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Fit-to-tire: connection of plastic sewer pipes

In this article I will write about how plastic sewer pipes are connected to each other, to cast iron pipes, and also to fittings different types. Some solutions may seem unusual, but they are quite capable of helping you out when installing complex sewage system configurations.

General rules

A number of rules are relevant for the installation of any sewer system, regardless of the type of pipes and fittings used.

• Socket connections of gravity sewers are always assembled so that the sockets are directed against the flow of drains. In this case inner surface the pipeline will be as smooth as possible, free of irregularities that can cause blockages;
• The pipe is laid with a constant slope along the drainage path. The optimal slope value is determined by the diameter:

• Pipes are not installed with bends or tension. Turns are carried out only due to shaped elements;

Due to the elasticity of the polymer, a polyethylene sewer pipe still allows minor bends.
For PVC, polypropylene and especially cast iron internal stresses contraindicated: in combination with temperature changes, they often lead to cracks.

• Connections at turns and branches are made with oblique tees and half-bends at angles of 30 - 45 degrees. This eliminates overflow of the pipe during volley discharges and simplifies cleaning in case of blockages: the cable or sewer wire passes through a smooth bend with minimal resistance. In addition, on a tee they always move along the course, without bending in the opposite direction;

• Complex assemblies with several shaped elements must be fixed with clamps. This instruction will prevent spontaneous uncoupling of socket joints;
• Horizontal sections assembled from plastic pipes are fixed with clamps, clips, supports or hangers every 8-10 pipe diameters. Otherwise, after 1 - 2 years of service, the pipes sag, forming areas with counter-slopes, each of which is a potential point of blockage;
• When assembling risers, pipes are attached to each socket. A cast iron bench (horizontal sewer) is installed in the same way;

• The connection of cast iron and plastic sewer pipes is carried out with a number of restrictions related to the difference in strength and ring stiffness. In particular, you cannot mint plastic pipe in a cast iron socket and use a cast iron fitting or pipe to replace the section of the plastic riser. In the first case, the plastic will crumple, in the second, the plastic sockets will collapse over time under the weight of the cast iron.

Bypass last problem It's still possible. To do this, it is enough to ensure rigid fastening of all cast iron fittings and pipes to the main wall.

Chasing a plastic pipe into a cast iron socket is a bad idea.

Plastic with plastic

How to connect sewer plastic pipes when assembling a gravity drain domestic sewerage? For connection, both pipes and fittings are equipped with sockets with rubber O-ring seals. The pipe is inserted into the socket with some effort - and the next joint can be installed.

Unlike cast iron sockets, which require hammering, plastic sewer if necessary, it can be just as easily dismantled or disassembled for cleaning.

How to cut a plastic pipe in place with your own hands and prepare it for joining with the socket?

I do it like this:

1. I mark the position of the cut taking into account the depth of the socket;
2. I wrap the pipe with a piece of paper, aligning its edges, and draw a circle along the edge of the sheet. It will be exactly perpendicular to the longitudinal axis;

1. I cut the pipe according to the markings with a grinder and an abrasive wheel. Whether it’s metal or stone, it doesn’t matter;

It is the abrasive wheel that gives a perfectly accurate cut with minimum quantity burrs.
Circular Saw, hand saw and even a diamond wheel cuts plastic much more roughly.
Abrasive cutting is not applicable only for polyethylene pipes: the polymer has a lower melting point than PVC and polypropylene and begins to flow.

1. Using the same abrasive wheel, I remove the outer chamfer. It will greatly simplify the assembly of the socket connection;
2. Using a sharp knife, I clean the inner surface of burrs.

How to assemble a socket if the pipe does not want to fit into the O-ring?

• Make sure that the sealing ring is not twisted and is placed in the annular groove in the socket along its entire circumference;

• Apply a little to the inner surface of the bell liquid soap or any other lubricant water based. Under no circumstances use machine oil or other fuels and lubricants for lubrication: they will cause the rubber seal to crack.

Is it possible to connect two socketless plastic pipes together? Of course. For this purpose, a sewer coupling is used - a short pipe with two sockets.

Installation is carried out in exactly the same way as in the case of joining socket pipes.

When installing horizontal sections of sewerage that are not supposed to be disassembled for installation, assembly with silicone sealant is practiced.

