How to properly weld a pipe near a wall - Metals and their processing

Welding a pipe - a fixed joint with a horizontal pipe position

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Welding these welds is the most difficult to perform and requires special skills and high skill of the welder. Only with solid skills in welding in the down position, vertical seams (section 3.3) and ceiling seams (section 3.

4) it is possible to achieve high-quality welding of a non-rotating pipe in a horizontal position. With constant forward movement of the electrode, it is necessary to constantly change the angle of inclination of the electrode in relation to the surface of the pipe perimeter (Fig. 68a and 68b, pos. 1-11). The pipe is divided vertically into two sections.

According to the position of the weld in space, each section can be divided into three positions:

I-th - ceiling (electrode position from 1 to 3).

II – vertical (electrode position 3 to 8).

III-e - lower (electrode position 8 to 11).

When welding pipes with a diameter of more than 150 mm and a wall thickness of more than 6 mm, it is recommended to select the welding current value for each position. The welding current in the ceiling position should be 10% higher than in the vertical position.

Welding starts from the ceiling position and ends at the bottom position.

With optimal selection of welding current for each position, it is recommended to carry out welding continuously. Welding is carried out only with a short arc. Welding of any section begins from another section 10–20 mm from the vertical axial. The length of the “lock” (20-40 mm) depends on the diameter of the pipe. The larger the diameter, the greater the overlap in the “lock”, vice versa.

When starting welding from the ceiling position, welding should be done “backwards” (Fig. 68a, pos. 1-2). After moving beyond axial welding, welding should be done “forward” (pos. 3-7). When moving beyond the horizontal axial electrode, align it to a perpendicular position (pos. 8). Welding the lower position (upper part of the pipe) is performed “at an angle back” (pos. 9-11).

Finish the first half of the seam 10-15 mm behind the vertical axial in another area.

The bead must be “normal” along the entire length of the seam, which is achieved by a certain speed of translational movement of the electrode, manipulation and delay at the edges, using all methods and techniques for welding ceiling, vertical and bottom seams.

Before welding the second half (second section Fig. 68b), if necessary, clean (cut) the beginning of the weld in the ceiling position and the end in the lower position until a smooth transition to the gap or the previous bead. Weld the second section using the same technique as the first section.

Welding the root bead (Fig. 70)

Welding of the root bead is performed with an electrode with a diameter of 3 mm. The magnitude of the welding current in the ceiling position, depending on the wall thickness, is 80-95 A. Depending on the technical conditions, it is recommended to make the root bead in two ways.

1st option - when welding small-diameter pipes, when it is impossible to weld the back side of the weld root, and technical requirements require reverse bead formation, then when welding the root bead, high-quality formation of the reverse bead should be achieved.

Penetration, especially in the ceiling position, can be achieved by constantly feeding the electrode into the gap.

By achieving penetration into the pipe, the formation of the bead on the outside may turn out to be “humpbacked”, which will require, after welding the first section, to clean up the “humpbacked” seam in the ceiling position.

When welding a vertical zone, it is recommended to reduce the welding current to 75-90 A. Make the bead with a small cross-section, avoiding excessive penetration into the pipe. When welding the upper part of the pipe (lower position), increase the welding current to 85-100 A in each specific case, avoiding burn-through or lack of penetration.

After welding the second half of the pipe, the second bead is also made with an electrode with a diameter of 3 mm, but at an increased welding current.

2nd option - when welding large-diameter pipes, where back welding of the weld root is available and laid, for the sake of productivity, you should not pay such careful attention to the formation of the reverse bead. It is recommended to form the root roll “normal” in all positions and with a fuller cross-section. This will allow you to avoid stripping along the outer seam and use an electrode with a diameter of 4 mm when welding the second bead.

Filling the groove (Fig. 70)

Here it is necessary to apply all the methods and techniques of groove filling welding described in the previous sections. It is recommended to weld pipes with a diameter of less than 150 mm using an electrode with a diameter of 3 mm.

Filling of pipe grooves with a wall thickness of more than 8 mm occurs unevenly. As usual, the bottom position lags. To level out the filling of the groove, it is necessary to lay additional layers in the upper part of the pipe in each specific case. Make the penultimate layer so that the depth of the unfilled groove is no more than 2 mm.

Welding the face layer (Fig. 71)

Depending on the width of the cut, the face layer is performed in one or more passes. Welding techniques are described at the beginning of the section and in previous sections. Pay special attention to the forward movement of the electrode, the delay at the edges and the manipulation step.

Welding of pipes with a diameter of less than 150 mm and a wall thickness of less than 6 mm, as well as in difficult installation conditions when the power source is remote from the welding site, is mainly performed with one welding current value.

It is recommended to select the welding current according to the ceiling position, the value of which is sufficient for the lower position. To avoid excessive penetration when lifting from a ceiling position and in a vertical position, welding must be carried out intermittently. Break the arc at one of the edges.

Depending on the wall thickness, gap and edge blunting, it is recommended to perform intermittent brush stroke welding in the following manner:

Rice. 72a - overheating of the edges does not allow a long delay of the electrode. It is recommended to ignite constantly on one of the edges, breaking the arc (after connecting the edges with weld metal) on the other edge. The time between the break and the new ignition of the arc must be such that at the point where the arc begins to ignite, the weld metal does not have time to completely crystallize and the slag does not have time to cool.

After the arc breaks, having described a semicircle in the opposite direction, ignite again slightly above the place of the previous ignition. If you follow the end of the electrode, you get manipulation in a spiral.

