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What electrodes are needed for welding pipes, profiles and other metal structures. What specific electrodes are needed for pipe welding Good electrodes for pipe welding

Using welding equipment to connect elements requires certain skills and abilities. To perform this procedure, it is important to consider different nuances and parameters. Particular attention is paid to the choice of material for each individual case. It is the electrodes that influence the welding mode, the size of the seam and its properties. However, they have the most important effect on the strength of the joint.

When making any connection, you should take into account the characteristics of the material, since each type of electrode for welding pipes has its own individual characteristics. This means that each specific connection is made by specific electrodes. This means that all varieties need to be studied to determine their suitability for a specific process.

Welding parameters of electrodes for pipes

The main advantage of rutile acid electrodes for welding pipelines is the removal of slag during narrow joints of elements.

Rutile coating forms a seam with an attractive appearance, removes slag well, and ignites quickly when reused. Application – creating corner joints and tacks.
Rutile + basic coating makes it possible to obtain root joints. Mainly used on pipelines whose elements have medium and small diameters.
Electrodes with rutile-cellulose coating are considered universal solution for welding elements with thick coating.
The cellulose coating makes it possible to perform circumferential seams when connecting pipes with a high diametrical index. These are the best electrodes for pipe welding.
The main electrodes are used for any joining, regardless of the position of the seam. Despite the fact that the seam from such welding has a less attractive appearance, the risk of cracks in the weld is reduced. The greatest effect from the use of such electrodes can be obtained when connecting elements with thick walls and poor welding properties. It is also effective to use basic electrodes when joining strong steel.

Material properties

The weld metal must have similar toughness and strength as the base metal. Therefore, it is necessary to study the brand of electrodes for pipe welding, which must comply with the DIN EN 499 standard. This document regulates the tensile strength, yield strength and toughness of the weld metal.

For example, electrodes with the designation E 46 3 B 4 2 H5 have the following parameters:

The letter E denotes electrodes intended for manual welding. These electrodes can be used for welding water pipes.
Next comes the yield strength indicator, 460 N/mm2 is considered the minimum limit.
The next designation is the temperature conducive to crack development, -300C.
B - means the type of coating, in in this case– main.
The next number is the applied current. 4 – welding using direct current.
Next comes the designation of the direction of the seam. 2 – any, excluding vertical.
The last designation is the amount of hydrogen that the deposited metal may contain. H5 means 5 ml/100 g.

Diametral section

The diameter of the electrodes for pipelines is of great importance. This value affects the consumption of filler material and the properties of the seams.

The nominal diameter is the thickness of the rod without coating. The coating thickness is different for each type of electrode and is regulated by GOST 9466-75.

The coating can be determined by the ratio of the total diameter of the electrode to the diameter of the rod:

A coating is considered thin if the ratio is equal or less than 1.2.
Average coverage is defined as equal to or less than 1.45.
If the diameter ratio is equal or less than 1.8, the coating is thick.
If the diameter ratio is more than 1.8. That coating will be especially thick.

It is worth noting that imported products must also meet these rules. However, it is rarely possible to note that their diameters comply with Russian standards.

Calculated power of electrodes

Depending on the diameter, the main capabilities of the electrodes are determined:

When working with electrodes with a diameter of 8-12 mm, the current should not exceed 450 A, the thickness of the material being welded can be higher than 8 mm. The length of such electrodes is 35-45 cm. The main application is industrial equipment with high productivity.
Electrodes with a diameter of 6 mm allow you to work with any type of steel at a current of 230-370 A, the thickness of the material being welded is from 4 to 15 mm. Used for professional purposes.
For welding products made of alloy and low-carbon steel, electrodes with a diameter of 1.5 to 3 mm are suitable. In this case, the materials being joined can have a thickness in the range of 1-5 mm. Using a material with a diameter of 2-5 mm, you can solve the problem of which electrodes are best for welding heating pipes.

It is worth noting that each type of electrode has its own current strength.

Before starting work, you should decide which electrodes to weld pipes with. The correctly selected material for welding allows you to make a high-quality and durable seam.

trubaspec.com

Electrodes for welding joints of pipes and pipelines

The quality of the resulting weld seam significantly depends on how correctly the electrodes for welding pipes 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.

