Chasing cast-iron pressure pipes: problems and their solution. How to mint a cast-iron sewer with your own hands What does it mean to mint a hole

The main advantage of cast iron is durability, its main disadvantage is brittleness. These two features must be taken into account when maintaining and repairing cast iron pressure pipes.
The brittleness of cast iron imposes certain requirements on the connection of cast iron pipes. On the one hand, it must be strong and tight, and on the other hand, it must be sufficiently elastic. The fact is that pipes laid in the ground do not lie motionless. The soils are also characterized by shrinkage and blurring. When freezing, the water in the ground expands. All this leads to the movement of the ground. The pipe, as they say, "walks". Traditionally this problem is solved chasing pipes- connecting pipes in such a way that there is a margin of elasticity at the joints.
The smooth end of one pipe is inserted into the socket of the other. A small 3-5 mm gap remains at the junction, which is caulked with a resin strand (kabolka) two-thirds of the depth. The strand is a thin rope, which is inserted into the gap in layers. After each turn, the strand is compacted with a caulk - a special tool. Such a connection allows you to connect the pipe hermetically, but with a margin of elasticity.
To increase the strength of the joint, the remaining third of the gap is cemented or filled with lead. The second option is more reliable and preferable, because. connections in pressure pipes experience significant loads. Both procedures are quite complex and time-consuming. Cement behaves capriciously at high or low humidity, work with the melting of lead requires dexterity and additional preparations.
More advanced methods of connecting cast-iron pressure pipes are currently being used. For example, a socket with a rubber sealing ring and a socket-screw connection. But these compounds began to be used relatively recently. Recall that the advantage of cast iron is durability. The service life of cast iron pressure pipes is more than a hundred years. And, therefore, pipelines made according to old technologies are still actively exploited.

Chasing cast iron pipes: process features

Chasing socket connection can be safely called the weakest point of the cast-iron pipeline. Under the influence of moisture, temperature changes and soil movement for decades, the coinage is destroyed. Typically, accidents caused destruction of coinage, are eliminated for a long time. Procedure minting time-consuming, requiring a certain skill. But even high qualification does not guarantee the absence of marriage. The liquidation of an accident is often carried out in difficult conditions: low temperatures, difficult access to the damaged area, watering of the pit, humidity that prevents the solution from hardening. Fussing with molten lead in such conditions is generally more like a repairman's nightmare. Alas, this dream often comes true. It is almost impossible to perform high-quality coinage during the liquidation of a complex accident.
Our company's product range includes a special type of fittings that can significantly reduce the time required to eliminate this type of accident and improve the quality of repair work on a cast-iron pipeline. This is a DZ socket sealer. With him, all work comes down to installing the product on the socket connection and fixing it with a conventional wrench. The rubber gasket securely seals the joint, without depriving it of the necessary elasticity, and the design itself firmly fixes the joint. Work can be carried out even without completely shutting off the pressure, but only by lowering it so that the leak does not interfere with the repair team. The reliability of the connection of cast-iron pressure pipes with the help of a socket joint sealer is several times higher than the reliability of traditional caulking. And, therefore, once the work is done, the problem will be eliminated once and for all.

Cast iron pipes tend to be strongly associated with sewerage. Few people know that for more than two centuries they have been massively used for laying water supply lines. In this material, we will study the features of cast-iron water pipes, the GOST requirements for them, the methods of installation and repair used.

Cast iron or steel

Those who were in the cellars of Peterhof must have paid attention to the massive pipes that supply water to its famous fountains. This is one of the oldest cast-iron water pipes functioning to our time. It was built to last; at the same time, the builders of the royal residence, frankly, did not particularly consider the costs.

In the second half of the last century, economic expediency came to the fore. Indeed, why build a water supply system with a century and a half resource, if in 40 years the city area will be expanded and rebuilt with the laying of new highways?

It was then that steel main water pipes became widespread - relatively cheap and, most importantly, much more technologically advanced in terms of installation.

Tip: electric welding and external waterproofing with bitumen are performed much faster than manual chasing with pouring a socket.

The consequences of savings are quite predictable and are still being felt:

The resource of a pipe laid in the ground, despite waterproofing measures, rarely exceeds 30-40 years. After this time, numerous fistulas in it make the amount of drinking water loss unacceptable.

It is curious: according to local authorities, in Sevastopol, the city where the author of the article lives, 40% of water is lost due to the deterioration of the water supply network.