From left to right, the arc burns, a break to the right and towards itself, a transition from right to left, the arc does not burn, then from left to right, while simultaneously bringing the electrode closer to the ignition site, and while the slag is still red, the arc is lightly excited, etc.;

Rice. 72b - when the thickness of the metal allows you to make two or more oscillatory movements, then interrupt the arc and resume again.

Not recommended:

1) ignition is carried out at the place where the arc just broke;

2) without completely breaking the arc, move the electrode forward along the cutting and then return to the roller.

Such methods lead to significant overheating and burn-through, unevenness of the roller on the sides, and frequent sticking of the electrode during a new ignition.

Tudvasev V.A. "Recommendations for welders."

How to weld a pipe

There are few real specialists in electric arc welding of steel pipes. This work requires meticulous precision and a lot of practice. Welding the root seam is the most critical stage of the process.

The highest quality connection of steel pipes of any size is provided by electric arc welding. The parts being connected melt under the influence of an electric discharge. The article contains visual lessons on welding.

Technology of electric arc welding of metal pipes

Electric arc welding has technological standards and specific features depending on the material, wall thickness and intended purpose of the pipes.

Welding of fixed pipe joints

The connection of fixed joints is carried out in three ways, which depend on the location:

vertically;
horizontally;
at an angle of 45 degrees.

The vertical method includes 4 stages:

Welding a pipe to create a root bead. The most important stage is the formation of the joint, which will be the basis for all work. The inclination of the electrode relative to the surface: “backward angle.” The length of the arc should be adjusted: if penetration is insufficient, set it to short; if it is normal, set it to medium. Keeping the weld bead in a liquid state for a long time leads to the occurrence of defects. Therefore, with a large volume of the weld pool, the welding speed is reduced.
Welding three beads and sealing. The rollers are performed at high speed. Depending on the direction of the slag, rectangular or “backward angle” welding is used. The top edge of the last roller must have a minimum value up to the top edge. Usually equal to the diameter of the electrode.
Forming a lock at the beginning and end of the rollers. The formed lock is the beginning of the roller with a 5 mm offset from the previous one. When making a joint, the roller must be continuous along its entire length.
Welding on the front side. It is performed at high speed and aims to form a flat surface. Welding ends when it goes beyond the beginning of the seam.

The horizontal method requires professional skills. It is produced at different welding current values and at different angles to the part. This technique involves three stages:

ceiling;
vertical;
lower.

Within one stage, welding takes place continuously, starting from the “backward angle” position and ending with the “forward angle” position.

Welding at a pipe angle of 45 degrees begins with creating the first bead at an electrode angle of 90 degrees. The seam is made by continuously melting the second roller. After filling the base, the first roller is melted. This creates connections horizontally and vertically.

Welding pipes “under clearance”

The technology provides the following conditions:

dullness size: 2-2.5 mm;
gap between edges: no more than 3 mm;
opening angle: in the range from 60 to 70 degrees;
additional processing of edges by chamfering to give them the required shape and eliminate irregularities;
the difference in the thickness of the welded walls should not exceed 3 mm or 10%.

Welding of high pressure pipelines

A feature of welding high-pressure pipelines is the need for preheating of the joined elements to 300 degrees C, which is maintained throughout the entire tack and welding process.

When cooking gas pipelines, take into account:

That thick-walled pipes are used for gas mains, which increases the overall labor intensity of the work.
There are increased demands on the quality and reliability of the weld, so professionals with extensive experience are involved in the work.
The entire system as a whole (pipe, as well as joints, welds) must be resistant to corrosion. After the end of cooking, to relieve thermal stress, a section of 10 cm in each direction from the seam is heated to 500-600 degrees C. For this, thermal ovens, induction heaters, and gas burners are used.

When heated, the ends of the pipes are closed to prevent cooling and air movement in the pipe.

Automatic welding

The so-called submerged arc welding involves feeding an electrode wire into the combustion zone of an electric arc using an automatic welding head. In the molten state, the wire metal enters the weld pool and mixes with the base metal.

Automatic welding allows:

speed up and stabilize the process;
make the arc invisible;
expand the range of parts in thickness;
make the seams more resistant to the formation of cracks and pores.

Flux has a positive effect on the stability of the arc and the chemical composition of the weld. To carry out automatic welding, the ability to rotate the joint is necessary.

Welding large diameter pipes

In more than half of the cases, the connection of steel main pipelines is carried out using pipe welding machines. When it is impossible to use the mechanical method, for example, due to localization features or limitations in manipulating the pipe, manual welding is used, carried out by a team of welders.

For main pipes with a wall less than 6 mm, two layers of welding seam are used, and more than 6 mm - three. The reverse roller of the root seam can have a height of up to 3 mm.

In those places of the root weld that are welded poorly, additional welding is carried out from the inside of the pipe. This requirement also applies to that part of the root that was made in the ceiling position: the lower quarter of the joint perimeter is welded from the inside.

Rotary joints require welding along the entire perimeter of the joint. Welding is carried out with 3-4 mm electrodes.

Large diameter pipes require the use of special centering equipment.

Welding steel pipes “through transmission” - step-by-step instructions

Pipes with thick walls, in which 2 mm is only the amount of dullness, are welded “through the light”.

THIS IS INTERESTING: How to make a mixture for welding with your own hands

Preparation and cutting of edges

The abrasive method is the least reliable due to the introduction of abrasive particles into the metal, which interferes with high-quality melting and leads to the appearance of cracks.

