How to weld pipes correctly

How to properly weld heating pipes using electric welding - expert advice

In autonomous heating systems, where a boiler with a high-temperature coolant is used to connect pipes, electric welding is most often used. This method of connecting pipe joints is airtight and reliable, which is especially important under severe thermal loads.

Types of welds and joints

Electric welding is a method of joining metal fragments (profiles, pipes) by local melting of the metal. It is heated to the desired temperature using an electric arc using a welding machine that converts alternating current into direct current.

An electric arc is formed on an electrode - a metal rod. In the area of ​​the arc, a special environment is created that simultaneously melts the metal, but does not allow it to come into contact with air and oxidize.

Using welding, you can create a tight connection between two pipes, in which there is a risk of leakage, as with flange or coupling joints. To do this, it is important to make a high-quality weld by fusing the metal on the edges of both pipe sections. Welders use several basic types of seams, depending on the type of metal, the thickness of the elements being welded and their relative position:

• butt welding is the most common method of welding pipes, in which they are located opposite each other, connected by sections;
• in a T-bar - two pipe fragments are arranged perpendicularly in the shape of the letter T;
• angular - parts are located relative to each other at an angle of 45 or 90 degrees;
• overlap - one piece of pipe is flared and put on top of another, then welded.

Important! Steel pipes for heating and water supply systems are butt welded or corner welded. This gives the most reliable and durable seam.

In addition to the connection method, there are also several types of welds that are used in certain cases:

• horizontal seam - performed when the pipes are positioned vertically (most often used in the installation of water supply and heating systems);
• vertical - the connection is made with a mutual horizontal arrangement of pipes, in which the master makes vertical movements with the electrode (from bottom to top, top to bottom, etc.);
• ceiling - during welding, the electrode is located under the part being welded, the welder has to hold his hand above his head;
• bottom - in contrast to the ceiling, the electrode is located on top of the parts being connected.

The most convenient way of welding is using a bottom seam, in which the specialist clearly sees the working field and can rotate pipe fragments for faster and more productive work.

Ceiling joints are usually not used when constructing an engineering system from scratch, because this method is quite inconvenient (the welder gets tired quickly, has difficulty seeing the working field, and drops of molten metal may fall on him). A ceiling weld is usually used for repairs when a worn or deformed piece of pipe is cut out and a new one is welded in its place.

Some tips for performing quality welding

The quality of welding depends on proper preparation for welding work, the choice of electrodes and process technology, which is somewhat different when connecting joints.

Selecting suitable electrodes

The quality of the weld largely depends on which electrode is used for welding. It is a thin metal rod with a special coating. The inner part of the electrode serves as a conductor to create an electric arc, and the coating ensures its stability and also participates in creating the weld.

Based on the type of core, electrodes are divided into consumable and non-consumable . In the first case, the product is based on steel wire, in the second - a tungsten, carbon or graphite rod.

Based on the type of protective coating, electrodes are divided into:

• cellulose - marked “C” - used for labor-intensive and complex welding work with large-diameter pipes, on long technological lines;
• rutile acid - “RA” - the most used type of electrode for welding water supply and heating utilities;
• rutile - “RR” - can also be used for welding water supply and heating pipes, they are distinguished by greater thickness and better quality of the weld;
• rutile-cellulose - “RC” - provide a more durable seam when using the vertical joining method;
• universal - “B” - suitable for welding pipes of various diameters and thicknesses, in a wide temperature range.

Another classification of welding electrodes is the diameter of the rod. The strength of the electric arc, which can cope with pipes of a certain thickness, depends on it:

• 3 mm – electrodes are suitable for welding pipes up to 5 mm thick;
• 4 mm – electrodes allow you to weld up to 10 mm thick, as well as make multilayer metal seams.

Attention! In addition to the thickness and material of the electrode, for high-quality welding it is also necessary to take into account the current strength, which depends on the method of connecting the pipes. For example, for a simple butt joint an arc of 80 to 110 amps is suitable, but for lap welding you will need to switch the machine to 120 amps.

How to make the right seam

To make a high-quality seam, proper preparation of the pipe for welding is necessary. The quality of the pipe edge is decisive for a durable and airtight seam.

For example, for butt welding, the pipe cut must be strictly at a right angle. Before starting work, it is thoroughly cleaned with sandpaper 1 cm from the edge of the pipe, then oil, paint, metal dust are removed and degreased.

The welding technique depends on the cross-sectional shape, thickness and diameter of the pipes being connected. Simple round pipes for heating systems are welded using a simple continuous seam, moving the electrode along the surface of the pipe until the two pieces are completely welded.

For relatively thin pipes (up to 6 mm), a two-layer weld is suitable; for thicknesses from 6 to 12 mm, three-layer welding is used. Massive and thick pipeline fragments are connected with four or more seams.

The seams are performed alternately, one after the other. The next seam can be started only after the previous one has cooled. To achieve a high-quality and beautiful seam, you need to periodically remove the slag formed at the welding site by lightly tapping the pipe with a hammer.

Features of welding rotary and non-rotary joints

To make a high-quality rotary joint (where two pipes are connected at a certain angle), you can use a special rotator, which fixes and provides the most convenient access for the welder.

In the absence of a device, you will have to rotate the pipe manually, using an electrode to treat a section of the pipe cross-section of 60-110 degrees.

When making a rotary joint manually, the diameter of the pipes is first welded 2/4 from the outside in two layers, then unfolded and the joint is welded using all three or four layers.

A fixed joint is much easier to make: combine two pipe fragments and make several welding points (for example, in the form of an imaginary cross, or only on two opposite sides). Cook the pipe, starting from the bottom point, moving the electrode to the top section.

How to check the connection reliability

The tightness of the weld can only be checked in one way - pass water or gas under pressure through the pipe and check visually for leaks of the working medium. For example, if you are welding pipes for a heating system, you can attach a section of pipe to the system and fill it with water. If no drops of water appear on the weld area, the welding is done efficiently.

