Connecting polyethylene pipes - methods. Flange connection of polyethylene pipes with steel pipes, transition of HDPE to metal Saddles and their scope

When installing water and gas pipelines, there is a constant need to connect pipes made from different materials. To connect polyethylene pipes (HDPE, PE) with steel pipes, the following are used: special polyethylene-steel adapters (NSPS), threaded compression couplings or a bushing for a flange connection.

Types of connections between PE pipes and steel pipes.

1. Permanent connection of polyethylene-steel (NSPS)

One-piece polyethylene-steel connection (NSPS) or PE-steel adapter used in the construction of gas pipelines, water pipelines, pressure sewers to make the transition from steel pipe to polyethylene HDPE or vice versa. Used during installation pipeline fittings or insertion into an existing steel pipeline. The steel-PE transition does not require maintenance; it can be placed directly in the ground without wells on straight sections of the pipeline.
The polyethylene-steel transition is a connection obtained by welding a steel pipe to a polyethylene one. The length of the pipes is regulated technical specifications for gas pipelines TU 4859-026-03321549-98, for pressure pipelines according to TU 2248-001-86324344-2009. Maximum operating pressure for gas pipelines made of PE80 0.64 MPa, PE100 1.0 MPa. The maximum operating pressure for pressure water pipes is PE80 1.25 MPa, from PE100 1.6 MPa.
In the manufacture of permanent polyethylene-steel joints, HDPE polyethylene pipe is used GOST R 50838-95 for gas pipelines and GOST 18599-2001 for water pipelines. And steel water and gas pipe according to GOST 10705-80, GOST 10704-91, GOST 8731-74, GOST 8732-78. NSPS is a connection that is made by welding a steel pipe to a polyethylene pipe. The length of the product is regulated by specifications for pressure pipelines and gas pipelines. Pressure for gas pipelines PE 80 - 0.64 MPa, PE 100 - 1 MPa; for pressure pipelines PE 80 - 1.25 MPa, PE 100 - 1.6 MPa.

Most often NSPS is used for connecting metal shut-off devices to a polyethylene pipeline, gradual replacement of sections of a steel pipeline with polyethylene, inserting a branch made of polyethylene. The principle of the NSPS part is a strong and tight connection of a pipe or part made of steel with a polyethylene pipe of the same diameter.

The permanent connection to the end of the pipe occurs through thermistor welding, which requires special equipment. The end of the polyethylene pipe is heated to a viscous-ductile state and is connected under pressure to the steel end. To strengthen the connection, polyethylene couplings are used, but you can do without them. It allows the use of such a connection in high-pressure pipelines.

NSPS allow:

• Use them as plugs;
• Use shut-off valves made of metal on polyethylene pipes on HDPE wires
• Produce gas inlets of various diameters based on them
• Drain polyethylene into an existing steel pipe
• Use welding on steel pipelines with steel pipes in accordance with regulatory documents.
• Installation of metal shut-off valves in HDPE polyethylene pipelines
• Alternately replacing sections of steel pipelines with polyethylene ones with permanent connections until the complete replacement of the existing steel pipeline with polyethylene
• Inserting branches from HDPE polyethylene pipes with permanent connections into an existing steel pipeline
• Welding with steel pipes according to the current regulatory documentation on steel pipelines with permanent connections.

2. Threaded compression couplings

Compression polyethylene HDPE fittings. This type of connection hardware is called compression tube fittings. They are attached to the system using gasket material and crimp rings. To use this type you do not need any optional equipment. In addition, when producing gasket material, you can replace the old gasket with a new one. That is, HDPE fittings of this type can be used repeatedly, especially in hydraulic systems Oh.

Compression products are mainly used for hydraulic water supply systems. They can be built into such a system even if they are not fully assembled. This allows their application in water supply systems to vary widely. Compression fittings come in the following types:

• adapter couplings of different diameters;
• couplings, including those with internal and external threads;
• tee without thread and adapter with thread;
• square;
• tap;
• stub.

They come with both internal and external threads. Like other fittings, these have various shapes. They are: coupling, triple, cross, plugs, flanges, bends.

They are made different diameters: from 16 to 110 mm. Working pressure, depending on the diameter, can range from 10 to 16 atmospheres.

All design components are modular and can be disassembled. This has good advantage, since in the future such pipes will be easy to replace and the connection to be reused.