Types of electrodes used for pipe welding

Now there are many types of electrodes, which differ in purpose, coating and production method.

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

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 pipeline welding are made from welding wire, which is coated with a coating to protect, stabilize and impart the desired magnetic properties.

The coatings prevent air from getting onto the metal of the electrode, which gives the welding arc combustion stability, and this, in turn, helps to obtain a better and more uniform seam. The electrode is coated by pressing or dipping into molten material.

Advantages and disadvantages of consumable electrodes

Consumable electrodes have the following advantages:

Ability to work from almost any position.
Oxidation has little effect on the process.
Higher performance.
Good protection worker during welding.

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

Large radiation electric arc.
Limitations on current parameters.
Significant metal spattering.

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.

Decoding the letter markings 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 groups of steels the electrode can be used.

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

The thickness of the electrode coating is also indicated by letters. A thin layer of coating is marked M, a medium layer is marked C, and even thicker layers are marked D and G.

The type of coverage is indicated as follows:

A – sour.
B – 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

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

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

To ensure a good seam, the surface of the pipe being welded must be thoroughly cleaned of rust, dirt or soil. The presence of dents or other types of deformation can significantly complicate the welding work or make them completely impossible.

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

After analyzing all the material presented, you can come to the conclusion which electrodes to use to weld pipes. Only if you select them correctly and comply with all the requirements for the technical process, you can with a high probability obtain a high-quality result from welding work.

steelguide.ru

Choosing electrodes for pipe welding

The selection of electrodes for welding pipes is a fundamental process on which the quality of the seam and its reliability will ultimately depend. It is necessary to take into account absolutely all the nuances, even the most insignificant ones, but, unfortunately, many welders, including professionals, do not always pay due attention to this.

If we're talking about about laying profile or standard pipes, sooner or later you will have to use a welding machine. When choosing an electrode, you should know about the first and most important difference between them: they can be melting or non-melting.

Features of consumable electrodes

For the production of this type of electrodes, welding wire is used, it has protective covering, which is necessary to stabilize operation and the required magnetic characteristics. And the non-melting one is made from graphite, tungsten and electric coal.

The coating for the consumable electrode is also necessary to be able to obtain a high-quality and reliable seam; it is applied by immersion in molten metal and pressing.

What are the advantages of consumable electrodes:

They allow welding from any position.
Increased productivity.
Minimal influence of oxidation on the joining process.
Safe for the welder while working.

Flaws:

high radiation of the welding arc;
spattering during welding;
Current limits have been set.

These are the main parameters that should be taken into account before selecting the required electrodes.

How to choose the right electrode

The rods may differ in their thickness and amount of coating. For welding galvanized pipes or any other, electrodes with a diameter of 2-5 mm are used. And the coating itself will amount to from 5% to 20% of the total mass of the product.

Most often, specialists use thicker rods. This happens because they are able to provide the necessary atmosphere to the welding process, which prevents air from entering the joint area. But it is also worth considering that they are distinguished by a large amount of waste released. And they, in turn, can affect the reliability of the docking. Therefore, it is necessary to learn to find golden mean For optimal performance with pipeline welding.

How to choose an electrode, taking into account the thickness of the pipe?

If the thickness of, for example, stainless pipes is 5 mm, then the electrode should have a diameter of no more than 3 mm.
When the pipe is larger than 5mm, 4mm rods will be required.
Also, a diameter of 4 mm is used for multi-layer formation of a welded joint.

It is also worth taking into account the maximum current that the rod can pass through, and the consumption of electrodes when welding pipes, which will help reduce financial investments.

Pipeline welding process

Once the choice is made, you can proceed to the welding process. To begin with, it is worth understanding how to move the arc along the connection; several help with this simple tips from the experts:

the arc is drawn transversely, using oscillatory movements to obtain the required seam thickness;
if you move the arc longitudinally, this will allow you to make a thin seam with a height that completely depends on the speed of movement of the selected rod along the surface to be joined;
To maintain the stability of the electric arc, it must be carried out gradually throughout the welding process.

Note!

