Steel pipes are among the most popular products in this segment of the building materials market. In everyday life they are most often used to create heating and water supply systems, as well as gas pipelines. Assortment and types of steel pipes are determined, primarily, features of the technology of manufacturing such products. And their production is regulated by separate sections of the corresponding GOST, in which all technical characteristics of pipes are specified.
Steel pipes are a material, which is used in a variety of systems, buildings and structures
Methods of steel pipe production
Modern metallurgical plants have only one in their arsenal 4 classical technology:
- cold rolling - production of seamless pipes from pre-cooled blanks;
- hot rolling. This method produces seamless pipes from the heated workpiece;
- welded spiral rolled metal. The final product, produced by this technology, characterized by the presence of a spiral seam. As raw materials in this case sheet blanks are used;
- welded longitudinal rolled products. The source material is the same sheet blanks. Distinctive features - the presence of a longitudinal straight seam.
The use of the above technologies allows to produce steel pipes of any kind, starting from the "sanitary" round ones used in water supply, including oval and thick-walled, and ending with "structural" - square and rectangular. exept this, features of the technological process impose restrictions on the size of the pipe. Let's touch on the range of steel pipes in more detail.
Electrowelded straight-seam products
In the range of steel pipes of this type there are products with an outer diameter of millimeters and a wall thickness of millimeters, that meets the requirements of GOST 10704-91.
Straight seams are a popular type of material, which is used in water- and gas pipelines
Useful Information! This normative document also contains requirements for the mechanical properties of straight-seam pipes. exept this, the standard establishes the uniformity of wall thickness and the degree of their ovality. But the need for chemical control is not conditioned.
The maximum permissible deviations of the dimensions of steel straight-seam pipes are presented in the table below.
Table 1
| Outer diameter, mm
| Maximum deviations of the outer diameter depending on the accuracy of production | |
| increased | ordinary | |
| over 1 020 | ± 6 mm | ± 0,6% |
| 426,0-1020,0 | ± 0,65% | ± 0,7% |
| 193,70 — 426,0 | ± 0,65% | ± 0,75% |
| 51,0 — 193,7 | ± 0,7% | ± 0,8% |
| 30,0 — 51,0 | ± 0,35 mm | ± 0,4 mm |
| 10,0 — 30,0 | ± 0,25 mm | ± 0,30 mm |
| 10 | 3/4 | ± 0,2 mm |
Permissible exceedances of the dimensions of measuring tubes can be found in table №2.
Table 2
| Length of pipes, meters | Maximum deviations in the length of measuring tubes, millimeters, classes | |
| I | II | |
| to 6,0 | +10,0 | +50,0 |
| over 6,0 | +15,0 | +70,0 |
in addition, in assortment on straight-seam steel pipes, which is determined by GOST 10704-91, the requirements to uniformity of thickness of their walls and degree of ovality are specified.
Spiral welded pipes
Production and assortment of these products are regulated by GOST 8696-74.
One of the options for welded pipes is spiral seam products, different from straight seams with higher strength
Unlike straight seams, as it is easy to guess, the workpiece in this case is rolled into a pipe in a spiral, then welded. This technology gives the final product the ability to withstand higher pressures. in addition, it has the following advantages:
- the possibility of using high-speed technological welding provides a high rate of formation (close 12 m / min.);
- improving the accuracy of formation (geometry of pipes) by removing obstacles, which are produced by electric arc welding under flux. It is performed separately;
- possibility of full process automation. This eliminates the "human factor" and ensures the high quality of the final product.
This method of production allows you to use these products as high-pressure steel pipes for heating mains, main oil and gas pipelines and water supply systems.
In the above-mentioned GOST 8696-74 contained 21 standard size of spiral seam pipes. In the range of products of this type defined by him it is specified, that the minimum diameter is equal to 159, and maximum - 2520 millimeters. Recommended length - about 10 and 12 meters. The permissible deviation of the overall dimensions does not exceed 0,3 percent.
Hot and cold deformable seamless steel pipes
Hot and cold rolling are two fundamentally different technologies. Each of them has its advantages and disadvantages.
For the production of hot-rolled pipe requires a high temperature to heat the workpiece
Cold rolling involves the processing of plastic material only by pressure. Hot-rolled pipes are made by rolling in a continuous state heated to a given temperature of the workpiece.
Cold-formed pipe. The range of products of this type is determined by GOST 8734-75. The full list of possible sizes here is quite large. The diameter can be 5 … 250 millimeters, and the wall thickness from 0,3 to 24 millimeters. Pipes of measured and unmeasured length are issued. In the latter case, the value of this parameter varies in the range 11,5 meters.