Not only that: the steel pipe is actively overgrown with lime deposits and rust from the inside. For a couple of decades, the clearance can decrease by 3-4 times with a corresponding drop in pressure and permeability.

And how does cast iron look against this dull background?

With the proper quality of external waterproofing, the actual service life of a pipe laid in the ground is at least a century.
The pipeline practically does not overgrow from the inside.

The only problem with a cast-iron water pipe is its high sensitivity to ground movements: where the steel pipe is slightly deformed, the cast-iron pipe will burst.

Standard

The current iron standard was introduced in 1977; the last changes were made to the text quite recently, in 2011. So, what should be the cast-iron pipes for water supply in accordance with GOST 9583-95?

Dimensions

The standard provides for cast-iron water pipes of three classes according to wall thickness - LA, A and B.

Conditional passage, mm	Wall thickness, mm
Conditional passage, mm	LA	BUT	B
65	6,7	7,4	8,0
80	7,2	7,9	8,6
100	7,5	8,3	9,0
125	7,9	8,7	9,5
150	8,3	9,2	10,0
200	9,2	10,1	11,0
250	10,0	11,0	12,0
300	10,8	11,9	13,0
350	11,7	12,8	14,0
400	12,5	13,8	15,0
500	14,2	15,6	17,0
600	15,8	17,4	19,0
700	17,5	19,3	21,0
800	19,2	21,1	23,0
900	20,6	22,3	25,0
1000	22,5	24,8	27,0

The mass of a linear meter of the pipe varies from 11.3 kg (65 mm, class LA) to 627 kg (1000 mm, class B). The standard provides for the production of socket pipes of measured length (2; 3; 4; 5; 6; 7; 8; 9 and 10 meters) and random lengths from 2 to 10.5 m.

Requirements

The transition of the cylinder into the socket can be made with a slope or in the form of a ledge.

The dimensions of cast iron pipes for water supply may differ from the nominal within the following limits:

Measuring tube length – +-20 .
Wall thickness - -1 + 0.5.
Outer diameter (up to 300 mm) - + - (4.5 + 0.0015D).
Outer diameter (over 300 mm) - + (4.0 + 0.0015D) - (5.0 + -0.0015D).
Inner diameter in the socket - + (2.5 + 0.002 D) - (1.5 + 0.002D).

Please note: D is taken as the nominal diameter when calculating tolerances.

The ovality cannot lead the pipe beyond the normalized deviations from the nominal size. The deviation of the actual mass of the pipe from the calculated one cannot exceed five percent. Pipes undergo hydraulic pressure tests, which are determined by their class and nominal size.

Note: the working pressure in the water supply lines usually does not exceed 3-4 atmospheres.
Up to 8-10 kgf / cm2, it can rise only after pumping, within the engineering system of a house or a small microdistrict.

The end of the pipe, opposite the socket, must be cut perpendicular to its axis with a deviation of not more than 0.5 degrees.

Inside and outside of the product are covered with a protective non-toxic material. In this case, the coating should not interfere with the sealing of the butt joint, peel off and soften at temperatures up to +60 C.

Important: at the request of the customer, pipeline elements can be supplied uncoated.

Installation and repair

How to caulk a cast-iron water pipe during installation? Can cracks and chipped sockets be repaired?

The main stage is its compaction with a cable, oiled organic fiber. The bundle fits into the centered socket connection as tightly as possible, after which it is additionally compacted manually using a chasing and a hammer.

It is not enough to seal the joint: the cable must be protected from biological decomposition, mechanical damage and other adversities.

How it's done?

Ordinary cement brand 400. The water-cement mixture, prepared in a ratio of 1: 9, is hammered into the socket as tightly as possible and compacted by chasing until it starts to bounce off the cement plug. Then the socket is wrapped with wet rags for up to a day.

Asbestos-cement mixture, prepared in a ratio of 1: 2, followed by the addition of 10 - 12 volume percent of water. It compacts like cement; asbestos fibers prevent cracking.

Important: with the same success, you can use fiber - chopped fiberglass.

Expanding cement. Unlike conventional, it does not require sealing.
Sulfur melt with the addition of 10 - 15% ground kaolin. For obvious reasons, only a vertical or inclined socket can be poured; as a rule, gray assemblies are factory sealed.
Lead melt.
Finally, lead can be used for embossing on top of the caboose.. A thin bar of soft metal tightly fills the groove, reliably protecting the organic fiber.

