Connecting a cast iron funnel with a plastic pipe. Connection of plastic and cast iron pipes. Step-by-step connection instructions

Cast iron sewerage lasts a long time, but after several decades of operation the system needs to be replaced. When conducting repair work you can purchase new cast iron elements, but most owners prefer to use more convenient ones polymer products. If a partial replacement of the system is underway, the question will certainly arise of how to connect cast iron pipe with plastic.

During renovations in a bathroom, sewer pipes are often replaced from cast iron to plastic, since the old sewage system has already served its purpose, and the lungs polymer parts more convenient to use than cast iron products.

When staying in apartment building It is rarely possible to agree with all the neighbors on the riser about the simultaneous replacement of pipeline elements, so you have to think about how to connect a cast-iron sewer pipe with a plastic one.

Dismantling

If cast iron sewer pipes are being replaced with plastic ones, then you need to start with dismantling. Of course, breaking is much easier than building, but one important circumstance must be taken into account: cast iron is a fragile material, so it must be handled with care.

If you break the pipeline with a hammer, pieces of cast iron can get into the system and cause a serious blockage. Particular care must be taken during dismantling in the area where it is planned to connect the cast iron pipe to the plastic one.

The section of the pipeline that cannot be replaced must not be damaged under any circumstances. Since previously the joints were sealed by placing a cement-based mortar inside, it will not be easy to clean the bell accurately.

Advice! If during the dismantling works The socket part of the remaining part will still be damaged, it will have to be carefully cut off, and then a socketless connection of cast iron and plastic sewer pipes will be made.

Connection methods

Let's figure out how to replace a cast iron sewer with a plastic one. Since, unlike water supply, sewerage is gravity system, then when installing a pipeline they rarely resort to welded joints.

As a rule, “socket” connections are used. Special fittings are used less often. First, we will describe connection methods that can be used if the socket of cast iron pipes remains intact.

Rubber seal

This pipe connection is done quite quickly and simply. The connection can last 8-10 years, after which the rubber gasket will most likely need to be replaced. Before connecting a plastic pipe to a cast iron socket, you need to perform the following operations:

• thoroughly clean all parts, it is necessary to remove remnants of previous sealing materials and dirt;
• Next, you need to prepare a rubber seal; sealant is applied to it (on the outside;
• the prepared seal must be inserted into the cast iron socket.

Now all that remains is to forcefully insert the smooth end of the plastic sewer pipe into the socket. The depth of insertion is 5-8 cm.

Caulking

This traditional method, it has been used for many years to create connections for cast iron pipes. But caulking is also suitable if you plan to connect a plastic pipe with a cast iron pipe that has a socket. How to do the work:

• a flax winding is wound onto the smooth part of the prepared plastic pipes, and the material is wound in several layers;
• Now you can insert the polymer element into the cast iron pipe;

Advice! To make it easier to insert a plastic product with a winding into the socket, it is recommended to use a small narrow spatula, with which the winding is pushed into the gap between the inserted part and inside bell

• Having completed the embossing, that is, filling the gap between the elements, you will need to cover the joint. To do this, prepare a solution of cement, water and PVA glue.

The advantage of this joining method is that it is very durable. If the rubber seal has to be replaced after a few years, this connection will last much longer.

The disadvantage of this method is that the solution needs to be given time to dry, so it will be possible to use the sewer only after a couple of days, and you won’t have to wait when installing a rubber seal.

Silicone

This method of connecting cast iron pipeline parts with plastic ones is used if, after introducing plastic part a gap of no more than 2 mm wide remains in the socket. In this case, it is irrational to use caulking; it is much more convenient to use plumbing silicone. Work order:

• plastic part, as well as inner part The cast iron socket must be cleaned most thoroughly. In addition, the joint must be dried;
• the plastic element is inserted into the socket, after which, using construction pistol the gap between the pipeline parts is filled with silicone. You need to try to ensure that the silicone is located not only on the surface of the socket, it should fill the gap. Moreover, the deeper the material penetrates, the more reliable the connection will be;
• Now you need to let the silicone harden, this will take 3-5 hours depending on the thickness of the layer.