Useful Information! The advantage and distinguishing feature of cold-deformable pipe is significantly increased (compared to the usual pipe, the margin of safety is almost a quarter. In accordance, the working medium pressure can be increased by the same amount.
Seamless hot deformation pipes. Production and assortment of such products is regulated by GOST 8732-78. The size chart is also very large. It includes pipes with a diameter 20 … 550 millimeters and with a wall thickness of 2,5 to 75 (!) Millimeters. Such standard sizes cause considerable weight of hot-deformed products. Suffice it to say, that is the mass of one running meter of pipe 550? 75 is without a small ton, more precisely 878 kg. They are able to withstand high pressure. Even 16 MPa they are not afraid!
In today's market you can find both types of products with pre-insulation. The advantages of insulated pipes abound. It is also resistant to chemically aggressive compounds, and minimizing heat loss during transportation of the working medium, etc. But, apparently, the most important thing is that, that the service life of insulated steel pipe is about 30 years.
Black steel pipe
This is the name of a steel pipe without any coating.
The gas or water main can be mounted from a steel pipe of the 2nd class
IN 70-90 In the last century, they were widely used to create water supply pipelines, heating systems, as well as a gas steel pipe. Usually used VGP pipe, produced in accordance with the requirements of GOST 3262-75. Parts of this type are easily welded by any type of welding - this is their undeniable advantage. Also, don't forget that, branches made of black steel pipes, valves, tees, transitions, etc..
Production and assortment of these products are regulated by the requirements of GOST 3262-75. The standard length of uncoated steel pipes is considered to be 5,5-11,7 meters. Their division into groups is carried out according to the following parameters, as a brand of steel, outer and inner diameter, wall thickness and other physical and technical characteristics. Special marking of steel pipe is applied with indelible paint only when the wall thickness is greater 3,5 mm and diameter from 159 mm
Depending on the field of application, such pipe products are divided into the following classes.
- 1-and class. Used to transport gaseous or liquid compounds, in the construction of building pillars and forests, as well as fencing structures;
- 2-and class. Products of this class are used in the construction of main pipelines, designed for gas pumping, oil and petroleum products under high pressure. in addition, they can be used as steel pipes for water supply;
- 3-and class. They are widely used in the most difficult operating conditions. This is a high temperature, and the same pressure. Most in demand in the chemical and food industries;
- 4-and class. Well suited for exploration of oil and gas fields, as well as their drilling and operation.
- 5-and class. Used in the manufacture of furniture, stairs, metal structures for supports, rigs, transport equipment, etc..
- 6-and class. Play an important role in the manufacture of components in the engineering industry.
Pipes are divided into two types depending on the wall thickness, this parameter affects the strength of the pipes and their other characteristics
Depending on the thickness of the walls, black pipes are of two types:
- to 3 mm - thin-walled;
- more 3 mm - thick-walled.
When choosing pipes for heating and water supply systems, do not forget about the problems, which are waiting for you when using ferrous metal products. Firstly, this is poor tolerance of contact with water. Rust, scale, slag, as well as lime deposits and sand gradually reduce the lumen of the pipes.
pay attention! This problem is more common in cold water supply. However, if you open the elevator unit, the degree of overgrowth of heating pipes will also impress you.
Secondly, theoretically, the heating system must be continuously filled with water. In practice, in the summer heating is turned off. Access of oxygen to internal surfaces of pipes in combination with humidity causes the accelerated corrosion.
But, ferrous metal pipe products are currently the most common. Their cost is determined by the production technology and brand of steel used. In case of emergency, such pipes can withstand incredibly high pressure. And the increased level of thermal conductivity allows to create on their basis radiant forms of systems of water heating.
Of course, from an aesthetic point of view, black pipes are not particularly attractive. However, steel chrome-plated pipes do not have this disadvantage. in addition, chrome product has new useful properties. The main ones are as follows:
- susceptibility to corrosion;
- scale resistance;
- shiny surface.
Polished pipes, mirror or even chrome-plated outer surface have high aesthetic qualities, and the strength is not inferior to ordinary pipes
The combination of these characteristics allows you to use chrome-plated pipe not only when creating a water supply system, ah, example, as it improves the interior of the bathroom with a heated towel rail, curtain rail, shower racks, mirror holder, etc.. And another important detail. Chrome-plated products are highly resistant to atmospheric oxidation. Therefore pipes with such covering can be established and in other extreme places of habitation: kitchens and toilets.
oval pipes
The production of oval steel pipes is regulated by the requirements of GOST 8642-68. Systematization of the sizes of such production is carried out according to the following parameters:
- width and height. Width means the length of the major axis of the ellipse. And height is the value of this parameter of its minor axis. And, the start and end points of these segments do not lie on the inner, and on the outer surface of the pipe. When choosing a product you need to know both of these dimensions. Due to the curvilinear shape, the assortment is formed on the basis of these dimensional parameters. The height is within, and width mm;
- radii of curvature. These characteristics determine the level of bending of each side of the oval tube. Values of smaller radius are within mm. The larger one can be in the range of mm.