Application polyethylene HDPE fittings

Most often, these fittings are used to connect pipes in places where a change in the direction of the pipeline is expected, as well as the presence of branches or transitions to pipes of a different material. They are used for both technical and drinking water supply, in irrigation systems or as cable ducts. Thanks to the material, these fittings allow for complete tightness of pipe joints.

Application of compression fittings for connecting pipes

Also, their ease of installation allows you to install parts of small diameters without outside help and special equipment. These parts are stored in dark rooms, away from direct sunlight.

This part consists of 5 collapsible parts. To secure the crimp, there is a nut cover, which has external grooves for ease of tightening and an internal thread. It is made from polyethylene copolymer.

The crimp ring is a part that allows you to prevent any movement of the pipe, including spontaneous unscrewing.

Structure of compression fittings

The sleeve fixes sealing gasket in a stable position, limits its compression and deformation of the pipe. Made from polypropylene copolymer.

The sealing gasket is made of rubber. Provides good tightness, even if the pipe is kinked.

The body itself is made of polypropylene copolymer, has a special pipe stop and trapezoidal thread.

3. HDPE bushing for flange

Polyethylene sleeveunder the flange is used for connecting a PE pipe to a steel pipe through a flange connection, as well as fastening to control or shut-off valves.

Among HDPE bushings there are 2 groups:

Segmental bushings HDPE - Such bushings are butt-welded elements made of HDPE, partially or entirely consisting of HDPE pipe.

Cast HDPE fittings - They differ from segment ones in that they are made by injection molding and do not have welded seams. Fittings of large diameters are sometimes produced by casting followed by machining.

The principle of using this fitting is to provide support for the flange placed on the sleeve and eliminating the possibility of disconnecting the unit during its operation. Use a bushing for the flange at the transition points of the polyethylene pipeline on the valve or a steel pipe if there is a counter flange on it.

The HDPE bushing for the flange is used in conjunction with a pressure flange, which must have a wider inner diameter than a normal standard flange. The need for boring the inner part of the flange lies in the presence of a reinforcing expansion of the polyethylene part of the sleeve at the base of the collar, which prevents the flange from fitting tightly to the clamping part.

After installing the sleeve on the pipe, using a steel flange and bolts with nuts, the pipe is attached to the valve, and the collar on the sleeve prevents the flange from coming off when the pipeline is operated at operating and maximum pressures.

Using HDPE bushings

Installation of bushings is quite simple, because everything modern elements connecting fittings strive to simplify their use. This saves time and money when creating the pipeline, and also allows for long-term operation of the system without problems. The benefits of installing different types of system elements using bushings are as follows:

• complete tightness of the connection points and no risk of sudden breakdown;
• the system does not require maintenance, any problems can be quickly corrected;
• installation of HDPE pipeline elements is quick and very simple;
• You can find a wide range of bushing diameters in stock from the supplier.

When organizing a pipeline for liquid or vapor working environment You can rely on the quality and reliability of injection molded plastic flange bushings at the joints. These elements will help organize a reliable and durable pipeline system.

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Flange adapter - special device to create a tight connection in pipelines. The part serves as an adapter for firmly connecting parts of a pipeline or flange for connecting shut-off and control valves and other parts of the system. The flange adapter for polyethylene pipes differs from other types in terms of temperature and pressure limits in the system, and also cannot be used in lines with an aggressive working environment.

The design is a device consisting of a coupling and a flange. You need to use bolts to connect the adapter to the pipeline flange, and the coupling to the smooth end of the pipe.

When the bolts are tightened, the clamping rings move towards each other, the seal is deformed, pressing tightly against the outer surface of the pipe, thereby creating a strong connection between the parts of the pipeline.

Advantages and disadvantages of the device

The adapter acts as a compensator for compression and tension of the axis and smooths out minor deviations from initial project in progress installation work and operation.

The part allows you to install pipes made of polyethylene and polyvinyl chloride into a metal pipeline. The device is resistant to vibrations, elevated temperatures and pressure surges.

Thanks to the gasket-seal, the part can be used, including in systems with an aggressive working environment.

To make the connection, no special tools are required, except a wrench, and no special skills or abilities, which saves both time and money.

Note! The only drawback is that due to too strong clamping, over time the gasket that ensures a tight fit is destroyed.

