The metal structures that are used in the automotive industry, the creation of machines and mechanisms, construction, repair and advertising simply could not help but be standardized. For these purposes, for each channel, GOST stipulates a certain set of characteristics. Below we will consider the most important standards in this area.

**Standard 8240**

This document establishes an assortment of hot-rolled steel products that can be used to solve general or special problems. The standard contains tables where the sizes of products, their cross-sectional area, weight of 1 meter and other reference data are indicated.

If the channel GOST 8240 97 is selected, then it must be remembered that this is a product of steel, the density of which is assumed to be 7.85 g / cm, which must be taken into account when calculating.

The shape of the product must be fully within the tolerances given in the standard. The values of the curvature radii, as well as the slopes of the inner faces, are given in table. 1-5 standards and can be used to build calibers.

The U series should be made with slopes ranging from 4 to 10 percent. If you need a channel, GOST 8240 97 recommends that you specify the slope of the internal faces in advance, since it often varies. For example, for large consumers, a manufacturer can go forward and offer some suitable option. In general, the angle of inclination cannot be higher than 8 percent for shelves with a height of less than 30 cm and 5 percent for 30-centimeter shelves.

Right angles are often obtuse. The amount of blunting depends on the distance between the shelves and is 2.5 mm for all products up to number 20 and 3.5 mm for numbers above. To order exactly what you need, you need to not only know which channel, assortment is required, GOST, too, must be studied.

In general, you can order products from 2 to 12 m long, but if the order is large and you are working with the manufacturer, the company will also manufacture special metal products. This is often required for the construction of any extended structures, buildings or other specific tasks. A similar case is provided by the standard, where it is clearly stated that such a situation is permissible if there is an agreement between the customer and the manufacturer. They produce a long channel GOST 8240 97 using the same technology as its shorter versions.

When the length of the product is more than 12 m, then it can be made:

- measured length;
- measured and unmeasured, where the latter is less than 5% of the total weight of the batch;
- multiple measured or unmeasured, up to 5% of the lot weight.

Limit deviations of parameters are also collected in the standard. So the height of the shelf can differ by 1.5 mm with a total value of up to 80 mm. Within 80..200 mm, 2 mm deviation is already allowed, and for a range of 200..400 mm this parameter can be 3 mm. When ordering the GOST 8240 97 channel, it must be remembered that for the width of the shelf, a manufacturing error of 1.5 mm to 40 mm inclusive, 2 mm within 40..89 mm and 3 mm when exceeding 89 mm is allowed. Deviations of the thickness of the shelf are also normalized and are -0.5, -0.8 and -1.0 for 10, 10..11 and t> 11 (t is the thickness of the shelf), respectively. If the hot-rolled channel GOST 8240 97 has a wall thickness denoted by s: s = 5.1, s = 5.1..6.0, s> 6.0, then deviations of 0.5, 0.6 and 0.7 mm, respectively, are allowed.

Products of series A can have a wall deflection of not more than 0.15 s, where s is its thickness. Deviations in the wall thickness of the P and U series are not controlled, and the skew of the shelf is measured in accordance with the methodology given in the standard.

When ordering the GOST 8240 channel, it should be remembered that it regulates only hot-rolled channels directly, since their other standards have their own standards.It should be noted the fact that today in the global network you can find a variety of information, so it is advisable to understand that it is sometimes outdated. In order to order a channel, GOST 8240 89 is not the best clue, since it is very outdated with respect to the 1997 standard.

**Channel steel bent equal hollow**

A similar product is a corner having a U-shaped cross section. As well as other types of metal rolling, it falls under the action of the state standard. During the construction process, it becomes possible to save more than 30% of the metal precisely through the use of such metal structures.

Channel GOST 8278 83 is manufactured on a roll forming mill in accordance with the standard and can be:

- high precision: class A;
- high accuracy: class B;
- conventional accuracy: class C.

The first two points are indicators of the highest quality category. Tabular values of the characteristics of metal structures are given in GOST, so we note only the magnitude of the maximum deviations for the width of the shelves, height and right angle.

We will consider the deviation of the height of the channel for increased strength, and in more detail this issue can be studied in the standard itself. According to GOST, a hot-rolled channel with a wall height of 50 mm should have a deviation of no more than 1 mm, for a range of 50..100 mm, this parameter is allowed less than 1.3 mm, and a height of 100.150 mm corresponds to 1.5 mm. If the height exceeds 150 mm, then the accuracy may already be 2 mm.

Deviation of the width of the shelf for increased profiling accuracy is also selected taking into account the dimensions. As well as the hot-rolled channel channel GOST 8240 97, this product can be manufactured with small deviations, which grow with increasing size. If the width of the shelf is less than 50 mm, then the deviation is selected no more than 1 mm, for the range 50..100 they are guided by 1.5 mm, and 100..150 mm - by 2 mm. This parameter can be 2.5 mm only if the width of the shelf is more than 150 mm.

Channel GOST 8240 97 and a bent channel should resist torsion well. In the latter case, it should not be greater than the value of the product L * G * 0.1, where L is the length of the product, and the G coefficient is constant for each metal structure.

In addition, standard 8278-83 regulates such characteristics as curvature, which should not be more than 0.1% of the length of the product, as well as the waviness of the shelves, which is less than 2 mm per 1 m. profiling. If it is high, then the distance from the ends should be up to 80 mm, increased - 100 mm, normal - 200 mm.

Channel GOST 8240 89 may have some deviation from the declared mass. Its value is given in the tables of standard 8240 1997. In general, when calculating the mass of a batch, it is necessary to add half the sum of the maximum deviations along the length of the products.

Summing up, it must be said that above we have provided only the basic information that will be required to choose a channel, dimensions, guests. In the event that you need more detailed information, it is better to refer to the source - the state standard, on the basis of which this material was written, since numerous statistics and other information given in the tables are omitted here. It is necessary to choose a standard that will be used for study taking into account the date, since today the GOST 8240 89 channel is no longer manufactured, because the outdated GOST has been replaced by a new one, released in 1997.

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