What electrodes are needed for welding pipes, profiles and other metal structures. How to weld pipes, select electrodes and make seams? Which electrodes are best for pipe welding

Metal pipeline and electric welding are inseparable concepts. When arranging water supply, heating, high or low pressure sewerage in everyday life or at work, pipes are joined by welding.

This is due to the fact that the welding seam does not differ in strength and structure from the material of the pipeline elements. It provides a solid CIP design with the guarantee of absolute sealing and durability.

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Pros and cons of pipe welding

Like any method in construction, electric welding of steel pipes has its advantages and disadvantages.

The advantages of this method include:

the ability to connect pipes of any diameter, regardless of wall thickness;
thanks to the welded seam, the initial outer and inner diameters of the pipe are preserved. In the case, for example, with couplings, the diameter of the joint increases significantly in comparison with the joined elements;
the same material is used for welding as for the pipeline itself. This makes it possible to ensure complete solidity of the structure without changing the properties of the material used;
welding does not require the purchase of additional fittings, which are often quite expensive;
this method is quite cheap and simple, provided that specialists take up the matter.

In fact, there is only one drawback: only a specialist can weld pipes correctly.

If you take on such work on your own, you can get a poor-quality seam with significant cracks, slag accumulations, etc. In the future, this will lead to leakage and rotting of the pipe near the joint.

Briefly about the welding process

The process of joining metal pipes by electric welding is to create an electric arc between the electrode and the welded elements.

Under the influence of an electric arc, two similar materials are melted, mixed and create a monolithic seam in the course of removing the electrode.

Due to the special coating of the electrode, special conditions are created in the arc that do not allow oxygen to enter the melting point of metals and create a protective film.

The width and thickness of the seam depend on the thickness of the electrode, the materials of the elements to be welded, the welding mode, the arc speed, and the mains voltage. The formation of slags on the surface depends on these same parameters, especially on the latter. The slag formed during the welding process must be removed.

Before starting to weld the system, it is necessary to understand many nuances, prepare tools and equipment, purchase electrodes, and prepare the welded edges of the pipes.

The process of electric arc welding of steel pipes (video)

Welding tools

For welding, first of all, electric welding is required. There are two types of welding machines:

the basis of the first type is a step-down transformer. The regulation of the current of such welding is carried out by changing the magnetic gap or the position of the rheostat. To date, such a device is considered obsolete. It has a significantly large weight and requires special skills;
the second type is inverter welding. Thanks to the use of a much smaller transformer, the apparatus has become compact and fairly light. It can be easily moved around the room or even hung on the shoulder. Adjustment of current of inverter welding is carried out by regulators with high accuracy.

In addition to the welding machine we will need:

electrodes. We will talk about the choice of electrodes later;
mask. It is needed in order to protect the face and eyes from welding burns. It was quite inconvenient to use the old versions of masks. It was necessary to tune in, attach an electrode, and only then put on a mask, since they did not let light through at all. Today the market offers so-called chameleon masks. They are able to automatically adjust the degree of darkening of the glass;
overalls. In the process of welding, splashes of hot metal fly from the joint. Therefore, it is better to protect yourself from burns with the help of welding overalls;
metal brush or other abrasive tool for cleaning the edges of the joined elements;
hammer for upholstering slag.

Choice of electrodes

Weld quality directly depends on the correct choice of electrodes. They are selected based on the material, diameter and wall thickness of the pipe. Welding of thin-walled pipes is carried out with an electrode of 2-3 mm, a thick-walled heating pipe must be welded with an electrode of 4-5 mm.

In addition to the thickness of the metal rod, the electrodes also differ in the thickness of the coating and its material. The coating can be from 3 to 20% of the total mass.

Recall that the coating in the electrode is needed to create a special environment in which welding is carried out without access to oxygen. But, the larger the coating layer, the more slags are created, which negatively affect the quality of the seam and the solidity of the structure.

Therefore, when choosing electrodes, it is important to find a compromise between the thickness of the rod and the coating layer, taking into account the characteristics of the pipe.

Understanding which electrodes and at what amperage is it correct to cook this or that pipe comes with experience. Such experience is usually obtained by the method of "scientific poke". However, in order to avoid a large number of errors, it is worth first referring to the tables of correspondences between electrode types, types of pipes and electric welding current.

Joint preparation

You can start cooking heating pipes only after their joints are completely cleaned of debris and raids. If you are a beginner, do not try to weld wet pipes, as the water will boil, evaporate and make the process much more difficult.

