as for metal pipes of small diameter.
5. Orange. Anaerobic gel used for plumbing and sealing automotive components. Deadly connects parts, has a high degree of adhesion to metal and plastic. If necessary, to destroy the joint will have to break it or subject it to strong heat.
6. Yellow.Typically, this tool can withstand temperatures of not more than +40 degrees. Most often used for working with sewer pipes.

Advantages and disadvantages

High-quality sealant for threaded connections has a lot of advantages, so its popularity is very high.

The advantages of such compounds:

• ease of use - you can work with the latch even without skills, the process will take less than a minute;
• high speed of polymerization - it will be possible to use the unit in a few hours;
• profitability - sealant consumption for thread fixing is minimal;
• efficiency - the connection will be 100% tight even with increasing pressure in the system;
• additional protection of products from rust - this is true for metal parts;
• long service life - many tools last 5 years or more (in extreme conditions - up to a year);
• the ability to apply in gaps of any thickness - from fractions of a millimeter or more;
• resistance to mechanical stress and vibration, the action of chemicals, insolubility in water;
• suitability for a variety of materials, the ability to connect products that are heterogeneous in structure.

Good sealant has a few disadvantages. In fact, they appear only when it is necessary to dismantle the unit, which will require heating with a building hair dryer or other professional tools. In addition, FUM tape may cost less than an anaerobic sealant, but its quality seriously exceeds all known analogues.

Criterias of choice

To choose a really good thread sealant, you need to be guided by the advice of masters. When buying, you should take into account the size of the gap, the features of the thread, as well as the material of the pipes - the product should be suitable specifically for the particular situation, as there are indications on the package.

If in the future it is planned to regularly dismantle the joint, it makes no sense to buy a sealant with the highest adhesion - its removal will cause a lot of problems. If it is necessary to carry out urgent repairs, you need to choose a latch with a minimum polymerization time. It is better to purchase a sealant of a well-known brand that you can trust than to save and get a low-grade composition that quickly fails.

Instructions for use

Before starting work, the contacting surfaces are prepared. They are cleaned of dirt, degreased with acetone or isopropyl alcohol. Some sealants require pre-treatment of the joint with an activator (sold in the kit), which is applied with a brush. After the preparatory stage is completed, the parts are allowed to dry completely, then the composition is distributed with a dense ring evenly over the entire surface of the thread. With a large gap, the thread, nut and fitting are lubricated with sealant.

The parts are interconnected, the surplus funds are wiped off with a dry cloth. If necessary, excess sealant is collected and applied to the next joint. The knot is left until fully set (the exact time is always indicated by the manufacturer). When performing a seam and subsequent operation, it is imperative to comply with the recommended temperature regime.

Drying time

Usually, after 15–20 minutes, you can check the quality of the resulting threaded connection, giving a little pressure to the system. If there is no leakage, the sealant must be left to cure completely. Usually this time does not exceed 24 hours, and for many compounds it is 3-4 hours.

DIY removal of anaerobic sealant

If there is a need to disassemble a tight pipe connection, you need to take into account the period of application of the composition and its strength. When the sealant has not yet had time to harden, it will not be difficult to remove it. When hardening, you will have to use a building hair dryer and a key. The order of work will be as follows:

1. Turn on the hair dryer, direct the air flow to the junction.
2. Wait for the sealant to melt or crumble.
3. Use a rag to remove any remaining product.
4. Apply a key to parse the node.

Popular manufacturers

Among the most famous brands of anaerobic and other thread sealants are the following:

1. Loctite. It occupies a leading position in the market of anaerobic compounds, produces liquid sealants, pastes, medium-flowing products, as well as sealing threads. All clamps have a long service life, high strength.
2. Anaterm. Sealants of the brand are widely used for joining welds, steam pipelines, sealing any cracks, defects.
3. SantehMaster. Russian brand of sealants, under which means are produced for sealing threaded and flange joints. Sealants do not deteriorate from the effects of gasoline, oils, alcohols, are suitable for extreme operating conditions. They have a low consumption, do not emit harmful substances.

Sealants are universal and the most convenient means when working with threaded connections. They allow you to easily seal the nodes, which seriously increase their strength and durability.