Use a double-sided Y-shaped symmetrical groove with an angle of 65 degrees, an optimal amount of bluntness and a gap of 2 mm.
When preparing bevel edges, use thermal or mechanical methods. Due to the high cost of thermal cutting (laser, plasma), various types of mechanical processing are used in practice, which make it possible to obtain a plane with high accuracy:
processing on a milling machine;
manual bevel processing;
cutting using abrasive wheels;
processing with slotting-type edge cutters.
Clean the joints of the welded products to white metal. There should be no irregularities, burrs or rust left.
Treat surfaces with acetone or any similar substance.
The presence of grease, dirt, and dust prevents the high-quality connection of metal molecules.

Centering and joining of pipes

Centering and joining of small-diameter products is carried out by fixing them using improvised means or using assistants.
Center large pipes (from 60 mm) with special equipment - a centralizer: internal or external. Both have an electro-hydraulic drive.
Internal ones are more preferable due to the fact that when they are used, the joint remains uncovered. This allows the use of automatic welding machines, and also does not limit manipulations during manual connection.
Do not allow deviations when using the manual alignment method. It is impossible to dock perfectly without a centralizer, but try to minimize the deviation.
Having connected the pipes exactly, proceed to welding the root seam.

Root welding

Cook the seam under the following conditions:
minimum current;
reverse polarity;
short electric arc;
dry electrodes;
lack of wind in the pipe.
Cook vertically, the electrode is perpendicular to the plane.
Use an electrode to melt the edges - a bridge will appear between them, which is called a weld pool.
In front of the jumper there is a so-called technological window.
Carefully monitor the size of the technological window: throughout the entire process it should remain the same diameter.
Make a root seam no more than 1 mm high. The return roller should also not exceed this value.

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Clean the beginning and end of the seam and the transition area between the electrodes to avoid the formation of pores in the metal, the presence of which will sooner or later lead to loss of the pipe’s tightness.

Filling and capping of the weld

After welding the root, fill the entire seam section.
Depending on the wall thickness and material, use a single-layer or multi-layer penetration method.
The movement of the electrode during filling is a triangle: edge 1 - edge 2 - technological window.
Pay attention to the heating of the edges and root seam. The greater the heating, the wider the filling step.
After each layer, clean the surface of slag.
If you have the skill, and if the wall diameter allows, fill and cover in one pass.

Welding gas pipes under pressure

Welding special gas pipes for transporting high-pressure contents places increased demands on the process.

Gas pipe welding technology

Features of welding pipes for transporting high-pressure trains are determined by two characteristics:

Thick walls and small diameter.
Aggressive effects of transported gases.

Pipes up to 10 cm in diameter are welded manually, above - using semi- or automatic welding with manual welding of the root of the seam. For diameters greater than 6 cm, special rings are used. The weld is made multi-layered - from 4 layers and above, depending on the load on the pipeline and the characteristics of the material. After completing the work, a mandatory inspection is carried out - flaw detection inside and outside the welding site.

Yulia Petrichenko, expert

Possible errors and defects in the weld

A large current when cooking the root leads to the formation of a hole instead of a technological window through which the metal will drip down. Provide a current of such strength that the metal has time to cool literally immediately after the movement of the electrode.
If the process window is not visible, most likely the current strength is too low, and it must be increased.
A small bluntness leads to an increase in the technological window and to sagging of the metal inside the pipe.
A gap of more than 2 mm guarantees the appearance of pores in the seam - the work will be unsatisfactory.
When welding with an electrode, you cannot make jump movements of more than 5 mm in length.

Welding steel pipes is not an easy task for a beginner.

With practice will come experience and an intuitive feeling of what should be done and at what moment in order for the weld to come out perfect.

Perhaps you are a professional welder and have something to share with your readers. Leave your opinions in the comments.

Yulia Petrichenko

Expertise - cost estimate engineer

Welding a pipe through transmission: video tutorials on how to weld pipelines of any diameter - printable version

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“Pipe Welding”

How to weld pipes using electric welding: video of the technological process

Source: https://shtyknozh.ru/kak-zavarit-trubu/

Welding heating pipes: what and how to weld? Let's figure it out together

Welding heating pipes is one of the most reliable types of joining. The process of joining structures is carried out using special devices under high temperature. This type of welding is used for both metal and plastic pipes.

If you lack any welding skills, it is preferable to seek help from specialists.

Some docking methods can be carried out independently using the necessary tools and observing safety precautions. Welding heating pipes by a welder can cost you a very high price. At the same time, the cost of the welding machine is low.

Note: the price depends on the diameter of the pipes, the number of joints, passages, and the price will also increase if pipes need to be welded at height, in cramped or cold conditions.

Welding plastic pipes

You can cope with welding plastic pipes with your own efforts; this process does not require special knowledge or skills.

Plastic pipe welding machine

To work with this material you need:

Please note that by following the links above to the store, you can quickly and easily compare the models you need and choose the most suitable one.

When working with plastic, you need to be careful and careful, since such material can easily be damaged or spoiled when exposed to heat.

The temperature during welding should not exceed 1800 C, since above this indicator the plastic can melt and spill inside the pipeline. Also, the use of low temperatures during the joining process risks a leaky connection; gaps may form, which will lead to leaks during operation.

See below for the welding process of polypropylene pipes. Remember that it is very important that water does not get into the soldering area; the author of the video pays special attention to this; he also says that the pipeline should be filled with water no earlier than one hour after completion of work.

Electric welding of metal pipelines

For welding metal heating pipes, a joint method with a gap of 2-3 mm is used.