Welding safety rules

The electrical welding process poses three potential hazards:

• receiving electrical injury from contact with live wires or electrodes;
• skin burn from molten metal;
• Arc flash burn of the retina.

To avoid undesirable consequences, you should take care of electrical insulation: use special rubber mats and galoshes, ground the welding machine, and insulate the conductors.

It is important to use personal protective equipment - special gloves, as well as a protective helmet or face shield.

Source: https://InfoTruby.ru/soedinenie/svarka-trub-dlya-otopleniya

How to properly weld pipes using electric welding: process technology, secrets and welding lessons for beginners

In a situation where it is necessary to connect metal parts, they most often resort to the method of creating a weld, since it can provide fairly high reliability. This method has become widespread not only in industry, but also in ordinary everyday life.

The vast majority of home craftsmen periodically use welding. Those of them who have welding skills are lucky. If they are not there, then in this case there is nothing left but to contact specialists.

But anyone can learn to cook if they want. And the first thing you should pay attention to at the very beginning is to familiarize yourself with the basics of electric welding for beginners . We are talking about lessons that tell you about the features of creating various seams. More complex work should be started only after the owner has gained sufficient experience. Next, we will dwell in more detail on the nuances of welding work and certain tricks of this process.

Where to start the preparatory stage?

The first thing those who want to learn how to cook need to do is purchase the necessary equipment . The complete kit that will be required to complete such work will include:

• welding machine;
• set of electrodes;
• hammer for beating off slag;
• brush.

When choosing an electrode, you need to pay attention to its diameter, which will be determined by the thickness of the metal sheet being welded . You should also take care of protection. For welding we need:

• welding mask with a special light filter;
• thick clothes with long sleeves;
• gloves, preferably made of suede.

The tools required for welding work must include a welding rectifier, transformer or inverter. It is with the help of these devices that the problem of converting alternating current into direct current will be solved, which will allow welding.

Welding process technology

When starting electric welding, you should remember that this work is carried out at high temperatures. Such work is ensured by an electric arc, which must be maintained between the electrode and the workpiece being welded.

It is during its contact with the workpiece that the base metal and welding electrode melt. At this moment, a phenomenon occurs, which among specialists is called a weld pool. In it, the base and electrode metal are mixed into a homogeneous mass.

The bath can have different sizes, which is determined by the welding mode used, spatial position, speed of arc movement , shape and size of the edge, etc. Usually it reaches a width of about 8–15 mm, a length of 10–30 mm, and a depth of about 6 mm.

Each electrode has a special coating called coating. At the moment of its melting, a special gas zone appears in the arc area and above the bath. Thanks to it, air leaves the welding zone and the interaction of molten metal with oxygen is eliminated. It also contains pairs of base and electrode metal.

Already on the seam itself an alloy appears that does not allow the melt to come into contact with air, which would deteriorate the quality of the welding. As the electric arc is removed, the metals crystallize, resulting in a seam , thanks to which the welded parts are firmly connected. At the seam itself there is a protective layer of slag, which must be removed after welding.

Basics of electric arc welding

To get the best possible results when creating a weld, novice welders first need to familiarize themselves with the lessons, which pay attention to the correct execution of this work in the first stages.

It is also advisable to get practice in performing welding work under the guidance of an experienced specialist, who will not only point out mistakes, but also tell you how to avoid them in the future.

Before you start welding parts, you need to make sure that it is securely fixed enough.

It is equally important to take care of compliance with fire safety rules: for this it would be useful to place a bucket of water nearby. This also explains the ban on welding on a wooden base. You should also pay attention to small remnants of used electrodes , which should not be left at the workplace after completion of work. Without this, it is impossible to learn how to weld metal correctly.

It is imperative to make sure that the “ground clamp” is securely fixed. Make sure that the cable is insulated and accurately inserted into the special holder. Before working with a welding inverter, you should select a calculated current power indicator, which should be determined based on the diameter of the electrode.

After this, you can strike the arc . This is done as follows: you need to place the electrode at an angle of about 60 degrees relative to the product. Next, you need to slowly move it across the surface. At this moment sparks appear, now you need to touch the metal with the electrode and then lift it, but not higher than 5 mm.

If all recommendations are strictly followed, the arc should light. Until the welding is completed, you need to keep the electrode at a distance of 5 mm. It should be borne in mind that during metal welding, the electrode rod will gradually begin to burn out.

Therefore, at regular intervals you need to reduce the distance between it and the metal. Approach the electrode to the workpiece slowly. A situation may arise where it sticks. In this case, you need to slightly turn it to the side . If all attempts fail to ignite the arc, then you can try increasing the current.

When the arc ignites and its flame becomes stable, you can begin fusing the bead. The electrode with the other one lit must be slowly and smoothly moved horizontally, making gentle oscillatory movements. This will cause the liquid metal to begin to move on its own directly to the center of the arc. If you follow all the recommendations, you can make a reliable seam formed in the form of small waves that were created using deposited metal.

A situation may arise that during welding of products the electrode will be completely used up, but at the same time it will not be enough to create the entire seam. In this case, you need to take a break from work.

After turning off the machine, you need to insert a new electrode , remove slag from the surface of the weld, and then continue welding. From the depression created at the end of the seam, often called a crater, you need to make an indent of about 12 mm and light the arc.

The electrode should be brought closer so that upon contact an alloy is formed from the metal of the old and newly installed electrode. Next, welding is performed as usual.

Features of welding a pipeline with an inverter

The electric arc welding method is suitable for creating a vertical seam, provided that it is located at the end of the pipe. If a horizontal seam is created, the latter should be on its circumference. If you have to make ceiling and bottom seams, then they should be at the top and bottom. Among all those mentioned, it is the last one that creates fewer problems in implementation.