Before starting work, you need to properly clean the edges of the joined elements. To do this, use different abrasive tools, ranging from sandpaper and ending with a grinder, depending on the thickness and quality of the pipe. You can start welding joints only after as they will not remain burrs and sharp edges.

before starting welding work, you need to make sure that there are no combustible or explosive objects near the junction of the heating pipes. If they are, and it is not possible to remove them, it is necessary to enclose the place of work with non-combustible material, for example, asbestos;
next to the place of welding, you need to put a container with water, in case of an unexpected fire;
make sure that the grounding and the integrity of the wire of the welding machine are securely fixed;
check the mains voltage. If the voltage is weak or its drops are observed, increased slagging may occur during the welding process. To avoid this, it is better to use a rectifier;
clean and dry pipe joints. An experienced craftsman can weld heating pipes with a wet joint, but this will seriously interfere with a beginner;
put on a welding suit and mask;
set the desired current on the transformer of the welding machine. As a rule, welding of heating pipes up to 5 mm, with an electrode thickness of 3 mm, is carried out at rotary joints with a current of 100 - 250 A, at fixed joints - 80 - 120 A;
check if the voltage is correct. To do this, we ignite the arc by moving the electrode at a distance of 5 mm until sparks appear. If there are no sparks, adjust the current;
after completing all of the above steps, you can start welding heating pipes.

Welding steps

After setting up the welding machine and achieving a stable arc, we begin to connect the elements of the pipeline.

There are three options for moving the welding arc:

The translational movement of the electrode along the weld, ensuring the stability of the arc.
Along the junction. Provides a continuous seam, the height of which depends on the speed of movement of the electrode.
Across the joint with oscillatory movements. This method provides not only the required height, but also the width of the seam.

Welding of pipes of small diameter with a wall thickness of up to 5 mm made with a continuous seam. Similar products of larger diameter are cooked intermittently.

It is necessary to weld pipeline elements with a wall thickness of up to 6 mm in two layers, from 6 to 7 mm - in three, over 7 mm 4 welds are laid.

It is necessary to brew the joints until the connection is complete without interruptions in the seam.

The first layers are best welded in steps to connect the joints. All subsequent layers are carried out with a continuous seam. After welding the first continuous layer, it is necessary to knock off all the slag and carefully inspect the junction for cracks and burns. If there are any, they need to be melted and boiled again.

When building a country house, it is important to properly plan engineering communications. At the project stage, schemes for heating, water supply and sanitation are laid. Today, there are a large number of technological solutions to these issues. There are PVC plumbing and heating pipes and classic metal pipes on the market.

The choice of pipe type is influenced by a large number of factors. But, despite the increased popularity of polymer products, metal pipes remain popular and are often used to create engineering networks.

In order for the finished structure to be strong and durable, it is necessary to correctly connect all the joints. The main method of joining metal pipes is welding. And the quality of welding is affected not only by the skill of the master, but also by the correctly selected brand of electrode, suitable for connecting such products. With basic skills and the necessary equipment, welding of heating pipes can be done by hand.

Welding of heating pipes can be conditionally divided into several stages.

Preparation of equipment and tools.
Preparation of the welded surface.
Welding process.

To perform welding work, you will need a welding machine, a grinder, a hammer, a protective mask and gloves, as well as welding electrodes. The pipe surface to be welded must be clean up from rust, dirt and paint, as well as degrease. Cleaning must be done inside and outside to a depth of at least 1 cm. After that, you can start the welding process.

For beginners, rutile electrodes of the OK46, ANO-21, MP-3 and OZS-4 brands are recommended for welding heating and plumbing pipes. These electrodes are of the same type and have similar characteristics. Professionals can use UONI-13/45 brand electrodes. The choice of electrode diameter depends on the wall thickness of the pipe. With a metal thickness of up to 5 mm, electrodes with a diameter of 3 mm are suitable. For welding pipes with a wall thickness of up to 10 mm, electrodes with a diameter of 4 mm must be used. In this case, the surfacing is performed in several layers.

The strength of the welding current for each diameter and brand is set individually. Experienced welders are guided by their feelings. Beginners are advised to choose the welding modes indicated on the package with electrodes. The package also indicates the calcination modes. And if rutile-coated electrodes can be stored without calcination, then main brands necessarily subject to calcination. This is necessary to remove excess moisture from the coating, to ensure a high-quality and durable seam.

When performing welding work, remember to safety precautions. Use special protection and ground the welding machine. Do not use shoes with metal inserts.

After completion of work, it is necessary check tightness designs. Run water or gas through the pipes. There must be no leaks at the welding site. If everything is done correctly, then the pipe connection was successful.

You can choose welding electrodes and learn more about welding on the manufacturer's website: https://goodel.ru/

Video: How to replace batteries with your own hands?

The welding process is a rather complex and multi-component procedure that requires certain knowledge and skills. To perform a high-quality connection by welding, many nuances and parameters should be taken into account. In particular, the correct choice of electrodes for a particular case is of great importance. After all, the welding mode, the amount of deposited material, the composition of the weld metal, and hence the characteristics of the resulting weld, will depend on this. Therefore, the strength of the connection largely depends on this choice.

