Metal pipes have many advantages, but during their operation everyone can face one problem - corrosion. Corrosion of pipes leads to a reduction in their service life and waste of a huge mass of metal, especially if we're talking about O steel pipes Oh. In connection with it, accidents and water leaks occur on water supply lines; because of it, the roughness of the inner surface of the pipes increases, which is accompanied by the appearance of additional resistance, a drop in water pressure and, ultimately, an increase in the cost of its supply.
In other words, metal corrosion creates the need for additional construction and operating costs in water supply systems. That is why special attention is paid to the fight against corrosion in plumbing practice.

Causes of corrosion from outside and inside pipes

Both the internal and external surfaces of pipe walls suffer from metal corrosion. Corrosion from outside pipes occurs due to metal contact with soil, which is why it is sometimes called soil corrosion. Solutions of salts contained in the soil are liquid electrolytes, and therefore they destroy the structure of the metal during prolonged interaction with it. As a special characteristic of soil, its corrosive activity is distinguished, which is in reverse proportional connection with the electrical resistance of the soil, that is, the higher the electrical resistance, the lower the corrosive activity of the soil, and vice versa - the lower the electrical resistance of the soil, the higher its corrosive activity. Thanks to the fact that this dependence is known, specialists can determine the corrosive activity of soils by measuring only their level electrical resistance.
Corrosion inside pipes occurs from the corrosive properties of the water itself. Water with a low pH value and a high content of oxygen, sulfates, chlorides and dissolved carbon dioxide quickly leads to corrosion of the inner surface of the walls of metal pipes.

Methods for protecting metal pipes from corrosion

External insulation

The first and most important way is external insulation. In addition to anti-corrosion functions, it reduces heat loss and provides mechanical protection. Different materials can be used to create insulation; we will briefly consider the possible options.
1. Bitumen insulation. Consists of a layer of polyethylene that is protected bitumen coating. Sometimes there may be fiberglass wrapped around the pipes. Can be used for pipelines located in clay, sandy and rocky soils.
2. Polyethylene anti-corrosion insulation. It consists of a multi-layer coating, specially designed to protect pipelines from corrosion.
3. Polyurethane foam insulation. There are two types. The first is the use of polyurethane foam shells, used for above-ground and underground pipelines for channel and non-channel pipe installation. The second is the creation of a polyurethane foam shell by injecting liquid polyurethane foam between the pipe and pre-created polyethylene insulation, after which the polyurethane foam hardens and turns into a complete shell.

There is also insulation with glass wool and mineral wool, however, these options are initially designed to reduce heat loss and prevent the creation of condensation, and not to protect against corrosion, which is why they are used primarily for insulating pipelines of heating networks.
The thickness of the insulating layer can vary. In each specific case, the thickness is calculated depending on the functional load on the pipeline, the importance of the water line and the corrosive activity of the soil in which it is located - the higher this activity, the thicker the insulating layer should be.

Internal insulation

It is advisable to insulate pipes not only from the outside, but also from the inside. For example, in the USA for steel and cast iron pipes Previously, internal cement coating with a thickness of 3–6 millimeters was successfully used, and this for a long time kept throughput pipelines to high level. Cement-sand mortars and varnishes can be used. In addition, it is possible to deprive the water itself of its corrosive properties through special treatment.

Cathodic protection

Cathodic protection is another method of protecting metal pipelines from corrosion, fundamentally different from those discussed above. It is based on the electrochemical theory of corrosion, according to which corrosion is associated with galvanic vapors that are formed in the area of ​​contact of metals with the soil environment, and the destruction of metals occurs in places where current flows out of it into the environment. Therefore, if you connect an external source direct current and direct the current into the ground through old ones previously buried near the pipeline iron pipes, rails and other metal objects, then the surface of the pipeline will turn into a cathode, which will protect it from the destructive influence of galvanic couples. And the current must be diverted from the pipeline through a special wire to the negative pole external source. The disadvantage of this method is that it requires energy, so it is often used as an additional, but not the main method.