Safety regulations

Safety is a component of the welding process that should be approached with great responsibility. After all, if you ignore the rules, you can get serious injuries, such as burns from molten metal, eye burns from an arc flash, or become a victim of electric shock. You can avoid such situations by following simple recommendations, namely:

the welder should not wear wet clothes while working;
It is imperative to use a protective face mask;
All wires through which current flows must be insulated with any in an accessible way;
Before starting welding, do not forget to ground the unit and additional devices, if they are;
V small rooms It is necessary to use rubber shoes or lay a rubber mat, it will act as an insulator.

Conclusion

To make the choice of electrode more prepared, it is worth taking into account the consumption rate of the rods and taking into account the connection of a certain type of pipe to the material from which the rods are made. And for an even better understanding of the selection procedure, it is best to seek advice from experienced specialists who have great experience in carrying out this type of work.

Sergey Odintsov

electrod.biz

What electrodes are needed for welding pipes, profiles and other metal structures

There is a misconception that the quality of the weld depends only on the performer, but this is far from true, and any good welder understands this - electrodes for welding heating and water pipes play an important role in such work.

First of all, it should be noted that such conductive rods can be either metallic or non-metallic, that is, carbon or graphite, but in this case, we are not interested in the second type.

A good welder always knows which electrodes to weld pipes with.

Let's look at what characteristics can be used to distinguish consumables of this type, how best to select them, and the video in this article will demonstrate visual information on our topic.

How are they distinguished?

The photo shows the wire for welding

Electrodes made of metal can be consumable or non-consumable. The first type can be coated, with a steel, cast iron, bronze, copper or aluminum rod, but uncoated ones are currently used only in the form of wire (see photo above) when welding work is carried out in a gas protective environment.

The non-melting type includes intruded, thoriated, lanthanum, and tungsten, therefore, it is quite natural that their price is much higher.

In addition, electrodes are classified according to their purpose, that is, according to the type of material to be processed. For high-carbon steel according to GOST 9467-75, the material is marked with the letter U, for alloy and heat-resistant steels - with the letter T, but for deposition of the surface layer - with the letter T.

Tungsten - TIGWIG

In most cases, there is a coating on the rods, but it also varies and has its own marking according to GOST 9466-75.

For example:

thin coating is marked with the letter A (international format - A);
middle - letter C (international format - B);
thick - letter D (international format - R);
and especially thick - the letter G (international format - C).

In addition to the thickness of the coating layer, it is classified according to its type:

A - sour;
B - basic;
C - cellulose;
R - rutile;
P - mixed.

In addition, the mixed layer can be:

AR - acid-rutile;
RB - rutile-basic;
RP - rutile-cellulose;
RZh - rutile, with an admixture of iron powder.

Note. Due to the fact that welding work can be carried out in different positions, electrodes here are classified into different types. So, they can be for the lower position, vertical from bottom to top, horizontal and lower in a boat.

The instructions also include rods for any position.

By appointment. Types of materials

Welding gas pipe high pressure

Carbon and low-alloy structural steels. In this case, the temporary tensile strength can be up to 60 kgf/mm or 600 MPa.
High-alloy types of steel that are endowed with special properties.
Structural steels where arc welding is used. Here the temporary tensile strength will already be more than 60 kgf/mm or 600 MPa.
Surfacing of a surface layer of metal having special properties.
Cast iron.
Non-ferrous metals. (See also the article Sewerage in a cottage: features.)

More about coverage

Various coatings

A - acid or sour coating. It contains oxides of iron, manganese and silicon.
B - basic. It contains calcium fluoride and calcium carbonate. Welding work using such electrodes is carried out DC variable polarity.
C - cellulose. It contains flour and other organic components, which are intended to create a gas protective shell during welding work.
R - rutile. It contains rutile as the main component, as well as other mineral and organic components. In addition to gas protection, such components can significantly reduce spatter during weld production.

Note. IN household use(heating, frames) everything is somewhat simpler, since for all cases they usually use electrodes with a main (B) coating, the diameter of which depends on the thickness of the metal. For example, if you are interested in what electrodes to weld a profile pipe with, then given the thin profile wall (1.0-1.5 mm), you are better off using a rod with a cross-section of 2 mm.

Depending on the welding (transformer or inverter), you will select the consumables itself (for alternating or direct current).

