Threaded connections are put on the tube as well as the connecting and diverting fittings. But the simplicity and reliability of the connection of any pipeline with the use of cutting still does not ensure its complete impermeability. Therefore, mandatory supplement is sealed tubes in all places of threaded joints. Only this combination allows you to create a secure connection.
Forms and sealing conditions
Isolate joints when laying pipes necessary for the different types of pipe. The only exceptions are weld joints, but this and the lack of them - they are one-piece. A joints with thread makes it easy to replace the damaged area, or insert a new harness.
Therefore, sealing is required for threaded pipe connections:
- hot water and cold water,
- gas pipelines,
- heating.
In practice, the thread used in the lines of small diameter - in the internal wiring of the house and in apartments, country houses and when installing networks for freestanding buildings with low power consumption water and gas. and welding the flange connections are used for water pipes and heating of large diameter.
Ventilation line, typically have a large cross section and made of a thin sheet or corrugated pipe. Therefore, the threaded connections they do not use, but the sealing of joints is still necessary.
When choosing a method of sealing pipe joints is required to consider its properties and the conditions under which they will operate:
- The outer and inner temperature of the medium in the medium conduit. Some types of sealants lose their properties at elevated temperatures or in the cold.
- The line pressure. Liquid insulators can be extruded from the compound under high pressure.
- Diameter pipe.
- The final bond strength. This is the force required to disassemble the insulated joint in the event of repair or modification.
- Environmental Safety. When laying pipes for drinking water can not be used substances capable of releasing toxic compounds.
Most drugs and substances used for sealing, these parameters fall within the range required for docking domestic pipelines. But the most careful selection is required for sealing joints of gas pipes. Leakage in the water mains markedly from the beginning in the footsteps of leaks at the joints. Gas leaks are not manifest themselves visually, and can remain undetected for a long time.
Methods for sealing threaded connections
By Applicability distinguish materials filling space between the threads or pasty solids sealants.
Standards recommended for conventional paste passes to 65 mm. For solid insulating materials have stringent restrictions.
Consider the basic options for sealing the threads on the pipes.
plumbing flax
Winding strands of linen thread on coils used for a long time and is still considered a reliable method of sealing. But it is also the most difficult to work. Sequencing:
- are applied to the threads of the sipe, the material does not slip during winding;
- flax beam separated by small strands,
- first turn is wound crosswise to fix it on the thread;
- after winding of the total material, linseed oil is applied on top of it or waterproof paste.
Without the experience of working with this material winding often get sloppy, with protruding strands of flax. In addition, easy to soil all over the details and hand superimposed grease. But the main problem - it is necessary to put in the desired number of turns of the flax. If it is small - Tightness eventually broken. With a large tightening compound layer will be difficult, and dimmed fittings of low-quality material may burst.
tape FUM
This fluoroplastic film can be called a compactor for amateurs. Work with it does not involve any difficulties because it easily fits into the threads. Only at the beginning it is necessary to keep the tape from slipping. The softness of the PTFE allows not much care about the number of wound tape. Even when excessive winding thread fittings welling in effortlessly. And if everything is done according to the rules, the connection can be carried out hands, without the use of keys. But the flip side of this ease is likely loosening.
Pros:
- ease of use,
- chemical resistance,
- low price.
Minuses:
- because it is not recommended for threads of diameter greater than an inch (25 mm) of low quality tightening,
- shall not be used under the condition of vibration in the pipeline,
- at high temperature drops violation occurs sealing.
Convenient for use on water and heating pipes in the home.
Sanitary sealing thread
In fact, it combines the benefits of flaxseed and ribbon seals. Made of synthetic materials impregnated with additional sealant. It is also useful when winding as FUM-tape, but much stronger than her. If necessary, you can even slightly loosen and re-tighten the connecting element - the tightness of it will not be broken.