With such a connection, melting of the edges of the pipes should not occur; the joining is carried out with fused wire in the gap.

It is advisable to select pipes of equal size for stronger and more reliable welding.

The surface of the pipelines should be cleaned before performing work. The ends of the pipes must be straight. The pipe installation scheme and the size of the required sections must be thought out in advance; therefore, it is necessary to cut metal structures.

The welding process is carried out in a circle. Depending on the thickness of the pipes, several layers of welding are used, but not less than two. Before starting a new seam, the slag must be removed.

The video below shows how to weld steel pipes with a gap in two passes. Very detailed and useful video.

Gas welding

Gas welding of pipes is a more expensive type of connection than electric welding.

When using a gas tool, the connection occurs by applying molten metal to the surface of the weld.

Shows how to connect pipes using gas welding

To create a seam, the circumference of the pipes along the proposed seam is divided into 4 conventional segments along which the seam is filled. When welding in four sections, each worked part is turned down.

Welding, as a joining method, is regulated by GOST and SNiP for heating networks.

When performing gas welding, safety precautions must also be taken. You must put on a protective suit, and put a special helmet-mask over your head and eyes. All work must be carried out away from flammable objects.

Cold welding

This connection method is also known as cold welding of heating pipes.

A man applies cold welding to a pipe joint

It is an epoxy adhesive with steel powder. Used as putty. The method allows you to glue virtually any material, including plastic and metals. This welding method is most often used for individual seams or for closing gaps.

Read also: How to properly connect a heated floor to a thermostat?

By the way, you can cold weld not only pipes. For example, Victor from the video below repaired an ax handle in this way. Quite useful and educational.

Source: http://kvarremontnik.ru/svarka-trub-otopleniya/

How to remove a pipe from a stove through a wall with your own hands | Finishing experts

Gusevsky Andrey Anatolievich

A stove pipe with an exit through the wall is an essential element of any heating apparatus. But not many people think at the construction stage, where it will take place, and how to arrange it correctly. And after building a house, it is not always easy to build a structure for removing smoke. The article will tell you how the pipe should pass through the wall.

Features of the location of the chimney outside the house

When placing a chimney inside a wall, you can hide unnecessary communications; this is a more correct structure, but external installation of the system has many positive aspects:

Higher fire safety. Sometimes the soot accumulated in the pipe ignites, usually at a temperature (+1200ºC). Only ceramics can withstand such heat. If a pipe embedded in a wall heats up to this temperature, a fire is most likely inevitable. Given the same situation with the external structure, the consequences will not be so catastrophic.
There is no smoke . Over time, the smoke and gas exhaust system becomes unusable and smoke begins to seep through the cracks and then enter the room, which can be avoided by placing the channel outside.
Useful space is saved. When the chimney is located inside, it will occupy some living space.
Installation can be carried out after completion of construction.
There is no need to interfere with the integrity of the roof covering.
To improve traction, it is possible to extend the pipe to a greater height.

There are also a number of disadvantages of such a structure.

These include:

Quite a high windage at a considerable height.
The need to use additional fastening material.
It is necessary to properly insulate the pipes.
High heat loss.
Sometimes the type of chimney does not match the style of the building.

Chimney installation rules

It is necessary to remove combustion products from the furnace for several reasons.

Chief among them:

Life and health of people.
Efficient operation of the furnace or boiler.

Advice: It is necessary to properly organize the removal of carbon monoxide; poisoning with it can even lead to death.

Any fuel does not burn without access to oxygen, which enters through the smoke channel.

There are several rules for installing chimneys:

There should be no communications where the channel passes.
The areas where the chimney passes through the wall are covered with a protective casing or plastered after first filling the space with heat-insulating material.
The chimney fixation is installed in increments of 60 millimeters.
This design usually uses dual-circuit systems that are better protected from mechanical stress. In this case, it is necessary to install a valve that allows you to adjust the draft.

Construction of a double-circuit gas exhaust system

What is needed to install an external chimney

To install a chimney you will need:

Bulgarian.
Electric drill with a set of drills of different diameters.
Riveter.
The sealant is heat-resistant.
Aluminum tape.
Clamps for fixing the outlet pipe.
Corners.

The main elements for installing an external chimney are shown in the photo.

Parts and components of the external chimney

An external smoke exhaust pipe is installed for:

In addition to the heating device itself, to install the device you will need:

Tip: When constructing a pipe, you should take into account the angle of deflection, which is necessary for the correct direction of smoke movement.

Welding of tap elements must be performed with tungsten electrodes. The number of elements depends on the design and length of the chimney.
If necessary, install:

dampers that are mounted in pipes, transitions, bends or tees, which depends on the customer’s wishes;
viewing windows.

Tip: Dampers should be installed so that they do not come into contact with the walls of the stainless steel pipe. Otherwise, the damper will jam due to exposure to high temperature.

Tee stand. To make it, you can use a square metal pipe made of stainless steel, which is attached to the wall with dowels.

Tip: When making a stand for a tee, you should choose the correct distance between the wall and the chimney.

When installing a chimney through a wall, heat-insulated tees made of stainless steel are installed. They are used when connecting a heating device to a chimney. Further, during operation, these elements will be used for cleaning, inspection and removal of existing condensate.
Tubes for removing condensate and windows for inspection are installed in the lower or side part of the tee.
After assembling all the elements, in accordance with the requirements set by the instructions for compliance with fire safety rules, the inspection window door must be “seated” on silicone.

Tip: Tees can be made in one piece, prefabricated or through. They should be connected at different angles.