Removing water pipes from electric transport routes

Corrosion of metal pipes can be facilitated by the influence of stray currents, which are especially exposed to pipes laid near the tracks of intra-factory or urban electric transport. This can be avoided in two ways - by removing water pipes from electric transport tracks and adhering to the known rules for constructing rail roads for electric transport.

The listed methods for protecting water pipes from corrosion are usually used in combination. These methods summarize the experience of many years of practice and various technical studies, so their effectiveness is not only proven, but also tested by life.

10790 0 5

Corrosion protection of steel pipes: 3 gifts from the “old lady” of chemistry

Metal pipes have the highest strength characteristics, but they are also subject to an incredibly destructive phenomenon called corrosion. Excessive humidity can destroy even the strongest steel. In this article I will tell you about what methods I used to protect my own iron pipeline from such a harmful effect, based on the knowledge of chemistry acquired in school.

General provisions

Corrosion processes are the oxidation of a metal, in which its atoms change from a free state, losing their electrons, to an ionic state. An underground pipeline is subject to two types of corrosion, the nature of which is worth understanding before starting to deal with them. Therefore, I will pay a little attention to their description:

Soil

As you probably guessed from the name and the accompanying diagram, soil corrosion occurs due to contact of steel with soil. In turn, it is divided into the following subspecies:

• Chemical. Appears as a result of exposure to iron by gases and non-electrolytes of the liquid type. It is noteworthy that with it the material is destroyed evenly, and the formation of through holes is almost impossible, which makes this type of corrosion process the least dangerous for a highway laid underground;
• Electrochemical. The metal acts as an electrode, and groundwater, of which in our climatic zone incredibly a lot of electrolyte. The ongoing process is very similar to the work of a galvanic couple and provokes the destruction of point areas on the surface of the pipes, which ultimately leads to their emergency condition;

• Electric. It occurs due to the impact of stray currents on steel, which can “drain” from rails, substations and other electrified devices that fill modern cities. It is the most dangerous and destructive corrosion process.

Internal corrosion

If the transported liquid has a low hydrogen index, but its content of oxygen, sulfates and chlorides, on the contrary, is high, then internal corrosion processes cannot be avoided, as a result of which:

• Roughness level increases the inner surface of the wall, which leads to a decrease in water permeability;

• The quality of the transported liquid deteriorates, because rust gets into it;
• With time a through hole may appear, which can cause a pipeline rupture.

Chemistry on guard

Protection of pipelines from corrosion according to SNiP includes many different comprehensive measures, but I want to give some specific methods that great science so graciously “gives” to us, and which I was able to put into practice:

Gift #1: External insulation

We figured out above that most troubles occur due to chemical reactions that occur as a result of long-term contact of metal with the ground. Therefore, the simplest and surest step is to eliminate it completely. Moreover, in this case, it is also easy to protect pipes from freezing, that is, “killing two birds with one stone.”

I will describe to you the option that I used myself, as well as alternative ways insulation of the pipeline being laid:

1. Petroleum bitumen. It was this material that I took as the basis for protecting metal from rust in underground conditions. Its price fluctuates around 18-22 rubles per kg, which is quite favorable to family budget. The working process:

• First thing I do is shine cleaned the surface pipeline with a steel brush;

• Then I diluted some of the purchased bitumen with gasoline to obtain bitumen primer in the following proportions:

• Thoroughly treated with the resulting solution metal surface water main;

• Next on fire prepared bitumen mastic with the addition of crushed asbestos to enhance the strength characteristics of future insulation. Cement and kaolin are also suitable for this purpose;

• I applied the first layer of hot mixture, after which I wrapped the pipeline with waterproofing. I used a model with the following characteristics:

• Then he repeated the procedure two more times. For your region, you may need less or, conversely, more layers of bitumen with waterproofing, depending on the corrosive activity of the soil, which is affected by its moisture level, chemical composition, acidity and structure;

1. Polyethylene. It is worth noting two completely different situations:

• The first includes the personal execution of the plan. This method can be called the easiest to implement, since you just need to wrap the pipe in several layers with polyethylene cloth and secure it with mounting tape. But this material itself has low strength characteristics, so I would be careful not to use it to protect long sections of the highway;
• In the second, we are talking about the factory application of reinforced extruded polyethylene. That is, you buy metal pipes that have a special protective layer. Of course, such products will cost more, but they will provide quite effective protection against corrosion;