Important: Lead and its compounds are toxic.
Asbestos fiber and fiber are also not so good for the respiratory system.
Hence the obvious instruction: when doing the corresponding work with your own hands, do not forget about personal protective equipment.

Repair of cast-iron water pipes is possible only with minor transverse or longitudinal cracks at a distance from the socket: in this case, a prefabricated cast-iron or steel clamp with a rubber gasket is applied to the pipeline section. In other cases (chipped sockets, longitudinal cracks of considerable length), the pipeline section is replaced.

Alternatives

VChSHG

First meeting

Under this abbreviation lies the so-called ductile cast iron with nodular graphite.

To explain the meaning of the term, you need to briefly delve into the jungle of physics.

All the main differences between cast iron and steel - brittleness, low ductility and high resistance to corrosion - are determined by the presence in it of one of the forms of carbon - graphite.
Ordinary graphite has the appearance of miniature flat flakes. However, during recrystallization, which occurs when certain additives (in particular, magnesium and its compounds) are introduced into the gray cast iron melt, it changes its shape to spherical.
At the same time, the physical properties of the metal change significantly: it acquires toughness, ductility and resistance to shock loads, while maintaining corrosion resistance.

What is especially pleasant is that the price of a ton of material changes slightly during transformation. The total proportion of additives that cause carbon recrystallization does not exceed 0.08% by weight of cast iron.

Socketed water pipes made of ductile iron today are the main alternative to gray cast iron.

They surpass cast iron pipes in compressive and bending strength, not to mention all types of polymer pipes. Accordingly, water supply lines can be laid with ductile iron pipes under busy highways and on unstable soils. They have all the qualities of steel, except for their Achilles' heel - low resistance to corrosion.
The problem of time-consuming and low-tech chasing of bells has been completely solved. Instead of embossing, bells with annular rubber seals are used. Of course, with significant pipe sizes, the assembly of sockets involves the use of heavy equipment; however, the mass of these pipes will in any case prevent manual installation of the pipeline.

Note!
The use of rubber seals makes it possible to slightly deform the socket connection (change in the mutual position of the pipes) without impairing the tightness.

Normative documents

The production of elements of pressure pipelines from ductile iron is regulated by a separate standard - GOST R ISO 2531-2008.

Let's highlight its key points.

According to the document, pipes and fittings can have nominal sizes from 40 to 2600 millimeters, which makes it possible to use ductile iron to create highways that feed entire cities.
The composition of the metal, according to GOST, should not have a harmful effect on the composition of water.
The length of the pipes is regulated by the standard depending on their nominal diameter:

The maximum allowable curvature is no more than 0.125% of the pipe length.

As an external coating of the pipeline, depending on the operating conditions, the following can be used:

Metal zinc.
Zinc paint (zinc powder in a polymer binder).
Polyethylene.
Polyurethane.
Fiber cement.
Adhesive polymer tape.
Epoxy resin.
Bituminous mastic or paint.

For internal protection of pipes and fittings, the use of:

Cement mortars (Portland cement, Portland slag cement and aluminous cement).
Polyethylene.
polyurethane.
Epoxy resin.
Bituminous paint (mastics).

The marking of pipeline elements should indicate:

Manufacturer (name or trademark).
Year of manufacture.
Indication of the material (VChShG).
nominal size.
The standard to which the product is manufactured.

Polyethylene

Polyethylene pressure pipes are the main alternative to cast iron plumbing today.

A detailed acquaintance with them is clearly beyond the scope of our material, so we will pay attention only to their key properties.

The service life of polyethylene is estimated by manufacturers to be a vague “50+” years. In practice, this material can be considered almost eternal.
Deposits on the walls, which reduce the lumen of the pipe, cannot be in principle. The smooth surface of the polymer with extremely low adhesive qualities simply does not allow blockages to form.
All connections are made by butt welding. The strength of the joint is at least 80% of the strength of the whole pipe.

The only claim to polyethylene, which allows cast-iron pipes to remain on the market to this day, is high ductility and, as a result, very moderate ring stiffness. A polyethylene main pipeline can be laid in deformable soil only with protection by a reinforced concrete gutter.

Conclusion

This article will discuss the caulking of cast-iron pipes - what this procedure is, how to prepare for it and prevent the need to perform it, as well as an example of caulking using the example of a cast-iron pipe.