To build a chimney, fasteners are used, which are special brackets; you can make them yourself from metal tubes made of stainless steel.
The external chimney must be covered with a layer of heat-insulating material, which is usually mineral wool, and then the heat-insulated chimney is placed in a protective casing made of galvanized or stainless steel or other materials.
To install an external chimney through a wall, additional reinforced fasteners may be required:

for installation of installation and unloading cups;
so that the structure can withstand lateral loads.

The top of the structure is a heat-insulated pipe in a protective casing. Its length should be over one meter. For it, the upper caps are made of stainless steel.

How to install a chimney through a wall

Installing a chimney through a wall must comply with certain conditions:

In the place where the chimney goes, radiator pipes should not pass through the wall or other communications.
You need to start installation by connecting the pipe to the heating boiler. The chimney through the wall is made at an angle of 90°.
The next part of the structure is placed perpendicular to this element. A condenser tank is installed in its lower part, and the main mass of the chimney is connected at the top.
Pipe passages through walls are sealed. It is best to use thermal insulation materials for this. It is recommended to plaster the exit and entry areas of the pipe or cover it with a protective casing.
Using corner connections, sections are constructed that take into account the architectural features of the house.
Each joint must be secured with a clamp.
Clamps for the chimney to the wall are installed in one step.

Advice: Fastening elements must be installed in increments of no more than a meter. The optimal distance is 0.6 meters.

After the structure is constructed, a cap is installed above the chimney neck.
The pipe is insulated from the wall of the building, for example, with basalt fiber. This is necessary so that when heated, the chimney does not transfer some of its heat to the wall and thereby destroy it.

How a chimney is mounted through a wooden wall

A special feature of arranging a chimney passage through a wooden wall is that the pipe must be lined with fireproof material, such as:

This is necessary to:

Prevent the wood from drying out.
Follow fire safety regulations.

These rules allow you to use the chimney for a long time, and the cost of subsequent repairs will be minimal.

Chimneys in a wooden house

Installation of a chimney inside the house is carried out using double-circuit chimney systems.

Wherein:

The best option is a vertical arrangement of the chimney, consisting of one straight long pipe, without any geometric deviations.
As part of such a system:

damper, used to regulate draft in the chimney;
the pipe itself. Its neck is covered with a protective cap.

Pipe fastening elements are placed in increments of one meter.
The passage of the chimney through the metal tile is carefully sealed with a protective casing, which will prevent moisture from entering the attic of the house.

All the nuances of the pipe outlet for the chimney, how the cable pipe is routed through the wall, are shown in the video in this article.

Installing a chimney is a very responsible procedure that requires good preparation. The functionality and efficiency of the entire heating system depends on the correct installation of the chimney.

Gusevsky Andrey Anatolyevich Leading specialist in a large construction company engaged in the construction of multi-storey residential buildings. Graduated from the Faculty of Architecture of the Penza State Institute of Architecture and Construction. Total work experience in the specialty is 18 years.

Source: https://otdelka-expert.ru/pechi-i-kaminy/kak-vyvesti-trubu-ot-pechi-cherez-stenu-2812

What is the best way to weld heating pipes?

When installing heating pipes, you often have to connect them by welding. Of course, in some cases a threaded connection may be suitable, but the percentage of this method is much smaller.

Welding metal heating pipes

As for welding steel pipes, this method has several varieties. For example: manual electric arc, gas welding (semi-automatic, automatic). To connect steel heating elements, the first type of welding is often used.

Heating registers made of steel pipes.

The manual arc technology is quite simple, so you can do it yourself. It all starts with preparation.

Preparation

First you need to start preparing the pipes. Surfaces that are planned to be welded must be cleaned and degreased. This is the only way to avoid defects in the seams.

Products must have an appropriate opening angle of the edge; perpendicularity to the plane of the end of the product axis must be maintained. The preparation of large-diameter heating pipes is carried out using milling machines or gas-acid cutting.

Dimensions, compliance with the thickness of products, chemical composition, mechanical properties - everything must be combined with the requirements of GOST.

It should be noted that often the amount of blunting is about 2 mm, and the opening angle is about 65 degrees.

An important stage of preparation is the choice of materials.

You can weld steel heating pipes correctly if you choose the right electrodes. There are two types of them: non-melting and with a melting base. The gradation is based on the type of electrode core.

For the non-consumable type, electrical coal, graphite or tungsten is used. As for the melting one, it is made from welding wire, which can have different composition and size. In our case, electrodes with a diameter of 2 to 5 mm are often used.

Larger products can be cooked with a larger electrode diameter.

As for the coating, it also influences the choice of one or another electrode for welding steel heating pipes. There are such electrodes:

With basic coating. Thanks to this consumable material, seams have a low probability of cracking and have good viscosity indicators.
With rutile-cellulose coating. They are used for a variety of cases, including the most difficult one: a vertical seam from top to bottom.
With rutile coating. The seams come out with excellent appearance. Slag is easily removed and ignition is easy. Therefore, such electrodes are often used for tack welds and fillet welds.
With rutile acid coating. The slag is formed of a special structure; it is simply removed at the end of the process.
Cellulose coated. Suitable for large diameter products, for creating vertical and circular seams.

This is a non-metallic alloy that weighs less than the products being welded. It is located at the top of the seam, forming a cover. Perform a protective function. The slag protects the seam from environmental influences. Once it cools and hardens, it can be easily removed.

Schematic diagram of welding metal pipes

If slagging of the seam is observed, this is a defect. After all, this reduces the strength of the connection.