Types of adapters and scope of application

The flange adapter is used in shipbuilding systems, automotive, construction and housing, oil and gas industries.

There are several types of flange adapters:

• adapter for cast iron pipes;
• for installation of PVC pipes;
• for PE pipelines;
• for AVK (applies to both PE and PVC pipes nal products).

Note! The device for polyethylene pipes is used only in systems operating at standard pressure values ​​and a maximum temperature of 700 C only for transporting water and other neutral liquids.

Flange adapter for PE pipes: technical specifications

The adapter for PE pipes features an epoxy coating, which is applied electrostatically.

When installing PE pipelines, for joining them together or for installing fittings, flanges for polyethylene pipes are used.

This part is capable of providing the most reliable, durable and leak-tight flange connection.

Contents of the article

Part Features

The fixing fitting for PE and PVC pipes is a flat disk with equally spaced holes for bolts. This product is installed together with a collar or bushing.

Types of products

The main parameters by which flange products for PE and PVC pipes are characterized are the internal diameter, external dimensions, weight and working pressure.

Depending on what tasks these parts perform, The following types of adapters exist:

• adapter with special welded bushings;
• slip-on metal flange;
• flange adapter free type, resting on a straight or tapered collar.

The best way to connect light and medium PE pipes with a diameter of no more than 150 mm and light pipes with a diameter of up to 300 mm is a loose flange supported by a straight collar. A loose flange with a tapered collar is used for fittings with a diameter of more than 200 mm.

Characteristics of the fixing flange for polyethylene pipes (video)

Advantages and disadvantages of a flange for PE and PVC pipes

The clamping steel loose flange adapter has several advantages over other parts, which makes it more popular to use. The main ones are as follows:

1. The adapter allows you to install PE in a metal line, which also makes the repair of such systems more accessible.
2. To install the flange there is no need to use any special tools or spend a lot of time: wrench and a little skill allows you to install the part without any problems.
3. Also, the clamping flange adapter has the ability to compensate for the process of compression and extension of the axis and this is Allows you to simplify the process of installation and operation, and reduce installation time.

As for the disadvantages, the most significant is the fact that the gasket that ensures a tight fit is destroyed. This occurs due to the fact that they are clamped as tightly as possible, and this leads to exceeding the tensile strength of the material.

Structurally, the most unsuccessful in this regard, since it cannot protect the gasket from deformation.

Those product models in which gaskets are provided in some recesses are considered more protected from gasket rupture, however, they do not provide full protection, especially with a long service life of the part.

When installing the flange, take into account the fact that When exposed to heat, metal can expand. This causes the fastener elements to elongate more than the adapter itself, which can compromise the seal of the flange connection.

IN Lately very often when installing various systems water supply and heating connection required plastic pipes with metal ones. To solve the problem of installing pipes from various materials you can choose one of the options proposed in our article - threaded or flanged connection.

Types of connections

There are two types of connections:

1. Threaded connection. For connecting polyethylene pipes with metal pipes, do not large diameter(up to 40 mm) it is best to use special fittings with threads for metal pipe and a smooth coupling for the plastic one.

Pro tip:

To securely seal threaded connection metal part of the structure, use bleached flax fiber, as when assembling ordinary steel pipes.

1. Flange connection. For large diameter pipes they are used various types flanges, since it is difficult to imagine threads on a large diameter pipe, for example 600 mm, that can be tightened by hand.

We will look at a threaded connection using an example polypropylene pipes, and flanged - polyethylene, however, it is worth noting that each type of connection is suitable for both types of pipes.

Technology for connecting plastic pipes to metal ones

Using Threaded Fittings

To install polypropylene pipes with metal parts (pipes, mixers, meters, filters, etc.), fittings with a thread of the required diameter on one side and a coupling for soldering a plastic pipe on the other are used. The thread on such fittings can be either internal or external.

Connecting steel and polypropylene pipes using fittings:

1. Unscrew the coupling of the steel pipe where you intend to connect it to the plastic pipe, or cut off part of the old metal pipe, lubricate the edge with grease or oil and cut a new thread with a thread cutter.
2. Wipe the threads, wrap tow (or fum tape), and lubricate with silicone. Make no more than one or two turns so that the edge of the tape, when clamped, is directed along the thread.
3. Screw on the pressfitting without using a wrench to avoid cracking. If necessary (if water flows after turning it on), tighten the fitting.