If you have to deal with steel pipes, then the butt welding method is most often used, which involves welding each edge along the height of the walls. To minimize sagging inside the pipe, the electrode should be positioned at an angle of no more than 45 degrees relative to the horizontal. Such a seam should reach a height of 2–3 mm and a width of 6–8 mm. If the products are overlapped, then the seam will have a height of 3 mm and a width of 6–8 mm.

Preparation

Before you begin electric welding of metal products, you need to complete the following preparatory measures:

• It is necessary to remove the top layer from the welded aliment.
• If there are any irregularities at the ends of the pipe, they need to be cut off or straightened.
• Next we begin to process the edges. Here it is necessary to smooth out at least 10 millimeters of the surface adjacent to the edges of the pipe outside and inside until a metallic sheen appears.

Main stages

Next, you can begin directly welding the pipe. Each joint must be processed continuously until they are completely welded. Rotary and non-rotary joints of pipes with walls no larger than 6 mm should be created in at least two layers.

If the walls have a width of 6–12 mm , then three layers should be created, more than 19 mm - 4 layers.

When welding pipes, it is necessary to take into account one important nuance: it is necessary to remove slag from the next seam created at the joint, only after this can you proceed to creating a new one.

Particular attention should be paid to creating the first seam, since a lot depends on it. It must be performed in such a way that it melts every edge and dull areas. It is very important to examine it very carefully, as there may be cracks on it.

If they are found, they must be melted down or cut down, after which the area is welded again . When creating the remaining layers, you need to slowly turn the pipe.

It must be remembered that the beginning and end of each layer should be located with an offset relative to the previous layer at a distance of 15–30 mm.

The finishing layer must be created so that it provides a smooth transition to the base metal and at the same time has a flat surface. You can achieve the highest quality of welding pipes using welding if the next layer is performed in the opposite direction with respect to the previous one, while their closing points should be scattered from each other.

Conclusion

Welding work is quite complex, so novice welders will have to spend a lot of time and effort to create high-quality and durable welded joints. But first, they should get an idea of ​​the main points from the lessons , without which it is impossible to weld metal efficiently and correctly.

It is important not only to prepare all the necessary tools and materials, but also to study the technology of the welding process with special care. This is very important because any mistake can subsequently affect the quality of the weld, and if attention is not paid to this at the initial stage, then in the future all efforts will be in vain, as a result everything will have to be redone.

Source: https://stanok.guru/oborudovanie/svarochnyy-apparat/kak-pravilno-varit-truby-elektrosvarkoy-invertorom.html

How to weld heating pipes using electric welding

01.03.2019

The main method of installing autonomous and centralized systems is heating welding. Unlike threaded connections, it does not require regular maintenance. When welding heating pipes, it is necessary to take into account that the connection is subjected not only to mechanical, but also to thermal influences. Therefore, it is necessary to choose the electrodes correctly, otherwise it may crack when heated.

Types of welds and joints

Depending on the relative position of the pipes, they are connected:

• end-to-end, when the ends are adjacent to each other;
• in a T-bar, if the pipes are arranged in the shape of the letter T;
• at an angle when it is necessary to change direction by 45 or 90˚;
• overlap by flaring the end of one pipe and putting it on the other.

Depending on the possibility of access to the joint, the connection is made:

1. With a horizontal seam, if a vertical section of the pipeline is being installed.
2. Vertical when the pipeline is in a horizontal position.
3. Ceiling when the joint is welded from below. Such a seam has to be applied during repair of the heating system when replacing the damaged area.
4. Pipes are welded bottom when installing new systems, when it is possible to rotate them so that the electrode is on top of the joint.

Preparatory work

To ensure that the connections are made without defects, preparation is carried out before welding heating pipes using electric welding. The perpendicularity of the cut ends relative to the axis is checked and adjusted if necessary. The edges are chamfered, leaving a dullness of 2 mm, so that the angle between them is 65 - 70˚. The surface of the pipes at a distance of at least 1 cm from the joint is cleaned to a shine with sandpaper and degreased with a solvent.

Correct preparation and joining of pipes

Selecting Electrodes

In most cases, welding of metal heating pipes is carried out using consumable electrodes. For wall thicknesses up to 5 mm, a diameter of 3 mm is sufficient, for walls up to 10 mm - 4 mm. The welding current for a butt connection is set to 90 - 110 A, for an overlap connection - at least 120 A. Non-consumable electrodes made of tungsten or graphite using filler wire and inert gas are rarely used. The scope of application of steel electrodes depends on the composition of the coating:

• cellulose (marked C) is intended for welding large-diameter main pipelines;
• with rutile acid (RA) are often used in the installation of municipal water and heat supply systems;
• rutile (RR) allows you to create seams of better quality than the previous option;
• rutile cellulose (RC) increases the strength of the weld joint when installed vertically;
• universal (B), also the main one, is used when welding pipes of different diameters and wall thicknesses operating in a wide temperature range.

Source: https://svarkaprosto.ru/tehnologii/kak-svarit-truby-otopleniya-elektrosvarkoj

How to properly weld pipes using electric welding

26.11.2019

You can often hear the opinion that welding pipes is not something too special and, if necessary, even an amateur can cope with such a task. Indeed, at first glance it may seem that this is so. Large surfaces with well-fitted and processed edges - all conditions for the formation of a high-quality seam are met. All that remains is to bring the electrode and

But here practice begins, which has completely different laws than theory. It turns out that doing this kind of work is very difficult. Especially when it comes to creating a high-pressure pipeline. The slightest defect in the weld seam leads to a breakthrough in the main line. That is why only highly qualified specialists are attracted to such projects.

Pipeline welding technology

The most common pipe welding method is electric arc. Compared to alternative gas technology, this technology is characterized by simplicity and reliability. To start the process, you will need a minimum set of tools, and the result will meet the most stringent regulatory requirements. But to achieve the desired quality, a professional approach to using welding capabilities is required.