This certainly won’t make things any worse: silicone will ensure a tight seal even if the rubber seals lose their elasticity and leak after a long period of inactivity. However, I strongly recommend that the reader refrain from skimping on sealant: cheap silicone does not adhere to smooth plastic, depriving additional sealing of any meaning.

Compensating pipe

What to do if an additional shaped element (tee, cross, revision, etc.) needs to be cut into a straight section of the pipe?

A compensating pipe equipped with an elongated socket will come to the rescue.

The insertion is done like this:

1. A section of pipe is cut out. Preferably - near the bell. If the nearest socket is far away, a sewer coupling is put on the smooth end of the downstream pipe;
2. The compensator is pulled all the way onto the upper pipe;
3. The smooth end of the fitting that we want to mount is inserted into the socket of the lower pipe or coupling;
4. The compensating pipe is lowered through the pipe into the socket of the shaped element;
5. The neck of the latter is fixed with a clamp or clip to prevent it from moving and undocking the connection.

Plastic with cast iron

How to connect a cast iron sewer pipe to a plastic one when replacing a section of an old sewer?

• The plastic pipe is inserted into a cast iron socket of the appropriate diameter through a rubber cuff - seal. The bell must first be cleaned of rust, deposits and residues. old stuff(cement mortar and cables). It wouldn’t hurt to apply silicone sealant between the bell and the cuff: the inner surface of the bell almost always has significant unevenness;

Sealing collar - adapter.

• A cast iron pipe with a nominal diameter of 100 mm fits into the socket of a 110 mm plastic sewer after the surface has been cleaned of paint and rust layers. And in this case, it is advisable to chamfer the end of the pipe (using a grinder with a metal wheel or a regular file);

The compensating pipe mentioned above also fits perfectly onto a cleaned cast iron pipe.
I have had occasion to use it to insert additional bends into a cast iron riser. A compensator with a coupling can also be used to repair a damaged cast iron socket.

• Those who are too lazy to bother with stripping cast iron can connect a sewer pipe - plastic to cast iron - using a special adapter equipped with a wide socket and a thick sealing collar. The price of the product is about 200 rubles.

Adapter from cast iron to plastic. His distinctive feature— extended bell with a thick sealing collar.

A special case

As a separate point, I will mention the connection of the siphon elbow under the sink with the socket of the old cast-iron comb (indoor sewerage). In theory, this connection should be airtight. The gap between the socket and the elbow often leads to a persistent sewer smell in the bathroom or kitchen.

Most often, this problem occurs in winter, when snow caps form at the outlets of the risers on the roof, interfering with normal ventilation.
The draft in the riser, clogged at the top, begins to transport air along with accompanying aromas from the apartments lower down the riser to those above.

The standard sealing of the connection in most sink trim kits is beyond criticism: it is a plastic semicircular plug with a hard rubber gasket.

The situation can be saved by a cuff for a toilet with an upper tank, made in the form of two rubber cylinders different diameters. It is pulled with the narrow side over the knee, and the wide side over the cast iron socket, after which you can forget about foreign odors in the apartment.

Pressure sewer

Typically, in domestic conditions, the sewage system is gravity-fed; however, in difficult terrain or when placing plumbing fixtures in the basement, individual areas can be completed fecal pumps. How are pressure sections installed?

• Regular gravity pipe with mandatory fastening of all necks. The strength of the pipes and fittings is quite sufficient to withstand a pressure of 3 - 5 meters. Rigid fixation of all connections will not allow them to undock;
• Flared pipe under adhesive connections. Solvent adhesive for PVC is applied to the outer surface of the pipe or to the inner surface of the socket, after which the parts are aligned, turned a quarter turn and fixed for a couple of minutes in a stationary position;

• Pressure polyethylene pipe. Its diameters correspond to the diameters of free-flow sewers and make it fully compatible with plastic fittings.

crazy hands

Finally, a couple more recipes that can help you in emergency situations.

Corrugation

It is a corrugated polyethylene tube with a diameter of about 100 mm with a smooth section on one side and a cuffed socket on the other. The corrugation is intended for connecting a toilet offset relative to the sewer pipe.