Features of manual arc welding

It is carried out in several passes, after each it is necessary to remove the slag. Each subsequent seam is made overlapping the previous one. This method allows you to achieve maximum tightness and reduces the likelihood of fistulas.

Welding process

You should start welding heating pipes with tacks. This is the technology of butt connection.

https://www.youtube.com/watch?v=Tvhw5VG5qTI

They are part of the seam. To perform them, electrodes of the same type are used that will be used for main welding.

If the diameter of the products is up to 30 cm, you can make four tacks, evenly spaced. Length – 5 cm, height – about 3 mm.

You can butt weld a large diameter product by making tacks every 25-30 cm. Welding is performed in three layers if the wall thickness is up to 1.2 cm. You should strive to ensure that most of the joints are made in a rotary position.

Rotary method

First, a seam with a height of about 3 mm is made, using electrodes with a diameter of 2-4 mm. Then electrodes with a larger diameter are selected to create subsequent layers.

Welding large diameter heating pipes

The joint should be divided into four sectors. They are performed in two sectors in the upper hemisphere of the pipe, gradually rotating the product. And only the third layer is performed in one direction, rotating the pipe.

If you are connecting products that operate under pressure, they are usually located near the walls of the room, so welding such pipes is not very convenient. The process begins at the lower section of the heating system, from the center.

The electrode should be positioned perpendicular to the welding site. If a vertical seam is being made, the electrode is placed upward at an angle.

After creating the layer, the slag must be removed.

Welding steel heating pipes with your own hands
If you have instructions, you can independently weld large-diameter steel pipes into a joint when installing a heating system.

Source: https://gscomplect.com/chem-luchshe-varit-truby-otopleniya/

How to weld pipes using electric welding

The most common method of connecting pipes both on main lines and on various secondary branches of pipes with low or high pressure in industrial, production and domestic conditions is a welded connection.

This is due to the fact that it is capable of providing strength and high sealing of the connection, comparable to the strength of the walls of a solid section of pipe.

This type of connection is non-separable and therefore is used on branches, tie-ins, turns, pipe joints in places where constant maintenance by technical personnel is not required. In this article we will talk about how to weld pipes using electric welding.

Advantages and disadvantages of electric welding

It is possible to highlight the following advantages of welded joints:

Possibility of obtaining connections of enormous sizes.
No transformation of external and internal dimensions due to the connecting seam.
Use for welding of a material similar to the pipe material, due to which all the properties of the pipeline are preserved.
simplicity and low cost of the method.

Defects in welded joints are mostly caused by the low qualifications of the welder due to his inexperience, technology requirements and non-compliance with the rules, which caused incomplete welding, the formation of cracks, residual stresses and displacements in the weld area as a result of underheating or overheating.

Another drawback is the difficulty in adjusting the arc to ensure uniform conditions for the formation of a seam joint, since the electrode in the arc invariably melts and moves unevenly along the surface of the pipe.

In addition, it is possible to determine the level of quality of the connection without the use of special devices, and to evaluate the structure of the replaced metal only by external indicators.

Process Bases

The process of electric arc welding consists of creating an electric arc between the electrode being welded and the metal material, under the influence of which the electrode and a certain section of the pipes are heated, as a result of which they melt and the two compositions are mixed. The amount of melting depends largely on the diameter of the electrode, the material of the pipe, the welding mode, and the speed of movement of the arc along the surface.

The electrode has a special coating, which during melting creates special conditions in the arc that interfere with the cooperation of the metal with air and the formation of a protective film. At the same time, the pipe material and the molten electrode material, when in the arc, help create a weld when the arc is removed and cool. Slag forms on the surface of the welded joint, which must then be removed.

What tool is useful for welding work?

For electric welding, the first thing you need is a welding machine. Today there are two types of such devices:

Devices made on the basis of a step-down transformer, in which the welding current is regulated by transforming the magnetic gap, the position of the rheostat, or other regulators. It is already obsolete and is actually not used, since it is heavy and its transportation may be difficult.
Inverters operating at high frequencies. They use a smaller transformer, making the device lighter and more transportable. It is possible to regulate the welding mode with high precision. But in operation they are less reliable and require appropriate qualifications from the welder.

Advice! Welding machines can be powered from a 220 V or 380 V network; there are also combined options. Designed for 380 V, they are more suitable for a network in which there are no voltage surges or sags. For weak power grids, modern inverters are the best choice.

In addition to the welding machine, the following auxiliary equipment will be useful:

It is imperative to have a mask with a special light filter so that you can see the welding site, and your eyes and face are protected from sparks and molten metal. In addition, you will need protective clothing that completely protects parts of the body and thick gloves made of suede so that the clamp with the electrode is held securely in the hand.
A metal brush for cleaning the area before welding and for removing scale.
Electrodes suitable for specific conditions.
Hammer for knocking down scale.

How to choose an electrode?

Before welding pipes using electric welding, you need to choose a suitable electrode, since the level of quality of the seam, and, accordingly, the duration of operation of the pipeline, greatly depends on its choice. It is an iron rod coated with a special layer for welding. Electrodes differ in the amount of coating and the thickness of the rod. For pipes, rods with a thickness of 2 to 5 mm are used. The coating can also range from 3 to 20% of the total mass.

Advice! Since creating an arc requires a special atmosphere that prevents air from entering, therefore, rods with a thicker coating will be of better quality. But their size must be uniform throughout the entire length of the rod, and not have cracks or cavities or any other defects.

But the more coating, the more slag is formed, which is a non-metallic compound that significantly loses its strength properties after cooling, based on this, it is necessary to find some compromise when choosing.