If the bell is damaged

If the bell is damaged, then the methods described above are not suitable. When performing installation, you will need to purchase an additional part - an adapter that allows the transition from a cast iron pipe to a plastic one. The procedure for connecting pipeline elements is as follows:

• the damaged socket is carefully cut off with an angle grinder;
• the edges are processed;
• put on the prepared part of the cast iron pipe sealing ring made of rubber and a rubber cuff;

• the edge of the rubber part is lubricated with sealant, then a plastic adapter is put on;
• lubricate the adapter pipe with sealant and install another rubber O-ring;
• After this, you can insert the plastic part into the adapter.

Which method should I use?

In practice, if it is necessary to connect the plastic part of the system with a cast iron pipeline, most often a combined method is used. If there is a wide gap between inner wall bell and plastic pipe use the installation of a rubber seal and caulking. After the solution has hardened, you can additionally treat the joint with silicone.

We use fittings

To make the connection, you can use a special fitting - an adapter. To seal the connection you will need to purchase Teflon tape. Work order:

• the cast iron pipe is cut using a grinder;
• the treated edges are coated with lubricant;

• Next you need to cut a thread to connect to the adapter fitting; for this you will need a thread cutter;
• sealing tape is applied to the prepared thread and lubricated with sealant;
• screw a fitting onto the prepared threaded connection;

Advice! The fitting must be installed manually, as using a wrench may damage the fitting.

• V reverse side a plastic pipe with a crimp collar put on it is inserted into the fitting;
• The coupling is crimped; a special press is used to perform this work.

So, if a replacement is carried out cast iron sewer on plastic, you will have to make pipe connections from different materials. There are several ways to do this work; which option to choose must be decided on site, depending on the width of the gap between the pipes.

If you are deciding how to connect a cast iron sewer pipe to a plastic one, you need to consider everything possible ways. Metal communications have been in use for long period, however, sooner or later they need to be changed. Sometimes only a section of pipe needs to be updated. This method has its drawbacks, because cast iron and plastic are characterized different properties. When choosing a suitable method, you should take into account the state of communications and the availability of free access to pipes. All actions must be carried out in accordance with SNiP.

Connecting a cast iron sewer pipe with a plastic one

The connection of cast iron and plastic sewer pipes is carried out in stages. First you need to prepare workplace. Free up space in the area where repairs will be carried out. It is necessary to determine the type and quantity of components for installation. Most often, 2 standard sizes are used: 50, 110 mm. If you plan to change the sewer pipe in the toilet, use the second option. Communications with a diameter of 50 mm are installed in the bathroom.

At the next stage, the number of knees is calculated. On open area a straight pipe is installed. If the room is small or there are incoming elements that interfere with the installation of communications, turns of 45-90° are provided. Their number varies depending on the configuration of the room. However, the more bends are installed, the more difficult the outflow of the sewer system becomes. You should not install more than 2-3 similar elements. Before starting work, it is necessary to shut off the water riser.

Removing cast iron pipes

Prepare the following tools:

• corner grinder(angle grinder), it is called an angle grinder;
• hammer (rubber or mallet).

Cast iron communications are fragile, so you need to work with them carefully. If you remove a section of pipes with a hammer, you can damage the pipeline that is planned to be connected to plastic products. There is a high probability that pieces of cast iron will fall into the opening of the riser and a clog that is difficult to remove will form. For this reason, it is better to use an angle grinder. The cuts will be smooth, making it possible to connect a plastic pipe.

There is no need to remove the bell during dismantling. Thanks to this design element it will be possible to obtain reliable connection. After removing a section of the pipeline, the cut is cleaned. It is necessary to remove the remains of the cement mortar that is used when installing cast iron communications. Additionally, attention is paid to rusted areas. All contaminants are removed from the pipe cavity, the internal and external surfaces are cleaned and wiped dry. If you plan to use silicone sealant, the products at future joints are additionally degreased.

Methods for connecting cast iron sewers to plastic ones

Exist various methods installation of a pipeline made of materials characterized by different coefficients of thermal expansion. In this case, it is permissible to use auxiliary means (sealant, rubber gasket, flange, press fitting), but it is also permissible to use combined methods that require simultaneous use different ways. If the question of how to connect a cast iron pipe to a plastic sewer is being decided, the choice of option should be made taking into account the state of communications.

