Fittings for plastic pipes: types, photos, device, marking, application, purpose, advantages, installation rules

With the development of polymer technology, gradually plastic pipes are displacing steel pipelines. Steel can be connected with flanges, bends, welding. While polymer communications can only be spliced ​​using fittings for plastic pipes. Otherwise, the joint is not reliable enough to withstand mechanical stress.

What are the advantages of plastic pipe fittings

The use of fittings makes it possible to:

The main advantage is the increased bond strength. On fittings, plastic pipes for water pipes are able to withstand pressures up to 25 atm. Sewer communications are able to function for many years without loss of tightness.

Types of fittings for plastic pipes

For plastic communications, two types of fittings are used - for pipe joints under pressure and assembly of sewer systems. The first are thick-walled plastic products, often with metal inserts.

The performance and design depend on the function of the fittings. The latter, on the contrary, are made thin-walled, often with grooves for rubber sealing rings.

The group for high-pressure plastic pipes includes:

• fittings for easy connection of PP, HDPE and PVC pipes. This includes couplings, adapters used for splicing lines of different diameters;
• adapter couplings for connecting consumers, connecting a line to a manifold, central heating pipes;
• corners, tees, bends, providing a turn or branching of plastic pipes.

Depending on the connection technology, fittings are divided into brazed-welded, "American", crimped, glued and under a rubber ring. Docking by soldering or compression crimping is used on polypropylene communications, low-pressure polyethylene pipes. "American" can be used on PVC and HDPE. Glued is used for PVC fittings. Docking under the ring is used exclusively when assembling sewer communications.

How are fittings for plastic pipes

Regardless of the type of connecting device, whether it will be used to simply join two plastic pipes, turning or branching, the body of the fitting includes a polymer base, plus one or two parts that provide a threaded compound. With one exception - the cheapest models for soldering are entirely molded from plastic.

Compression (crimp)

This type includes couplings in which at least one of the pipe blanks to be connected was fixed by mechanical compression of the walls on a metal base.

In fact, this is a linear coupling, on one side of which there is a plastic spacer made of polypropylene for a soldered joint. At the opposite end is a metal nipple with a crimp nut. The nipple is inserted with little effort into the inside of the plastic pipe to be connected and tightened with a crimp nut.

Compression couplings for joining plastic pipes made of cross-linked polyethylene and polypropylene are arranged according to the same principle.

If metal-plastic pipes are used in the heating or water supply system, then the connection, connection to the shut-off fittings or lines made of polypropylene can be made using a plastic fitting with a metal cone nipple and a union nut.

Inside, a rubber gasket is placed under the nut. The nipple is made with a "socket" outward. As a result of crimping the fitting, the edge of the metal-plastic pipe is crimped. To prevent the plastic section soldered on the reverse side from turning, a hexagon wrench is made on the coupling housing.

Cast

For joining pipe blanks, couplings cast from polypropylene or cross-linked polyethylene are often used. The simplest solder connector is a cast body with two annular grooves.

In addition to the classic "barrel", the connection uses fittings for brazing pipes of different diameters, for example, according to the docking scheme "internal-external" or an adapter with internal soldering for the connected segments.

Plastic fittings are also molded in the form of corners, crosses, contours for avoiding obstacles by pipes.

All cast fittings are assembled by soldering, the only exception are plastic pipes and PVC couplings, they can be joined with glue.

Detachable

In addition to simple pipe joining, couplings are used to connect plastic pipelines to heating or pumping equipment. For these purposes, polypropylene adapters are used with a groove for soldering on one side, a nipple, a union threaded nut on the other.

If, according to technical conditions, it is required to make a collapsible connection at an arbitrary section of the pipe, then a threaded coupling is used. In fact, these are two halves of nickel-plated brass with external and internal threads, respectively.

Plastic inserts are pressed inside. Each half is welded to the end of the pipe with a standard soldering iron. If necessary, the connection can be disassembled and reassembled an unlimited number of times.

Consumer couplings

In addition to a simple connection, fittings are used to output fittings and create connection points for plumbing, mixers using a flexible hose. In the classic version, the branch is made in the form of a plastic tee made of polypropylene with a side metal insert.

But there are also more complex devices, for example, with a built-in tap or a water supply check valve.

What are sewer plastic pipe fittings

Modern sewage systems are assembled from thin-walled plastic pipes with a diameter of 50 mm or 100 mm. The individual segments are joined to each other according to the insert pattern with sealing of the junction with a rubber ring or spliced ​​with glue.

Sewer fitting - thin-walled plastic injection molding. More like a piece of pipe with a soldered branch. Mini-pipe ends of different diameters. The one with the ring spacer is larger, the opposite end is smaller by twice the wall thickness. The outer surface is slightly tapered.

There is a branch on the body of the sewer fittings. It will also be made with a spacer ring. This design makes it possible to insert the fitting into one another or into the sewer pipe, collecting an unlimited number of them. If the assembly of the plastic sewer is completed, a plug must be installed on the cut of the pipe section.

For the manufacture of parts, three types of plastic are used:

• polypropylene;
• polyethylene;
• polyvinyl chloride.

Polyisobutylene pipes and fittings are used for sewage drains of aggressive liquids, but they are more expensive than PP, HDPE or PVC, have not received wide distribution, and there is a special need to use an expensive polymer in the domestic sewage system no. On sale you can find products from a cheaper analogue based on polybutylene.