Therefore, it must be done taking into account the properties of the material and parameters. After all, each type of electrode has its own characteristics, therefore it is suitable for performing some specific tasks. Therefore, it is worth considering each type of electrode that may be suitable for a particular case.

Selection by welding parameters

Products of the rutile-acid type have the advantage of slag removal in narrow joints.

Rutile allows you to get an attractive look of the seam, the slag is well removed, re-ignition is easy. Used for tacks, overlays and fillet welds.
With a rutile-basic coating, electrodes are used to obtain root welds, as well as in the construction of pipelines of medium and small diameters.
Rutile-cellulose perfectly proved themselves in different positions. This is a universal option if the product is with a thick coating.
Cellulose are used to connect large diameter pipes with circumferential seams. They are suitable for making vertical seams from top to bottom. Therefore, such products are used for laying pipelines.

Basic electrodes can be used for connection in any position. However, the appearance of the seam is a little worse than in other cases. However, such products reduce the likelihood of cracks in the weld metal.

Effective with large wall thicknesses, as well as with poor weldability of the material. These electrodes are effectively used for welding strong steels.

Selection by material properties

In the weld metal, as in the main, almost the same indicators of toughness and strength should be observed.

In order to make the right choice according to DIN EN 499, there are indications of the values of tensile strength, yield strength, as well as the toughness of the weld metal.

Let's take an example. Let's say the designation E 46 3 B 4 2 H5:

E - type of electrode - manual welding.
46 - yield strength 460 N / mm 2, minimum.
3 - at a temperature of minus 30 degrees, a crack develops, the work of which is 47 J.
B - the main coating of the electrode.
4 - DC welding.
2 - welding in all positions, with the exception of vertical from top to bottom.
H5 - hydrogen content in the weld metal up to 5 ml/100 g.

The same designation systems exist for stainless, high temperature and high strength electrodes.

Diameter

When choosing an electrode for pipe welding, determining its diameter is important. The characteristics of the seam, as well as the filler material consumption, depend on this.

It must first be noted that the nominal diameter is the size of the rod, without coating. As for the thickness of the coating, it is individual, it is determined by GOST 9466-75 according to the formula: D / d. D is the coated diameter and d is the rod diameter. Ratio:

Equal to or less than 1.2 - thin coating;
Equal to or less than 1.45 - medium coverage;
Equal to or less than 1.80 - thick coating;
More than 1.8 - extra thick coating.

Interestingly, foreign manufacturers also adhere to similar rules, but the diameters of their products do not meet Russian standards.

Here are the main features of electrodes that differ in diameter:

8-12 mm - current strength up to 450 amperes, and the metal being welded has a thickness of over 8 mm. Their length is 35-45 cm. For all types of steel, for high-performance industrial equipment.
6 mm - current strength 230-370 amperes, and the metal being welded has a thickness of 4-15 mm. Their length is 35-45 cm. For all types of steel, for professional equipment.
5 mm - current strength 150-280 amperes, and the metal being welded has a thickness of 4-15 mm. Their length is 35-45 cm. For all types of steel, for powerful equipment.
4 mm - current strength 100-220 amperes, and the metal being welded has a thickness of 2-10 mm. Their length is 35-45 cm. For all types of steel.
3 mm - current strength 70-140 amperes, and the metal being welded has a thickness of 2-5 mm. Their length is 30-45 cm. For alloy and low-carbon steel.
2.5 mm - current strength 70-100 amperes, and the metal being welded has a thickness of 1-3 mm. Their length is 25-35 cm. For alloy and low-carbon steel.
2 mm - current strength 50-70 amperes, and the metal being welded has a thickness of 1-2 mm. Their length is 25-30 cm. For alloy and low-carbon steel.
1.6 mm - current strength is 25-50 Amperes, and the metal being welded has a thickness of 1-2 mm. Their length is 20-25 cm. For alloy and low-carbon steel.
1 mm - current strength 20-25 amperes, and the metal being welded has a thickness of 1-1.5 mm.

It should be noted that each brand of electrodes may have its own current strength, therefore the indicated parameters are indicative. The cost will also differ.

The correct choice of the electrode is the key to a high-quality and durable seam, and hence the entire structure. Therefore, such a choice should be approached especially carefully.

Electrodes for welding pipes for heating and water supply. Which electrodes are best for welding heating pipes

Electrodes for heating and water supply pipes

The strength of the weld depends not only on the professionalism of the welder performing the work, but also on the quality of the electrodes used, although their importance is not appreciated as highly as they deserve.

The role of electrodes, with which welding is carried out, for connecting heating and water supply pipes, is very important if you need to get a high-quality weld. Welding electrodes used for pipe welding are rods that conduct current to the welding site. Currently, the modern market provides a huge selection of welding electrodes with various types of coatings designed for welding work.

At the moment, electrodes are divided into two large groups, consumable and non-consumable, and many subgroups differ in the type of coating. Separation into consumable and non-consumable electrodes according to the type of metal used for their manufacture. Non-consumable electrodes for pipe welding are produced from graphite, tungsten or electrical coal.

