According to regulatory requirements, the dimensions of the finished product can vary within the range of 15x10 - 180x150 - 230x100 mm. The cross-sectional area of the rolled pipe is in the corridor 0.44 (for products 15x10 mm) - 70.97 sq. cm (for products 180x150 mm). The largest cross-sectional area of products with dimensions of 196x170 mm is 113.24 square meters. cm.
According to state standards, rectangular rolled products measuring 196x170 mm have a wall thickness of 18 mm, and pipes 180x145 mm have a wall thickness of 20 mm.
Another important indicator, which is strictly regulated by GOST, is weight linear meter pipe rolling So, for products 15x10 mm this figure is 0.348 kg (with a pipe thickness of 1 mm), and for rolled products 196x170 mm - 88.89 kg.
Rectangular steel pipes GOST 8645-68: assortment and permissible deviations
Limit values for errors in external dimensions of rectangular pipes according to state standards:
- for high-precision products: ±1.25% (hot-deformed), ±0.25 mm (cold-deformed and electric-welded up to 30 mm), ±0.3 mm (cold-deformed and electric-welded 30-50 mm), ±0.8% (cold-deformed and electric welded more than 50 mm);
- for products with standard accuracy indicators: respectively, ±1.5%, ±0.3 mm, ±0.4 mm, ±0.8%.
Maximum values of concavity/convexity of sides (mm):
- for seamless hot-deformed: 0.5 (normal accuracy) and 0.75 (high accuracy) for rectangular rolled products with sides ≤ 50 mm; 0.8 and 1 (50-70); 1.2 and 1.5 (70-100); 1.5 and 2 (≥100);
- for electric welded and cold-deformed: 0.5 (pipes ≤50 mm; 0.5 and 0.75 (50-70 mm); 0.8 and 1 (≥70).
Limit errors of wall thickness:
- ±10% – for welded pipes of all accuracy classes;
- ±12.5% – for cold- and hot-rolled pipes of any accuracy with walls ≤3.5 mm; 10 and 12.5% for pipes with walls >3.5 mm.
The permissible twist angle is no more than 2°/1 m of finished products. This parameter can be set by individual agreement with the consumer.
In addition, GOST 8645-68 excludes the possibility of deviation of any angle of a rectangular pipe by more than 1.5° from a straight line, and also sets the maximum threshold for curvature per 1 m of rolled stock at a level of no more than 2 mm.
Stainless steel rectangular pipes
The range of corrosion-resistant rectangular pipes coincides with the range of conventional ones. The difference between the two types of pipes lies in their areas of application and source material.
It is obvious that stainless steel pipes are used in structures that require high wear resistance, as well as aesthetics.
If for the production of ordinary rectangular pipes according to GOST a strip or rod is used, then for the production of “stainless steel” ready-made electric welded pipes, manufactured using the induction method (HF). The surface of the welded stainless steel pipe is also subjected to grinding or polishing.
Types of steel rectangular pipes according to GOST 8645-68
According to the production method, rectangular steel pipes can be seamless hot- and cold-deformed, as well as electric-welded.
Hot-formed seamless rectangular pipes
The raw material for any seamless pipe rolling is a rod, which is a monolithic cylinder made of steel of the required grade.
The production process of rectangular hot rolled pipe is as follows:
- The steel billet is heated to the temperature of metal plasticity.
- The hot billet is removed from the furnace and transferred to the piercing mill.
- At the piercing mill, the steel workpiece is shaped into a cylindrical shape using a press. The sleeve, which is hollow inside, differs significantly from the finished pipe in dimensions.
- The hot sleeve is transferred to the rollers, where it takes on the diameter and wall thickness specified by the customer and GOST.
- The round pipe is transferred to sizing rollers, which give it the shape of a rectangular profile.
- The finished pipe arrives at the cooling table and is cut into pieces. required length and sent to the finished goods warehouse.
The main advantage of rectangular seamless pipes is the absence of weak points - seams, joints, due to which this pipe product is characterized by high mechanical strength.
Rectangular hot-rolled pipe can be produced with ultra-thick (up to 75 mm) walls. Such pipes are characterized by extreme strength, but are not included in the general assortment according to GOST.
