Connections of a plastic pipe with a cast-iron sewer riser. How to connect a cast-iron pipe to a plastic one: tips and tricks

V Lately during the laying of new sewerage systems or the repair of old ones, plastic pipes are often used. Such products are characterized by low weight, anti-corrosion properties and long service life. In this article we will tell you how to connect a cast-iron sewer pipe with a plastic one, if necessary. urgent repair sewer systems.

One of the advantages of plastic pipes is their low tendency to clog. However, if plastic pipes are not mated correctly with cast iron pipes, the system may lose tightness and leak, since the linear expansion rates for cast iron and plastic vary.

Preparatory stage

During repair work with cast iron and plastic pipes, care should be taken, it is advisable to use rubber or wooden mallet. This is necessary so as not to accidentally split the brittle cast iron and cause clogging of the channel.

In the process of installing plastic pipes, you should take care of the presence of inspection hatches. They will allow in the future to diagnose the condition of the pipe in case of any malfunctions. Please note that for a riser with a cross section of 110 mm, it is optimal to use pipes with a diameter of 50 mm.

To connect sewer pipes from cast iron to plastic, you will need the following fixtures and consumables:

plastic pipe of the required size;
connecting elements;
wrench;
grinder or hacksaw for cutting pipes;
hammer with a wooden or rubber nozzle.

Connecting elements can be all kinds of fittings, adapters, couplings, gaskets.

Common methods for joining pipes made of cast iron and plastic

Choose how to connect cast iron pipe water supply with plastic, one of the two most popular - flanged or fitting connection. If we are talking about the flange method, then two disks with holes are used, which are tightly pressed against each other with bolts, forming a joint. Often this method is used if the cross section of the pipeline is large enough.

But when making the transition from a cast-iron sewer pipe to a plastic one, the cross section of which does not exceed 110 mm, you can safely use fittings - to choose from, crimp or cast. A cast fitting is a product having a socket in which a sealing gasket is pre-laid. But compression fittings are prefabricated connections, and their installation is somewhat more complicated. They have a crimp ring in which there should be a cut. It will prevent an early breakdown of the fitting and the occurrence of leaks in the sewer pipes.

According to the type of installation, fittings are classified as press fittings and compression products. Installation compression fittings somewhat simpler and faster, they allow you to create reliable connection. However, after some time after installation, the fasteners may loosen, which will lead to leaks and loss of tightness of the system.

An alternative is to use press fittings. Such connecting elements provide a reliable connection without any risk of depressurization. Therefore, subsequent monitoring of the state of the connections is not necessary.

Among the varieties of fittings on the market, you can always find suitable products for sewer pipes.

Please note that the joining of cast-iron and plastic sewer pipes in no case can be done with cement.

Rubber seal for connecting sewer pipes

In this way, pipes can be joined in cases where, after dismantling the defective section of the cast-iron pipe, a section remains without damage, chips and cracks, which has an even socket and an expanded part at the end, or you can use an adapter for a cast-iron sewer pipe. In this case, a rubber cuff is first mounted, and then the plastic pipe is deepened into the cast-iron pipe at a distance of 5-8 cm.

Please note that before installing the sealing collar, the inner surface of the cast-iron pipe is cleaned from dirt and rust. It can be said that this way allows you to use the system immediately after the repair.

In some cases, the remaining section of the cast-iron pipe does not have the necessary expansion. Then you will need to use an adapter from a cast-iron pipe to a plastic one. Before its installation, the cast-iron pipe must be cleaned, rust removed and the end part trimmed with a grinder. A rubber gasket is first put on the processed segment, and then a plastic insert is put into the cast-iron pipe. After that, a segment is mounted plastic pipe and all seams are sealed with silicone.

Scope and advantages of press fittings

You can use press fittings not only to connect cast iron and plastic pipes, but also to fix problems in the finished sewer system. Please note that such products have a service life of about 50 years, and the acceptable pressure is up to 0.1 MPa.

First, a piece of cast-iron pipe is cut off, without looking at whether it has a socket or not. The resulting cut is cleaned with emery and a file so that the end is absolutely smooth, without burrs. Next, the outer surface of the pipe is lubricated with grease or mineral oil and a thread 3-5 cm long is cut on it, after which a plumbing thread is wound around it. Now you can just roll plastic fitting on the pipe.