1. Polyurethane foam. Here you can also take two roads, but in any case it is worth immediately noting the very high thermal insulation qualities of the finished anti-corrosion protection:

• Use special polyurethane foam shells. They are two halves of a cylinder, which are put on both sides of the pipeline and are joined to each other, creating a connection;

• Injection of liquid polyurethane foam between the pipe body and a pre-installed shell of extruded polyethylene or other suitable insulating material. After the substance hardens, the seams are completely absent, which, of course, significantly improves the quality of the insulation, although the process itself is more labor-intensive to implement.

External insulation is not limited to the above options; here you can use many more moisture-resistant materials that can take a cylindrical shape. Therefore, in any case, also be guided by the current offers of a specialized store located near you.

Gift #2: Internal Insulation

As I noted above, liquid transported through pipes can also provoke the occurrence of corrosive processes, and here things are somewhat more complicated. The fact is that without special equipment at home, high-quality internal insulation is impossible. Then all that remains is to order the appropriate services from specialists or immediately buy already protected products.

The most common option today is applying a cement-sand mixture to the internal walls of the pipeline followed by crimping it using a special pulled device. The result is a smooth, non-corrosive coating.

When I ordered this type services, I was offered the following prices:

It is noteworthy that the instructions allow processing of both new metal pipes and old ones.

In addition to cement it can also be petroleum bitumen used. In this case, products with a large cross-section are dipped into a liquid solution, and the joints are then processed manually. And samples with a small diameter are coated after welding, passing a mixture with a hollow copper cylinder through them under the influence of constant electric current. Due to the influence of electricity, bitumen particles adhere tightly to the iron, creating a thin, reliable film.

Gift #3: Active Insulation

This includes electrical protection methods, which I was quite able to implement on my own. Here is their description:

1. Cathodic protection:

• We apply a negative potential to the pipeline, transferring it to the cathode zone;
• Near the pipes burying iron pipes, pieces of rails or other ferrous metal products that will take on the role of an anode;

• We connect a source with negative direct current to the pipeline;
• We connect a source with positive direct current to a rail or other product that you used as an anode;
• So a closed circuit of electric current is formed, which flows from the positive pole to the anode grounding, spreads over the ground, hits the pipe and then to the negative pole;

• Because from the rails the current comes out in the form of positive metal ions, then it is gradually destroyed, and not the pipe. So much for chemistry;

1. Tread protection. Much easier to implement because does not require an external power source. This is the option I prefer to use:

• We place a metal rod next to the water supply, having a negative chemical potential, which exceeds that of steel. This may be a product made of zinc, magnesium or aluminum;
• We connect it to the protected structure using;

• The entire impact will fall on the anode protector, excluding pipe corrosion;
• Once the zinc or magnesium rod is completely destroyed, it must be replaced;

1. Drainage. With its help, pipelines are protected from stray currents:

• We connect the pipe with a cable to the nearest electrified source, through which the currents that fall on it return back;
• Metal ions stop going into the soil, due to which corrosion processes stop.

So everything active methods protection comes down to preventing the loss of metal ions due to “sacrifice” or getting rid of stray currents.

I recommend using an integrated approach to waterproofing your pipeline. That is, combine external, internal and active protection.
This will give the most effective result, allowing you to extend the operational life of the highway for decades.

Conclusion

When installing a water supply system on your own suburban area I ordered processing of its internal walls cement-sand mixture , then on your own covered it with bitumen insulation on the outside and for greater confidence I buried a magnesium blank connected by a cable nearby. Now I have no reason to doubt the durability of the created structure, since the existing knowledge of chemistry guarantees the absence of corrosive processes, taking into account all the precautions taken.

The video in this article contains some additional information that is directly related to the topic presented.

If you have any questions after reading the material, you can ask them in the comments.

July 25, 2016

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

Almost any system of internal infrastructure and life support for residential buildings, municipal and commercial buildings or industrial facilities, by and large, represents a developed network of pipelines connecting certain system objects with each other in a certain order.

