Few construction can not do without the use of welding, it is used in the construction of various types of buildings and structures, from offices to skyscrapers. By means of it several components are combined into one whole. In the process of work, a weld seam is formed. It provides reliability and durability of the connection. The seam can last a long time, if it does not damage any mechanical forces.
The welded seam is able to connect various metal parts made not only from a homogeneous material, but also from alloys. However, in order to perform this process, it is necessary to select a certain welding technology and consumables.A worker who will combine the details must have high qualifications and work experience. It takes into account the features of the metal and connects it in such a way that when the load is applied to it, it does not collapse.
The designation of welded seams, as well as their types and locations of use, is specified in the regulatory documentation. This information is used for various technical documentation. It is indicated in special training aids that are used in training welders or improving their skills. Describing welded joints GOST 5264-80 is the main directing document. That is, all information for teaching aids is taken from it.
You can determine the type of connection, and without looking at the documentation. The designation of welded seams in drawings at any place in the building structure is carried out by means of lettering. So, we distinguish such types of welded joints by letter designations:
- "C" - butt;
- "Н" - overlapped;
- "T" is T-shaped;
- "Y" - angular.
The welded seam is classified according to several criteria. So, by the form of the final cross-section are divided:
- butt - when connecting metal parts must be in the same plane;
- angular - products must be at a certain angle to each other;
- slotted - when welding metal parts lie on each other. In this case, the top product melts completely, and the lower one - partially.
The next indicator is the configuration. Welded seams (GOST 5264-80) can be rectilinear, curved and annular.
Welding can be performed in several ways. It is worth noting the application of a continuous seam or intermittent. In the first case, the weld may have a length of 300 mm or more. The second embodiment is performed in extreme cases, as the seams are staggered. The connection also depends on the technology of the operation. Welding is performed both with the use of additional gas, and without it.
When performing construction work, the seam can be performed a different number of times. That is, it can be single- and multi-layered. This is done to strengthen the connection and increase its strength characteristics. In the process, additional fusion may form on the joint. According to this indicator, the seams are classified into normal, strengthened and weakened.
As a rule, such connections are not shared. They can be performed in different ways and combine several types of work. It depends on the qualification of the welder, as well as the quality of consumables.
The quality of the welded seams depends on the chosen technology of implementation, as well as the qualifications of the worker. Metal parts are attached to each other by the process of melting. When using arc welding, they should be located in the same plane.
Such parts can have different shapes and edge condition. The latter is processed depending on the thickness of the elements. When joining products with different thicknesses, it is necessary to adjust the large sheet to a smaller one. In this case, the seam will be reliable.
In accordance with this characteristic, the type of edges of welded joints are:
- with a skewed edge (the thickness of the seam should be 5 mm);
- with curvilinear;
- edge of U-shape. In this case, the thickness of the joint should be from 20 to 60 mm;
- edge with an X-shaped shape (the thickness of the seam should be from 12 to 40 mm).
One of the main positive properties of welded joints is low voltage. This means that they are not subject to bending and fracture. This is why this type of connection is often used. In addition, the process consumes a minimum amount of metal. To perform high-quality welding, you must carefully conduct the preparatory stage. Let us examine in detail the characteristics of compounds of different types.
To get a T-joint, you need to fasten two pieces that will be perpendicular to each other. The designation of welded seams in drawings of this type is represented by the letter T.
Welds can be located not only on one side, but also on the other.
It all depends on where it will be applied, and what requirements are imposed on it. This kind is used for the construction of various columns and frameworks.
If a certain place will not be a significant load, use an angled view of the connection. Most often it is used in the manufacture of various containers. This should be done such a requirement: to design last longer, the metal thickness should not exceed 3 mm. For the manufacture of such compounds one detail is applied at a certain angle to each other and are welded on both sides. This is done so that moisture does not fall and destroy the structure. The welded seam in the drawing is indicated by the letter Y.
The last kind of connection is the lapping, where the parts are attached perpendicular to each other. The seam is formed on the side of the structure. In addition to this procedure, it is necessary to secure the connection by fusing. In this case, a considerable amount of metal is consumed. In this case, the thickness of the structure should not exceed 12 cm. To prevent moisture from entering the product, the metal fuses on both sides. The designation of welded seams of this kind is indicated on the drawings with the letter "H".
In the manufacture of any weld, a spot welding method is used. An exception is the case where fusion is necessary. Then the seam is of a circular shape.
Arc welding can be performed by two methods: manual and mechanized. It all depends on the thickness of the metal. With a manual method, weld elements with a thickness of not more than 4 mm, and with a mechanized method - 18 mm. Details of large thickness can be processed manually. However, it is necessary to process the edge further.
Between the two welded elements, gaps can be formed, as well as deviations of the parts at a certain angle, i.e., a bevel and cutting angle is formed. To perform a quality seam, you must correctly determine the angle of the bevel. This indicator indicates the availability of the arc. Depending on the type of connection, the values of this angle range from 20 to 60 degrees, including the minimum error.
Burning can occur during welding. The main cause is the unadulterated edge. Welding is not possible if the distance between two metal parts is too large.
To determine how the weld should be determined with the material and with the degree of difficulty. During the construction of any building will prepare the documentation. It should be made information about the material processing of metal parts. The legend of the welds are indicated in the relevant drawings. They can be seen in the photo below.
As can be seen, the shade of the detail is significantly different, and the thickness of the joint (joints) is twice as thin as the others.
Inspection of welds
Their quality can be controlled by many methods and methods. So, the methods used are the following:
The most common is visual inspection of the finished connection. This is the easiest and most affordable way that does not require material costs. Every weld undergoes visual inspection, regardless of future operations. But you can perform other checks. With the help of external inspection to determine the many visible defects caused in the process. Thanks to him, find various fusion and beading. Visually they are practically not visible. To determine them, you need to use a special magnifying glass that increases the surface tenfold.
In the process of this operation, not only the visible defects are determined, but also check and measure the prepared edges. In the mass production of welded joints, special templates have been developed. They allow you to measure the seam in a short period of time. The remaining methods require financial investments for individual substances and equipment.
So, we found out what a welded seam is. The requirements for it are quite high, since it is on it that the responsibility lies for the reliable connection of metal structures.