It is not necessary to make significant efforts during the winding of the fitting, so as not to deform the cast iron. To avoid water hammer, it will be possible to finally tighten the thread after the system is started.

A crimp collar is put on the plastic pipe and inserted on the other side of the fitting, after which they are crimped special tool. It should be noted that the press fitting provides a very high-quality and durable connection, since a sealing rubber ring is installed on one side, and the threaded connection is sealed on the other.

Subtleties of mounting flange fasteners

As a rule, flanges are used to work with pipes of large sections. If you need to join the flange of a cast-iron pipe with a smooth plastic product, you will have to use special adapters. Best Choice there will be free flanges for working with plastic products. When choosing a fastener, carefully check that there are no burrs or sharp edges on it that could ruin the plastic pipe.

When installing a flange mount, it is worth considering the following subtleties:

a stronger connection can be provided by a straight collar with a conical transition;
for pipes with a cross section of more than 20 cm, you need to use a free flange based on a conical collar;
for light pipes with a cross section of up to 30 cm, as well as for heavy and medium-heavy pipes polymer products with a cross section of up to 15 cm, free flanges are used, based on a free collar.

First of all, they cut the pipe where they are going to establish a connection, making sure that the cut is perfectly even. A free flange with a rubber gasket is placed on the end, the overlap of which on the end should not exceed 1 cm. Next, the flange is pushed onto the seal and the connection is fastened with bolts. The tightening of the bolts must be uniform on all sides, and the allowable force on them is indicated in the specifications.

The use of silicone for sealing joints

The method of connecting cast iron and plastic pipes is determined largely based on their technical condition. For joints in an acceptable state, between the elements of which the distance does not exceed 2 mm, you can use sanitary silicone.

Remember that in the process of silicone hardening, no mechanical impact on the joint is allowed.

The sequence of work is as follows:

a piece of cast-iron pipe is first cleaned and dried;
on the plastic patch the pipeline is wound with a plumbing thread and deepened by 10 cm into the socket;
the remaining gap is filled with silicone, applying it under pressure with a gun, so that a uniform and deep layer is obtained.

Silicone hardens within 3-5 hours, however, it is better to start the system a day after sealing.

If the main element that your new sewer will consist of is a plastic pipe, the cast iron pipe must be removed. Or at least cut it down as much as possible.

Why change

Soviet plumbing was uncomplicated and monotonous. A tiny toilet with a cast-iron riser in the corner, a bathroom next to it, another riser in the kitchen, that's it. But times change, new ideas in planning appear, new plumbing and new requirements for it.

All currently produced plumbing fixtures are unified and adapted for attaching plastic pipes to them. Their design does not provide for the use of cast iron sewer pipes. Plastic has a lot of advantages. It is much lighter than cast iron, easy to install and much more economical than a steel or cast iron pipe..

Plastic pipes are sold in various lengths, with ready-made branches and corners. Each of them has a socket for tight and reliable entry of one pipe into another. All this allows you to assemble the entire sewer system in just a few minutes. Thanks to this simplicity, it is possible to put other plumbing, while slightly changing its location. But there is one problem that cannot be avoided. Through the whole multi-storey building a common cast-iron riser is installed from top to bottom. And there is a need to make the transition from cast iron to plastic.

How to go

How to connect a cast-iron sewer pipe with a plastic one, while ensuring the reliability of the connection? This can be done in several ways.

The simplest is the connection through a rubber adapter. The size of the pipes is standard, and therefore this transition provides that a plastic pipe will be tightly inserted into it, and it will hermetically enter the cast iron one. Connect your sewer system to the common house in this way quickly and reliably. Unfortunately, this is not always possible.

Connecting a cast-iron pipe to a plastic one using one adapter is possible only when its seat is in perfect condition, smooth, free of cracks and chips.

And this does not always happen. Pipe joints burst from time to time, covered with cracks.

Chasing with winding

It may happen that the diameters of the pipes to be joined do not match each other, or the condition of the inner surface of the socket of the cast-iron pipe does not allow the use of such a method. In this case, they use the good old "chasing" method, with the help of which they used to connect cast-iron pipes. This will require sanitary linen winding.