Consumption rates

Vertical connection without bevel of edges

For heating installation, the consumption rates of electrodes when welding pipes may be different, depending on the joining of the heating pipes being welded and the type of seam, but we will consider only a vertical connection without beveled edges, as the most commonly used.

Consumption of electrodes when welding pipes per meter of seam

Consumption of electrodes when welding pipes per joint

Note. By and large, electrodes of any type are classified as one of the groups of welding materials. In addition to them, this includes filler rods, wire, shielding gases and filler fluxes.

Conclusion

As you noticed, there are quite a few brands of electrodes, but if you want to heat your home with your own hands, then you immediately need to select materials for high-alloy and non-ferrous steels, as well as cast iron.

In addition, the thickness of the walls of heating pipes is usually at least 2 mm, then a 3 mm rod is needed. In addition, you will need an electrode for all positions, with a medium coating (C) type, acid (A) or basic (B), for carbon and low-carbon steels.

This page shows information on the topic "Electrodes for welding pipes" and everything related to it. See further information on this issue, and at the bottom of the page there are selected brands of electrodes with this label on the website.

Electrodes for pipe welding

In practice, the need to weld metal pipes is encountered quite often. Such work must always be taken with a great deal of responsibility, especially if these are pipes for the heating system, plumbing or high-pressure systems. For welding VGP pipes(water and gas) requires appropriate welding materials

When welding such pipes, the seams must withstand maximum loads and skill alone, of course, will not be enough. To obtain a high-quality, durable and strong seam, it is also necessary to use suitable welding materials, which are able to provide the necessary seam, thanks to their special composition. On this page we will try to describe in detail which electrodes are best for welding pipes.

Electrodes for welding high pressure pipelines

Experts recommend electrodes for welding high-pressure pipelines of such brands as: and, companies,. If the pipes are made from steel 20, then type is used, and if ZOKHMA metal was used in their manufacture, 20KhZMVF is suitable EP-60, TsL-19ХМ And VSN-2. MP-3s electrodes may have a blue or green coating. They are easy to use and make it possible to operate at low current from a device connected to a regular network.

OK 53.70 electrodes make it possible to perform one-sided welding of high-pressure main networks and many other similar very important structures in the construction of which low-carbon steels were used. They are coated with a special flux. Thanks to it, a small amount of gases is released. The low content of non-metallic impurities makes it possible to create a weld characterized by high ductility and good impact toughness.

Electrodes for oil pipelines

Today, pipe electrodes are widely used for oil pipelines. foreign production eg (Japan) and OK 53.70 Sweden. There are many similar to these, designed and manufactured locally. These include LEZ LBgp, this brand was tested at VNIIIST and received a NAKS certificate. They are covered with sulfur, carbon, silicon and manganese. They are produced in diameters of 2.5, 3 and 4 mm. They are used to weld pipes made of low-alloy metal.

For a household inverter and welding black pipes, you can buy MP-3s electrodes. They allow operation at low current. They are good for welding pipes made of carbon and low-alloy metals.

The main water supply, which is usually laid underground and consumers are connected to it in manholes, is made of cast iron.

To create a seam in the lower, floor-ceiling, and vertical positions, it is best to use the MNCh-2 brand. Used for welding gray and ductile cast iron. Using the brand, you can cook using the cold and hot method. This electrode is only suitable for the down position. Its peculiarity is that you can weld a valve or any product made from other types of metal to cast iron.

On a note! Selecting an electrode for welding water pipes must be coated with a coating that will protect the melting bath from nitrogen. This important condition. If the seam contains oxygen or nitrogen in large quantities, then its plastic properties will be characterized as weak, and the strength will not meet the standard. Electrodes with a thick coating allow you to obtain a high-quality water supply connection.

You can choose the most suitable electrode for a certain type of work based on the data indicated on the packaging. In most cases, the brand is suitable, ESAB. Stainless steel pipes tap water is cooked with an electrode similar to ESAB OK 61.30. Electrode manufacturing plants have proven themselves well.

Useful video

Electrodes for welding galvanized pipes

To prevent pores from forming during galvanizing welding, it is better to increase the current by 10-50 amperes more than usual. Between the pipes and sheets being connected, the gap must be doubled.