Non-consumable electrodes, in turn, are made from welding wire. Magnetic, protective and stabilizing coatings are applied to the finished rods. With the help of marking, that is, letters on the box, it is enough just to choose the electrode suitable for this or that welding work. Make sure the pipe surface is dry and clean before welding. When welding pieces of pipe, be sure to straighten the edges and only after that proceed to welding. When the pipe is deformed in the form of dents, welding work is not carried out.

Thin-walled water pipes, as well as gas pipes made of identical material, are welded with electrodes, avoiding downtime in the welding process, and apply at least two layers. To overlay the next layer, the previous one is carefully cleaned and prepared for welding.

A high-quality pipe connection can be made if all technological rules are observed and the correct electrodes are selected. One of the best electrodes are OK-46, which burn well, fill large gaps with ease and can be used to weld from above and below.

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How to weld a pipe for heating?

April 27, 2017

It is quite possible to tie into a heating pipe without using welding, but it will not work to do it yourself without the use of special equipment. Therefore, to connect to the main heating system, you will also need to use welding. In order to qualitatively weld metal elements of various kinds together, it is necessary to understand what exactly welding is.

The principle of this technology is as follows: a metal workpiece under the influence of high current and a certain voltage begins to melt and joins with the same edge of another workpiece. Products begin to penetrate each other, their particles intersect with each other at the molecular level. Largely due to this, electric welding of metal heating pipes is considered to be one of the most reliable technologies, which makes it possible to provide a very high level of joint strength.

Varieties of electrodes

An electric welding electrode is a metal rod of a certain diameter, which has a special coating for welding. The thickness of this consumable is different - this indicator should be chosen depending on the thickness of the metal you plan to connect. The coating of the electrode is intended for additional protection of steel elements and the weld pool from direct exposure to the external environment. Moreover, it helps to make the arc burning much better.

Before directly buying electrodes, it is advisable to consult with welders or neighbors who periodically carry out welding work at home, what kind of consumables they use. Welding metal heating pipes with fake or poor quality electrodes will result in a poor quality joint that will leak over time. It must be said that reliable electrodes cannot be cheap.

In the manufacture of home pipelines using electric welding, it is desirable to use electrodes with a diameter of 2 to 5 mm. Coverage also plays an important role. It comes in different types:

the main thing is that it is universal, it contributes to obtaining a high-quality joint even when using cold welding. During subsequent operation, the seams almost never crack, they have excellent viscosity indicators;
based on cellulose and rutile. It is intended for the formation of complex joints, in particular a vertical seam that runs strictly from top to bottom;
rutile coating will look the most attractive. Slag can be easily removed from the joint surface, the arc is ignited very easily. These electrodes are typically used in the tacking process or fillet welds;
A rutile-acid based coating makes it possible to obtain not only a high-quality seam, but also a slag with its own structure. After welding of heating pipes by electric welding is completed, it will be very easy to remove;
cellulose coating is ideal for structures with large diameters. Thanks to this coating, it is possible to quickly and reliably form not only a vertical, but also an annular seam.

Surface preparation

Before proceeding with the direct work, the surface of the elements to be joined should be thoroughly dried and cleaned with a brush in order to obtain a metallic sheen, clean off all traces of corrosion, and so on. If the pipe has a deformed section, then it must be removed. They clean about two centimeters from each end of the workpiece.

If the pipe has a diameter of no more than 89 mm and a thickness of 2 to 5 mm, then it is best to use electrodes with a thickness of about 3 mm. Thinner electrodes will not melt the metal over the entire depth, and thick products are inconvenient during the work.

To understand how to cook correctly, it must be borne in mind that there are several types of welded joints:

butt;
overlap;
angular;
tee;
crosswise.

Work technology

First of all, the electrode is inserted into the holder and the arc is ignited by striking it on the base metal. Thanks to this, it becomes possible to weld heating pipes by electric welding. If everything was done correctly, a corresponding electric arc will be obtained, due to which the metal will be melted. The electrode must be kept at a distance of about 5 mm from the surface of the workpieces in the area where they are planned to be connected. The pipe should be welded by electric welding at a certain angle - about 70 degrees. The seam is applied carefully, with oscillatory movements, only in this case the production of the connection of elements will be of the highest quality.

It is possible to conduct the electrode along a zigzag crescent-shaped trajectory. In the region where the arc is formed, a corresponding bead will form. When the connection is completed or the electrode runs out, it is necessary to allow the joint to cool slightly, and then knock off the slag from the surface of the connection. It is possible that a few additional stitches will be needed. The main thing to remember is that after each pass it is required to knock down slag.