However, it can be used for other purposes:

• For installing a toilet with an oblique or horizontal release in a Stalin-era house built with vertical outlets. In many houses built between the 30s and 50s of the last century, the sewage system is located in the toilet at floor level; to connect to the riser there is a ladder installed under the ceiling of the lower apartment;

• To turn the toilet at a right angle to the outlet. If necessary, two corrugations can be connected in series for this purpose. I have had occasion to unfold the toilet this way in own apartment: its dimensions and installed in a cramped bathroom washing machine made using the bathroom impossible;

• For connecting two plastic pipes at an arbitrary angle (in particular, to bypass water supply risers and other obstacles).

When installing corrugation, it is worth remembering a couple of subtleties:

1. It shouldn't sag. I have already written about the dangers of counter-inclinations above. In the case of corrugation, the situation is aggravated by the uneven inner surface;
2. Corrugation cannot be embedded in boxes and false walls. Its service life rarely exceeds 5 years. Typical problem of this fitting - to flow along the corrugation fold.

Socket for glue

Ordinary gravity flow PVC pipe with special requirements to the strength of the connection can be converted into an adhesive socket.

This is done like this:

1. The end of the pipe is heated to a plastic state over gas, an electric stove or using a hair dryer;
2. Then the pipe is slightly stretched (with hands in thick gloves or by pulling on a liter glass jar, the diameter of which approximately corresponds to a 110 mm sewer);
3. An improvised bell is put on smooth pipe with silicone applied to its outer surface. The pipe should go into it about 10 cm; As a rule, it has to be reheated two or three times. Silicone acts as a lubricant and, after setting, as a sealing adhesive.

Why is such a connection better than one assembled with sealant from conventional socket pipes? The absence of a gap between the smooth section and the socket and, accordingly, exceptional fracture and tensile strength.

Conclusion

I hope that the solutions I described will help the dear reader in construction and repair. As always, the video in this article will provide you with additional thematic information. I would appreciate your comments and additions. Good luck, comrades!

July 18, 2016

If you want to express gratitude, add a clarification or objection, or ask the author something - add a comment or say thank you!

Hello, dear reader! In many houses and apartments, cast iron pipes are often adjacent to the water supply and. Therefore, situations arise in which the home master is faced with the question: how to connect a cast iron pipe to a plastic sewer?

In this article we will look at the methods of this connection, the step-by-step process of the operation and advice from practitioners.

The need for such a procedure arises in the following cases:

• replacement of cast iron elements of the sewer main with more modern smooth plastic pipes;
• making new wiring from polymer pipes for pressure sewerage;
• pad plastic pipeline from home sewerage to septic tank;
• emergency breakdown of a tee or socket made of cast iron;

Connection methods

The choice of connection technology must be based on the integrity of the cast iron socket. Either it is intact and suitable for further use, or it has burst, damaged, or cut off.

Connection with fittings

The use of the fitting looks like the best solution from the point of view of ensuring a reliable connection.

A press fitting is a polymer adapter, at one end of which there is a thread, at the other there is a socket extension for the joint with a PVC pipe.

Scheme for installing a press fitting on cast iron:

The method is used in cases where the cast iron pipe does not have a socket at the end, or it cannot be used. The reliability of the connection is ensured by the tightness of the thread and rubber seal fitting.

• At the end of the cast iron pipe, 5.5 threaded turns are cut with a die.
• Wrap the FUM tape, you can use plumbing paste, and screw the fitting.
• A plastic pipe is inserted into the fitting collar at the other end.

Connection with rubber gaskets

Rubber seals are suitable when the bell is safe and sound, thoroughly cleaned, and internal walls there won't be a lump. Otherwise, leakage cannot be avoided.

The rubber cuff must be selected according to size.

1. The inner walls of the cast iron socket and the outer turns of the rubber adapter.
2. The seal is carefully and tightly installed in the socket.
3. The plastic tube is inserted into the socket through the cuff at least 5 cm, or deeper.
4. The joints are once again coated with a sealant composition.

This connection is quite reliable and easy to disassemble.

If you have to make a joint with a pipe without a cross, use a polymer adapter with a rubber cuff.

1. The end of the cast iron element is leveled by cutting with a grinder.
2. Place a rubber ring and seal on it. All this is lubricated with sealant.
3. A plastic adapter, also treated with a sealing compound, is placed over the edge of the pipe.
4. A plastic pipe of the appropriate size is connected to it.