Depending on the thickness of the pipe, electrodes are selected as follows:

If the wall thickness of the pipes being welded is less than 5 mm, an electrode with a thickness of 3 mm is selected.
For a thickness of more than 5 mm, select a 4 or 5 mm electrode depending on the required degree of welding and the thickness of the seam.
With a multilayer method of forming a weld, 4 mm electrodes are used in most cases.

Advice! It is possible to select the thickness of the electrode using an experimental method. Since the current is directly proportional to the thickness of the rod, the electric arc will accordingly increase and the pipe will melt faster. At the same time, there is a minimum current value, below which the level of welding quality deteriorates noticeably.

Based on this, you need to know how to choose the right electrode that ensures sufficient passing current. The dry crackling sound of the arc without additional noise can serve as a guide.

Preparation for the process

Before starting welding, you must make sure that there are no flammable materials or explosive substances nearby. If there are any, it is better to protect them with some kind of non-flammable material and place a container of water nearby just in case. The surfaces and edges of the pipes near the weld must be cleaned. Then you need to securely secure the grounding and check the integrity of the cable.

The required current is set on the transformer of the welding machine in accordance with the thickness of the pipes being welded. After this, light the arc by slowly moving the electrode at a distance of 5 mm from the pipe surface at an angle of approximately 600, as a result of which sparks should appear.

Then the electrode must be moved to the welding site, keeping it at the same distance from the pipe.

Advice! Because the electrode will decrease during welding, it should be brought closer as necessary so that the distance does not change. If the arc does not ignite, then expand the current until sparks appear. If you still fail to light the arc, then go pick up a thicker electrode.

In most cases, for rotary joints, the current on the welding machine with an electrode thickness of 3 mm and a pipe up to 5 mm must be in the region of 100 to 250 A, and for non-rotary joints - 80-120 A.

Description of the pipe welding procedure

Once a constant arc has been achieved, it is possible to begin welding. During welding, move the arc as follows:

progressively throughout the weld, due to which the arc will be stable;
longitudinally for a narrow seam with a height depending on the speed of movement of the electrode along the surface;
transversely in order to ensure the required thickness of the seam, moving the rod with oscillatory movements.

Pipes with small wall thickness and diameter are welded with a constant seam, while pipes with thick walls are welded with an intermittent seam. Welding of joints should be carried out until the joint is completely welded without interruptions. When welding joints with a wall thickness of up to 6 mm, two welded layers are made, with a thickness of up to 7 mm - three layers, and with thicker walls - four.

Advice! Any layer being welded must be cleaned before welding the next one to ensure uniformity of the weld.

In most cases, the first layers are welded in stages, starting from the edges of the pipes with fusion, and the subsequent layers are welded evenly in a continuous layer.

The stepped option is used for pipes with a thickness of more than 8 mm: the base layer is applied by dividing the surface of the pipes into certain areas with a small area and welding through one area, and later the missing ones are welded.

After welding of the first layer is completed, it is inspected for cracks, since the quality level of the entire seam depends on this. If there are any, they are melted down and welded again.

Subsequent layers are welded by turning the pipe or uniformly moving the electrode along the surface of the seam, and the starting point of welding is shifted rather than the end point by about 20–30 mm relative to the previous layer and the direction of movement of the electrode is changed to the opposite.

The last seam is made with a smooth transition and a smooth surface to the size of the pipe diameter. If pipes with a square cross-section are welded, their ends must be firmly secured so that the metal does not lead and the pipe does not deform. Upon completion of welding work, the surfaces are cleaned of slag.

Welding pipes using electric welding is a simple process, but important, requiring adherence and care to the sequence of actions performed.

Source: https://uchebniksantehnika.ru/truby/kak-varit-truby-elektrosvarkoi.html

How to insulate a pipe in a bathhouse from the ceiling, roof and wall - Russian Bath

Many people believe that to properly arrange a bathhouse, it is enough just to install the stove correctly and bring the pipe to an acceptable height. However, just when this work is completed, the time comes to think about how to insulate the pipe in the bathhouse from flammable elements in order to avoid a fire, as well as the roof from leaks.

In the best case, you should think about insulating the pipe in the bathhouse at the design stage, because in this case the finished structure will be of higher quality and more reliable. It is much more difficult to insulate an already built chimney; in some cases, it is necessary to dismantle certain parts or change the configuration of the pipes.

What is the best thing to do?

First of all, the chimney pipe must be protected from two main negative influences: overheating and moisture ingress through the joints.

In this regard, the two main stages that must be completed in the process of insulating a chimney in a bathhouse are:

Fire protection;
Waterproofing.

Thermal insulation of the pipe in the bathhouse, which runs through an unheated attic, allows you to prevent heating of the structural elements of the roof, as well as to avoid the appearance of condensation, which has a very negative effect on the metal.

Waterproofing also performs a very important function, because it can protect the truss system of a bathhouse, as well as other wooden elements, from rotting. Thanks to waterproofing, a pipe subject to constant wetness will not collapse.

Fire insulation

Of course, the safest option would be to install a sandwich pipe for the chimney, since this design already includes insulation.

This option is not suitable for everyone, since high-quality sandwich pipes cost a lot. That is why classic metal pipes are more popular.

Insulation of a single metal pipe is done by installing boxes and winding the pipe with basalt wool insulation.

Of course, you can do without using thermal insulation, but in this case the design will be less safe. It is worth noting that fire cutting is carried out without fail and in accordance with all the rules.