By using polypropylene fittings various configurations it is very convenient to make various kinds of bends and turns in the mounted pipeline system. It is also possible to change the fitting configuration by heating it with construction hair dryer, but not more than 140 degrees. It should be remembered that polypropylene ignites when heated above 350 degrees, and you should not allow it to overheat.

Polypropylene pipes have the ability to expand and contract at different temperatures. Therefore, when using them for heating or supplying hot water When installing pipes in the wall under a layer of plaster, you should leave a gap in the grooves of at least 1 cm using tubular insulation, especially around the contours and tees.

Using flanges

A fairly frequently used detachable type of connection for polyethylene pipes is a flange connection. To implement this, bushings for flanges are used, welded to the ends of the pipes, or slip-on flanges made of metal.

Installation of plastic pipes using flanges is used:

• for connecting polyethylene pipes to steel components systems: pipes, pumps, valves;
• to allow quick disassembly of the pipeline in case of need for cleaning or repairs;
• when connecting large diameter pipes.

Free flanges supported by collars are most suitable for plastic pipes. To connect steel and polyethylene pipes,

free ones are selected steel flanges in sizes that correspond to the sizes metal parts of the installed pipeline.

Pro tip:

Pay special attention to the absence of sharp elements and burrs on the metal flanges that could damage the polyethylene pipe.

Some features of flange connections:

• for medium and heavy polyethylene pipes with a diameter of up to 150 mm and for light pipes with a diameter of up to 300 mm the most suitable option– use of loose flanges resting on a straight shoulder;
• a straight collar with a tapered transition is used to increase the strength of the connection;
• free-type flanges supported by conical collars are used to connect pipes with a diameter of more than 200 mm;
• a wedge connection, which has a shaped flange and a steel projection, can be used for pipes of any diameter.

Work order:

1. Cut the pipe at the connection point. Make sure the cut is even.
2. Place a loose-type metal flange onto the pipe.
3. Put on the rubber gasket. Do not allow it to overlap the pipe cut by more than 10 mm.
4. Slide the flange onto the gasket and connect it to the counter flange with bolts.

Pro tip:

Tighten the bolts evenly to no more than the torque specified on the flange and accessory specifications.

As you can see from the instructions, both methods are quite simple to perform. The only condition for their operation is to carefully follow the description - then your pipeline will be of high quality and reliable.

Modern water pipes are rarely made of metal. It has worthy competitors - polymers, which are gradually replacing it in many areas. One such material is polyethylene. low pressure. Pipes for pressure pipelines, that is, for water pipelines and even gas pipelines, are made from this material. This type of material is becoming increasingly popular, since connecting polyethylene pipes is easy to do with your own hands. You just need to follow very simple rules.

Advantages and features of application

Polyethylene pipes are made from low-density polyethylene. This material is abbreviated as HDPE. It is characterized by increased strength and elasticity, and has good performance properties:

• chemically neutral, can be used for transporting food products;
• smooth walls prevent the formation of plaque inside;
• not subject to corrosion;
• small coefficient thermal expansion— about 3% at maximum heating (up to +70°C);
• They react normally to the freezing of water inside, due to elasticity they increase in diameter, and after thawing they return to their original dimensions.

One point to remember! If you need frost-resistant pipes (for example, for), when choosing, look at the description or specifications. Not all types of copolymers used for pipe production tolerate freezing well. So be careful.

The main disadvantage of polyethylene pipes is the restrictions on the temperature of the transported medium: it should not be higher than +40°C, that is, only cold water supply can be made from HDPE; they cannot be used for hot water and, especially, heating.

Another point: polyethylene does not tolerate UV radiation well. When constantly exposed to the sun, the material loses its elasticity and, after some time, breaks (some manufacturers make HDPE pipes that are UV-resistant, but they are more expensive). Therefore, open laying of water supply pipes from plastic pipes is very undesirable. But lay the pipe in a trench from the well or well to the house, make the wiring cold water It’s very possible to do it around the house. It's quite economical and convenient solution, since installation and connection of polyethylene pipes is not very difficult. If we're talking about About the detachable connection, it does not require any equipment. All you need is fittings and hands.

Which polyethylene pipes are better?