Silicone sealing

This method is the easiest and widely applicable at home. It is suitable if you simply need to cover up the gap that has formed between the walls of the socket and the plastic. In this case, the gap should not exceed two mm.

1. The bell is cleaned and dried with a hair dryer.
2. A special plumbing thread is wound around the end of the plastic pipe, which is a kind of sealant made of polyamide thread and silicone coating.
3. The pipe is inserted into the socket and the cracks around it are filled with silicone. The silicone should go as deep as possible in the socket, to the very end of the plastic pipe.
4. The drying time of silicone sealant is about 5 hours.

Socket connection

The most popular, which has become a classic, method of connecting a cast iron pipe through a socket is caulking linen winding and cement.

Since cracks almost always form in the socket during a joint, so-called caulking is used.

1. A plastic pipe is inserted into the cleaned socket until it stops, the end of which is wrapped linen rope. The winding is coated with plumbing paste.
2. Using a simple screwdriver, push and seal the winding into the crack. The sealant tightly fills two-thirds of the joint space.
3. Then they point cement mortar, add PVA glue to it, and insert it into the joint until the gap is completely closed.
4. The mixture will completely harden only after a day, so using the pipeline at this time is not recommended.

With the advent of silicone, cement mortar is often replaced silicone sealant.

It is believed that this method is unreliable: the coinage deforms plastic part, moreover, under the influence hot water plastic and cast iron expand with different forces and the cement joint will quickly become loose.

Flange connection

The flange is used for joining pipes with a large diameter. It is difficult to use threaded fittings here, but the connection with flanges is strong and reliable. The connection can be easily disassembled if repairs or cleaning are necessary.

To make the connection, welding work will be required.

Today there is a wide variety of flanges on the market that allow the transition from cast iron to plastic.

Step-by-step connection instructions

Let's take a closer look at the work on flange connection with your own hands. First of all, you need to prepare for the operation: decide on the sizes and types of flanges, materials, and select a tool.

Set of tools and materials

To dismantle a cast iron pipeline element you will need:

• a mallet with a rubber attachment (with a regular hammer you can easily split brittle cast iron);
• grinder for cutting cast iron pipe parts.

To install the structure you need:

• welding machine;
• plastic pipe cutter;
• plastic pipes;
• flange;
• appropriate seal;
• for cleaning the end of a cast iron pipe - a file or a cleaning disc for an angle grinder;
• a screwdriver with bolt bits or socket wrenches of a suitable size.

Work progress

1. Using a grinder, cut off the end of the pipe to the required size.
2. Clean it from nicks with a file or a special disk using a grinder.
3. A flange is welded to the end of the cast iron pipeline.
4. The crimp coupling is put on the plastic part of the structure, and its flange part is bolted to the flange of the cast iron pipe. A sealing gasket (ring) is placed between them.

Connection video

Flange connection video

For insertion into a sewer pipe and transition from cast iron to plastic, a fitting such as a compensating pipe can be successfully used. It is able to compensate for deformation and failure of the network due to its linear temperature contraction/expansion. In addition, it can give the desired slope to sewer sections.

The pipe is used along with the corrugation when it is necessary to change the height of the cross in order to create optimal angle for installing a toilet.

Nuances

The pipeline is always routed from the riser.

Remember that cast iron and polymer have different coefficients of thermal expansion. Therefore, it is important to use plastic materials such as silicone for sealing.

Using threaded connection, be sure to wrap tow around the threads and lubricate it with plumbing paste.

It is always necessary to start assembly from the riser

Is it necessary to dismantle the old pipe?

If we're talking about about the sewer cast iron riser in apartment building, then, firstly, this should be done by specialists invited management company, secondly, this operation in a separate apartment is very undesirable. As practice shows, it is better to replace the entire riser throughout the entire entrance during a major overhaul.

Sometimes when carrying out plumbing work it becomes necessary to connect pipes made of different materials. For example, those used today metal-plastic pipes have to be combined with cast iron. This is usually required when you need to connect plumbing pipes apartment water supply system to sewerage. In old houses, the risers are made of cast iron, and therefore the question of how to connect a plastic pipe to a cast iron one is quite pressing.