In most cases, for example, when installing a gas pipeline, hot and cold water supply, sewage or cable and ventilation, underground, air or internal laying of metal pipes is used various diameters and size.

Depending on operating mode and conditions environment, metal pipes during operation can be exposed to prolonged exposure to various unfavorable factors. To solve this problem it was specially developed comprehensive protection pipelines against corrosion according to SNiP 2.03.11-85 “Protection building structures from corrosion."

Corrosion control methods

To help the reader understand how to ensure maximum pipeline longevity, this article will discuss some options for active and passive protection of metal products that are part of pipeline utilities.

There will also be detailed instructions, which describes in detail the basic principles of anti-corrosion protection for metal products intended for use in aggressive conditions.

Classification of harmful factors

As mentioned above, the nature and degree of influence external factors largely depends on specific operating conditions, such as the location of the pipe, the chemical composition of the soil, the average annual temperature and relative humidity of the environment, the presence of nearby DC sources, etc.

According to the mechanism of occurrence and the degree of destructive impact, all harmful factors can be divided into several types.

1. Atmospheric corrosion occurs when iron interacts with water vapor contained in the surrounding air, as well as as a result of direct contact with water during precipitation. During the chemical reaction, iron oxide is formed, or, more simply, ordinary rust, which significantly reduces the strength of metal products, and over time can lead to their complete destruction.

1. Chemical corrosion arises as a result of the interaction of iron with various active chemical compounds(acids, alkalis, etc.). In this case, the ongoing chemical reactions lead to the formation of other compounds (salts, oxides, etc.), which, like rust, gradually destroy the metal.
2. Electrochemical corrosion occurs in cases where an iron product is in an electrolyte environment (an aqueous solution of salts of varying concentrations) for a long time. In this case, anodic and cathodic areas are formed on the surface of the metal, between which an electric current flows. As a result of electrochemical emission, iron particles are transferred from one area to another, which leads to the destruction of the metal product.
3. Impact negative temperatures in cases where pipes are used to transport water, it leads to freezing. Upon transition to a solid state of aggregation, it forms in water crystal cell, as a result of which its volume increases by 9%. Being in a confined space, water begins to put pressure on the walls of the pipe, which ultimately leads to their rupture.

Note! A significant difference in average annual and average daily temperatures leads to significant fluctuations in the total length of the pipeline, which are caused by the linear thermal expansion of the material. To prevent pipe rupture and damage load-bearing structures, after a certain distance on the line it is necessary to install thermal compensators.

Soil analysis

In order to choose the most effective method protection, it is necessary to have accurate information about the nature of the environment and the specific operating conditions of the steel pipeline. In case of laying internal or overhead line this information can be obtained on the basis of subjective observations, as well as based on the average annual climate regime for a given region.

In the case of laying an underground pipeline, the corrosion resistance and durability of the metal largely depend on the physical parameters and chemical composition soil, so before digging a trench with your own hands, you need to submit soil samples for analysis to a specialized laboratory.

The most important indicators that need to be clarified during the analysis process are the following soil qualities:

1. Chemical composition and salt concentration various metals V groundwater. The density of the electrolyte and the electrical permeability of the soil largely depend on this indicator.
2. Qualitative and quantitative indicators of soil acidity, which can cause both chemical oxidation and electrochemical corrosion of metal.
3. Electrical resistance of the soil. The lower the electrical resistance value, the more susceptible the metal is to the destructive effects caused by electrochemical emission.

Advice! To obtain objective analysis results, soil samples must be removed from the soil layers in which the pipeline will pass.

Low temperature protection

In case of underground or airborne, the most important condition their uninterrupted operation is to protect pipes from freezing and maintain the water temperature at a level not lower than 0°C during the cold season.

To reduce the negative impact of the environmental temperature factor, the following technical solutions are used:

1. Laying an underground pipeline at a depth exceeding the maximum soil freezing depth for a given region.
2. Thermal insulation of overhead and underground lines using various materials with low thermal conductivity (mineral wool, foam segments, foam propylene sleeves).