Connection with rubber gasket

This method is considered the easiest to implement and affordable. The cost of the rubber gasket is minimal and no experience is required to install it. The advantage of this method is an increased degree of elasticity, which is important because... cast iron and plastic are characterized different indicators coefficient of thermal expansion. As a result, the likelihood of product deformation is reduced due to the flexible ring.

The service life of the rubber seal is 8-10 years, but taking into account its minimum cost, there will be no problems with replacement. If this element is not changed for a long time, it loses its elasticity, cracks, and ceases to restore its shape after exposure to loads. As a result, a leak will appear in this area. The dismantling process when replacing the seal is carried out according to the same scheme as installation.

The rubber cuff is characterized by a complex configuration. Surface of this element has many protrusions that run along the entire circumference of the product. This ensures maximum compaction when installing pipes. Using a cuff, it is preferable to connect cast iron communications with a socket. IN in this case The expansion on the pipe allows you to easily install the plastic product.

Cast iron pipe with socket

Connecting cast iron communications through a rubber adapter can be done following the instructions:

1. The metal pipe is cleaned of rust and contaminants. To do this, use abrasive devices (metal brush). If depressions have formed on the inside of the pipe, the unevenness can be smoothed out using silicone sealant. It is applied and distributed evenly. When irregularities are eliminated, excess material must be removed, and this should be done carefully, otherwise the deformed areas will again be cleared of sealant.
2. To ensure that the rubber seal is firmly fixed, before installing the metal pipe, it is necessary to apply a sealant to the outer surface of the product. After this, you need to immediately install the adapter into the pipeline.
3. The plastic pipe should be inserted into the socket of the cast iron pipeline. The installation depth is 50-80 mm.

Cast iron pipe without socket

If for some reason there is no extension at the communications section, the connection can still be made, but its reliability will be lower, because in this case, a plastic adapter is additionally used. Instructions for installing pipelines made of different materials:

1. If the cut is uneven, you should remove the section of pipe along with it. Then the edge is cleaned.
2. A rubber gasket is installed in the pipe cavity, having previously treated its outer side with silicone sealant.
3. At this site, a plastic adapter is being installed into a cast iron pipeline. The configuration of this product varies. The plastic adapter can be made in the form of an elbow or have the shape of a cylinder. It is installed in the cavity of a cast iron pipe to a depth of 50-80 mm.
4. On last stage installation in progress plastic pipeline into a pre-mounted adapter. In this case, a rubber seal should also be used. When installing it, the outer surface is treated with silicone sealant.

Caulking

This method has been used for a long time. It is used when installing cast iron pipelines. In this case do not apply rubber seals. The joints of communication sections are sealed using tow (winding made of flax). Used for strengthening cement mortar. This method is used when the leak between the walls of cast iron and plastic pipes is 3-5 mm. Instructions for installing communications using the caulking method:

1. Plumbing paste is applied to the plastic pipe, and tow is wound on top. The caulking depth is 2/3 of the socket length.
2. The product is inserted into the cast iron pipeline until it stops.
3. Compact the tow using a narrow spatula and a screwdriver.
4. The remaining 1/3 of the socket is filled with polymer cement mortar. At home, it is prepared from cement, water and PVA glue.

The advantage of this method is a high degree of reliability. If the rubber adapter is used for 8-10 years, then thanks to the caulking method the pipeline joint will last much longer. It also has disadvantages. So, they note the need to wait 1-2 days until the cement mortar hardens. During this period the pipeline cannot be used. This will lead to deformation of the seam joint, which in the future will cause destruction of the polymer-cement layer and the appearance of a leak.

Silicone sealing

This method is recommended for use when the gap between communications does not exceed 2 mm. It is not advisable to use tow and cement mortar, because... It will be difficult to compact the flax. The tool will not fit into a narrow gap. The level of effectiveness of the method based on the use of silicone when sealing large leaks is reduced, but for small gaps it is suitable because provides high degree reliability.