The joints are prepared as follows: the inside of the cast-iron pipe is carefully cleaned, and the end of the plastic pipe is wrapped with several layers of winding. Then we insert one pipe into another. What happened is a weak and unreliable connection.

It needs to be sealed. The winding is folded into a kind of bundle or rope, which is pushed in a circle with a thin spatula into the gap between the pipes. The joints are clogged to about 2/3 of the depth, while trying to ensure the maximum packing density. The remaining space is filled with a mixture of cement, glue and water.

Difference from old methods

V Soviet times before connecting the cast-iron pipe, the sulfur mass was heated and the cracks were filled with it. But this is very dangerous for health, so more civilized methods are now being used.

It will not be possible to immediately connect the resulting connection to work, you will have to wait for the cement to harden, but the joint made using this technology is strong, reliable and simple.

Very often, at present, even winding is not used to resolve the issue of how to connect a plastic pipe to a cast iron pipe. Hardware stores abound with all sorts of sealants. This is silicone, which qualitatively fills the free space of the joint, reliably sticking to the walls. At the same time, it does not harden completely, remaining moderately plastic. Due to this, the joint is insensitive to vibration and slight bending loads.

Connect pipes from different materials maybe. Sometimes this is done quickly, sometimes you have to tinker, but this work is quite within the power of any masterful owner. Therefore, if you have new ideas for the placement of plumbing, then you should not be stopped by the lack sewer outlet near your chosen location. This is a solvable problem. You simply make the transition from cast iron to plastic and make the wiring you need.

Old and bulky cast-iron pipelines can still be found in many apartments. But no matter how reliable they may seem, sooner or later their service life comes to an end. Great solution it may be a complete replacement of cast iron with plastic, but, unfortunately, this is not always possible.

Someone stops the financial side of the issue, others fail to agree with their neighbors. It is in such situations that it becomes necessary to connect plastic and cast-iron sewer sections. There are several techniques that allow you to carry out such work quickly, efficiently, and without the involvement of professional help.

The whole complex of works can be conditionally divided into four stages:

Preparation of the place of work and the necessary tools.
Dismantling of the old pipeline.
Installation of plastic pipes.
Connection of elements.

To make the connection of a plastic pipeline with a cast iron one reliable and durable, it is worth preparing everything in advance the right tools and materials:

Special hammer with rubber or wooden head. An ordinary iron hammer will not work here, since it can easily damage such a strong-looking, but very sensitive to impact cast iron.
Cutting tool. It can be a grinder, or a hacksaw for metal.
Wrenches.
Depending on the chosen connection method, a hand press, a thread cutter or a welding machine may be required.
plastic pipes right size. To connect the toilet to the riser, elements with a diameter of 110 mm are required, for laying pipes to the bathtub and sink the best way suitable plastic with a diameter of 50 mm.
Required adapters, gaskets, couplings, seals, sealing agents.

Note! Installation of a plastic pipeline should provide for the presence of inspection hatches. Failure to comply with this rule will greatly complicate repair work if the need arises for them.

Dismantling the old pipe

It is necessary to dismantle the cast-iron pipeline very carefully to prevent the appearance of chips or cracks.

Cast iron pipes in the sewer system are rarely used today. But if you decide to use them, then you should know the method of their connection. That is what this article will be about. We will also talk about how to connect cast iron pipes with other materials, what devices can be used and how to seal the joints.

Connection of cast iron pipes with sockets

The process of connecting cast iron pipes will depend on their type. As a rule, for the installation of sewerage systems, structures with a socket at one end are used. In this case, the connection process will consist of the following steps:

The first step is to clean the socket itself and the smooth end of the cast-iron pipe from debris and dirt. Also check for foreign objects in the pipe itself.
The smooth end of the cast-iron pipe is inserted into the socket of the previous one.
Then the so-called minting of tow is carried out. This will provide improved sealing at the junction. For this procedure, tow, a special stick and a hammer are used. The wound tow is hammered into the socket. At the same time, try not to overdo it, if the material gets inside the pipe, it can cause a blockage. Minting occurs until the bell is two-thirds full.
The next step is to fill the remaining socket space with cement mortar. This is guaranteed to prevent leaks from appearing. To do this, you can use cement grades 300 or 400. It is diluted with water (in proportions of 9 parts of cement to 1 water), and the resulting solution is poured into the socket. To prevent cracks from appearing on the surface during drying, cover the pouring place with a wet rag. For such work, you can use modern materials. For example, great fit bituminous mastic and silicone sealant.

