Welding is the most popular way to connect metal and polypropylene pipes. And if only professionals with great experience and special equipment could be performed before this work, then today any hardworking owner can contact him. But still, facing such a task for the first time, a number of questions arise: what device to buy, what electrodes will fit, what kind of seam apply? In this article we will discuss in detail the technology of pipe welding, so after reading you will have a complete picture of the theoretical part of the question.

Selection of pipe welding equipment

Before you begin the description of the technique of pipe welding itself, let's talk about what tools and materials for this are needed. One of the main work parts are electrodes. It is round metal rods coated with a special substance for welding. Their thickness can be the most different, which is also necessary to take into account when buying, but about it a little later. The coating on the electrodes is directly involved in the processing of the seam and protects this place from atmospheric influences, while ensuring uniform and stable burning of the arc.

Electrodes for pipe welding

Simply put, the electrodes are needed to carry out the current to the arc and fill the space between the pipes. All specifications, including the composition and size, up to millimeters, are established by GOST. It is recommended to purchase electrodes from proven manufacturers with quality certificates to avoid fakes and not get a seam harvester. Of course, the quality of work depends largely on the skills of the welder itself, but a certain proportion of success falls on the electrodes and the type of welding machine. In this case, one simple rule does not care about it - high-quality electrodes are not cheap.

When you were convinced of the proposed products, you can select the diameter of the electrodes. This parameter depends on the size of the joint between the connected pipes. So, for pipes with a small diameter, the use of electrodes by 3 mm is permissible. Such products will cope with welding steel 2-5 mm thick. If you connect metal pipes with a thickness of up to 10 mm, you will need thicker electrodes.

Useful Tip: If you need to create a multi-layer seam, choose the electrodes of 4 mm in diameter to be able to create a large seam depth.

The selection of equipment for welding pipes also affects the material from which they are made. For example, electrodes with main or rutile outer layers will be required for carbon steel. If you are going to make seams on a galvanized pipeline, buy a special welding material for galvanizing. The main complexity in this case lies in different boiling temperatures of zinc and steel - zinc boils much faster and simply evaporates when heated.

Each of the types of coating electrodes is designed to perform a certain number of tasks, so it is important to make the right choice:

1. Cellulosic coating of the brand with suitable for pipes with a large diameter and creating vertical and circular seams.
2. Rutil-acid coating of the Ra brand electrodes gives a specific slag structure, which is formed during the welding process - it is much easier to remove it than when working with other types of electrodes.
3. Rutile turning of the grades R and RR is easily alleged again, it forms an easily hit slag and allows you to make beautiful neat seams with a commodity surface. Most often, such electrodes are used to form tapes, the organization of angular seams, as well as the processing of external layers of compounds to give them a more aesthetic species.
4. Rutil-pulp coating of the RC brand on the electrodes is designed to create seams in any directions. Related by the fact that they can be used even for vertical seams running from above.
5. The main coating of the brand B is used to create durable seams with increased viscosity characteristics and minimal risk of cracking. Such electrodes are recommended for pipes with thick walls and in situations where the connection viscosity is required, for example, when organizing pipelines used at low temperatures.

Special electrodes made on the basis of copper and iron, nickel alloys are also needed to work with cast-iron pipes.

Welders

As we have already spoken, a significant part of success depends on the correctly selected tool for welding pipes. Today, lovers and professional masters use welding transformers, welding inverters and rectifiers. In stores you will easily find a wide range of household and highly professional devices. The latter are more expensive than domestic, but also the specifications of them are significantly higher. If you are not going to link your life with professional welding activities, it makes no sense to acquire an expensive car - there are many models of household apparatus capable of making high-quality seams, but not distinguished by high performance.

Electric welding machines are most popular at homemade masters, since the transformer is very easy to use and completely undemanding. It is capable of working from a network with a frequency of 50 Hz. Unfortunately, at the initial stage, an overload may occur due to a discharge on the network, and as a result, the risk of deterioration of household electrical appliances. Therefore, to avoid such cases, it is recommended to install fuses.

Inverter welding machines are more expensive, but guarantee safe operation. In addition, they can function at frequencies more than 50 Hz, less weigh, and even look more compact. The ability to change the settings allows you to adjust the modes of operation. Such devices are classified as semi-professional, but also for home use they are also suitable.

Also for welding metal pipes you need special devices: cables with crocodiles connectors, protective equipment (mask, gloves, clothing, etc.).