Selection of electrodes

Equally important for obtaining high-quality seams is the use of proven consumables. Bad electrodes will become an insurmountable obstacle to achieving the desired result. The following brands are considered the best today:

• ANO-21, ANO-24 and MR-3 . AC power required for use. Due to its low cost, consumables are in demand in a wide variety of human activities, including household plots. Such electrodes do an excellent job of welding structures for a private farmstead: gates, greenhouses, canopies, etc. The listed consumables are not suitable for connecting pipes, and especially high-pressure lines;
• SSSI . The high quality cores have earned the praise of professionals. However, electrodes also have negative aspects. For example, they do not allow welding work to be performed at a fast pace. The weld forms slowly and it is very important to maintain a stable arc. Those who have experience with ANO and MR analogues will be able to work with such electrodes;
• LB-52U . Of all the brands under consideration, they are best suited for welding pipes using electric welding. Japanese development is preferable in the implementation of large projects. The electrodes form an even, attractive seam and hold the arc perfectly. Their only drawback is their relatively high cost.

Basic pipe welding techniques

Connecting parts of main pipelines can be done in different ways:

• Butt weld the pipe . The surfaces to be connected are placed opposite. This is the most common method and is characterized by ease of execution. However, there are also some difficulties. It will be much easier to cope with them if you take into account some nuances. Firstly, it is better to form the welding seam in the direction from the bottom up. Secondly, the metal should be welded to the entire thickness of the pipe wall.
• Overlap . The method can only be used in cases where the surfaces to be joined have slight differences in diameter and one of them fits tightly into the other. this may be a difference in the size of the pipes or a special mechanical treatment of the end part of one of them - flaring.
• Tavrovoe . This method of connection involves the arrangement of surfaces at right angles to each other.
• Angular . The two parts are connected to each other at an angle of less than 90 degrees.

Tips and tricks

Good quality welds are not obtained immediately. Only with time comes experience and the required skill. To ensure the final result is as good as possible, you should follow the advice of experienced experts:

• When using butt or tee methods for connecting parts, it is advisable to use electrodes with a thickness of 2-3 mm. They are the ones who show the best results.
• It is recommended to set the current strength in the range of 80-100 amperes. If overlap welding is performed, this figure can be increased to 120 amperes.
• When filling the weld pool, you should be guided by the height of the weld: it should protrude 2-3 mm above the metal surface.
• If work is carried out with profile pipes (the cross-section is not round, but square or rectangular), then the point connection method is used.

A few words about the point method of joining workpieces. It is also called “tack” and boils down to the fact that small areas are welded on diametrically opposite sides. And only after this a solid seam is placed. The approach eliminates the possibility that one of the parts will “lead away” under the influence of temperature.

Features of pipe welding

Technological operations for welding pipes require compliance with the basic rules and principles:

• continuity of the weld seam. Having gone around the pipe in a circle, it should end at the starting point. The electrode must not be torn off during the formation of the bath. In cases where the pipe diameter is too large and it is impossible to maintain this rule, the principle of multilayer welding is applied. The number of applied layers should be compared with the thickness of the walls. Walls less than 6 mm thick are boiled in two layers, 6-12 mm - 3 layers, over 12 mm - 4 layers. Each subsequent layer is applied after the previous one has completely cooled;
• Before starting welding work, both pipes must be well fixed. You can use a point connection - tacking surfaces to prevent movement of parts and create a strong seam without unnecessary problems;
• if the wall thickness exceeds 4 mm, it is recommended to create a root seam. It is needed in order to completely fill the void between the connected sections of pipes. An alternative to this method is the roller method, which involves forming a roller about 3 mm thick over the seam;
• quality checking. The seam is tapped with a hammer. The slag is knocked down and you can visually inspect the result of the work.

If the line will be operated under pressure, a test run is required. It makes it possible to check the tightness of joints and promptly eliminate identified deficiencies.

Source: https://vtmstol.ru/blog/kak-pravilno-svarivat-trubyi-elektrosvarkoj

Electric pipe welding technology

There are several methods for welding pipelines (steel). But the advent of inverters pushed back all methods, and now pipe welding in everyday life is carried out with this particular device. Firstly, it is the simplicity of the welding process, and secondly, accessibility and high safety. Moreover, the technology for welding pipes is not very complicated; the main thing is to carry out the preparation correctly and select the necessary consumables.

Preparing pipes for welding

The welding process begins with preparation. First of all, you need to select the electrodes with which the pipes will be welded. There are two selection criteria here: the material from which the metal rod is made, and the coating - the material covering the rod.

For welding metal pipes, consumable and non-consumable electrodes are used. In the former the rod melts, in the latter it does not. In the second case, an additional material is used - an additive, which fills the welding seam. Practice shows that welding pipes with consumable electrodes is used more often in domestic conditions today. Simply because this method is easier.

Now, as for coating the electrodes. There are several positions here where different materials are used to form a protective surface.

• Rutile.
• Acidic.
• Rutile acid.
• Cellulose.
• Rutile-cellulose.
• Basic.

Each position has its own pros and cons, so when choosing, it is necessary to take into account the conditions for welding pipelines. But among them there is a universal option - these are electrodes with a basic coating. This category includes such brands of electrodes as UONI, OZS, VI, EA, NIAT, OZSh and other less known ones. Beginner welders are recommended to weld pipes with UONI electrodes.

Before welding two pipes, you need to understand that there are several types of welded joints.

• Butt joint, when two pipes are located opposite each other.
• Overlapping, this is how two pipes of different diameters, or the same diameter, are usually connected, only one of the pipes is flared, that is, its diameter is mechanically increased.
• T-joint, when two pipelines are joined in perpendicular planes.
• Corner connection, when the joint is made at an angle of less than 90°.

By the way, option number one seems very simple. But it conceals the complexity of the process itself. Firstly, it is better to weld such a seam in the lower position, this is when the electrode is fed into the joint from above. Secondly, the metal must be boiled through the entire thickness of the wall.