Smooth pipe connection

In addition to cast-iron pipes with a socket, smooth structures are also used in the creation of piping systems. To connect them, various devices are used. Among them there are couplings, saddles, crosses, bends, etc. Which one to use will depend on the diameter of the pipe and the type of connection.

The most common fitting is the coupling. It comes in three main types:

If pipes of the same diameter are connected, then a sleeve in the form of a cylinder is used. Inside such a fitting there is a thread.
To connect pipes with different diameters, a device in the form of two cylinders is used. This coupling is also equipped with an internal thread.
The heating system uses a futorka. Such a coupling is still the same cylinder, only with a thread, both on the inner and on the outer surface.

The connection process using a coupling is quite simple. First you need to mark them to see how much each pipe should go into the coupling (it is necessary to calculate so that the ends connect exactly in the middle). Then both pipes are simply inserted into the coupling. For sealing, you can use a special sealant.

But the pipeline may run at an angle or include branches. There are other devices for this. For example, the connection of cast-iron sewer pipes at an angle is carried out using bends. They are a piece of pipe bent at a certain angle (10, 15, 30, 60 and 90 degrees).

In addition, there are other devices for connecting pipes. For instance:

Tee. With it, you can connect three pipes at once into a single system. As a rule, such a connection is necessary at the branching of the sewerage system.
Cross. A design that helps connect four pipes at once.
Saddle. Such a device allows you to connect a smaller diameter pipe to the main line (for example, from a separate plumbing fixture).

All these devices can have sockets or straight sections at the ends. Used to seal connections various sealants or tow.

Combining cast iron and plastic

If you decide to change the sewer system using modern materials, then you may have a question - how to connect a plastic pipe with a cast iron one? Many home craftsmen simply insert one into the other and close the connection. cement mortar. In this case, the plastic can be deformed and a leak will appear.

The junction of the cast-iron pipe and plastic products must be done very carefully. The fact is that when heated, these materials expand in different ways. As a result, the seal will be broken and leakage becomes inevitable. Also, the appearance of a leak can be affected by mechanical influences (for example, constant vibration or shock).

There are two ways to properly connect pipes made of plastic and cast iron. The choice will depend on the presence of the bell. If it is, then the first step is to visit the store. Here you need to purchase a special adapter that will be installed in the socket. It comes with a standard diameter for sewer pipes (usually 50 and 110 mm), but you can also find a non-standard option (if you need it). Therefore, before buying, check this value.

Now you need to clean the socket of the cast-iron pipe from rust and dirt. The purchased adapter is inserted into the pipe. It is better to lubricate the socket itself and the plastic element with a sealant (for example, silicone). Make sure it goes in completely. Then a plastic pipe is inserted into the adapter. This completes the connection. This method is quick and easy, and the connection is reliable. In addition, it is easy to dismantle for cleaning. When installing, do not forget about the slope, it should be towards the riser.

If there is no socket on the cast-iron pipe, then two adapters of the required diameter must be used for the connection. First of all, we clean the ends of rust and dirt. Then a rubber adapter is put on the cast-iron pipe, and a plastic one is put on it. The plastic sewer pipe will be inserted into the latter. Coat all joints with silicone (or other suitable) sealant. This will prevent leakage and bad smell. The connection using two adapters, like the previous one, can be easily disassembled for repairs.

If your toilet is drained from old cast iron pipes, then when buying a new toilet, find out how to connect it. Everything here will depend on the direction of the toilet outlet (that part of the structure from where the drains enter the sewer system).

If your sewer has not changed since the day the house was built, then the pipe may stick out of the floor, at a decent distance from the wall (unless it is a common riser going to the upper floors). For this case, you need to buy a toilet with a vertical outlet (at the bottom of the structure). The vertical outlet toilet is very easy to connect, just insert it into the socket of the pipe.

A toilet with a horizontal outlet is also connected. Such designs can often be found on imported products. To connect such a toilet, you need to insert the outlet into the socket. The place of docking is best sealed with sealant or tow. So, you will not allow leakage and prevent the appearance of an unpleasant odor.