Due to the significant complexity technological process manufacturing everything seamless pipes significantly more expensive than electric-welded analogues.
Cold-deformed seamless rectangular pipes according to GOST
The technological process for manufacturing cold-rolled rectangular pipes is practically no different from the process for producing hot pipes described above. There are only two unique points here:
- The cold-deformed pipe, immediately after passing through the piercing mill, is transferred to a cooling bath with water and undergoes all subsequent technological operations in a cold state. Hence its name.
- At the final stage of production, a cold-rolled rectangular pipe in accordance with GOST is subjected to mandatory heat treatment: the product is reheated to the point of steel recrystallization, after which it is sent for cooling. This allows the steel to relieve internal stress and gives it greater toughness and ductility.
The seamless method of producing rectangular rolled pipes is characterized by a relatively high cost, which is justified by the possibility of producing particularly thick-walled products. In addition, hot- and cold-formed rectangular pipes much stronger than electric welded ones.
Electric-welded rectangular pipes GOST
Of all the rectangular pipes, the cheapest to produce is the electric welded pipe. Low cost is, first of all, distinguishing feature rolled pipes welded with HF high-frequency induction currents.
There are two methods of producing welded pipes: products are made with a straight seam and with a spiral seam. In this case, profile pipes are produced straight-seam. Spiral welded products are used on main pipelines.
The raw material for the production of welded pipes of rectangular cross-section is the so-called strip. It is a flat sheet of steel supplied rolled into rolls.
- At the first stage of the technological process for the production of rectangular electric-welded pipes, the strip is cut into narrow stripes. After cutting, the finished strips are welded one after another into a long strip. This tape allows for continuity of the production process. The strip is fed onto rollers, which give it the shape of a pipe - forming a round steel billet with an open seam.
- At the next technological stage, the seam is welded using one of the following methods: TIG ( arc welding in inert gas) or HF (welding with induction currents). The latter welding method is up to 20 times more productive than the first, however, TIG allows you to obtain high weld strength.
- Next, the workpiece is placed on sizing rolls, turning from a round product into a rectangular pipe.
- At the final stage, the electric-welded pipe is cut into pieces of the required length and subjected to mandatory visual inspection. After this, the products are subjected to flaw detection: the quality of electric welds is monitored for geometric defects. For this purpose, equipment using eddy currents is used, and ultrasonic devices are also used.
The pipe that has passed the inspection is cut into pieces of the required length. Cut pipes are also subject to careful visual inspection. In addition to the quality of the electric weld, the geometry of the finished rectangular pipe is also checked, which may be disrupted due to a defect in the rollers. Upon completion of the final inspection, the pipes are packed and sent for storage.
The described standard contains an assortment, but the production of rectangular rolled pipes is also regulated by GOST 8639-82, which formally regulates the production of square steel pipes. The described standard contains a number of references to it: rectangular pipe rolling is mentioned repeatedly in the text and tables.
Square pipes
Electric welding technology is also used to produce square pipes. Below we give a general description of the technological process of their production.
- to produce a square pipe, a rolled sheet of steel is used, which is cut lengthwise and takes the form of a continuous strip;
- on the rollers the tape is bent and modified into a round product with an open seam;
- The seam is welded using fast HF induction welding or TIG electrode welding.
- the welded pipe is transferred to the rolls for final calibration.
Square electric-welded steel pipes emerge from the cooling table (regulated according to GOST 8639). The seams undergo a final eddy current test. The geometry is checked by visual inspection.
Where are rectangular steel pipes GOST 8645-68 used?
Before moving on to listing the areas of application of rectangular steel pipes, we will describe its main features that distinguish it from round pipes.
Firstly, compared to a round pipe, a rectangular pipe has significantly greater bending strength. Moreover, the degree of this strength varies depending on the load vector. If the load vector is parallel to the wide side of the product (located perpendicular to its axis), this ensures the maximum degree of strength of the pipe.
However, profiled pipe products are inferior to round rolled products in terms of maximum pressure, which leads to wall deformation. With equal wall thickness and the same specific gravity The cross-sectional area of a rectangular pipe is much smaller in area than that of a round pipe. Hence, throughput the first is very limited.