For this purpose, plumbing or universal silicone sealant is used. The substance is applied to the surface of communications using a special gun and a plastic nozzle. Installation instructions:

1. The pipeline section must be thoroughly cleaned. Remove rust, large debris and dust. It is important to degrease the surface of communications, which will help increase the adhesion of materials.
2. Before application, it is necessary to dry the joint area; for this purpose it is recommended to use a hair dryer.
3. A plastic pipe is installed in a cast iron socket.
4. The gap between the communications is filled with silicone. If possible, it is recommended to seal the connection along the entire length of the socket, then the degree of reliability of the fastening will increase.
5. Additionally, you can treat the joint area with sealant on the outside.

The material dries within 3-5 hours. The pipeline should not be used before the end of this period. Important condition— communications must be securely fixed during work, because joint mobility will lead to deterioration in the quality of sealing.

Combining different methods

If the leakage between the pipes is large enough (from 5 mm), it is recommended to use various methods simultaneously:

1. Rubber seals and silicone sealant. First of all, a flexible adapter is installed. Then a plastic pipe is inserted into the socket, and the gap is filled with silicone sealant. The principle of using these materials is described above. In this case, technologies are combined, but installation is carried out in stages.
2. Caulking method and silicone sealant. In this case, instead of a polymer cement solution, a sealant is introduced into the gap between the communications, but first it is partially filled with tow.

Connection using a press fitting

In this case, a special adapter made of metal (steel) is used. On one side there is a thread for connecting to a cast iron pipe, on the other there is a socket for connecting a plastic pipeline. To work you will need an angle grinder and a thread cutter. Installation instructions:

1. It is necessary to prepare a cast iron pipe. Make a cut using a grinder. If a coupling is installed in this area, unscrew it. The threaded connection is already ready. Otherwise, you need to do the thread yourself, for which you use a thread cutter.
2. A sealing tape is applied to the prepared cut. As alternative option tow can be used.
3. For strengthening threaded connection sealant is applied on top.
4. Install the press fitting. However, it must be screwed onto the pipe manually. Use adjustable wrench in this case it is impossible, because the fitting may burst.
5. On the other side, a plastic pipe with a crimp collar is connected.

In order for this section of the pipeline to operate without interruption, you must remember that a fitting made of polyvinyl chloride cannot be installed on a metal base.

Flange connection

This method is more suitable for installing large cross-section communications. The flange is durable and provides a reliable connection, but it can damage the plastic pipe if it has burrs or sharp edges. The choice of flange is made taking into account the diameter of the pipeline:

• to increase strength, a straight collar with a tapered transition is used;
• loose flanges (focus on a straight collar) are prepared for connecting light pipes with a diameter of 30 cm, as well as heavy products with a diameter of up to 15 cm;
• a free flange (focus on a conical collar) is used to install communications with a diameter of 20 cm.

First, a cut is made on the cast iron pipe. It should be smooth without errors. Then a rubber O-ring is installed on the end of the pipe. At the last stage, a flange is pushed onto the seal and secured with bolts. It is important to ensure uniform tightening at all points.

If installation is planned new sewer, switching from cast iron to plastic will be a must. The reasons for replacement can be different, for example, old pipes becoming unusable, rust, and others.

Very often, if it is necessary to replace old pipes with plastic products disagreements arise with neighbors, so connections have to be made new design with cast iron.

How to properly connect a cast iron pipe to a plastic product?

To connect plastic to cast iron, it is advisable to use rubber cuffs and plastic adapters.

Connecting a new plastic pipe with an old cast iron one

If cast iron has a socket, then you only need to purchase a rubber adapter. In another case, you will also need a plastic adapter.

To understand the process of joining parts, consider specific example, when from sewer riser two sockets are allocated, one is intended for the toilet and has a diameter of 110 mm, the second is for apartment sewerage with a diameter of 50 mm.

First you need to thoroughly clean the bell, removing dirt and rust, and then lubricate the inside of the rubber cuff with sealant. It is inserted into a cast iron socket, only after this sewage pipe inserted into the cuff.

In some cases, the bell is simply missing, and there is only a small section of the old product. If the edges of this segment are not even, then you should trim them using a grinder. A rubber cuff coated with sealant and a plastic adapter are put on top.