1. Backfilling of a pipeline trench bulk material with low thermal conductivity (expanded clay, coal slag).
2. Drainage of adjacent soil layers in order to reduce its thermal conductivity.
3. Laying underground communications in rigid closed boxes made of reinforced reinforced concrete, which ensure the availability air gap between the pipe and the ground.

The most progressive method of how to protect pipes from freezing is to use a special casing consisting of a shell made of thermal insulation material, inside of which an electric heating element is placed.

Note! The depth of soil freezing for each specific region, as well as the methodology for its calculation, is regulated regulatory documents SNiP 2.02.01-83* “Foundations of buildings and structures” and SNiP 23-01-99* “Building climatology”.

External waterproofing coating

The most common way to combat metal corrosion is to apply a thin layer of durable waterproof material to its surface. protective material. The simplest example of an external protective coating is ordinary waterproof paint or enamel, for example the protection of a gas pipe passing through the air is always done with weatherproof yellow enamel.

Underground water and gas pipelines are usually assembled from pipes that are pre-coated on the outside with a thick layer of bitumen mastic and then wrapped in thick technical paper. Also high efficiency have coatings made of composite or polymer materials.

The metal elements of underground sewer communications are covered with a thick layer from the inside and outside cement-sand mortar, which after hardening forms a homogeneous monolithic surface.

To choose your own suitable material for an external coating, you need to know that to provide maximum protection it must simultaneously have several qualities.

1. After drying, the paint coating must have a continuous, uniform surface with a high mechanical strength and absolute resistance to water.
2. The protective film of the waterproofing material, with the specified properties, must be elastic and not collapse under the influence of high or low temperatures.
3. The starting material for coating must have good fluidity, high covering ability, as well as good adhesion to the metal surface.
4. Another indicator of a high-quality insulating material is that it must be an absolute dielectric. Thanks to this property it is ensured reliable protection pipelines from stray currents, which increase the adverse effects of electrochemical corrosion.

Advice! Most effective solutions to isolate metal from the environment, it is customary to consider compositions based on bitumen resins, two-component polymer compositions, as well as roll polymer materials on a self-adhesive basis.

Active and passive electrochemical protection

Underground engineering Communication are more susceptible to the occurrence of corrosion centers than air and internal pipelines, because they are constantly in an electrolyte environment, which is a solution of salts contained in groundwater.

In order to minimize the destructive effects caused by the reaction of iron with a water-salt electrolyte solution, active and passive methods of electrochemical protection are used.

1. Active cathode method consists in the directed movement of electrons in a direct electric current circuit. To do this, a pipeline is connected to the negative pole of the DC source, and an anode grounding rod is connected to the positive pole, which is buried in the ground nearby. After applying voltage electrical circuit shorts through the soil electrolyte, causing free electrons to move from the ground rod to the pipeline. Thus, the grounding electrode is gradually destroyed, and the released electrons react with the electrolyte instead of the pipeline.

1. Passive tread protection of pipelines consists of placing an electrode of a more electronegative metal, such as zinc or magnesium, next to iron in the ground, and connecting them electrically through a controlled load. In the electrolyte environment they form a galvanic couple, which during the reaction, as in the previous case, causes the movement of electrons from the zinc protector to the protected pipeline.
2. Electrical drainage protection is also a passive method, which is performed by connecting the pipeline to a grounding loop made in accordance with the PUE. This method helps to get rid of the occurrence of stray currents and is used if the pipeline is located near the contact electrical network of ground or rail transport.

Note! A clear example passive protective protection is the well-known zinc coating of iron products, or, more simply, galvanization.

Conclusion

Each of the above methods has its own advantages and disadvantages, so they should be used depending on the specific conditions prevailing. In conclusion, it should only be said that regardless of the chosen method, the cost of repairing and replacing the pipeline will be much more expensive than the cost of the most complex and time-consuming protection.

For more information, you can watch the video in this article or read similar materials on our website.

Without reliable anti-corrosion protection, not a single metal structure will last long. Rust protection is important unless you plan to replace the fence every few years.