Steel pipe with an oval profile is used in mechanical engineering, and in the decorative design of living spaces, buildings and porches (language, primarily, we are talking about a variety of fences and railings).
Oval and other profile pipes are more often used for decorative purposes and installation of various bearing designs
The question of such a plan may arise: is it really impossible to do in cooling radiators and hydraulic systems with a traditional round pipe? So here it is, her dignity, which is the maximum internal volume, is not always the case. Often the most effective heat dissipation from cooling coils and radiators is through their surface. And here the shape of the ellipse helps: with the same internal volume, the surface of the oval steel pipe can be in 2 times more, than in the round.
Useful to know! Pipes with this delineation are made of other metals, which improves the performance of the pipelines created on their basis.
Example, copper pipe, has less, than a steel pipe with thermal conductivity. This has a positive effect on the quality of operation of the hot water supply system. Aluminum pipe is characterized, among other things, low water resistance. Therefore, it is often installed in plumbing systems.
Branches - what it is and why they are needed
These are the same steel pipes, only bent, used to connect elements of pipelines in order to redirect the flow of the working medium at a certain angle. For their production mainly carbon and low-alloy steels are used, and in some cases heat- and corrosion-resistant grades of steel. The bending angle of the branch can be 45, 60 or 90 degrees. The diameter of products of this type is within cm. Temperature mode of operation of steel outlet at conditional pressure 16 kPa is -? WITH. Depending on the production technology, these components of steel pipelines are of the following types:
- Seamless taps;
- Suture taps:
- Threaded taps.
Seamless is performed by industrial casting technology, what is different from other types of such products. in addition, the design of these taps involves welding the fittings to the ends of both connecting pipes. Such a constructive solution, essentially, is the weakest point of seamless steel products, since the service life of steel pipes of this type is therefore, that they remain one on one in the fight against corrosion, decreases.
Steel pipes are not flexible, so, to make a bend in the highway, apply taps
The best option is threaded taps. Thanks to the internal thread, their installation can be performed at right angles. This connection ensures a low degree of corrosion damage to the pipeline, high level of safety and ability to pump the working environment under high pressure.
Manufacturers of steel taps have recently begun to practice applying a special coating on them. Such additional protection causes an increase in the service life of pipelines in general. Spray taps are the safest.
perforated pipe
Considering the scope of perforated steel pipe, it goes without saying, that there can be no question of any water supply. Products of this type are used:
- in car mufflers. For effective sound attenuation in the casing, a perforated tube is inserted with the device;
- in order to organize ventilation;
- as an element of the load-bearing structure.
Useful Information! Pay attention to that, that the presence of perforation does not lead to significant, but only to some reduction in bearing capacity. After all, the contours of the holes act as a kind of stiffeners.
Perforated steel pipes are most often used for groundwater drainage
Perforated pipes have become widespread in the creation of drainage systems. Holes in the perforated drainage pipe should be long and narrow. Wet soil forms lumps, which easily penetrate into round openings, and in the slit is not. At the same time perforated drainage pipes should be characterized by a larger volume. Essentially, they act as a drainage channel.
The most popular are perforated products with a diameter 100-110 millimeters. When the length of the drainage highway to 25 meters of such a section will not be enough. You will need perforated pipes with a large value of this parameter - 150-160 millimeters. If the length of drainage exceeds 50 meters, it is recommended to stop the choice on products with a diameter not less 200 millimeters. Good, modern industry produces such products with a wide range of sizes. So, the maximum length of the perforated pipe is 14 meters, the diameter may be in the range of millimeters, and the wall thickness varies within 0,5 … 15 millimeters.
Thick-walled steel pipe
Production and assortment of thick-walled steel pipes is regulated by GOST requirements 8734-75. Depending on the technology used, these products are of two types:
- seamless;
- welded.
If strength is put in the forefront when choosing, ie the ability to withstand high pressure, the best solution is to buy a seamless thick-walled pipe. When the price factor prevails, in order to save preference should be given to welded thick-walled products. Weight characteristics of large diameter pipes with thick GOST walls 10706-76 are presented in the table.