For production water pipes Two grades of polyethylene are used - PE 80 and PE 100. The hundredth polyethylene is more dense and durable than the eightieth. For water supply systems in a private home, the strength of PE 80 is more than enough - they can withstand pressure up to 8 atm. If you like a large margin of safety, you can take them from PE100. They work normally at 10 atm.

What you should pay attention to is the country in which it was produced this product. The leaders in quality are European manufacturers. High accuracy execution guarantees high system reliability. Average quality and prices are from Turkish companies, in the cheaper price segment are Chinese manufacturers. Their quality, as usual, is also much lower. It’s difficult to give advice here; everyone chooses at their own discretion (or what is available in the region).

Types of HDPE pipe connections

There are several types of polyethylene pipe connections:

• detachable (on fittings or couplings);
• one-piece - by welding:
  • using a special welding machine;
  • electric couplings - a heater is built into such couplings when power is applied to it electricity, the polyethylene heats up and fuses.

They mainly weld large-diameter pipes, which are used to create main pipelines. Pipes of small diameters - up to 110 mm, used in private construction, are mostly connected using fittings. Couplings are used more often when repair work, since their installation takes longer.

Fittings for polyethylene pipes are shaped parts (tees, crosses, angles, adapters, couplings) with the help of which the required system configuration is created. Because self connection Inspection of polyethylene pipes is often carried out using fittings, let's talk about them in more detail.

Assembly on compression (crimp) fittings

An entire system is installed on one or two sides of the fitting (sometimes on three) to ensure the connection. The fitting itself consists of:

How reliable is the connection?

Despite the apparent unreliability, the connection of polyethylene pipes to compression fittings reliable. Properly made, it can withstand operating pressures of up to 10 atm and higher (if these are products from a normal manufacturer). For proof, watch the video.

This system is good due to its ease self-installation. You probably already appreciated this from the video. Simply insert the pipe and tighten the thread.

Summer residents, in addition to the opportunity to do everything with their own lessons, like it because, if necessary, everything can be disassembled, hidden for the winter, and put back together again in the spring. This is in case the wiring is made for irrigation. The dismountable system is also good because you can always tighten the undercut fitting or replace it with a new one. Disadvantage - fittings are bulky and internal wiring in a house or apartment is rarely made from them - appearance not the most pleasant. But for the water supply section - - better material difficult to find.

Assembly order

The pipe is cut strictly at 90°. The cut should be smooth, without burrs. There should also be no dirt, oil or other contaminants present. Before assembly, the sections of the joined sections are chamfered. This is necessary so that the sharp edge of the polyethylene does not damage the rubber sealing ring.

During installation, the connection of polyethylene pipes to compression fittings tighten by hand

The spare parts are put on the prepared pipe in this order: the compression nut is tightened, then the collet, then the thrust ring. We install the rubber gasket into the fitting body. Now we connect the body and the pipe with the parts put on it, applying force - you need to insert it all the way. We pull all the spare parts to the body and connect them using a crimp nut. Tighten the resulting connection of polyethylene pipes with force by hand. For reliability, you can tighten it with a special mounting key. It is not advisable to use other tools for tightening: the plastic may be damaged.

Saddles and their scope

In addition to fittings, there is another interesting device that allows you to make branches from a ready-made pipeline. These saddles are specially designed couplings. This coupling has one or more threaded holes. A tap is usually installed in them, and a new branch of the water supply is connected to it.

The sedeks are put on the pipe and secured with screws. After that, a hole is drilled in the pipe surface with a drill and a thick drill in the branch. When it is ready, a crane is installed and the branch is assembled further. This is how the system is improved with minimal effort and cost.

Flange connections and transition to metal

System elements that have a flange rather than a threaded connection can be installed in the water supply system. Usually these are taps or other shut-off or control valves. To connect to such elements there is a special fitting for HDPE. On one side there is a standard compression version, on the other there is a flange version. Installation is standard - using a crimp nut on one side, gaskets and bolts on the flange side.

When installing a water supply system from polyethylene pipes, questions may also arise about the connection between polyethylene and metal. For these cases, fittings are used, on one side of which there is a thread. It can be external or internal, depending on the type of device or transition being installed. Such fittings are either straight or in the form of a 90° angle.

The installation is standard - a thread (with careful winding) on ​​one side and a compression nut on the other.