The process speed should be slowed down by 20%. The technique for creating a seam should be reciprocating.

Attention! To prevent harmful zinc fumes from leading to tragedy or suffocation, it is important for welders to remember to use protective equipment.

Suitable brands

For welding galvanized pipes, electrodes with a diameter of up to 3 mm are used. They must have calcium fluoride or coating.

Making the right choice is very important, quality depends on it. A special flux protects the zinc coating from evaporation.

Electrodes MP-3, ANO-4, OES-4, made of low-carbon steel, are suitable. They are covered with rutile. If the galvanized metal is made from low-alloy steel, then it is recommended to buy UONI-13/55, UONI-13/45, DSK-50.

Video from the manufacturer

See how UONI 13/55 is cooked without interruption:

Electrodes for welding water pipes

For the production of hot-rolled pipes that do not have seams, St20-10 metal is used. Carbon steel St3, St10-20, St17g1s-u is used in the manufacture of electric welded products. Cold-deformed pipes are made from grade 20. Corrosion-resistant pipes with thick walls are made from metal 08Х18Н10Т, 12Х18Н10Т, 08Х18Н12Т. Standard precision is made from metal that meets the requirements of GOST 380, increased precision – GOST 1050.

Most suitable brands

Depending on the thickness of the pipe metal, an electrode is selected. Its diameter can be 2-6 mm.

The brand allows you to weld pipes with thick walls.
The grade is necessary for welding large-diameter products.
Electrodes will allow you to make a seam in any direction.

For welding water pipes, UONI 13/45, OK 74.70, ANO-T, OK 46 are used. These grades ignite easily, burn well, and are capable of filling large gaps.

Electrodes for welding heating pipes

For heating piping, a pipe of grade St.3 is suitable - this is low-alloy carbon steel. The best option– conventional seam pipe St.3 with a passage of up to 20 mm and a wall of up to 2.8 mm. The choice of electrodes depends on the choice of pipes.

Carefully! A galvanized pipe will cause a lot of trouble during welding (see above).

For a high-quality and reliable connection weld steel pipes You can use electrodes of the following brands:

ANO-4;
MP-3;
UONI-13/45;
ANO-27;
ANO-21;
OK-46.

To select the correct electrodes for installation heating system you need to know them. For example, E50A-UONI-13/45-3.0-UD. E – electrode for manual welding, 50 – tensile strength in kgf/mm², 3.0 – electrode thickness in mm, penultimate letter U – for carbon steels, D – coating thickness coefficient.

Electrodes have different coating compositions. The quality of welding depends on the thickness of the coating, but for household work Brands M – thin and C – medium coverage are suitable. The diameter of the electrodes is up to 3 mm. The quality of welding also depends on the experience of the welder.

Electrodes for profile pipes

Properties profile pipe associated with the brand of material from which it is made. Typically this is steel 09g2s, 3SP, 1PS, 2PS with high tensile strength (45 kgf/mm) and elongation coefficient - 18%.

Decide on the thickness of the electrode. Its diameter:

1.6 mm if the metal thickness is 1 mm;
2 or 2.5 mm (part thickness 2-3 mm);
3 or 4 mm when welding elements with a thickness of 3-6 mm.

Consider the coverage indicated by the marking:

A – sour (manganese and iron oxides);
B – basic;
T – cellulose (creates a gas shell);
R – rutile (reduces spattering).

Welding of a profile pipe is carried out using electrodes with a basic (B) coating:

ANO: suitable for both experienced craftsmen and beginners;
MP-3S: to obtain a high-quality seam;
(universal): metal;
OZS: allow you to get a high-quality seam, cost little, but are afraid of moisture;
UONI 13/35: used by professionals for welding thick-walled pipes.

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

Types of electrodes used for pipe welding

Now there are many types of electrodes, which differ in purpose, coating and production method.

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

Advantages and disadvantages of consumable electrodes

Consumable electrodes have the following advantages:

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

Large electric arc radiation.
Limitations on current parameters.
Significant metal spattering.

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.

Decoding the letter markings 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 groups of steels the electrode can be used.

The thickness of the electrode coating is also indicated by letters. A thin layer of coating is marked M, a medium layer is marked C, and even thicker layers are marked D and G.