And some more useful tips.

• For butt welding of pipelines and tees, it is best to use electrodes with a diameter of 2-3 mm.
• Welding mode, that is, the value of the set current should be in the range of 80-100 amperes. When overlapping welding, the current must be increased to 120 A.
• The filling of the weld should be such that the metal rises 2-3 mm above the plane of the pipe.
• Welding of profile pipes (square) is done spotwise. That is, first a small section is welded on one side, then on the opposite, then on the adjacent and then on the opposite adjacent. After which the joints are completely welded. The goal is to prevent the pipe from warping as it heats up.

Before electric welding pipes, they must be prepared. This mainly concerns the edges. Here is the sequence of how to do it.

1. The geometric dimensions are checked for compliance with the ongoing installation of pipelines. Pipes with different wall thicknesses can be joined, which can lead to failure of penetration of a thick pipe or burn-through of a thin one.
2. In cross-section, the pipeline should be round, not oval or other shape. This will simply ensure the quality of the welded joint and simplify the process itself.
3. The walls of the pipes must be free of defects: cracks, creases, expansions, and so on.
4. The edge cut must be straight (90°).
5. The edges are protected to a metallic shine (use a brush or sandpaper). The length of the area to be cleaned is at least 1 cm from the edge.
6. Oil and grease stains and paint are removed, and the ends must be degreased using any solvent.

And although UONI electrodes are not capricious, that is, they can be used to weld even rusty parts, the quality of the weld is affected by any metal defects. Therefore, it is worth taking a little time to prepare the edges of the pipeline.

Welding steel pipes

Welding of round pipes is carried out using a continuous seam. That is, if the process began from one point, then it should end at that same point, without lifting the electrode from the surface to be welded. When welding large-diameter pipes (over 110 mm), it is impossible to fill the seam with one electrode. Therefore, it is necessary to use multilayer welding, where the number of layers is determined by the thickness of the pipe walls. Eg:

• If the wall thickness is 6 mm, then two layers of metal are sufficient.
• 6-12 mm – welding is carried out in three layers.
• More than 12 mm - more than four layers.

Attention! Multilayer welding is carried out with one requirement. Before applying the next layer, the previous ones must cool down.

Pipeline assembly

Before welding pipes, to simplify the task, it is necessary to assemble the welding joint. That is, you install the pipes according to the assembly design, clamp them so that they do not move or shift. After which the tack is done. This is when spot welding is done in one place; if the pipeline is assembled from large-diameter products, then tack welding can be done in several places.

In principle, everything is ready, you can weld the pipeline. It would seem that this could be the end of the conversation about welding. But for novice welders it is just beginning, because the welding process associated with pipeline assembly involves a large number of nuances. Here are just a few of them that need to be taken into account.

• Pipes with a thickness of more than 4 mm can be welded using a root weld, this is when the metal fills the space between the edges to the full depth, and a roll weld, when a roller 3 mm high is formed on top of the seam.
• When connecting pipes with a diameter of 30-80 mm with a vertical seam, the technology is slightly different from the bottom location of the seam. First, the volume is filled to 75%, then the rest of the space.
• With multilayer welding technology, a horizontal seam is welded in two layers so that the next one is applied in the opposite direction than the previous one.
• The connection point of the lower layer should not coincide with the same point of the upper layer. The locking point is the end (beginning) of the seam.
• Usually, when welding pipes, the latter must be rotated all the time. This is done manually, so you need to know that the optimal rotation sector is 60-110°. It’s just that in this range the seam is located in a place convenient for the welder. Its length is the maximum, and this allows you to control the continuity of the seam connection.
• The most difficult thing, as many welders believe, is to turn the pipeline 180° at once and at the same time maintain the quality of the weld. Therefore, with such a rotation, it is recommended to change the welding technology. That is, first the seam is welded to a depth of up to 2/3 in one or two layers. The pipeline is then rotated 180°, where the seam is completely filled in several layers. Next, there is a 180° turn again, where the seam is completely filled with the electrode metal. By the way, such joints are called rotary joints.
• But there are also non-rotating joints, this is when pipe is welded to pipe in a fixed structure. If the pipeline is located horizontally, then the joint between its parts must be welded by dividing it into two parts. Welding starts from the bottom point (ceiling) and moves to the top. The second half of the joint is welded in the same way.

And the last stage in pipe welding technology is seam quality control. It must be tapped with a hammer to knock off the slag. Then visually check for cracks, gouges, chips, burns and lack of penetration. If the pipeline is intended for liquids or gases, then after assembly, water or gas is introduced into it to check for leaks.

The welding process is actually a responsible undertaking. And only the experience of a welder can guarantee the quality of the final result the first time. But experience is a gain. We invite you to watch a video on how to properly weld steel pipes.

Source: https://svarkalegko.com/tehonology/kak-svarivat-truby.html

Pipe welding technology

A pipeline means an engineering communication in which the working substance is supplied through pipes (water, gas, oil, etc.).

To ensure a high-quality supply, it is necessary not only to lay it correctly, but also to carry out repair and maintenance work from time to time. Here you just can’t do without joining the elements together.

Let's look at what pipe welding is, how to weld pipes using electric welding, and what techniques need to be applied in practice to create a sealed pipeline.

Types of pipelines and welding

There are a huge number of pipelines that are used to move different materials and working fluids. Based on their purpose, there is the following classification:

• technological;
• main lines;
• industrial;
• gas supply pipelines;
• water;
• sewer.

In the manufacture of pipelines, various materials are used - ceramics, plastic, concrete and various types of metals.

Modern welders use three main methods for joining pipes:

1. Mechanical is carried out due to explosions as a result of friction.
2. Thermal, which is carried out by melting, for example by gas welding, plasma or electric beam.
3. Thermo-mechanical is produced by a magnetically controlled arc using the butt contact method.