Cast iron is a material with very high strength as well as high weight. The density of the structure allows the manufacture of massive and strong products from it that can withstand significant loads, due to which cast iron pipes are used as elements of water supply and sewerage systems.

Even with the development of chemical production and the active use of pipes from various plastic options, when laying an external water supply, cast iron is most often used as a more serious material. are usually used in the construction of sewerage systems with very heavy loads, significantly exceeding household ones.

Buildings of catering establishments, factories processing meat and other animal products, etc. they constantly create a stream of waste, quite often leading to ruptures of cast iron pipes, which should be immediately repaired.

And taking into account the fact that the caulking and caulking of cast iron pipes is quite difficult, experts recommend conducting annual scheduled inspections to avoid time-consuming repairs.

Start and sequence of repairs

It is necessary to think about how to emboss a cast-iron pipe if it is necessary to replace the element and it is impossible to correct the damage directly at the site of the accident.

First of all, they carry out preparatory work, that is, they carefully inspect the pipes and figure out exactly how they are welded to each other.

Quite often you have to deal with pipes filled with a special solution used to glue their parts.

In this case, while underground, the elements can grow together so firmly that they cannot be detached without effort. At the same time, experts recommend using a gas cutter, which allows you to quickly remove the fastening compound and separate the pipes.

Speaking of chasing a cast-iron pipe, it should be borne in mind that the work ahead is not easy and requires turning off the water in the whole house or even the area if an important area is being repaired.

Pipe preparation for repair is carried out using special tools:

Cut off the damaged or burst area with a grinder;
Install a new part of the pipe in place of the damage;
The seam is closed with a construction bandage with cement.

Preventing the Problem from Occurring

It should be borne in mind that with all the excellent physical qualities, cast iron is a rather fragile material. It deforms under the action of water and the chemical reactions that occur in it, so all changes affect the pipes, including temperature changes, which makes them fragile and unable to withstand high pressure.

Chasing cast-iron pipes is a rather complex process, the high-quality implementation of which includes leaving a certain margin for its expansion.

The new part of the pipe is inserted into the socket, after which the seam must be securely fixed with a resin strand. To tightly lay and secure the threads, a tool such as caulking is used.

Practical experience shows that the formation of cracks is only part of the problem, which grows if drastic measures are not taken. Patching holes with the help of special compounds temporarily helps, but sooner or later a replacement will still be required, so it’s easier to deal with the breakdown right away.

Chasing a cast iron pipe

When replacing a sewer riser, a lounger from a common riser, a toilet bowl, etc. many faced the problem of caulking a cast-iron pipe. It turned out that the procedure is not as simple as it seems.

Let us consider in more detail the process of caulking a cast-iron pipe:

At the same time, they begin to loosen the socket in different directions;
Pry off the rope with a screwdriver;
Grab the rope with pliers;
Slowly pull the rope, loosening the bell.

If the socket sits firmly, this indicates that it is most likely filled with sulfur and knocking on it is useless. In this case, using a burner or a blowtorch, they start in a circle. In this case, you should also be careful not to damage the socket.

Important: when burning sulfur, it is imperative to wear a respirator, since this procedure causes significant harm to health, even death.

Before the advent of new materials, such as metal-plastic or plastic pipes, most houses had steel or cast-iron sewers. Before installing a new pipeline, it is necessary to dismantle the old one, which is not an easy task, because earlier cast-iron structures were connected with cement mortar, aluminum or sulfur. Such a pipeline is difficult to dismantle, so it is worth preparing for a laborious and protracted process.

When a cast-iron sewer is being dismantled, a wide variety of tools can be used, because it all depends on the method and material of chasing. However, the most important devices can be distinguished - these are:

grinder, with which you can cut out a pipeline element;
grinding or cutting discs;
blowtorch;
a set of different screwdrivers, a hammer;
chisel;
special pipe wrench;
goggles, a mask, and when disassembling structures that were connected with gray, also a headdress;
perforator;
nail puller or crowbar;
pipe cutter;
chisel or steel wedge;
iron bucket with water.

Before starting work, it is worth determining the connection method in order to sketch out a rough plan for how to disassemble the cast-iron sewer.

Moments of dismantling cast iron

With a complete replacement of the structure with a plastic one, you can not do extra work and just smash everything with a hammer. This is quite easy to do, because cast iron is considered a brittle material. However, if only part of the pipeline needs to be dismantled, the work must be done more carefully.