The variant with an oblique release is more common. To connect such a toilet to a cast-iron pipe, you can use a tap with the desired angle. It is inserted into the pipe, and the toilet outlet is connected to the outlet. The connection point is also desirable to be sealed.

But with all these connection options, it is necessary to connect the toilet directly to the pipe. This does not allow you to install plumbing device to a place convenient for you. The installation location will depend on the location of the sewer pipe. That is why a special device, a corrugation, is used to connect the toilet bowl to the sewerage system.

The plastic corrugation is easily put on the toilet outlet (if it is oblique or horizontal), and the other end is inserted into the socket of the pipe. This method allows you to install plumbing in any place convenient for you. The corrugation is easy to stretch to the desired distance and rotate in any plane and at any angle. In this case, the junction can not be sealed. The corrugation is equipped with a rubber nozzle, which fits tightly into the socket of the pipe and does not allow moisture and odors to seep through.

Video

If in your apartment cast iron sewer, and you need to make the transition from cast iron to plastic, then after watching this video you can understand how to do this job correctly.

If you plan to install a new sewer, the transition from cast iron to plastic will be a prerequisite. The reasons for the replacement may be different, for example, the deterioration of old pipes, rust, and others.

Very often, when it is necessary to replace old pipes with plastic products there are disagreements with neighbors, so you have to make connections of a new design with cast iron.

How is the connection of a cast-iron pipe with a plastic product made correctly?

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

Connecting a new plastic pipe to an old cast iron pipe

If there is a socket in cast iron, then you only need to purchase a rubber adapter. Otherwise, you will need a plastic adapter.

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

First you need to clean the socket well, 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 that sewage pipe inserted into the cuff.

In some cases, the socket is simply missing, while there is only a small piece of the old product. If the edges of this segment are not even, then it is worth cutting them with a grinder. A rubber cuff is put on top, smeared with sealant and a plastic adapter.

The first way of docking with a rubber gasket

If the cast-iron pipe is easily removed, while the inside of the socket remaining from the riser is even, then the docking method can be used using a special sealant. In this case, the plastic pipe is inserted into the cast-iron segment by at least three centimeters, ideally it should be about eight centimeters.

bathroom drain connection with old cast iron pipe

Using this method, you can quickly connect, after which you can immediately use 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 socket;
install the cuff from above, while applying 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.

installation of a plastic riser instead of the old cast iron

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

the edges of the cast-iron pipe are leveled with a grinder;
a rubber adapter is put on this area;
the edge of this pipe with an adapter is coated with sealant;
a plastic adapter is put on top of the treated area, which is also lubricated with a sealing compound.

The collars and adapters used must be suitable for 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 more used for joining cast iron pipes, but despite this, it can be used for a mixed type of joining. Preferring this option, you need to perform a number of such actions:

on a plastic pipe, the butt areas are wrapped in several layers with sanitary winding;
using a narrow spatula or a wide screwdriver, this material must be well pushed into the gap formed at the junction of the pipes;
the transition to the cast-iron segment must be smeared with a polymer-cement composition several times. This composition is prepared on the basis of cement, water and PVA glue;
at the end of such work, it is not recommended to use the sewer for at least one day.

connection of cast iron and plastic pipes through an adapter

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

Connection method by sealing with sanitary silicone

If small gaps form in the process of connecting the pipe, then this method of transition from a cast-iron pipe to plastic sewerage will be efficient. When performing work, you need to pay more attention to sealing the joint in its lower area.

using plumbing sealant to join pipes

When docking in this way, you need to perform the following actions:

first you need to dry the junction well, for these purposes it is recommended to use a building hair dryer;
using a special gun, silicone is introduced into the slots. The deeper its penetration, the more reliable the docking with a plastic pipe will be;
it is important that the silicone layer dries well, about 3-5 hours will be enough for this. If the layer is large, it will take more time.

During the drying time of the silicone composition, it is not recommended to use the sewer system.

Combination of several pipe joining methods

In order to increase the reliability of joining a plastic and cast iron pipe, several methods can be used at once, as indicated above:

if there is a considerable gap at the junction, then it is advisable to use rubber gaskets, while caulking. To connect a toilet using corrugated pipe it is recommended to use linen winding, treating the joint area with silicone. This tool also coats the cast-iron cross and rubber seals;
when caulking, it is also possible to use not a polymer-cement composition, but a silicone sealant.