There are many types of welding, which are divided into many classifications. Before you weld pipes, you need to figure out what is the best way to do it. Theoretically, each type is suitable for welding pipes of small and large diameters.

It can be carried out by melting and pressure. Melting methods include electric arc and gas welding, and pressure methods include gas press, cold, ultrasonic and contact.

The most common methods for connecting communications are manual electric arc and mechanized.

Welding pipes using electric welding with consumable and non-consumable electrodes

It is most effective to weld technological pipelines with an electrode manually or using an automatic machine. This can be a method of working with a consumable or non-consumable electrode (argon-arc welding). Pipe welding technology is implemented in three main stages:

1. Preparatory, which is divided into two parts - preparation of the master and preparation of the material. The preparation of a welder should be taken very seriously, since his safety depends on it. Be sure to prepare special clothing and a protective eye mask to prevent burns from bright sparks. By preparing parts we mean thoroughly cleaning pipes for welding from corrosion, paint and contaminants. Before manual arc welding of pipelines, you need to thoroughly treat the joints and the area adjacent to them with a metal brush or sandpaper. If this is not done, there may be “gaps” in the seam itself, since the material will not “get caught” on the contaminated pipe.
2. Welding process. When everything is ready, you can start. The most important thing in the arc method (whether it is done manually or with an inverter) is to hold the arc. First you need to ignite the electrode and initiate the arc. Then the seam is fully completed. Its type is selected directly by the master during the work process. The method of guiding the electrode and the technology of pipeline welding in general is influenced by many factors - the location of the pipes, the material they are made of, and the preferences of the welder.
3. Checking the quality of work. When the seam is ready (do not forget to beat off the slag that forms above it in the form of a roller), you can start communication to control the quality of the connection.

The technology for welding water pipes, gas pipelines and other utilities is almost the same. It is important to follow the sequence of actions and take into account the types of seams in different positions, since the quality of communication will depend on the ability to weld them.

How to join pipes

For a beginner who wants to master welding perfectly, it is necessary to know all the intricacies of this process. There are more than 30 methods for welding two pipes. Let's look at the most common pipe welding methods:

• in the corner;
• in the Taurus (perpendicular to each other);
• into the joint;
• overlap

The type of pipe joining is selected depending on the type of metal, type of welding and nature of communication. For example, pipes for a central heating system are most often connected end-to-end using electric welding. For a high-quality seam, the main thing is to make penetration throughout the entire thickness of the product.

A major role in the technique of welding pipes using manual arc welding is played by seam types, which are classified into four main groups:

• horizontal;
• lower;
• vertical;
• ceiling

Each of these methods has its own implementation technology. The most convenient and easiest way to make a quality connection is the bottom position. If it is possible to move and rotate the element, then the master tries to install them in the lower position.

At the same time, during operation, the metal does not flow down, as with a vertical seam, and does not splash to the sides, as with a ceiling position. Welding of process pipelines is carried out using all these types, since communications have many branches.

Based on the type of seam duration on the pipeline, they are divided into continuous and intermittent seams.

How to weld pipes using electric welding?

Pipelines are designed to move liquid, gaseous and solid materials. The tightness of the engineering structure depends on the quality of the connection of pipe joints.

It is not enough to install the pipes correctly; you also need to carry out repair work and take preventive measures for the long-term operation of these elements of the supply of gas, oil, water and other necessary substances. At home, welding is often used for galvanized pipes.

Electric welding of heating pipes has its own nuances; if the work is done with cast iron alloys, then a beginner will need the help of a professional. In this article we will tell you how to carry out this work correctly, what methods and technologies are available for using welding processes.

Types of pipes and welding methods

Pipelines vary in purpose. Here are the most popular:

• the main pipeline is used to move hydrocarbons from supplier to consumer, has a diameter of up to 1420 mm;
• the process pipeline is used within one or more related enterprises to deliver the necessary mixtures;
• industrial pipelines are installed in factories to supply liquids and gases to workshops and are connected in a closed loop;
• a gas pipeline is used to supply natural gas under high pressure;
• a water pipeline is required to supply fluid. Experts with extensive experience can even repair a water pipe without draining the entire system;
• the sewer pipeline is used to remove human and industrial waste from enterprises.

Based on the requirements for operation, pipes are made from various materials: plastic, concrete, ceramics, metal.

The following methods are classified according to pipe joining methods:

• mechanical;
• thermal;
• thermomechanical.

In order to start welding, you need to familiarize yourself with the most appropriate method suitable for welding a certain type of pipe, and also figure out which welding machine from the many types will be used for the work.

By and large, pipes from small to large diameters can be welded using any method, but the effort expended and the energy applied to the finished result may not be comparable.

Electric arc welding and mechanical joining are often used when working with pipe communications.

Application of consumable and non-consumable electrodes

When connecting pipes, manual or automatic welding is considered an effective method. To use it, electrode welding technology is used. The procedure includes three main steps.

1. First you need to prepare the parts to be welded. Use a special brush to clean the surface from dirt, varnish or paint residues. Otherwise, the contaminated areas may not be set, and subsequently the seam will leak and will not withstand the proper load. Also, the master’s equipment plays an important role. Hot sparks should not touch bare skin. Protective clothing, gloves and a mask are required to prevent damage to the retina. Don't be lazy and don't miss this detail when working with electric welding. Your health comes first.
2. After the preparatory work, the welding process itself begins. Light the arc and keep it burning steadily. The quality of the seam depends on this. The master chooses the type of joint independently, based on the quality of the material, the complexity of the seam, the angle of inclination or other considerations.
3. Carefully process the joint, that is, eliminate excess metal deposits and check the finished seam for strength.

These “three pillars” are used in welding of any pipeline structures. The specialist himself determines which method to weld the seam; the durability and reliability of the pipe in further operation depends on his qualifications.