In high pressure systems it is necessary to use pipes with a large wall thickness
Table 3
| Outer diameter, mm | Weight 1 meters (kg) thick-walled pipe with a wall thickness (mm) | |||||||||
| 20 | 18 | 16 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | |
| 1420 | 697,4 | 628,6 | 559,5 | 490,3 | 455,6 | 420,9 | 386,1 | 351,2 | _____ | ______ |
| 1220 | 597,8 | 538,9 | 479,8 | 420,5 | 390,8 | 361,1 | 331,3 | 301,4 | 271,5 | ______ |
| 1120 | 547,9 | 486,0 | 439,9 | 385,7 | 358,5 | 331,2 | 303,9 | 276,5 | 249,1 | 221,6 |
| 1020 | 498,2 | 449,2 | 400,1 | 350,8 | 326,1 | 301,3 | 276,5 | 251,6 | 226,6 | 201,7 |
| 920 | 448,4 | 404,4 | 360,3 | 315,9 | 293,7 | 271,4 | 249,1 | 226,7 | 204,2 | 181,7 |
| 820 | 398,5 | 359,6 | 320,4 | 281,1 | 261,3 | 241,5 | 221,7 | 201,8 | 181,8 | 161,8 |
| 720 | 348,7 | 314,7 | 280,6 | 246,2 | 228,9 | 211,6 | 194,3 | 176,9 | 159,4 | 141,9 |
| 630 | 303,9 | 274,4 | 244,7 | 214,8 | 199,8 | 184,7 | 169,6 | 154,4 | 139,2 | 123,9 |
| 530 | 254,1 | 229,6 | 204,9 | 179,9 | 167,4 | 154,8 | 142,2 | 129,5 | 116,8 | 104,0 |
Given the geometric dimensions of thick-walled pipes, their connection is performed by a special technology. Standard gas welding is inefficient here, because it can not heat the entire wall to the melting point of the material. The result is only an unreliable surface seam, capable of collapsing under high pressure. Therefore, special tools are required for the installation of thick-walled pipes.
Useful Information! Electric welding is best. However, you can only work with electrodes, whose diameter exceeds 4 mm and only at high voltage. Not every device is able to give such indicators during a long time interval when working with thick-walled pipes..
These products must be cleaned and prepared before welding. Often a special composition is applied to the surface of the thick-walled steel pipe.
It is necessary to understand, that the process of creating a quality connection will take a long time. Electric welding, even ordinary products can not be called fast. And the duration of work with thick-walled pipes will increase even more.
Steel pipes are connected only by welding, and this is quite a time consuming process
Assortment of steel profile pipe
Profiled pipes - rectangular and square - are used in those designs, where the maximum stiffness is required at minimum mass. It, example:
- frames of canopies from pipes and greenhouses;
- racks, as well as handrail railings;
- bearing racks and beams of metal structures.
Manufacturers must be guided by three regulations when releasing them:
- GUEST 13663-86. It contains technical requirements for the production process of these products. Interesting: though, that at different lengths of steel profile pipes, made of corrosion-resistant steel and stainless steel, are made according to the same standards - GOST 8645-68 and 8639-82.
- The assortment of profile products with square section is taken according to GOST 8639-82.
- The assortment of rectangular pipes is specified in Guests 8645-68.
Seamless profiled steel is produced by this technology:
- first a round pipe-blank is made;
- then it is pressed under a square or rectangle;
- at the final stage calibration of the heated pipe to the necessary sizes is carried out. This operation is performed on a rolling mill, more precisely, on its rollers.
Production of welded profile pipes includes the following technological operations:
- the steel sheet of the workpiece is cut into strips - measuring strips - and folded into a ribbon;
- deformation of the flat tape in the profile workpiece is carried out on the rollers of the forming machine, where it is refueled;
- welding of the butt joint is performed in a special chamber filled with inert medium.
Strips - strips from steel serve as preparations for steel pipes, on the width of which depends on the diameter of the future product
Strength characteristics of both options, almost identical. After all, the presence of a weld weakens the profile only to the mark 90-95% from the initial strength. in addition, in the welded production heat treatment does not change the structure of the ferrite grain.
Importantly! It is provided by that, that temperature, in which this process is performed, does not reach a critical level for a particular grade of steel.
Marking of steel pipes of any of the above types is based on the requirements of GOST 10692-80. Can be used for this:
- rubber stamp;
- electric pencil;
- indelible paint;
- electrograph;
- branding method.
The markings must be reflected: trademark of the manufacturer, dimensions, product name and steel grade.
Careful study of the range of steel pipes will allow you at the design stage of the building to assess the feasibility of using a product for certain purposes.