From a technical point of view, the methods will be somewhat different, and therefore it is worth considering each of them separately.

Simple connection

First of all, it is necessary to assess the condition of the cast iron part intended for connection. If the strength is at a sufficient level, then you can proceed to work.

• First of all, you need to remove the old metal pipe. Then you need to assess the condition of the pipe intended for connection. If it is strong, smooth and has a socket, then you can begin work.
• WITH inside All rust is removed from the pipes. To do this, you can use a wire brush and coarse sandpaper.

• Then a special rubber liner is inserted inside. It will act as a seal. It is important to remember that sealant must be applied to the adapter before insertion.
• After this, a plastic pipe is inserted into the cuff, and to a depth of at least 5–8 cm for maximum reliability.

This method is only relevant if the pipe has a special expansion socket. If it is not there, then a slightly different method is used.

• The upper part of the pipe is cut off using a grinder, after which the end will need to be processed with a file and sandpaper to remove all burrs.
• Then a special adapter is installed on the cast iron pipe, over which a plastic socket is placed.
• Then the above steps are repeated. A connecting element is inserted, inside of which a plastic pipe is in turn mounted.

Caulking with linen sanitary winding

As another method of connecting pipes, we can mention the method of caulking with plumbing winding. The method is simple, but requires experience.

• First, a plumbing pipe is wound onto a plastic pipe in several layers. The result should be a thickness of approximately equal to diameter cast iron pipe.
• A plastic pipe with a winding is inserted into a cast iron pipe.
• After this, a certain amount of winding is caulked into the gap between the connected pipes. For these purposes, you can use, for example, a narrow spatula.
• Then the rest of the gap between the pipes must be filled with a special solution. To prepare it, you need to mix PVA glue and cement, diluting it with water to the required consistency.

The resulting compound will be suitable for use in a day or two, when the mixture has completely dried. The described method is relatively easy to use and accessible. To use it you do not need any special tools, and all necessary materials available. Pipes connected in this way for a long time maintain tightness, and in the event of a leak, you can always caulk some additional amount of winding or apply a solution.

Connection using silicone sealant

It is worth saying that the above method was widely used before the advent of silicone fillers. Today a slightly modified version has gained popularity.

• Before connecting, the cast iron pipe must be thoroughly dried and cleaned.
• Then the pipe, wrapped with plumbing thread, must be inserted into the cast iron socket to a depth of 10 cm.
• Then into the remaining gap using a special mounting gun served required amount silicone sealant.
• Then the connection is left for about a day for the silicone to harden, after which the water supply can be used.

The described method is much simpler than the previous one and to some extent preferable, since silicone takes longer to decompose. This means that the joint will remain airtight longer.

Combined method

Each of the described methods has its own specifics and advantages, but nothing prevents you from using combined method. So, for example, a pipe can be wrapped with linen, but instead of caulking the gap, fill it with silicone sealant. Here you can experiment, so everyone can find a method for themselves.

Press fitting connection

Another way to connect pipes from various materials is a connection using special connecting elements called fittings.

• First, the cast iron pipe (regardless of whether it has an expansion or without a socket) is cut using a grinder. The cut end must be processed with a file and sandpaper to remove burrs.
• Further outer surface metal pipe needs to be coated machine oil or grease.
• Then using special tool external thread is cut.
• After this, it is wound onto the thread plumbing thread, over which the connecting fitting is screwed.
• On the other side of this connecting element, a plastic pipe with a crimp collar is put on. It must be remembered that everything O-rings must be in place.
• Using a special tool, crimp the coupling.

This method is reliable, strong and durable. Its use requires some effort, but the result will be valid for quite a long time.

Note! Remember to pay attention to detail and be sure to follow safety regulations.

Video

If you are going to make the transition from a cast iron sewer to a plastic one, you will have to caulk the fan tee. This video shows how to do this. You will also see how to connect plastic and cast iron pipes.

When is it necessary to replace cast iron sewer pipes? plastic products, many homeowners are interested in how such work should be done. According to experts, such a connection can be made using a press fitting or using one of four methods of simple joining without it.

All of the above methods provide reliable pipeline repair.