Connection types

Professionals identify more than 30 types of pipe connections. But for a beginner in welding, let's look at the most commonly used clutch methods, which are the easiest to master, namely:

• corner method, here it is important to understand at what angle the seam needs to be made, sometimes it is necessary to bevel the edge, and sometimes this is not required;
• at 90°, this is a method of welding one pipe into the side of another;
• end-to-end, the pipe size for this method is the same;
• overlap, this method can be used when pipes are of different diameters and they can be inserted into one another.

Regardless of what method is required to weld your type of pipe, the main thing to remember is that the weld must be made along the entire circumference of the pipe, without leaving the slightest defect.

What are the types of seams?

The types of welded elements are conventionally divided into four groups. These include:

• bottom seams;
• horizontal joints;
• vertical connections;
• ceiling couplings.

The most convenient type is the bottom seam. If conditions permit, the part can be rotated and clamped in any direction, installing it in the lower position, as convenient for the master. In this case, the metal does not slide down and is not sprayed to the sides, as when making other types of connections. But in each individual case, its own welding technology has been invented, which must be applied.

Distinctive characteristics of pipe welding

The welding process of flat surfaces is distinguished by its simplicity compared to welding circles. Pay attention to the main points of the manual method of coupling pipes. They are divided into four aspects.

1. Setting up the welding machine.

• to find out the strength of the welding current, it is recommended to multiply the pipe diameter by 35;
• It is easier to hold the arc if you correctly calculate the distance between the electrode and the surface; to do this, add 1 to the diameter of the electrode.

1. Welding pipes up to 10 centimeters.

• first grab them at two points;
• when connecting parts of more than 4 millimeters, they are boiled in two layers;
• alternating seams from right to left and left to right promotes a stronger connection;
• The pipes should be welded using intermittent seams.

1. Angular adhesion and welding of pipes larger than 10 centimeters.

• turn the pipe at the same speed as the seam is being made, for thick products - slower, for thin elements - faster, especially for work on welding profile pipes;
• the weld pool should be at 30 O from the top position;
• If it is possible to rotate the pipe 180°, take advantage of this privilege and connect the seams in three stages.

1. Joints that cannot be rotated.

• weld vertical joints with a short arc, according to the formula: electrode diameter divided by 2;
• horizontal seams are welded using backward angle technology.

Each type of work has its own tricks and algorithms that have been proven over the years. By using them, your connections will last for many years to come. It is worth noting that manual welding is possible for anyone who has the desire. But the most important thing is to prepare and clean the surfaces of foreign objects that interfere with a strong connection.

Source: https://svarka-weld.ru/pravilnaya-svarka-stykov-trub

How to weld pipes using electric welding

Electric welding has become quite widespread. When using it, you can obtain a high-quality weld, which is characterized by high strength and reliability, as well as an attractive aesthetic appearance. In the process of housekeeping, it is often necessary to connect individual pipes. Electric welding is best suited for this, since the resulting fastening is characterized by tightness. Let us consider the features of this processing method in more detail.

How to weld pipes using electric welding

Types of welding joints

Welding work can only be carried out if you take into account exactly what welding seams can be found. The most widespread are:

1. Placing and butt welding of parts. In this case, the products should be placed next to each other.
2. A T-joint is characterized by the fact that the products are located at right angles to each other.
3. The overlap fastening method has become more widespread due to the ease of welding and quality control of the resulting joint.

As a rule, in the case under consideration, the electric butt welding method is used. This ensures a high-quality connection of individual elements.

Preparing parts

Before carrying out electric welding, the parts to be joined should be prepared. The recommendations are as follows:

1. The evenness of the cut is checked, which should be 90 degrees.
2. The end and surrounding surface are cleaned with sandpaper and other abrasive until a metallic sheen appears.
3. All types of contaminants must be completely removed.

Preparation for welding, cleaning with a grinder

At the time of welding, all elements must be firmly fixed.

Pipe welding

A fairly common question is how to weld pipes using electric welding. Inverters and other devices are characterized by ease of use, as well as the ability to accurately adjust output parameters. Welding of metal pipes is carried out taking into account the information below:

1. The joint must be continuous.
2. Once you start welding, you don't need to stop.
3. All work must be carried out in several layers, thereby ensuring tightness. The number of seams depends on the thickness of the walls.

When considering how to weld pipes, you need to pay attention to the fact that each previous layer must cool completely.

Welding of pipes using electric welding should be carried out with control of the resulting fastening. In addition, the weld on the pipe is promptly cleaned of slag and other contaminants.

The process under consideration has a fairly large number of features. When welding pipes, the following information is taken into account:

1. The polarity of the current is selected depending on the wall thickness, type of material and the selected electrode. It is worth considering that all information about the parameters under which the electrode should be used is indicated by the manufacturer.
2. It is worth considering that the connection of pipes is also carried out taking into account the current strength. This indicator can be determined by multiplying the thickness of the rod by 30 or 40. The current strength that is installed on the device is determined in a similar way.
3. The speed of welding is not regulated in any technical documentation. However, you should not keep the electrode in one place for a long time, as this can lead to smudges. In addition, too high a temperature can lead to burning of the edge.

In order to simplify the task, preliminary fastening of the elements to be connected is carried out. Such welding features must be taken into account in order to improve the quality of the connection.

Assembling joints

Pre-assembly of joints greatly simplifies the task. The features of this stage are as follows:

1. The pipes are fixed in clamps. If the fastening is carried out at three points, the fixation will be more reliable.
2. If there is only one connection point, it is recommended to start welding from the reverse side.
3. If the walls are about 3 mm thick, then the thickness of the rod should be 2.5 mm.

The most difficulties arise with welding pipes that cannot be secured in a vice.

Welding rotary and non-rotary joints

Pipe welding technology changes slightly if you need to connect joints of this type. The features are as follows:

1. Cooking is carried out using a special rotator, for which the required speed is set.
2. Care is taken to ensure that the weld pool is positioned correctly.