Cold welding for heating pipes can be used even at home by a novice welder. The welding process itself begins with the formation of tacks, regardless of the type of connection. Tacks are made using the same electrodes that will later form the entire seam. If the pipe diameter is not too large, only two or three tacks can be made - they will hold the structure in one position, preventing the elements from moving relative to each other. In the future, this will greatly facilitate the work.

Choosing a welding machine

Recently, inverter welding machines have been the most popular both in domestic and industrial conditions. They are of excellent quality, allow you to ensure a constant burning of the arc and the formation of a reliable weld pool. As a result, by using this device, you can get the highest quality connection.

The inverter equipment is not too heavy, which makes it easy to carry it from one place to another - for ease of transportation, it is equipped with a special strap. If necessary, it can be used offline - it can be connected to a gasoline or diesel generator.

Transformer welding machines are more bulky and not very reliable. They create a rather serious load on the electrical network, which in the future can cause a short circuit. Because of this, it is undesirable to connect them to various kinds of gasoline or diesel-type generators.

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Selection of electrodes for pipe welding

The strength of the weld directly depends on the correct choice of electrodes for pipe welding, although many underestimate the importance of their correct choice.

Welding electrodes for pipes are rods through which current is supplied to the welding site. Nowadays, the range of such electrodes is very diverse. They differ in their purpose, the coatings used and the method of manufacture.

There are two main types of welding electrodes: consumable and non-consumable. This classification is determined by the metal from which the electrodes are made, as well as the technology of subsequent processing.

Non-consumable electrodes are made of graphite, tungsten, as well as electrical coal. Welding wire is used as a material for the manufacture of such electrodes. Various types of magnetic, stabilizing or protective coatings are applied to the resulting rod. A protective coating is necessary to resist the penetration of air masses onto the electrode layer. This contributes to a more stable burning of the welding arc and a more even welding seam at the exit.

If you carefully study the packaging of the electrodes, you can see various letters and numbers on it. Depending on the material of the products on which welding will be carried out, the following letters can be seen on the packages: T, L, V, U, N. The types of coatings are indicated by the letters C, B, R, P, A (coatings can be acidic, rutile , basic, cellulose, etc.). A mixed coating of electrodes is also used. In this case, there are two letter values in the name of the electrodes.

During the repair or construction of pipeline systems, electrodes are used mainly for welding horizontal joints, rotary and non-rotary. The choice of electrode diameter is carried out depending on the thickness of the pipe wall. For pipelines with thick walls, large electrode sizes are used.

The surface of the pipe is thoroughly cleaned of dirt and soil before welding. If there are dents or other deformations on the pipes, welding is not possible.

Electrodes welding of joints is carried out continuously, without downtime during the welding process and in at least two layers. Each subsequent layer is superimposed on the previous one only after its complete preparation and cleaning.

After analyzing the above, we can conclude that only with the right choice of welding electrodes and subject to all the subtleties and rules of the process, you can be sure of the good quality of the welding work performed.

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Recommendations for choosing electrodes for welding: electrode consumption

Selection by welding parameters

Products of the rutile-acid type have the advantage of slag removal in narrow joints.

Rutile allows you to get an attractive look of the seam, the slag is well removed, re-ignition is easy. Used for tacks, overlays and fillet welds.
With a rutile-basic coating, electrodes are used to obtain root welds, as well as in the construction of pipelines of medium and small diameters.
Rutile-cellulose perfectly proved themselves in different positions. This is a universal option if the product is with a thick coating.
Cellulose are used to connect large diameter pipes with circumferential seams. They are suitable for making vertical seams from top to bottom. Therefore, such products are used for laying pipelines.

Effective with large wall thicknesses, as well as with poor weldability of the material. These electrodes are effectively used for welding strong steels.

Selection by material properties

In the weld metal, as in the main, almost the same indicators of toughness and strength should be observed.

In order to make the right choice according to DIN EN 499, there are indications of the values of tensile strength, yield strength, as well as the toughness of the weld metal.

Let's take an example. Let's say the designation E 46 3 B 4 2 H5:

E - type of electrode - manual welding.
46 - yield strength 460 N / mm2, minimum.
3 - at a temperature of minus 30 degrees, a crack develops, the work of which is 47 J.
B - the main coating of the electrode.
4 - DC welding.
2 - welding in all positions, with the exception of vertical from top to bottom.
H5 - hydrogen content in the weld metal up to 5 ml/100 g.

The same designation systems exist for stainless, high temperature and high strength electrodes.

Diameter

When choosing an electrode for pipe welding, determining its diameter is important. The characteristics of the seam, as well as the filler material consumption, depend on this.

Equal to or less than 1.2 - thin coating;
Equal to or less than 1.45 - medium coverage;
Equal to or less than 1.80 - thick coating;
More than 1.8 - extra thick coating.

Interestingly, foreign manufacturers also adhere to similar rules, but the diameters of their products do not meet Russian standards.