The first method of docking using a rubber gasket

If the cast iron pipe is easily removed, and the inside of the socket remaining from the riser is smooth, then you can use the joining method using special seal. In this case plastic pipe is inserted into the cast iron section by at least three centimeters, ideally it should be about eight centimeters.

Using this method, you can quickly make a connection, after which you can immediately use the sewer system. Based on practice, it is worth saying that this type of connection will last at least 8 years without problems.

Typically, a sewer riser consists of two outlets: one for a toilet with a diameter of 110 mm, and the second for an apartment sewer with a diameter of 50 mm. In any case, the connection will be carried out according to one algorithm, in which you need:

• remove rust and dirt from the bell;
• install the cuff on top, and apply sealant to its outer transition;
• the rubber adapter is inserted into the cast iron socket;
• at the last stage, a new plastic sewer pipe is inserted into the cuff.

If there is a need to connect a pipe without a socket, then you will need to use a plastic adapter. In such a situation, the sequence of actions is different:

• The edges of the cast iron pipe are leveled using a grinder;
• a rubber adapter is placed over this area;
• the edge of this pipe with the adapter is coated with sealant;
• A plastic adapter is placed over the treated area, which is also lubricated with a sealing compound.

The cuffs and adapters used must match the dimensions of the pipes. The sequence of connecting cast iron and plastic pipes different diameters This method is no different.

Connection using caulking with sanitary linen winding

This connection method is mostly used for docking cast iron pipes, but despite this, it can be used for mixed type docking. If you prefer this option, you need to perform a number of steps:

• on a plastic pipe, the joint areas are wrapped in several layers with plumbing tape;
• Using a narrow spatula or a wide screwdriver, this material must be pushed well into the gap formed at the junction of the pipes;
• The transition to a cast iron section must be coated with a polymer-cement composition several times. This composition is prepared on the basis of cement, water and PVA glue;
• Upon completion of such work, it is not recommended to use the sewer system for at least one day.

A joint made using this technology will be reliable and of good quality. Earlier this method used quite often, even before the advent of silicone-based sealants. Even now, this is a convenient solution for connecting a plastic pipe to a cast iron pipe under a washbasin or sink. If leaks appear after some time, this has nothing to do with the docking.

Connection method by sealing with sanitary silicone

If small gaps form during the pipe installation process, then this method of transition from a cast iron pipe to plastic sewer will be effective. When carrying out work, you need to pay more attention to sealing the joint in its lower area.

When docking using this method, you need to perform the following actions:

• first you need to dry the joint well; for these purposes it is recommended to use a hair dryer;
• Using a special gun, silicone is injected into the cracks. The deeper its penetration, the more reliable the connection with the plastic pipe will be;
• It is important that the silicone layer dries well; about 3 to 5 hours will be enough for this. If the layer is large, it will take longer.

During drying time silicone composition It is not recommended to use the sewer system.

A combination of several pipe joining methods

In order to increase the reliability of joining plastic and cast iron pipe You can use several methods listed above:

• if there is a large gap at the junction, then it is advisable to use rubber gaskets and caulk them. To connect a toilet using a corrugated pipe, it is recommended to use linen winding, treating the joint area with silicone. Cast iron crosspieces and rubber seals are also coated with this product;
• When caulking, it is also possible to use not a polymer-cement composition, but a silicone sealant.

Method 1. Rubber gasket

If the old cast iron pipe can be easily removed and inner surface the cuff (socket) of the remaining cast iron pipe is flat, then simple will do joining method using a special seal. In this case, the plastic pipe is inserted into the cast iron pipe by 3, and if possible, then by 8 cm. This method allows you to make the connection quickly and immediately after that continue operation sewer system. Practice shows that such a connection of plastic and cast iron pipes can function normally for 8 years.

Most often, the sewer riser has 2 outlets, with the first having a diameter of 100 for connecting a toilet, and the second having a diameter of 50 for connecting a drainage system that provides the outlet for the apartment sewerage system. In both cases, the connection is made using the same technology. Necessary:

• clean the bell from rust and dirt;
• apply to the rubber transition with outside sealant cuffs;
• insert the rubber adapter into the cast iron socket;
• insert a new sewer pipe into the cuff.