The type of coverage is indicated as follows:

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

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

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

This is due to the fact that the weld seam does not differ in strength and structure from the material of the pipeline elements. It provides a monolithic, in-place design with a guarantee of absolute sealing and durability.

Contents of the article

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 weld, 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 elements being joined;
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 get down to business.

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

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

Briefly about the welding process

The process of connecting metal pipes by electric welding consists of creating an electric arc between the electrode and the elements being welded.

Under the influence of an electric arc, two similar materials melt, mix and create a monolithic seam as the electrode is removed.

Thanks to the special coating of the electrode, special conditions, preventing oxygen from entering the melting point of metals and creating a protective film.

The width and thickness of the seam depend on the thickness of the electrode, the materials of the elements being welded, the welding mode, the speed of the arc, and the network voltage. The formation of slag on the surface depends on these same parameters, especially the last one. Slags formed during the welding process must be removed.

Before you start welding the system, you need 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

To carry out welding work, first of all, electric welding will be required. There are two types welding machines:

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

In addition to the welding machine we will need:

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

Selecting 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 a 2-3 mm electrode; a thick-walled heating pipe must be welded with a 4-5 mm electrode.

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 range from 3 to 20% of the total mass.

Let us 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 slag is created, which negatively affects the quality of the seam and the integrity 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 current strength is it correct to cook? This or that pipe comes with experience. Such experience is usually obtained by the method of “scientific poking”. However, in order to prevent large quantity errors, you should first refer to the tables of correspondence between types of electrodes, types of pipes and electric welding current.

Preparation of joints

You can start welding heating pipes only after their joints are completely cleared of debris and deposits. If you are a beginner, you should not try to weld wet pipes, as the water will boil, evaporate and significantly complicate the process.

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 circle on a grinder, depending on the thickness and quality of the pipe. You can start welding joints only after how there will be no burrs or sharp edges on them.

Before starting welding work, you need to make sure that there are no flammable or explosive objects near the junction of the heating pipes. If they exist, and it is not possible to remove them, you need to fence off the work area with non-flammable material, for example, asbestos;
You need to place a container of water near the welding site in case of an unexpected fire;
make sure that the grounding is securely fastened and the integrity of the welding machine wire;
check the network voltage. If the voltage is weak or changes are observed, increased slagging may occur during the welding process. To avoid this, it is better to use a straightener;
clean and dry pipe joints. Experienced master can weld heating pipes at a wet joint, but this will seriously interfere with a beginner;
put on a welding suit and mask;
We set the required 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, at rotary joints is carried out with a current of 100 - 250 A, at fixed joints - 80 - 120 A;
check if the voltage is selected correctly. To do this, we light the arc by moving the electrode at a distance of 5 mm until sparks appear. If sparks do not occur, adjust the current;
Having completed all of the above steps, you can begin welding heating pipes.

Welding stages

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

There are three options for moving the welding arc:

The forward movement of the electrode along the weld seam, ensuring arc stability.
Along the junction. A continuous seam is provided, 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 small diameter pipes with wall thickness up to 5 mm made with a continuous seam. Similar products with a larger diameter are cooked intermittently.

Pipeline elements with a wall thickness of up to 6 mm need to be welded in two layers, from 6 to 7 mm - in three, over 7 mm, 4 welds are laid.

The joints must be welded until they are completely connected without interruptions in the seam.

It is better to weld the first layers in steps to connect the joints. All subsequent layers are made with a continuous seam. After welding the first continuous layer, you need to beat off all the slag and carefully inspect the joint for cracks and burns. If there are any, they need to be melted and boiled again.

How to weld pipes, select electrodes and make seams?

When connecting pipes, welding is most often used. You can find it on sale today big choice welding machines, both domestic and industrial, so many homeowners undertake welding work themselves.

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

Today in construction there are many various methods welding

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

Thermal, which includes all fusion welding methods.
Thermomechanical, which includes the butt contact welding, as well as a welding process using a magnetically controlled arc.
Mechanical, which includes friction and explosion welding methods.

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

Preparatory work

Before you begin making welded joints, you need to prepare the surfaces of the pipes and select the right materials for the job.