Before dismantling the cast-iron sewer, it is necessary to inspect the entire system to determine the area that will be repaired. Then be sure to turn off the water supply so that the drains do not enter the sewer. Further disassembly is carried out in stages:

The part of the pipe located below the connection is cut off.
The pipe is separated from the socket. The embossing methods will be discussed in more detail.
If you remove the connection just does not come out, use a blowtorch or make surrounding cuts 20 mm long.

When carrying out procedures, it is imperative to use all protective equipment due to the injury risk of this work.

Caulking of the pipeline with sulfur compound

Regardless of how the cast-iron sewer was connected, it is imperative to carry out some standard preparatory work before replacing:

turn off the water;
disconnect the hose leading to the toilet;
remove the toilet itself by unscrewing the bolts;
clean the bathroom of appliances and furniture.

To determine whether sulfur was really used when connecting pipes, you need to bring a blowtorch to the seam. Under the influence of high temperatures, sulfur melts, accompanying this process with an unpleasant odor.

When disassembling cast-iron sewer pipes, work begins from the farthest corner. The element must be broken with a hammer. It is better to use a tool with a plastic or polymer base, because the sewer can become clogged due to metal nozzles. Having found the cross leading to the riser, it is necessary to loosen it as much as possible.

Then you need to prepare a blowtorch or gas burner. At least two people should be involved in heating up the connections. While one warms up and melts sulfur, the other must loosen the structure. When doing this, be sure to use gloves and other protective equipment.

When the connecting substance is completely melted, the crosspiece can be removed from the riser. At the same time, you should be very careful, you need to remember to remove the remaining sulfur, and then let the riser cool thoroughly. If the cast iron structure is too strong, you can always make a few cuts near the pipe that needs to be removed. This will make the extraction process easier.

Cement bonded pipeline caulking

Dismantling cast iron pipes that have been connected with cement is practically the same as the above-mentioned sulfur option, but it is much safer. This is because when sulfur melts, a lot of carbon monoxide is released.

To start dismantling, you need to cut off part of the pipe. In this case, it is worth retreating at least 30 cm from the junction. The hardened cement is removed with a hammer, which must be beaten with a screwdriver or a chisel inserted into the hole. All procedures should be performed as carefully as possible so as not to damage the socket.

When the joints are freed from cement, you need to try to loosen the main pipe. In order not to process the sewer with a blowtorch or a burner, it is necessary to remove the cable, but if this cannot be dispensed with, it is necessary to heat it up strongly or use a specialized key. For example, for a 50 mm pipe, tool Nos. 3 and 4 are used.

The crosspiece is located below on the main riser. To remove it, you can simply use a hammer with a screwdriver. At the same time, for some time, you need to lightly tap on the tee itself in order to form a small gap between it and the pipe. Then you need to penetrate this opening, pry off the tee and remove it. It will take a lot of time to carry out these manipulations, in addition, this method is ineffective.

The next option is to use a blowtorch or burner. Dismantling is much faster, but the price for this is an unpleasant smell that takes a long time to disappear. First of all, you need to cut the socket of the cross. Then a heating device is placed in the pipe. A metal shield is applied to the upper part of the pipe in order to be able to regulate the draft inside the riser. When heated, you need to start swinging the pipe and, as soon as possible, remove the dismantled tee.

You can also use a grinder. To do this, you must first cut off parts of the tee, leaving a small piece in the pipe. Then put a medium-sized disk that could freely get inside, and cut through the remaining parts of the structure with a grinder, knocking them out with a hammer.

What to do in case of failure?

The dismantling of the pipeline is carried out to the permissible limit, because it is better to cut the pipe before it passes into the socket. At the same time, joining a cast-iron pipeline with a plastic one will take much less effort and time. It is better to cut the structure with a grinder, but if it is not there, you can use a hacksaw to work with metal. The use of this tool can greatly increase the duration of the dismantling process.

If the dismantling was unsuccessful, do not be upset, because you can simply purchase a specialized transitional coupling, with which cast-iron and polymer pipes are connected.

If you have difficulty cutting the pipe, you can cut it in half. Then you need to apply slight pressure or rotate so that the element bursts. If it cannot be removed from the socket, you just need to make several cuts in a circle with an interval of 20 mm, after which it can be removed from the riser.

Before starting the connection of the cast-iron and polymer pipeline, it is necessary to clean the first option of sulfur by heating. After removing the substance, it is necessary to leave the pipes for several hours and allow them to cool.