Methods of waterproofing from the ceiling and roof

Insulation against moisture penetration into the roof is carried out at the point where the pipe exits onto the roof.

The number and complexity of tests for a chimney pipe depend directly on its height and dimensions.

The fact is that the larger the pipe, the more influence it will have from wind, rainwater, and snow flows.

If you allow a misfire in the waterproofing process, natural precipitation will eventually begin to penetrate the roof, causing leaks and rotting of wooden structures.

The actual method of insulation from moisture depends on the material of the roofing and the shape of the pipe. Thus, when waterproofing round pipes, polymer grooves are used, and in the case of rectangular and square shapes, metal aprons and junction strips are used.

Metal structure

The most favorite material for building a bathhouse for many years has been wood. In addition to all its unique positive properties, wood also has increased flammability, which is why the bathhouse needs fire insulation.

In order to avoid fires, to insulate the pipes in the bathhouse with your own hands, as well as to insulate the walls and ceiling, we used a lot of different materials: asbestos, clay, various insulating boards. The most important thing in insulation is low thermal conductivity.

What to wrap: thermal insulation

Teploizol is a relatively new type of insulating material. It consists of foamed polyethylene with a foil surface on both sides.

Teploizol has excellent resistance to elevated temperatures, which is why it is so often used for insulating pipes in bathhouses. The thickness of this material varies from two to ten millimeters. The maximum temperature it can withstand directly depends on the thickness of the insulation layer:

The material with a thickness of two to five millimeters can withstand from -30 to +100 degrees;
From five to ten millimeters – from -60 to +150 degrees.

Before wrapping a pipe in a bathhouse with thermal insulation, you need to stock up on metallized tape or wire, since you will need these materials during the insulation process, which is completely simple and does not require outside help.

What to wrap in the attic: foil insulation

Folgoizol is also perfect for thermal insulation of a chimney, due to its resistance to temperature changes. It consists of a double layer of foil and insulation.

For the production of foil-isol, fairly dense food foil is used, due to which it is distinguished by its harmlessness.

Folgoizol is able to withstand temperatures from -60 to +200 degrees, which is why it is used not only for insulating pipes, but also for insulating walls and ceilings. Folgoizol is an excellent heat, hydro and vapor barrier material at a relatively low price.

Basic rules and regulations

Before insulating a pipe in a bathhouse from the ceiling, you should study the following SNiP requirements:

To ensure optimal draft force, a chimney pipe with a height of at least 5 m should be erected;
A minimum distance of 250 mm must be maintained between the chimney pipe and the nearest combustible elements;
If materials with insufficient fire protection are used for roofing, a spark arrester must be installed;
A certain distance must be maintained between the upper stove ceiling and the ceiling: for metal pipes - more than 1.5 m, for brick chimneys - 0.5 m.

Metal pipe: step by step process

In bathhouses with an installed heater, it is better to use brick chimneys, since refractory brick retains heat for quite a long time.

Many people wonder how to decorate the walls in the bathhouse near the stove, because these places also need protection.

Typically, sheets of asbestos or galvanized steel are used where the chimney comes into contact with the roof and ceiling.

Galvanized steel sheets are also used to protect walls near the stove.

A metal pipe without a heat-insulating layer is the most fire-hazardous option for arranging a chimney. In this case, there should be a distance of 60 cm, no less, between it and the nearest combustible elements.

The most popular and simplest option for pipe insulation is the use of heat-resistant insulation for its winding. Basalt wool is most often used as such insulation, which is protected on top with plaster or a metal sheet.

Isolation occurs as follows:

The first step is to stock up on mineral wool slabs, the thickness of which should be more than 5 mm. Next, the insulation material is used to completely wrap the pipe. The insulation is secured with steel wire, which also needs to be wrapped around the pipe;
On top of a pipe equipped with a heat-insulating layer, it is necessary to construct a reinforced mesh. Next, a cement-limestone mortar is made, with which the mesh is plastered;
Instead of plaster, you can use a metal sheet.

To do this, you need to roll it around a pipe with insulation and rivet the edges at the fastening point.

Roof and ceiling passages

It is very important to treat with the utmost care and responsibility the places of passage through the ceilings of the bathhouse.

These areas are insulated, regardless of the type of chimney used, be it sandwich pipes or ordinary metal ones.

To ensure that passage through the ceilings is as safe and high quality as possible, a special box is used. You can either make it yourself or purchase it in a store.

During the installation process, the following should be taken into account:

The diameter of the hole for the pipe should be much larger than the diameter of the pipe itself, since there should be a distance of 25-30 cm from the surface of the chimney to the ceiling structure;
There should be no free space left around the pipe, since all of it must be tightly filled with insulation;
The edges of the pipe connector should be treated with metal sheets before installing the box;
Nearby wood elements must be treated with fire retardants.

Conclusion

Arranging a chimney in a bathhouse is a very complex and responsible undertaking, and making a mistake in the process is unforgivable. It is best to contact a qualified specialist in order to be one hundred percent confident in the quality of the work done.

If you decide to take on the work yourself, then the information above will be very helpful.

In addition to proper installation, you should remember about proper operation of the chimney, because it must be promptly and thoroughly cleaned of accumulated soot and dirt. It is necessary to remove ash from the stove in a timely manner and not throw materials not intended for combustion into it.

Each of these points is the key to long and uninterrupted operation of the chimney.

Source: https://rubanya.com/pechidim/podrobnaya-informatsiya-o-tom-kak-izolirovat-trubu-v-bane-ot-potolka-kryshi-i-steny.html