Metal fencing is no exception. The service life of products can be extended by proper processing. Below we will talk about the technology of painting structures made of metal picket fences, profiled sheets and mesh, and also analyze the painting compositions that are optimally suited for metal surfaces.

Rust protection for fences step by step

We start by preparing the metal for painting.

This point is fundamental, as it determines how well it will fit on fences made of Euro picket fences or corrugated sheets. finishing layer. First you need to clean the fence from traces of paint, rust, oil, grease, and dirt. Conservative and radical methods are appropriate here.

• Conservative methods include removing rust using a scraper, a metal brush, special knife. Best result An acetylene torch or blowtorch will do.
• When exposed to metal, the outer layer of paint fades, and rust and scale come off due to temperature differences. If it is not possible to remove traces of corrosion, choose a paint composition that is suitable for application to an unprepared surface.

Padding

The next step is applying a primer, which simultaneously protects the metal from corrosion and ensures the paint adheres to the surface. For ferrous metals, experts recommend choosing anti-corrosion primers.

For people of color, on the contrary, property is more important adhesion (aluminum and copper are not subject to corrosion). The primer coat can be applied using a roller, brush or sprayer.

Applying the finishing coat

Once the primer coat has been applied, you can begin painting. You can apply paintwork using a sprayer, brush or roller.

It is better to paint in 2-3 layers with drying intervals. This will give a more uniform surface without blemishes. It is most convenient to use a spray bottle. To do this, you need to treat the surface from a distance of 15-20 cm.

The dwell time between coats is reduced to 20 minutes. Rollers are used for smooth surfaces. Before painting, it is recommended to dilute the mixture with a solvent in a ratio of 9 to 1. Hard to reach places and the corners are treated with a brush. Then the entire fence is rolled with a roller in 2-3 layers.

Choosing paint for metal

On the website masterovit.ru (the largest manufacturer metal fencing in the Russian Federation based on the results of 2015) there was recently a discussion on how to properly paint inexpensive fence from corrugated sheets and which paint and varnish materials are better to choose.

The company's specialists recommend water-dispersion and special acrylic paints for metal. Last option preferable, since it allows you to reliably protect the surface from corrosion and negative external factors (precipitation, UV radiation).

A good solution is to choose anti-corrosion compounds that can be applied to traces of rust and paint residues. The formulations contain a solvent, so they eliminate old layer and protect structures from destruction. There are also enamels on the market with additives: rust converters, anti-corrosion primer. They are applied to cleaned surfaces.

Pre-treatment of the base with a primer is not required, which shortens the process of painting the fence. For ferrous metals, anti-corrosion compounds based on water based. The finishing coating is highly resistant to ultraviolet radiation, rainfall, and sudden temperature changes.

There are many options for building fences, and their differences depend on the functions for which they are intended. The material of the future fencing is selected in accordance with the functions.

Functions and material of the fence

The fence is intended for simple and specialized fencing of the territory: land privately owned, parking areas, recreation areas, construction and specially protected sites, animal shelters. Fences are also often a decorative element in landscape design or form a single composition with architectural solutions.

This variety of functionality makes it possible to use different materials for their construction: ordinary wood or metal picket fence, decorative picket fence in the “Ranch” style, multi-colored profiled sheets, chain-link mesh, welded, sectional, forged, asbestos-cement and concrete spans. Like any structure, a fence requires the creation of some kind of base on which the material is attached. For a fence, the pillars are such a basis.

Pole material

Regardless of the choice of material for the fence itself, the posts can be made from:

• wood;
• metal;
• concrete;
• bricks;
• asbestos cement pipes.

Metal advantage

Universal materials for making fence posts are hardware, because in the vast majority of fence installation cases welding is used.

A special quality of metal poles is their durability. No matter how you process it wooden beam, it will rot much faster than the metal will collapse.

The process of metal corrosion occurs on average at 0.15 – 0.2 mm per year. This depends on external weather and climatic conditions, the composition of the metal and the quality of its processing. A positive advantage of metal poles is reliability and strength. Asbestos concrete pipes are not subject to corrosion and do not require additional maintenance, but they are fragile and cannot withstand rough mechanical loads.