Simple connection of cast iron and plastic sewer pipes

Method one - using a rubber gasket. If old pipe it can be removed from cast iron without problems, and the inner surface of its socket (cuff) is smooth, then you can use in a simple way connections using special seal. The plastic pipe needs to be inserted into the cast iron pipe by 3 centimeters, or better yet, by 8 centimeters.

The connection in both cases is made using the same technology, for which:

• first remove rust and dirt from the cuff;
• to the rubber transition located with outside cuffs, apply sealant (read also: " ");
• a rubber adapter is inserted into the cast iron socket;
• place a new plastic pipe in the cuff.

In the case when the connection is made with a pipe without a socket, then you need to use a plastic adapter.

In this situation, proceed as follows:

• a part of the cast iron pipe is cut off using a grinder and the edge is leveled, after which a rubber adapter is put on it;
• the “dressed” edge of the pipe is coated with sealant;
• A plastic adapter is placed on top of it, also treated with sealant (read also: " ").

The size of the cuffs and transitions must correspond to the diameter of the pipes used. The connection of cast iron and plastic sewer pipes according to the transition technology does not differ for products of different diameters.

In this case, the work is performed in the following sequence:

• at the junction, plumbing tape is wound onto the plastic pipe in several layers;
• using a wide screwdriver or a narrow spatula, firmly push the winding into the gap formed between the pipes (this is the work called caulking);
• the place of transition to a cast iron pipe is coated several times with a polymer-cement solution consisting of water, PVA glue and cement;
• After completion of work, the sewerage system should not be used for at least one day.

The joint, which is made in this way, is quite reliable and was used everywhere before it appeared on the domestic market. construction market silicone sealants, and now it is still used if you need to connect a plastic pipe to a cast iron pipe in a place under a washbasin or sink. Using high-quality sewer pipes and fittings, even after several years of using this method, leaks do not occur at the junction.

Method three - sealing using plumbing silicone. When connecting a plastic pipe to a cast iron pipe, a small gap may form, the dimensions of which do not exceed 2 millimeters. Then replacing sewer pipes from cast iron to plastic using this method turns out to be very effective (more details: " "). Special attention When carrying out work, care must be taken to ensure the tightness of the joint in its lowest part.

Docking in accordance with this method must be performed in the following sequence:

• Before connecting a cast iron sewer pipe to a plastic one, thoroughly dry the joint using construction hair dryer;
• the gap between the ends of the pipes using construction pistol filled with silicone. The deeper the sealant penetrates, the stronger and more reliable the connection between the pipeline elements will be;
• The silicone layer needs to dry well. As a rule, for completely dry It takes about 3-5 hours, which depends on the thickness of the applied silicone. The joint can be coated with it both from the inside and from the outside, as in the photo. You should not use the sewer until the silicone dries.

Method four - combining the three methods described above. In order to increase the reliability of the joint between plastic and cast iron pipes, it is permissible to combine the methods described earlier in the article. For example: if there is a large gap between the pipes at the joint, you can use caulking and rubber gaskets.

When connecting the toilet to sewer system with help corrugated pipe use caulking with linen winding and then cover the joint with sanitary silicone. At the same time, the same material is used to coat the cast iron crosspiece located at the junction and the rubber seals. When caulking, the polymer cement solution can be replaced with silicone sealant.

How to connect cast iron and plastic using a press fitting

Press fitting is a transition element for cast iron pipes with a thread for these products at one end, and on the other side there is a socket for sliding connections plastic elements. When using it, you will need tow or Teflon tape.

Technological process connecting pipes using a press fitting:

• first of all, using a grinder, cut off the old pipe or unscrew the coupling on the pipeline in the place where there will be a joint with plastic element;
• lubricate the edge of the pipe with grease or oil to the place where it comes out of the die;
• using a thread cutter, cut the thread, then wipe it and wrap FUM tape or tow on it, smearing the winding with silicone;
• Then screw the press fitting onto the thread by hand. Tighten it after turning on the water supply if a leak occurs at this location.

Before inserting a plastic sewer pipe into a cast iron one using a press fitting, you need to take into account the difference between the thermal expansion coefficients of cast iron and plastic. For this reason, experts do not recommend screwing fittings made from polyvinyl chloride onto a metal base.

By following all the rules for connecting plastic and metal pipes, you can do this kind of work efficiently. on our own without inviting professionals.