There are features of it:
- winding is carried out not by the thread grooves, and a little obliquely;
- to hold the yarn in position necessary incisions in the thread,
- the first two threads are left free, while the last two thread is wound with an additional seal;
- number of turns for proper sealing depends on the diameter of the pipe and is indicated in the instructions.
Temperature resistance, reliability and tightness of the sealing compound thread sealing permit it not only heating pipes, but the joints and gas.
it is considered the most reliable solid thread sealant. Of course, if you do not use a cheap knockoff. The most popular brand is the thread Tangit Uni-Lock.
liquid sealants
Such sealing compositions are filled into the screw groove of the pipe and fittings. After application they are not solidified but remain in a paste state, providing fluid tightness or gas tightness is maintained. Generally, the structure includes additives protecting the metal from corrosion.
The main drawback of such pastes - the impossibility of their application in lines with high pressure. The pressure of liquid or gas gradually squeeze the soft substance of the threaded gaps.
ease of connection of this sealant is wrapped so that it is effortlessly unscrewed. Therefore, the joints in the liquid sealant is necessary to control and pull in a timely manner.
anaerobic sealants
Composite polymeric compounds which retain air flow properties. As non-hydraulically paste, easy to apply to the threaded groove. After this connection is tightened effortlessly. Upon contact with the metal in the absence of air gaps in the transformation of matter, and it solidifies, providing reliable sealing and joint. The basic requirement before applying - metal connections should be cleaned of rust and degreased thoroughly.
They differ in the degree of the fortress hardened composition:
- The average fixation (Medium). Usually issued blue. After setting ensures reliable connection, but amenable to mechanical dismantling. His hands to unscrew unlikely to succeed, and the key - completely.
- Strong fixation (Strong). It is red. Compound formed by them virtually nonseparable, since under normal conditions even with a wrench when it is not amenable to loosening. Unlike welding, it can be disassembled after strong heating. Therefore, this type of sealant has no use for domestic routes.
It is not recommended to use a strong option for the compounds of metal pipes with plastic. If necessary, disassembly of the joint heating portion can deform plastic compound.
sealing gaskets
Gasket, abutting a pipe end, can also seal the joint. Clamp made union nut or the connecting fitting. Cutting itself when it can not be sealed, but sometimes it is also a safety net wrapped gasket. Rubber rings are gradually replaced by modern gaskets of Teflon and other plastics.
Not all screw connections can be sealed in such a way. To connect two pipes with each other using gaskets difficult. But the connection taps, mixers or flexible podvodok through polymeric ring is very convenient.
Duct Sealing household
Ventilation in apartments and suburban homes held by thin-walled elements. Often the ducts are made of rectangular cross section or a corrugated pipe. Thread on these connections is not possible. Therefore, sealing ventilation joints made in other ways:
- through the flanges,
- the imposition of the band,
- with flared by inserting one duct to another.
Flange connection is most often used for non-circular ducts. Sealing is carried out with the use of gaskets of soft material, such as foam rubber. The shape of the gasket should repeat the duct section.
Other methods of voids formed after joining air ducts are filled with mastic, on their temperature characteristics of the respective operating conditions of the air line. Sometimes the joint duct wrapped with adhesive tape.
Coupling of pipes of metal and plastic
Rating polymer pipes for household highways often require their connection to existing pipes of metal. To do this, use a special adapter. The most common of them - the fittings under the name "American" or "nipple".
American-adapter consists of two parts. At one end of the metal part is applied outside or inside thread, depending on the type of cutting the connecting pipe. At the other end - male thread. The second part of plastic, ending union nut with an internal thread. Both parts are joined together by nuts on threaded HERZ-TS metal element. Sealing joints - through gasket inside the coupling nut.
The first part of the adapter is screwed into the connectable metal pipe, and the outlet pipe is welded to the welding method of the polymer of the plastic conduit.
Nipple-fitting - a polymer sleeve, inside of which is soldered to the metal part of the thread. It provides a joint of a steel pipe, and the sleeve itself is welded to the plastic pipe.