Here are the main features of electrodes that differ in diameter:

8-12 mm - current strength up to 450 amperes, and the metal being welded has a thickness of over 8 mm. Their length is 35-45 cm. For all types of steel, for high-performance industrial equipment.
6 mm - current strength is 230-370 Amperes, and the metal being welded has a thickness of 4-15 mm. Their length is 35-45 cm. For all types of steel, for professional equipment.
5 mm - current strength is 150-280 Amperes, and the metal being welded has a thickness of 4-15 mm. Their length is 35-45 cm. For all types of steel, for powerful equipment.
4 mm - current strength is 100-220 Amperes, and the metal being welded has a thickness of 2-10 mm. Their length is 35-45 cm. For all types of steel.
3 mm - current strength 70-140 amperes, and the metal being welded has a thickness of 2-5 mm. Their length is 30-45 cm. For alloy and low-carbon steel.
2.5 mm - current strength is 70-100 amperes, and the metal being welded has a thickness of 1-3 mm. Their length is 25-35 cm. For alloy and low-carbon steel.
2 mm - current strength is 50-70 Amperes, and the metal being welded has a thickness of 1-2 mm. Their length is 25-30 cm. For alloy and low-carbon steel.
1.6 mm - current strength is 25-50 Amperes, and the metal being welded has a thickness of 1-2 mm. Their length is 20-25 cm. For alloy and low-carbon steel.
1 mm - current strength 20-25 amperes, and the metal being welded has a thickness of 1-1.5 mm.

It should be noted that each brand of electrodes may have its own current strength, therefore the indicated parameters are indicative. The cost will also differ.

The correct choice of the electrode is the key to a high-quality and durable seam, and hence the entire structure. Therefore, such a choice should be approached especially carefully.

www.trubygid.ru

What electrodes to weld pipes? - Welder's Handbook

As before, welding is currently used to connect metal pipes. With its help, you can quickly, reliably and efficiently weld pipes of various diameters. Thanks to the abundance of welding machines, today each of us can face this task at home.

In our article, we will talk about which electrodes should be used for pipe welding in one case or another, as well as how it is better to weld pipes.

How are welding electrodes classified?

More than half of the welding electrodes found are designed to work with carbon and low alloy steels. The type of this or that electrode has different parameters, which include, for example, the impact strength of the finished seams, the mechanical properties of the seams, as well as their ability to bend. What electrodes are most often used to weld pipes?

Acid coated electrodes. In the process of manufacturing such electrodes, metal oxides are used, and the electrodes themselves are used for welding under direct and alternating current. It is better not to use such electrodes for steels with a high content of carbon and sulfur.

Basic coated electrodes. In the process of their manufacture, fluorine compounds and carbonates are used. It is advisable to use electrodes of this type for welding pipes with thick walls. In this case, the seams are resistant to cracking, and also acquire high viscosity.

Cellulosic coated electrodes. Accordingly, cellulose is used in the manufacturing process, which allows welding from top to bottom, while overheating of the electrodes is unacceptable. The disadvantage of such electrodes is the high probability of metal splashing during operation.

Rutile coated electrodes. For the manufacture of rutile concentrate is used. In the process of welding, seams with high viscosity are obtained, and slag is also easily removed after the work done.

Mixed coated electrodes. With the help of such electrodes, it is quite convenient to weld pipes and obtain the necessary seams, depending on the composition of the incoming components.

Among other things, welding electrodes can also be divided into two more categories:

With a meltable core, which is made from a special welded wire, differing in diameter and properties.
With a non-consumable core, in the manufacture of which carbon, graphite or tungsten material is used as the core itself.

Thus, these types of welding electrodes are usually used for pipe welding. Which electrode to choose depends on the specific situation. In this case, it is best to take a reference book and find a match, which electrode should be used to weld a particular pipe.

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What electrodes to weld pipes

Of course, in modern industry, the mechanized method of fusion welding is widely used, but, despite this, the largest number of works on welding metal structures is still performed using manual arc welding. Welding electrodes are used to perform manual arc welding. The welding electrode is a metal or non-metal rod, the task of which is to supply current to the welding site.

In turn, they are divided into meltable and non-meltable, these characteristics depend on the material used in the manufacture of welding electrodes. So from synthetic graphite, tungsten and electrical coal, samples are made that are not amenable to melting.

Meltable electrodes are made from alloy, carbon or high alloy wire. Under pressure, using the pressing method, a special protective coating is applied to the metal rod. This in turn provides a stable and stable arc pressure. Consumable electrodes when welding use their own metal to hold the weld together.

Non-consumable electrodes only perform the function of AC conductors to the place of welding, and in this case, the bonding of the weld occurs due to the melting of the filler rod or wire and the metal to be fastened. They are called electrode rods and electrodes specially designed for contact welding.