Pillars made of metal, compared to reinforced concrete ones, are easy to repair and install, dismantle and can be reused.

Corrosion

Metal corrosion is a natural phenomenon, which cannot be completely prevented, but this destructive process can be significantly slowed down. The oxidation process occurs with the participation of oxygen and aqueous solutions containing acid, alkali or salt.

In nature, iron is in pure form not found, but found in iron ore. Humanity invented the production of steel and came up with ways to preserve it. Factories use methods of phosphating steel by immersing it in various solutions, as well as electrochemical treatment. This coating is in the nature of a primer and requires subsequent painting. Steel is coated with other metals. Cheaper ones are aluminum and zinc.

There are silicate coatings - these are various types enamels. Enamel is fragile and not entirely suitable for a fence. Cement has approximately the same expansion temperature as steel and serves as an insulator against aggressive environments. Good insulation is a polymer film applied in several layers in the factory.

Treatment

The durability of the metal depends on the grade of steel. More precisely, there is alloy steel with different additives. But for simple fence- this is an expensive pleasure. Usually they use factory rolled metal, or make poles with their own hands from what they can get. For temporary fences, poles welded from pieces of iron or previously used but still strong water supply pipes are suitable.

It is difficult to clean the internal cavity of the pipe, but the rust is removed from the outside using an iron brush and treated with a grinder or grinder. If necessary, degrease and apply a primer for metal, for example, GF-021. After the primer has dried, the pipe is painted in two layers.

To paint metal, the most common oil paint PF-115 is suitable. For the lazy, there is three-in-one paint. It neutralizes rust, primes and creates a protective surface.

But in practice, without prior machining It’s better not to do without, you need to at least clean the metal with sandpaper.

The most the best solution to select new fence posts there will be a combined version of metal coated with zinc and polymer film. Factory metal rolling produces painting, observing all technologies. It is best to purchase poles that are ready for installation, as this will significantly save time and labor costs. However, this option cannot be called financially economical.

In practice, most often iron poles are primed and painted themselves oil paint or bitumen varnish

There are special cans of spray paint that are convenient to use when welding. Coating powder paint will be more expensive and technically more difficult. The thinner the coating layer, the more durable the protection. Therefore, apply several layers with a spray or thoroughly rub in with a brush, avoiding air bubbles that provoke an oxide reaction.

The soil is more aggressive environment than air. Therefore, the part of the metal located in the ground is insulated with concrete or bitumen mastic. Rolled insulators are not suitable for these purposes. Scale generated during welding stimulates metal corrosion. It must be removed with a grinder.

Shapes of metal pillars

Fence posts can have a wide variety of configurations, from simple to designer:

• round;
• square;
• rectangular;
• screw;
• homemade.

Round pipes Easiest and cheapest to purchase. The choice of their diameter depends on the design of the fence, and most often they use a size from 57 mm to 108 mm, in exclusive options the diameter is increased to 159 mm. The thickness is selected taking into account the characteristics of the material filling the spans: from 1.5 mm to 4 mm. The thicker the longer term operation.

A good option with drill pipes with a wall thickness of 5 mm.

Transverse logs are attached directly to the pipes by welding, or guides for fastening are welded onto the pipes. The guides can be made in advance by welding them to a clamp, which is put on the pipe and tightened with a bolt. With this installation option, an insulating pad made of cotton material or a special plastic lining suitable for the diameter of the pipe is placed under the clamp.

Profiled posts have the shape of a square or rectangle. This form makes it possible to fasten the logs not only by welding, but also by using bolts or rivets. It is more convenient to work with them if the guide logs are made of wood or the fence is built in the “Ranch” style.

Screw posts are a pipe with a drill welded at its end. This option is used for quick installation fence, because there is no need to dig a hole for the post first.

Homemade pillars made from used material that is available (orphan), or from that which can be obtained. For example, iron corners are suitable.

Ground influence and installation

The choice of metal poles also depends on the installation method, and this, in turn, depends on the condition of the soil. For a light fence, you just need to drive a post into the ground if it is dense (gray soil, clay, sand). Two people are involved in the work - one drives it in, and the other holds the post, checking it for level in two vertical planes.