Selecting Electrodes

For performing manual arc welding as consumables electrodes are used. This material is available in a huge variety, so the question of which electrodes to use to weld pipes is extremely important.

The entire variety of electrodes produced can be divided into two groups:

Electrodes with a consumable base;
Non-consumable electrodes.

This classification is made by evaluating the material that is used to make the electrode core. Thus, 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 carbon.

In addition, the classification of electrodes is carried out by assessing their coating.

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

Cellulose coated electrodes (grade C) used for making circumferential and vertical seams on large diameter pipes.
Electrodes coated with rutile acid type (RA grade) They are distinguished by the special structure of the slag formed during welding, which can be easily removed at the end of the work.
Electrodes with rutile coating (grades R, RR) They are distinguished by easy re-ignition, a good degree of slag impact and allow you to create seams with a commercial outer surface. They are used for setting tacks, as well as for creating corner seams and welding the outer layers of seams, which should have a beautiful appearance.
Electrodes with rutile-cellulose coating (RC grade) recommended for making seams in any direction, including in the most difficult case - when forming a vertical seam from top to bottom.
Basic coated electrodes (grade B) allow you to create seams with excellent toughness characteristics and the lowest likelihood of cracking.
These electrodes are recommended for welding pipes with large wall thicknesses, as well as in cases where it is necessary to maintain high weld toughness, for example, to create pipelines that will be operated at low temperatures.

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, availability of a certificate, absence of deformation (ellipseness), no difference in the thickness of the pipes, compliance of the chemical composition of the metal of the pipes and their mechanical properties GOST requirement.
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 bluntness are measured.

The opening angle of the edges to create a good seam should be 60-70 degrees. The amount of dullness is usually 2-2.5 mm.

If the shape of the bevel of the pipe edges does not match, they are mechanically processed using chamferers, end-cutters 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.

Performing welding

Let's look at how to properly weld pipes.

Installation of potholders

Potholders are integral part weld, they are performed using the same type of electrodes that will be used for the main welding.
When performing welding with a diameter of up to 300 mm, four tacks are made, placing them evenly around the circumference. Each tack should have a height of 3-4 mm and a length of 50 mm.
When welding pipes of larger diameter, tacks are placed every 250-300 mm.

When assembling pipelines, you should strive to ensure that the maximum number of joints is made in a rotating position. Pipes with a wall thickness of up to 12 mm are connected by welding in three layers. Let's look at how to properly weld a pipe in a rotating position.

Rotary welding

The first welding layer is made with a height of 3-4 mm; for this, electrodes with a diameter of 2 to 4 mm are used. The second layer is created using electrodes of 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 which the pipe is turned and the remaining two sectors are welded.
Next, the pipe is turned again and a second layer of seam is made on the first two sectors.
The work is completed by making a second layer of seam in the third and fourth sectors, after first turning the pipe over again.

The third layer of seam is applied in one direction while rotating the pipe.

When welding pipes with a diameter of up to 200 mm, you can avoid dividing into sectors, performing all layers of the seam in one direction while rotating the pipe.

Welding plastic pipes

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

So the question is how to cook plastic pipes, interests many home craftsmen.

Special butt welding machines are used for this.

When designing a pipeline from polypropylene pipes, it should be taken into account that when heated, such pipes may stretch somewhat.

Heating nozzles are fixed in the device.

A temperature of 250-270 degrees is required.

Next, pipe sections of the size specified by the project are measured and cut. It is recommended to sharpen the edges of the parts 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 rest against it.
The surfaces of pipes that will be welded should be degreased.
The fitting takes a little longer to heat up than the pipe, so it is treated first. Then the 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 secured with a smooth movement without turning. The seam should be fixed until it cools down.

Thus, you can obtain reliable connections using plastic pipes - how to weld such parts is described above, however, when performing the work, the following should be taken into account:

To get a truly reliable pipeline, you need to carefully consider the choice of raw materials, namely, purchase high-quality pipes and connecting parts.
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. After cutting, the end of the pipe must be cleaned using trimmers, shaver or finely cut files.

conclusions

Making pipe joints during pipeline construction is a responsible job, the quality of which determines the reliability of the networks being constructed. Therefore, regardless of the material of the pipes used, welding work must be carried out in strict accordance with the requirements of SNiP.

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