Grooving edges for butt joints

Similar work can be done with the usual workpiece fastening, the pipe is rotated approximately 90 degrees. The most difficult thing to cook is when turning the workpiece 180 degrees.

Quality control

Often, the quality of the weld is checked by a routine inspection of the structure by the welder. Among the features we note:

1. The surface is cleaned of slag by simply tapping the surface with a hammer.
2. After this, a visual inspection of the connection is carried out.

The product must not have chips or cracks, or cuts. Burns and other defects can also be called a serious defect.

Safety precautions during work

When using electric welding, it is important to follow all common recommendations. Failure to do this may result in damage to the workpiece or injury.

Often, safety precautions require secure fastening of the workpieces being fastened. In addition, special protective clothing and shields are required, which eliminate the possibility of damage to the face and eyes from the arc. The body of the electric welding device used must be grounded.

Source: https://stankiexpert.ru/spravochnik/svarka/kak-pravilno-varit-truby-ehlektrosvarkojj.html

Electric welding technology for pipes. Useful tips

There is an opinion that welding pipes is a fairly simple technological operation that even a beginner can handle.

Indeed, it would seem that there is nothing complicated here. The parts are quite large, the connecting surfaces are well adjusted to each other and processed, the material is of high quality. At first glance, there is everything necessary to form an aesthetic and durable seam!

In practice, however, it turns out completely differently. This process is quite difficult, especially when it comes to the formation of a full-fledged pipeline operating under pressure. The best specialists are attracted to work with its segments.

Why is this happening? How to perform high-quality welding without significant experience? What tips and tricks should you follow?

Core Technology

The most common and popular technique is electric arc welding.

Yes, it has alternatives in the form of gas welding, but its undeniable advantages lie in simplicity, a minimal set of equipment and a result that meets the most stringent standards.

Even when designing main pipelines, this method is used. To achieve high quality, you must treat your work with full responsibility.

Basic methods

The connection can be made in one of the following ways:

1. Butt joint, when the pipes to be connected are placed opposite each other. The most common option, characterized by relative ease of implementation. However, it is also characterized by certain difficulties. The first point is that it is better to work from below. The second point is that it is necessary to thoroughly weld the metal so that the depth of penetration corresponds to the thickness of the wall.
2. Overlapping. This method is focused on connecting elements that initially differ in diameter, or segments, one of which is flared, that is, its diameter is intentionally increased by mechanical action.
3. The T-joint is made at a 90-degree angle.
4. A corner connection assumes that the angle between the connected segments is less than 90 degrees.

Useful tips

Before electric welding pipes, it is worth remembering a number of tips, following which will simplify the process and also improve the quality of the final result:

• If the connection is made using the butt or tee method, then electrodes whose diameter varies from 2 to 3 millimeters perform best.
• The recommended amperage is from 80 to 100 amperes, with the exception of overlap welding, when it is recommended to increase it to 120 amperes.
• When filling a welding seam, you need to ensure that the rise of the metal above the plane of the element reaches 2-3 millimeters.
• If the cross-section of the pipe is not the usual ovals or circles, but profiles, that is, rectangles and squares, then a point method of connecting it is used.

Its essence is that initially you need to weld a small area on one of the sides. Next - a similar section on the opposite side, then - on the remaining two planes. Only after this the pipe is finally welded.

This approach makes it possible to eliminate the possibility of warping of the product when the temperature rises; its geometry remains stable.

Preparatory operations

The final quality of the joint depends not only on the professionalism of the welder and the use of the “correct” electrodes, but also on how well the preliminary preparation is done.

It consists of the following operations:

• Checking the compliance of the geometry of the connected elements with the selected technology. It must be remembered that the wall thickness must be identical, otherwise it will not be possible to fully weld a thick-walled pipe, and in the case of working with a thin-walled product, on the contrary, the risk of burn-through increases.
• The presence of defects on the welded products, be it cracks, creases or deformations, is not allowed. During the process of thermal expansion, they can turn into areas of complete destruction of the structure.
• Geometric deviations of the cut are not allowed. Its angle must be 90 degrees, otherwise the welding seam will not be strong enough and problems will arise with its formation, which will pose a threat of destruction of the entire structure.
• The edges of the connected pipes must be cleaned until a shiny metal surface appears, for which coarse sandpaper or a special brush is used. The minimum length of the area to be cleaned is a centimeter from the edge.
• Grease and other contaminants, traces of paint and corrosion are removed. The most effective removal agent is a chemical solvent.

This video shows how to prepare the edges of a pipe for clearance using a grinder:

Process Features

Pipe welding technology requires following the following rules:

• The seam must be continuous, that is, end at the point of its beginning. Tearing of the electrode from the surface is not allowed. It is impossible to follow the rule if the pipe diameter is too large. In such a situation, multilayer welding is used. The number of layers must be correlated with the thickness of the walls.

2 layers correspond to a thickness of less than 6 millimeters, 3 – from 6 to 12, 4 – more than 12. Before applying subsequent layers, you need to make sure that the first one has cooled completely.

• Before welding two pipes, they need to be fixed. The tack will simplify the work, eliminate transverse and longitudinal movements, and allow you to form an even and strong seam without unnecessary effort.
• When the pipe wall thickness is more than 4 millimeters, it is possible to form a root seam, the main feature of which is to fill the area between adjacent edges to the full depth. An alternative to a root seam is a roller analogue, which is identified by a 3 mm bead on top of the seam.
• Checking the quality of the seam. It is tapped with a hammer, which allows you to remove slag inclusions. After this, a visual inspection is carried out; cracks, areas with insufficient penetration, chips, gouges, and burns are not allowed.

If a liquid or other medium under pressure will be transported through pipes, a test run is carried out to determine the tightness.

Source: https://plavitmetall.ru/svarka/trub-elektrosvarkoj.html