Thus, the scope of application of a rectangular pipe according to GOST is determined by the presence of large lateral loads. However, its use in water, oil and gas pipeline systems is categorically excluded.
Load-bearing metal structures
Rectangular pipes are widely used as elements of the base of metal frames of public buildings: supermarkets, exhibition pavilions, sports complexes, office centers.
External and internal panels are hung on a frame constructed from rectangular rolled pipes, window and door openings are constructed in the necessary places, and forced ventilation and air conditioning are organized. Speed of construction of buildings from profile metal frame combined with convenience and reliability of construction.
In this case, a significant part of the warehouse building frame is constructed from a rectangular pipe. IMPORTANT: the greatest strength for a given specific gravity is provided not by a rectangular pipe, but by an I-beam and channel. The advantage of the rectangular pipes themselves lies, first of all, in the fact that they combine high resistance to bending loads and an aesthetic appearance.
Railing
The strength of the rectangular pipe and its aesthetic appearance also play a role here. As decorative fencing They use not only rectangular, but also other profile pipes - square and even parallelepiped-shaped.
Regular black steel is not suitable for making railings, especially unpainted ones - it is susceptible to corrosion. Best choice for these purposes - chrome-plated pipes, as well as rolled pipes made of stainless steel or bimetal.
Decorative fencing
In most cases, corrosion-resistant rectangular pipes of small dimensions are used to create decorative fences. The choice in favor of stainless steel in this case is quite reasonable: rolled steel is attractive and almost eternal.
Furniture making
The main area of application of rectangular pipes in the furniture industry is the production of reliable furniture for public institutions, as well as educational institutions. Frames for desks and chairs, tables, benches and other pieces of furniture subject to intensive use are made from rectangular pipes.
Agriculture
Rectangular pipes are widely used to create frame agricultural shelters: greenhouse structures, greenhouses and winter gardens. Small rolled pipes serve as a reliable basis for glass or film panels designed to protect plants from adverse weather influences.
Auto and agricultural machinery
Rectangular pipes are used to create frames vehicles and agricultural machinery. High strength This rolled product, combined with its relatively low weight, ensures its wide demand among manufacturers of automobile and agricultural equipment.
Rectangular pipe GOST 8645-68: where to buy
The warehouse complex of the ChelPipe Group invites everyone who wants to order rectangular rolled pipes to cooperate! As a manufacturer, we offer the best prices for white metallurgy products, while guaranteeing their absolute compliance with current GOSTs, absence of defects and excellent quality.
Our catalog contains a full range of pipe products that interest you. We are waiting for your applications.
Rectangular and square steel pipes according to regulations 8639-82 and 8645-68 are mainly used in the creation of metal structures. At the same time, profile products are used as the main load element and also perform decorative functions of the structure.
Profile products are actively used in the following cases:
- Construction of power and load frames. Strong, lightweight and fairly flexible ribs of the profile pipe not only give metal structure their required degree of rigidity, and also significantly reduce weight. After all, when using an all-metal material (rod, channel, beam), the total weight of the structure is approximately half as much as when using a hollow pipe. By using profile products in the construction of various objects, it is easy to achieve different angles and rotations in the structure itself. After all, from the hollow profile of metal products you can initially create any workpiece. To do this, you do not need to heat the pipe metal for additional plasticity, but simply need to use a special tool - a pipe bender. With the help of such a tool you can build any frame, it all depends on how much imagination you have. As an example, we can cite various configurations of summer and winter options greenhouses for vegetables and flowers.
- Decorative use. In modern design art, it is stylish and fashionable to use profile chrome-plated products or made of stainless steel. It is these shiny products that perfectly form the visible frame of objects. Also, products made from false chrome and stainless steel are often used to imitate forged fireplace grates or fences, for staircase railings.
- Construction works. Here, profile pipes are used to replace beams and channels, or other components of load-bearing structures. At the same time, profile pipes, and especially the rectangular shape of the product, are rated higher than all-metal products. The rigidity of the profile remains the same, and the weight of the constructed object is reduced. In addition, the cost of estimate work is significantly reduced.