The specific version of the "pipe-fitting" pair is selected depending on the load, the nature of the sewage and the installation site, whether it will be an external or internal sewage system.

What types of sewer pipe fittings are used most often

In a private house or apartment of modern construction, the share of connecting elements is 15-20% of all sewer plastic. The smaller the area of ​​the housing, the greater the proportion of connectors in the total plastic wiring of the sewage system.

List of most used fittings:

1. Tee with angled outlet. Used to connect to sewer risers. Fittings with a diameter of 50 mm are used to connect sink or sink plastic corrugations.
2. Tee couplings. Used to connect plastic siphons of a shower or bath.
3. Corner turns. Applied to the sewerage plant in the house.
4. Revision block. It is used for cleaning pipes.
5. Adapter from 50 mm to 100 mm pipe. It is used at the terminal sections of the sewage system.
6. Tees with 30 branches^O and at 45^O. They are used in the arrangement of the branching of sewerage sections.

In addition to the above, sliding couplings, crosses, plugs are used a little less often in the home sewage system.

Fittings "for rubber ring" for indoor PVC drainage

PVC couplings for the assembly of sewer pipes are easily distinguished by their characteristic gray color. For internal sewerage, fittings with single-layer walls up to 2.2 mm thick are used. The surface of PVC plastic products features a smooth, almost glossy surface, which contributes to lightweight downstream sewage without additional pressure on the pipe walls, especially at the joints on the couplings.

Sealing at the joints is carried out by a rubber cuff ring. A characteristic feature of the ring is the presence of annular grooves on the inner surface. Ring diameter 55-110 mm.

Fittings "for rubber ring" for external sewerage

Systems for external drainage of sewage are of two types - pressure and non-pressure. They differ in the material used, wall thickness and connection method. For private households, non-pressure systems are used, respectively, fittings with pipes are connected to the seal with a rubber ring.

Plastic fittings and pipes for outdoor sewerage are painted orange, the body can have several layers of PP, PVC or XLPE. Usually the inner layer is made from the most resistant vinyl. The wall thickness is greater than that of couplings designed for internal sewer communications.

Sewer fittings for adhesive installation

The adhesive is used for joining plastic pressure pipes with fittings. Most often these are external sewerage lines, laid in areas with difficult rugged terrain. The glue method of connecting fittings to the sewer system is also recommended for private housing buildings of two or more floors.

The device of fittings for a glue joint differs from the scheme "for a rubber seal" only the presence of mounting pipes with a length of at least 50 mm, without any spacers and annular grooves under seal. Otherwise, the device of the couplings corresponds to the design of the models "for rubber".

How are plastic pipe fittings mounted

The assembly of polypropylene and polyethylene parts is performed by soldering. The pre-cut workpiece together with the sleeve is heated on an electric soldering iron, after which the parts are brought into contact, pressed and held for 10-15 seconds before cooling. If the technology is followed, a strong, cast connection is obtained, the structure of the weld does not differ from the parent material.

You can also solder water pipes with fittings made of PVC. For drinking water, this method is not recommended, as it requires heating to a temperature of 260 ℃, at which PVC can release organochlorine compounds.

It is easier to connect the PVC section to the sleeve using glue. It is enough to slightly remove the gloss from the end of the workpiece to be glued, degrease, apply glue and insert the pipe inside the tee or coupling. The connection will be ready for use in 2.5 hours.

Features of the wiring of the plastic line

Planning plastic water pipes does not differ from working with steel lines. There is only one feature - when wiring plastic communications, you need to take into account the high coefficient of thermal expansion of the polymer. This means that the plastic will expand when heated. This means that it will be necessary to make compensation loops, "pockets", which would compensate for the elongation of the pipe.

Therefore, first we select the places for installing and connecting fittings, couplings, taps, bends, and only then we solder or glue sections of PVC or PP pipes between them. It is clear that the workpieces need to be cut with a length allowance for each soldering point.

It is because of thermal expansion that domestic, domestic sewage is carried out on rubber sealing rings. Each section is cut with a small margin along the length of 25-30 mm, depending on the length of the drain. Thus, the absence of a rigid connection allows the plastic to "play" without breaking the joint.

It is impossible to assemble sewer systems of a long length on elastic bands with additional sizing with a sealant or adhesive. In the event of a large temperature difference, the seal can be pushed out of the O-ring groove.

How to install fittings for plastic sewer pipes

Initially, you need to collect the sewer dry. The workpieces are cut with a margin of length, couplings and tees for a glued joint are temporarily upset without glue. If the connection is on the cuffs, then the sealing gum is placed in the grooves and lubricated with liquid soap.

After the sewerage is assembled, the drain levels are set, the length of each section is determined, the notches of cuts are drawn, points for mounting clamps are applied to the walls, the system can be disassembled.

Next, we carry out the final assembly. Each workpiece must be cut with a hacksaw for metal to the size at risk, deburred, gently wiped off the soap on the rubber and insert the section. Next, extend the section by 2-3 mm so that a thermal gap remains, after which we grab the joint with adhesive tape and move on to the next coupling or tee.

If the sewage system is assembled with glue, then each joint of the fitting-pipe is glued "tightly", fixed with tape and immediately fastened with a clamp to the wall. The orientation and direction of the bends are set at the same time.

Fittings for plastic pipes simplify the installation of plumbing and sewage. In addition, any technical system is not insured against breakdowns or defects, in this case the problem is solved by simply replacing the fitting with a short pipe section.

Connection elements for polypropylene pipes (polypropylene fittings): video.

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