Carbon electrodes are used if you need to make a neat and aesthetically beautiful weld, they are also good if you need to perform air-arc cutting of metal with a large thickness. With the help of electrodes at the site of the weld, it is possible to significantly change its chemical composition and alloy it. The introduction of filler material during the welding process makes it possible to perform melting. The electrodes have their own unique marking and are divided by diameter and length.

The choice of electrodes involved in welding is carried out taking into account the coating, and are characterized by a different level of technological and welding properties. There are several main types of coating: rutile, acid, basic, cellulose, mixed and ilmenite. For each of the listed coatings, suitable welding electrodes are selected.

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How to cook pipes correctly, what electrodes to solder plastic communications

When connecting pipes, welding is most often used. Today on sale you can find a large selection of welding machines, both domestic and industrial, so many homeowners take up the welding work themselves.

At the same time, beginners naturally have questions: how to properly weld pipes, how to select electrodes, how to prepare surfaces for welding and check the quality of the seams. Let's try to understand these problems.

Today, many different welding methods are used in construction.

So, according to the method of joining the metal, welding is divided into:

Thermal, which includes all methods of welding by melting.
Thermomechanical, which includes butt resistance welding, as well as a welding process using a magnetically controlled arc.
Mechanical, which includes methods of welding by friction and explosion.

In enterprises and in the construction of pipe lines, in most cases, automatic and semi-automatic welding methods are used. In private construction, the method of manual arc welding is widely used.

Preparatory work

Before proceeding with the implementation of welded joints, it is necessary to prepare the surfaces of the pipes and select the right materials for work.

Choice of electrodes

To perform manual arc welding, electrodes are used as consumables. This material is produced in a huge assortment, so the question of which electrodes to weld pipes with is extremely important.

The whole variety of manufactured electrodes can be divided into two groups:

consumable base electrodes;
Non-consumable electrodes.

This classification is carried out by evaluating the material that is used to make the core of the electrodes. So, consumable electrodes are made from welding wire of various thicknesses and compositions. The core of non-consumable electrodes is made of tungsten, graphite or electrical coal.

In addition, the classification of electrodes is carried out by evaluating their coverage.

Each type of coating is designed to solve specific problems, so it is extremely important to take this circumstance into account when choosing.

Cellulosic coated electrodes (grade C) are used for making circumferential and vertical welds on large diameter pipes.
Electrodes coated with rutile acid type (RA brand) are distinguished by the special structure of the slag formed during welding, which can be easily removed at the end of work.
Rutile coated electrodes (grades R, RR) are distinguished by easy re-ignition, good slag impact and allow you to create welds with a marketable outer surface. They are used for setting tacks, as well as for creating fillet welds and welding the outer layers of the seams, which should have a beautiful appearance.
Electrodes with rutile-cellulose coating (RC brand) are recommended for seams in any direction, including the most difficult case - when forming a vertical seam from top to bottom.
Basic coated electrodes (Grade B) produce welds with excellent toughness characteristics and less chance of cracking. These electrodes are recommended for welding pipes with a high wall thickness, and also in applications where it is necessary to maintain a high weld toughness, for example, for the creation of pipelines to be used in low temperature conditions.

Pipe surface preparation

Before welding pipes, it is necessary to prepare their edges, that is, the surfaces that will be involved in the welding process.

Pipes should be checked for compliance with the requirements laid down in the pipeline design. Basic conditions: conformity of dimensions, presence of a certificate, no deformation (ellipticity), no difference in the thickness of the pipes, compliance of the chemical composition of the pipe metal and their mechanical properties with the requirements of GOST.
When preparing the joints, they are cleaned of dirt, oil and traces of rust, the perpendicularity of the plane of the end of the pipe axis is checked, the angle of opening of the edge and the amount of blunting are measured.

The opening angle of the edges to create a good seam should be equal to 60-70 degrees. The amount of blunting, as a rule, is 2-2.5 mm.

If the shape of the bevel of the edges of the pipes does not match, they are machined using bevelers, trimmers or grinders. To prepare large-diameter pipes, milling machines are used or thermal preparation methods are used, for example, gas-acid or air-plasma cutting.

Welding

Consider how to cook pipes correctly.

Installation of tacks

Tacks are an integral part of the weld, they are made using the same type of electrodes that will be used for the main welding.
When welding metal pipes (for heating, for example), having a diameter of up to 300 mm, four tacks are performed, placing them evenly around the circumference. Each tack should be 3-4 mm high and 50 mm long.
When welding pipes of larger diameter, tacks are placed every 250-300 mm.

When assembling pipelines, one should strive to ensure that the maximum number of joints is performed in a rotary position. Pipes having a wall thickness of up to 12 mm are connected by welding in three layers. Consider how to properly weld a pipe in a rotary position.

Rotary welding

The first welding layer is made 3-4 mm high, for this, electrodes with a diameter of 2 to 4 mm are used. The second layer is created using electrodes of a larger diameter.