Profile pipes are used in roofing frame systems, interfloor slabs, and in the construction of frame stairs. It is necessary to take into account that in the event of a fire and critical temperatures, the profile pipe is easily deformed. This situation can lead to great destruction. Therefore, you should first study the relevant guests.
Types of profile pipes
The regulations of State Standards 8639-82 (square type profile) and 8645-68 (rectangular shape) say that the range of pipe products can be produced in four types:
- Welded seam products;
- Cold rolled electric welded pipe;
- Seamless hot rolled products;
- Seamless cold-deformed pipe.
Let's take a closer look at the production of each type of pipe.
Electric welded seam products are the most common of all manufactured types of profile products.
The stages of production of such welded products are as follows:
Seamless profile pipe
The production process of a range of hot-rolled seamless products is more complex and labor-intensive. Unlike welded products, it does not use a strip strip, but a special pipe blank, otherwise called a “rod”.
At the piercing mill, the heated rod is transformed into a special sleeve. The mandrel remains inside the sleeve for several stages of production. The sleeve is supplied to rows of rollers, with the help of which it is rolled out to length and the cross-section of the product is calibrated to the initially specified dimensions. In this case, the workpiece still remains round in shape. Only on the next rolls does the workpiece acquire the desired shape - square or rectangle. Then the same process occurs as with welded products - cutting profile pipes by size, visualization appearance, non-destructive testing, packaging and shipment to the warehouse.
The fundamental differences between the production of hot-rolled products and cold-deformed products are that upon leaving the piercing mill, the steel billet is immediately cooled with water and then all further stages of forming are carried out on the cold metal - the cold-rolled method. Or, gradually losing the temperature gained, the workpiece is subjected to mechanical stress - hot-rolled production option.
The differences between the seamless version of profile pipes and welded products are not only in the absence weak point– the presence of a seam, and also due to the fact that the wall thickness in the seamless version can reach a size of 75 mm.
Range of manufactured profile products
Special tables have been issued for the regulations under consideration (located at the end of the article), which indicate the assortments of profile pipe sizes sides of the pipe section and wall thickness.
Table 2 shows maximum deviations according to product sizes. Depending on the manufacturing method and degree of accuracy
The regulation establishes the following size limits for product lengths:
- Seamless hot-rolled products - measured and unmeasured lengths from 4 to 12.5 m;
- Seamless cold-drawn - unmeasured 1.5-11 m, measured from 4.5 to 11 m;
- Welded hot-rolled - unmeasured 1.5-14 m, measured from 4.5 to 9 m;
- Welded cold-drawn - unmeasured 1.5 m -11 meters, measured 4.5-9 m.
When you think of a pipeline, what first comes to mind is a product with a round cross-section, which is used for laying water supply, sewerage and heating systems. But pipes whose shape differs from a circle, in particular rectangular, are also in demand. In order to choose the right pipe, it would be useful to familiarize yourself with the regulatory requirements and labeling rules.
general information
Square and rectangular sections are never used for plumbing or heating systems. The advantages of a square pipeline become obvious when installing, for example, the frame of a building.
When doing all the work yourself, you can note several advantages:
- low weight;
- high strength;
- excellent torsional resistance;
- speed of installation;
- graceful appearance.
In addition, the flat surface is also practical. It can be attached to the wall surface without any problems, but when installing, for example, a railing, it is much more difficult to install a top made of a profile pipe.
Normative base
The production of a profile pipeline is carried out by passing, which gives it the desired shape. At the same time, the compliance of the final product with the dimensions specified in the assortments is quite strictly controlled.
As for regulatory documents, we can single out a whole “bouquet” of standards containing comprehensive information on the standard sizes of profile pipelines:
- GOST 8645-68, GOST 8645-86 and GOST 8645-82 - these documents indicate the requirements and standard sizes of steel rectangular pipes;
- GOST 8639-68, and GOST 8639-82 for the range of steel rectangular pipes contain basic information on square sections;
- GOST 30245-03 - in it you can find data on a pipeline of both square and rectangular cross-sections. In addition, it also contains requirements for the strength of the weld.
