Metal products are widely used in engineering, manufacturing metal structures, construction and water supply. The most popular type of structural steel shapes - square. Range square steel pipe greatly varied. They are much stronger than round. It is important to know the properties of the popular types of rolled steel. You also need to learn how to calculate the dimensional weight of the length of the finished product. All this can be found in this article.
Key features and appointment of square profile
Square tube are made in steel mills. Production technology - convex rolling billets (GOST 8639-82). Distinctive features:
- high strength;
- high resistance to bending loads.
The basic material for the manufacture of - carbon (GOST 9045, 380, 1050) and low-alloy (GOST 19281 - 10HSND, 09G2S; GOST 4543 - 30KhGSA, 10G2) steels. The various chemical elements are used as dopants. The standard contains requirements for the square-finished products:
- chemical composition;
- appearance;
- manufacturing precision class;
- limiting the load.
To square it is critical that the principle of uniformity in the distribution of stresses over the cross section of the workpiece. His strength properties, despite the hollow internal structure, much higher than other types of steel. Square profile other stronger, since it high levels perimeter radius of gyration, and the cross sectional area of the finished product.
The main physical indicator of the ratio of flexural rigidity to that of the compression, - the radius of gyration of square profile. The most economical profiles equal to each other with the smallest / largest radii of gyration. Equality of the central moments of inertia - a guarantee of excellent indicator of strength.
An important physical characteristic profile is equilateral resistance torque. Its correct calculation will help to avoid mistakes in the design process of installation. For shirokostennyh pipes moment of inertia is the difference between the length of the fourth degree of the external / internal wall, divided into six lengths of the outer wall. The moment of resistance of thin-walled tubes - a square outer circumference, multiplied by 4/3 of its thickness.
product assortment
Equilateral in length / width of the steel section is of three kinds:
1) the cold-seamless.
Products manufactured in this manner of carbon steel, are not of high quality. The most attractive feature of such products - low cost. Gauge 17 includes sizes. Size hand may vary from 10 to 120 mm. Each of different sizes can have a wall thickness - from 1 to 8 mm.
2) Hot-seamless.
The method of thermal strain produced finished product sizes from 30 to 160 mm. The crystal structure of the metal during heating remains unchanged, and the quality is much higher than during cold deformation. The walls may have a thickness of from 4 to 14 mm.
3) Electro.
Tube profile equilateral direct weld seam manufactured with the use of automatic high frequency electric welding, has 15 sizes. Wall thickness ranges from 1 to 5 mm. The profile may have a cross section sides of 10 to 100 mm.
To meet the needs of customers cutting of finished goods produced in two types:
- off-gage length - from 4.0 m to 12.5 m (Hot seamless) from 1.5 m to 9.0 m (and seamless cold-electric);
- measuring length - from 4.0 m to 12.5 m (Hot seamless), from 4.5 m to 11.0 m (cold-seamless), from 5.0 m to 9.0 m (electrically).
All of the above indicators lengths dimensional / off-gauge lengths are strictly regulated by the requirements of the standard.
According to GOST 19903-2015 finished products equilateral cross-section may have the following limit values of deviations:
- a profile width of less than 100 mm - ± 1,0, but not less than ± 0,5 mm.
- a profile width 100 mm - ± 0,8 mm.
tolerances also apply:
- external radius of curvature t;
- on a deviation from the right angle 90about.
Scope of the square tube
The great majority of rolled steel, with equal faces is used in construction. It is used in the construction of frame metal structures of different types:
- pavilions;
- visors;
- awnings;
- gates;
- fences;
- greenhouses;
- trestles.
Due to the equal sides measuring intervals is very convenient interconnected. When mounting the coupling can be used or bolting. Furthermore, a hollow square with equal facets can be used as shuttering for reinforced fixing of hardening concrete mass.
In industry, a square steel frame structures are made different. For example, segments of the small cross section is used for mounting internal equipment truck carcasses. With the advent of a large number of different types of fittings square became widely used in the manufacture of furniture. Profile thus undergoes additional processing:
- chrome;
- galvanizing;
- applying a polymer coating.
How to calculate the weight per meter pipe of square profile
Crucial role to meet the parameters of structural strength is playing the correct calculation of metal weight. It is needed in order to plan costs. If the rental is realized in linear meters, when mathematical calculations of strength is used exclusively characteristic weight in kilograms or tonnes. Depending on what the settlement weight profile, you can easily determine the most convenient way to transport it.
There are three ways of calculating the weight of the metal profile:
- Tabular.
- Formular.
- Computer.
All methods of calculation based on a constant density of the finished steel - 7850 kg / m3. Tabular calculation is based on previously produced and included in the Standard calculations using constants. Actually, data on the size of the preform wall thickness and radius of curvature angles may differ for each individual sample. Therefore, this method is considered to be theoretical, and allows you to get information on the exact weight of the dimensional segment.
For ease of calculation the weight of the metal structure is used online calculator. This is a special program for engineering calculations. Find it on the Internet is very simple. It usually takes into account all the nuances. To get started, requires three basic parameters dimensional segment of the finished product:
- Length;
- Height Width);
- wall thickness.
The program will calculate three indicators:
- radius of gyration;
- moment of inertia;
- moment of resistance.
The object is to establish the weight calculation of a square segment of a predetermined length.
The most accurate from a mathematical point of view is a formulaic calculation. Weight of 1 meter square pipe is:
m = 2 * h * (A + B) * q
In this formula
m - mass of one meter, kg.
h - the wall thickness profile m.
A and B - equal to each other values of height and width, m.
q - density value of steel, kg / m3.
Typically, formulaic calculation result differs from the data which are indicated in the table. This is due to the fact that the formula does not include radii of curvature of inside / outside dimensional interval. Steel profile with perfect right angles does not happen. More accurately take into account all the nuances of shapes and sizes when calculating the weight of 1 meter table GOST. It is very important to choose the right online calculator.
Advantages and disadvantages of square steel profile
Metal structures, which are mounted with the use of finished articles square section of low alloy steels, characterized by the following performance:
- mechanical strength.
- durability.
- high corrosion resistance.
- a small materials consumption.
- ease of handling and installation.
A large assortment of products manufactured in accordance with GOST 8639-82, allows you to select the required measuring lengths of mounting the most complex designs. The square has a very good performance of the opposition to bending and twisting. Square tube operated under different conditions.
A disadvantage of the finished product is a high susceptibility to corrosion of pipes made of unalloyed steels by cold deformation. Oxygen has a negative influence on steel pipes equilateral. To resist corrosion, they need to undergo further processing.
The use of square profile significantly simplifies the production process. Assembling the frame construction is carried out much faster. The strength of such compounds is very high due to the progressive manufacturing methods and subsequent thermal and thermochemical processing.