They do the job like this:

The joint is divided into four sectors.
First, the first and second sectors located in the upper hemisphere of the pipe are welded.
After that, the pipe is turned and the remaining two sectors are welded.
Next, the pipe is turned again and the second layer of the seam is made on the first two sectors.
The work is completed by performing the second layer of the seam in the third and fourth sectors, having previously turned the pipe over again.

The third layer of seam is applied in one direction as the pipe is rotated.

When welding pipes with a diameter of up to 200 mm, it is possible not to perform division into sectors, performing all layers of the seam in one direction when the pipe is rotated.

Plastic pipe welding

In private construction, metal pipes are rarely used today, preferring to work with plastic.

Therefore, the question of how to cook plastic pipes is of interest to many home craftsmen.

When designing a pipeline from polypropylene pipes, it should be borne in mind that such pipes may stretch somewhat when heated.

Heating nozzles are fixed in the device.

For welding polypropylene pipes, a temperature of 250-270 degrees is required.

Next, pipe sections of the size specified by the project are measured, and they are cut. The edges of the parts are recommended to be sharpened at a slight angle.
A marker on the pipe marks the length of the connection with the fitting so that the end of the pipe does not abut against it.
Pipe surfaces to be welded must be degreased.
The fitting warms up a little longer than the pipe, so it is processed first. Then a pipe is put on the heated nozzle. After warming up (the time depends on the characteristics of the device used), the parts are removed from the nozzle and fixed in a smooth movement without turning. The seam should be fixed until it cools down.

Thus, it is possible to obtain reliable connections using plastic pipes - how to weld such parts is described above, however, the following should be considered when doing the work:

To get a really reliable pipeline, you need to carefully consider the choice of raw materials, namely, purchase high-quality pipes and fittings.
We must not forget about the need for mechanical processing of the joined edges, since otherwise it is impossible to obtain a high-quality connection. The end of the pipe after trimming must be cleaned using trimmers, shavers or files with a fine notch.

findings

The performance of pipe joints during the construction of pipelines is a responsible job, the quality of which determines the reliability of the networks under construction. Therefore, regardless of the material of the pipes used, welding must be carried out in strict accordance with the requirements of SNiP.

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The quality of the resulting weld significantly depends on how correctly the electrodes for pipe welding are selected. Unfortunately, many welders underestimate the importance of their selection.

Welding electrodes are rods that supply current to the place where the seam should be made.

Varieties of electrodes used for pipe welding

Now there are quite a lot of varieties of electrodes, which differ in purpose, coating and production method.

The most important difference is that the electrode can be consumable or non-consumable.

This parameter depends on the material from which the electrode was made and the method of further processing. For the manufacture of non-consumable electrodes, tungsten, graphite and electrical coal are used. Consumable electrodes for welding pipelines are made from welding wire that is coated to protect, stabilize and impart the desired magnetic properties.

Coatings do not allow air to get on the electrode metal, which gives the welding arc combustion stability, and this, in turn, contributes to obtaining a better and more uniform weld. The coating on the electrode is applied by pressing or dipping into the molten material.

Advantages and disadvantages of consumable electrodes

Consumable electrodes have the following advantages:

Of course, these electrodes also have certain disadvantages, which include:

Large radiation of the electric arc.
Limitations on current parameters.
Significant spatter of metal.

When working, these shortcomings should be taken into account. Electrode manufacturers are striving to improve their products to minimize the impact of these negative factors.

Deciphering the letter marking of the electrodes

According to GOST 9466-75, consumable electrodes have a number of letter designations indicating their parameters. The first shows the purpose - for which steel groups the electrode can be used.

Electrodes intended for welding low-alloy and carbon steels are designated by the letter U, alloyed - L, high-alloyed - B. Also, the tensile strength of steel is important for choosing an electrode. It is indicated in kgf / mm².

The thickness of the electrode coating is also indicated by letters. The thin layer of the coating is marked M, the middle one is C, and even thicker ones are D and G.

The type of coverage is indicated as follows:

A is sour.
B is basic.
C - cellulose.
R - rutile.
P - other.

The coating can be marked with two letters at once.

Features of welding joints of pipes and pipelines

A rather important parameter of the electrodes is the diameter. Electrodes for welding pipe joints are selected depending on the wall thickness of the pipe itself.

Accordingly, the thicker the pipe to be welded, the larger the required electrode diameter.

To make a good seam, the surface of the pipe to be welded must be thoroughly cleaned of rust, dirt or soil. The presence of dents or deformations of another kind can significantly complicate welding work or make it impossible at all.

Joint welding must be carried out continuously, without downtime or interruption. To make the seam strong, welding must be carried out in at least two layers. The next layer can only be applied when the previous one has been cleaned and fully prepared.

After analyzing all the material presented, we can come to the conclusion with which electrodes to weld pipes. Only with the right choice of them and compliance with all the requirements for the technical process, it is possible with a high probability to obtain a high-quality result from welding work.