Steel rectangular pipeline
In this case, attention should first be paid to the width and height of the product, as well as the wall thickness. In addition, you need to understand that the corners are rounded, so the radius of curvature is also controlled.
Note!
Rounding the corners of the pipeline is a necessary measure.
If the corners were not rounded, then during torsional deformation, stress concentrations would be observed in these places, which jeopardizes the stability of the structure.
GOST 8645-82 for rectangular steel pipelines applies to electric welded pipes, as well as hot and cold rolled pipes. According to the assortment, dimensions can range from 15x10 mm to 180x150 mm.
And if the minimum dimensions can only be used for railings, then a pipeline height of more than 10 cm allows it to be used as an element of the supporting structure.
Rectangular steel pipes in accordance with GOST 8645-86 must meet the same requirements as specified in the 82 standard. The differences are rather cosmetic and relate to the requirements for compliance with given geometric dimensions.
According to this standard, special sizes can be produced; by agreement with the customer, its diameter can range from 28x25 mm to 196x170 mm. As for the radii of curvature, it applies general rule– the radius should not exceed twice the thickness of the metal.
Note!
In some cases, the radius can be increased to triple the thickness of the metal.
But prior approval with the customer is required.
GOST 8645-68 for the range of steel rectangular pipes contains the same information, only the standard sizes are slightly different. According to this document standard sizes remain the same, and as for special sizes, they range from 28x25 mm to 230x100 mm.
The pipeline marking contains comprehensive information not only on the cross-sectional dimensions, but also on the material from which it is made.
The markings differ slightly depending on the length, the following options are possible:
- 90x40x4 GOST 8645-68/B10 GOST13663-86;
- 90x40x4x6000 GOST 8645-68/B10 GOST13663-86;
- 90x40x4x1250cr. GOST 8645-68/B10 GOST13663-86.
The instructions for decoding are the same in any case - from left to right the following are indicated: the geometric dimensions of the section and GOST, in accordance with which the pipe was produced, the length of the pipeline or a multiple of the length is also indicated, the denominator is the type of steel and the standard to which it corresponds.
The example shows the following standard sizes:
- in the first case, the steel rectangular pipe according to GOST 8645-68 has a cross-section of 90x40 mm, and a wall thickness of 4.0 mm, unmeasured length, B10 steel;
- everything is the same, but the length is 6.0 m;
- the geometric dimensions remained the same, but the length was a multiple of 1.25 m.
Note!
The moment of resistance, and other static characteristics, are calculated based on a wall thickness of 1.5 mm.
Considering that the thickness of the metal can reach 15-18 mm, if serious loads are planned, it is better to recalculate these characteristics based on the actual dimensions of the wall.
Square pipeline
GOST 8639-68 for the range of steel rectangular pipes is more correctly called the standard for a square pipeline, because the height and width of the section are equal. The standard sizes, of course, differ from the rectangle, the minimum size is 10x10 mm, and the maximum is 180x180 mm. In addition, it is possible to produce special sizes - from 32x32 mm to 65x65 mm.
Note!
In the range, some sizes are in brackets, which means that this size is considered recommended for most tasks.
The price-performance ratio is maximum.
Also, as in the case of a rectangular section, the value of the corner radius is normalized. In general, the radius should not be less than twice the thickness of the metal. And only for the standard size 60x60x4 mm can an exception be made and the radius can be increased to triple the wall thickness (but this requires the customer’s consent).
In addition, both standards contain rather stringent requirements for the geometry of the product itself; not only the cross-section dimensions are strictly controlled, but also curvature, angle deviation from 90ᵒ, etc.
For example, an electric-welded rectangular steel pipe according to GOST 8369-68 must meet the following requirements:
- the deviation of the wall thickness from the norm depends on the production method, so for seamless rolled metal the thickness of the metal should not differ from the assortment data by more than +12.5% or -15%, for an electric-welded pipeline - ±10%, and for a cold-drawn one - ±12.5 %;
- compliance with the form has a particularly strong effect on work under load, so the deviation of the angle between the walls should not exceed ±1.5ᵒ;
- the maximum curvature should not exceed 1 mm per 1 m of length, this parameter can be easily checked with your own hands;
In addition, restrictions are put forward on such parameters as tightening (implies concavity of the sides), length finished product etc.