Features of pipe welding

It may seem that welding is not so complex and time-consuming process, and it is possible to learn in half an hour of practice. However, in fact, you will certainly come across unforeseen difficulties, and to avoid it, it is necessary to develop a plan of its actions every time - a technological map of pipe welding. In this map, you must specify all the details of the work, including the diameter of the connected pipes, the locations of the seams, the thickness of the pipe walls, in which direction will be carried out and so on.

Shavi varieties

There are several types of compounds when welding steel pipes, each of which differs not only by the method of execution, but also strength, durability, sizes and appearance. So, the connection can be made online, brass, in a charter or an angular manner. In this case, the position of the seams may also differ horizontally and vertical, upper (ceiling) or lower position.

Professional welders recommend choosing the lower position of the seam, as the most profitable, therefore, if possible, perform swivel welding with exactly this way of work. Horizontal seams can be done for vertically installed pipes. If they lie in a horizontal position, it is logical that the vertical seam is suitable for them. The ceiling is obtained in the case when the electrode is located under the welded pipes right above the head of the welder. It is clear that it is not entirely convenient to work in this position, but sometimes the situation does not allow to apply other options for connections.

In most cases, all steel pipes are welded, baking edges over the entire thickness. To reduce the amount of metal spills on the inner walls of the pipes, the angle under which the electrode is located, should not exceed 45 ° relative to the horizontal surface. If you are welding the pipes of a small diameter of the online jack and in the TAVR, use thin electrodes by 2-3 mm, for example E-42, setting the power force at 80-110 A.. You can take the same electrodes to connect the volumetric, but raise current up to 120 A. In all cases, the seam height must be 3 mm.

Square pipes weld in the same way as round. The only one should pay special attention to the fixation of the ends of the connected pipes so that they are not taken from strong heating. Heat not in a circle, but evenly, welding all the vertical first, and then the horizontal points so that the heating takes place from different parts of the square. Only when the details are completely cooled, they can be released from fasteners.

Instructions for welding pipes

Clean the pipes from pollution and rust before welding, cut or straighten the ends if they are deformed. Carefully prepare the edges, shining them to the brilliance approximately in the centimeter before the ends.

Useful advice: To get a beautiful high-quality seam, the angle of opening the edges should be 60-70 °, and the recess value is 2-2.5 mm. If the shape of the edges of the edges does not match, they need to be treated by a hazard or grinding.

If you have to work with large pipes, use milling machines or thermal methods - air-plasma or gas-acid cutting.

Highlights of pipe welding with their own hands:

1. Take tacks - them, as composite parts of the seams, make the same electrodes as for the subsequent creation of seams. For steel pipes up to 30 cm in diameter, it will take 4 taps with a height of 3-4 mm and a length of 5 cm, placing them on an equidistant distance around the circumference. For the welding of pipes of a larger diameter, place the tape of 25-30 cm from each other. Collecting pipeline, try to make the maximum possible number of joints in the turning position.
2. For pipes with wall thickness up to 12 mm, three layers of welding are needed. The first layer should be 3-4 mm in height, so it is necessary to take the electrodes 2-4 mm thick.
3. The second layer should be created by thicker electrodes.
4. Conditionally divide the joint for 4 sectors.
5. First of all, welcome the first two sectors.
6. Turn the pipe and weld the third sector with the fourth.
7. Turn the pipe again and perform the second layer on the first sectors.
8. Make a second seam for 3 and 4 sectors, after which, by the same scheme, turning the pipe, make the last third seam.

Useful advice: If you work with pipes with a diameter less than 20 cm, you can not share the sectors, and simply make all three layers of the seam, moving in one direction and gradually turning the pipe.

In the process of welding on the surface there is a slag. It creates a protective film that does not allow the metal to contact with nitrogen and oxygen, which adversely affect the seams and make it less durable. Professional welders after metal hardening remove the cooled slag with the rampant trees with a hammer or electrode. It is impossible to leave the slag in any way, otherwise, with time, a fistula or leakage is formed in this place. To create the most sealed seam, use special techniques, making it in the form of horseshoe, eight or scales.

It is possible to estimate the quality of the work performed after removing the slag from the surface of the pipes. First, spend the outdoor inspection for detection of civilians, pores and other similar defects. After that, you can move to a more careful study, which will allow to identify microcracks, invisible to the eye. This can be done with the help of a soap solution. Apply it with a brush on the seam, after which the air is powered under strong pressure. If microcracks are present in the junction, bubbles will appear there.

The price of pipe welding in professional masters today is quite high, so many prefer to do their own. According to approximate calculations, the cost of processing a single fragment is almost identical to the cost of the purchase of a simple household welding machine and several electrodes. In addition, you will have the opportunity to get and improve useful skills that will help both our own farms and can become a spare source of income. Finally, we suggest to see the informative video about the welding of pipes.