If the connection has to be made with a pipe that does not have a socket, then you will have to use a plastic adapter. In this case, do this:

• a part of the cast iron pipe is cut off with a grinder, leveling the edge;
• a rubber adapter is put on this part;
• coat the edge of the “clad” cast iron pipe with sealant;
• A plastic adapter (cuff) lubricated with sealant is also placed on top of the pipe.

Appearance and application diagram of the plastic adapter: 1 - plastic socket; 2 - rubber ring; 3 - plastic adapter; 4 — rubber cuff; 5 - second rubber ring; 6 - cast iron pipe without socket.

The cuffs and transitions must be of the appropriate size for the pipes. The connection of cast iron and plastic pipes using the transition technology is the same for all diameters.

Method 2. Caulking with plumbing linen winding

Typically, this method is used when joining cast iron pipes, however, it is also well suited for mixed joining. When performing work in accordance with this method, perform the following actions:

1. in the area of ​​the joint, plumbing winding is wound onto the plastic pipe in several layers;
2. using a narrow spatula or a wide screwdriver, the winding is firmly pushed into the gap that exists between the two pipes (this is what it is);
3. the transition to a cast iron pipe is coated several times with a polymer-cement solution, which contains water, cement and PVA glue;
4. After completing the work, it is not advisable to use the sewer system for at least the first 24 hours.

The joint made in this way is quite reliable. This method was widely used before it became commercially available. silicone sealants However, even today it is often used when connecting a plastic pipe to a cast iron pipe under a sink or washbasin. Even several years after joining pipes in this way, if they occur, then, as a rule, not at the junction of the pipes.

Method 3. Sealing with plumbing silicone

If the connection of a plastic pipe to a cast iron pipe is accompanied by the formation of a small gap (no more than 2 mm), then this method turns out to be very effective. When carrying out work, special attention must be paid to ensuring the tightness of the joint in its lower part.

When performing docking in accordance with this method, you must:

1. Before joining, the joint area is thoroughly dried; it is advisable to use a hair dryer;
2. use a construction gun to push silicone into the gap between the pipes, taking into account that the deeper the silicone penetrates, the more reliable the connection between the cast iron pipe and the plastic pipe will be,
3. the silicone layer needs to dry - usually complete drying occurs within 3-5 hours, with more thick layer takes longer to dry.

It is highly undesirable to use the sewer until the silicone dries.

Method 4. Combining the above methods

To increase the reliability of the joint between plastic and cast iron pipes, you can combine the above methods, for example:

• If there is a large gap between the pipes at the junction, use rubber gaskets along with caulking. So, when connecting the toilet with a button accordion, that is, corrugated pipe, use caulking linen winding followed by covering the joint with sanitary silicone. At the same time, the cast-iron crosspiece at the joint and the rubber seals are coated with sanitary silicone.
• When caulking, silicone is often used instead of a polymer cement solution.

Connection using a press fitting

If you use a press fitting (an adapter for cast iron pipes with a thread for a cast iron pipe at one end and a socket for sliding connections plastic pipes - on the other) use tow or Teflon tape.

Technology for performing work using a press fitting:

1. cut off old pipe using a grinder or unscrewing the coupling on a cast iron pipeline at the future junction with a plastic pipe;
2. the edge of the pipe is lubricated with oil or grease until it exits the die;
3. use a thread cutter to cut a thread, wipe it and wrap tow or FUM tape on it;
4. lubricate the winding with silicone;
5. The press fitting is screwed onto the thread by hand (a wrench is not used so that the press fitting does not crack); it can be tightened after the water supply is turned on in case it is necessary to stop the resulting leak.

Important to remember:

• The joining of cast iron and plastic pipes using a press fitting must be accompanied by taking into account the difference in the coefficients of thermal expansion of metal and plastic. For this reason, it is not recommended to screw PVC fittings onto metal.
• During installation heating system or pipelines for hot water supply use detachable brass couplings with a PVC element, or transition couplings equipped with a rubber seal.

In conclusion, it should be noted that following the rules mandatory when connecting plastic and metal pipes, it is possible to carry out high-quality work both in case of repairs and during the planned replacement of cast iron pipes with plastic ones.