Modern regulatory requirements
If in the past the main characteristics of square and rectangular pipelines were standardized by different documents, then GOST 2003 combines the standard sizes of these two types of sections. This makes working with the document somewhat easier.
GOST 30245-03 for the range of steel rectangular pipes consists of 2 tables, the 1st shows the standard sizes of square pipelines, and the 2nd - for rectangular ones.
Compared to the documents listed above, the standard sizes have changed slightly:
- for a square section, the minimum dimensions are 40x40 mm, and the maximum are 300x300 mm;
- in the case of a rectangle, the dimensions range from 50x25 mm to 400x200 mm.
As for the length, according to GOST 30245-2003 it can be equal to 6.0, and the maximum is set at 13.0 m (but only with the consent of the customer). For mass production, a size range of 6.0 – 12.0 m is used.
The difference from the standards of previous years is also noticeable in the requirements for geometry. Attention is also paid to the strength of the weld, the rules of marking, storage, etc.
Criterias of choice
It is important to be able to work with assortment. That is, knowing the purpose of the structure and having a table with standard sizes (as well as static characteristics of the section), you need to be able to choose the right option. And if throughput was of decisive importance, then in the case of a profile pipeline, attention must be paid to the strength of the structure, the price is also taken into account.
The main requirement is that only elastic deformation is allowed (that is, after applying a load, the structure will return to its original position, and with prolonged application of it, the deformation does not increase). If the calculation is carried out independently, then the nature of the deformation (bending, axial compression, torsion) must be taken into account; GOST for pipes will be needed to determine the static characteristics of the section.
It is unlikely that anyone will want to calculate the design on their own, and not everyone will be able to. In such a situation, you can use tables that indicate approximate standard sizes for a specific type of load.
Finally
In order not to make a mistake when choosing a rectangular pipe, you need to understand the regulatory documentation and at least roughly imagine the operating conditions of the structure. A lot of regulations have been issued regarding profile pipes; the information presented in this article will help you navigate them.
The video in this article shows the use of a profile pipe as a frame for a future structure.
Steel profile rectangular pipes are a type of rolled metal that is in demand in various branches of construction. It is valued for its strength, durability and resistance to heavy loads.
According to the production method, steel profile rectangular pipes are divided into:
- electric welded
- seamless - cold-rolled and hot-rolled
The performance characteristics of products depend on the production method and steel grade.
How to order steel profile pipes?
Ariel Metal offers high-quality rental products at affordable prices. All items are certified. The metal is stored in a covered warehouse, which guarantees reliable protection from precipitation and temperature changes. We sell profile steel square and rectangular pipes at retail, large and small wholesale. The volume of the order is not limited: we will quickly deliver from one pipe to several rental cars.
Prices for rectangular pipes depend on:
- standard size
- steel grades
- production method, etc.
The prices for rectangular pipes indicated in the catalog are valid for a one-time purchase of more than 5 tons of metal. Discounts apply for large wholesale orders.
Regular customers can take advantage of additional services:
- reserving goods in the warehouse for the required period
- buying metal on credit or in installments
The price list shows the price per ton of steel electric-welded rectangular pipes. The metal calculator on the website will help you calculate the approximate weight of the batch.
Shipping and payment
We will promptly deliver steel profile rectangular pipes to any region of the Russian Federation. Delivery is carried out by railway or our cars. We accept payment different ways. Cash payment is possible on the day of delivery: the driver will bring along with the ordered batch of metal cash machine and all accompanying documents.
Large vehicles are needed to transport long cargo. To reduce shipping costs, order pre-cutting of square and rectangular pipes from us. Please check prices for metalworking with our managers when placing your order. Services are available for wholesale and retail sales of metal: we will cut to individual sizes from 1 pipe.
To order steel profile rectangular pipes, leave a request on the website. The manager will process the request, calculate the discount amount and promptly respond to you.