Steel pipes are widely used in a wide variety of industries. They are used in mechanical engineering, the oil and gas industry, utilities, etc. There are several types of steel metal pipes . They can differ in the method of manufacture, size and type of material used for the production. The assortment of steel pipes of different types is determined by GOSTs.
Seamless products
Basically, all modern steel pipes are divided into two large groups: hot-rolled and welded. The first variety has a higher cost. Therefore, such products are used less frequently than welded ones. The range of seamless steel pipes is determined by GOST 8732-78. The ratio of the size of such pipes and their weight is given in special tables. The parameters may, for example, be as follows.
The size | Weight 1 m |
38x4 mm | 3.35 kg |
70x5 mm | 8.02 kg |
108x10 mm | 24.17 kg |
219x8 mm | 41.63 kg |
377x9 mm | 81.68 kg |
426x10 mm | 102.59 kg |
The range of steel pipes electrowelded and made by means of furnace welding will be examined by us a little later. Their parameters are also precisely determined by GOSTs.
How to make seamless pipes
Products of this variety are produced from steel grades 35 and 45 on a continuous mill. In this case, the so-called black blanks are used. The latter are stitched on a roll mill, and then sent to a circular saw to cut the end of the pipe. Then the finished product enters the Kosovalkovy mill for dressing and reducing the ovality of the section.
Welded pipes: reasons for popularity
Products of this type, as already mentioned, are more popular than seamless. Such pipes have been used in the national economy for quite some time. However, in recent years, their popularity has increased significantly. This is primarily due to the development of new, more advanced welding methods, allowing to obtain the most reliable and durable products. So, for example, in 1941 only 38.8% of welded pipes were produced. The rest was seamless. At the same time, the share of electric-welded was only 0.8%. By 1965, these indicators increased to 50% and 35%, respectively.
Scope of use of welded pipes
Today, such products are used everywhere. Most often they are used for laying various kinds of highways designed for pumping oil, gas, water, etc. Also, this type of pipe is usually used in public utilities. In this case, they are used for laying water pipes and sewer systems. Welded pipes are also used for the assembly of gas aboveground pipelines, drainage systems, etc.
Engineering is another area in which welded pipes are used. They are also used for the manufacture of various kinds of architectural elements: peaks over porches, awnings, children's swings, horizontal bars, etc. In agriculture, irrigation systems are assembled using them.
The main varieties of welded pipes
Products of this type can vary in:
Manufacturing method. In this case, pipes made using furnace welding and electric welding are isolated. Both that and other variety are considered rather reliable. Electric-welded pipes can be produced by methods of arc, contact or induction welding.
Type of coverage. On this basis, galvanized and non-galvanized pipes are distinguished.
Depending on the direction of the seam (straight- seam and spiral).
The type of material used for the manufacture. Welded pipes are usually made of low alloy or carbon steel. In this case, either sheet metal or strips are used. Sometimes other metals can be used for pipe production: nickel, copper, magnesium, etc. In this case, gas or gas-electric welding is usually used.
Profile view. On this basis, round, rectangular profile, oval pipes are distinguished.
How do
Next, let's see how a steel welded pipe is made. The GOST assortment in this case regulates exactly. This applies to both the size and weight of the products. Actually, the production process itself consists of the following stages:
preparation and formation of a sheet;
welding, which consists in creating an electric arc between the edges of the workpiece and the electrode;
final finishing (calibration, chamfering, dressing, etc.).
The main steps in the manufacture of pipes with a spiral seam are sheet formation, welding and cutting on the go. In this case, sheet metal in the form of a tape is fed into a special unit of the mill, where it is rolled into a spiral. At the same time, welding takes place.
Despite the fact that it is easier to produce spiral pipes, in factories they mainly produce straight-seam pipes. The fact is that such products are more popular in the market.
GOST
In the production of welded steel pipes, certain standards must be followed. The quality of such products is regulated by GOST 10704-91. The assortment of steel electric-welded straight-line pipes according to the standards specified in this document includes product groups:
with rationing of mechanical properties (marked “A”);
with control of chemical composition ("B");
with control of both of these parameters ("B");
with the regulation of hydraulic pressure during testing ("D").
As for the dimensions and weight, welded straight-line pipes are made in accordance with GOST 10705-80 (for products with a diameter of 10-500 mm) and GOST 10706-76 (for diameters 478-1420 mm).
Assortment of welded steel pipes
Below we present to your attention a table of the ratios of pipe diameters, their wall thicknesses and permissible deviations according to GOST.
Outside diameter | Welding method | Wall thickness | Deviations |
Wall thickness | In diameter |
13.5-114 mm | Stove | 2-4 mm | -15, + 8% | from 0.5 mm to 40 mm, 1 - over 40. |
6-125 mm | Electric | 0.4-5.5 mm | 0.1 mm to 0.75 mm and 10% over 0.75 mm | from 0.3 mm to 2 cm, from 2 to 5.1 cm - 0.5 mm, more than 51 - 1% |
159-529 mm | 3-8 mm | In accordance with standards regarding thickness deviations used for the manufacture of metal sheets (according to GOST 5587-58 and 8597-57) | 1% up to 400 mm, over 400 mm pipe ends calibration applied |
426-1420 | Electric arc | 6-14 mm | from 2 mm to 720 mm, from 3 mm to 1020 mm, from 4 mm to 1220 mm, from 5 mm over 1220 mm |
159-2020 | 4-15 mm |
GOST also regulates the ratio of the outer diameter and the weight of 1 m of the pipe at a certain wall thickness. The assortment of steel pipes in this case is also presented in special tables. Below, for example, several such relations are given.
D | Weight 1 m pipe with wall thickness |
1 mm | 2 mm | 3 mm |
10 mm | 0.222 | - | - |
20 mm | 0.469 | 0.888 | - |
30 mm | 0.715 | 1.38 | - |
40 mm | - | 1.87 | 2.74 |
60 mm | - | 2.86 | 4.22 |
The difference in electric welded pipes in length
Steel longitudinal pipes, the assortment of which is presented above, may also vary by:
Products of multiple and measured lengths can have two accuracy classes: with trimming the ends and turning of the burrs and with cutting in the mill line (without trimming).
What is a strip
From English this term is translated as “tape”, or “strip”. Strips for the production of welded pipes are used very often. Actually, these tapes themselves are made of sheet metal. There are strips:
steel;
galvanized;
stainless tapes;
with polymer coating.
Depending on the thickness of the material used for its manufacture, a strip can weigh from fifty kilograms to five tons. He enters enterprises specializing in the manufacture of pipes in baboons or in a bundle, always on a pallet.
Design Features of Pipe Welding Mill
Such equipment can be used for the manufacture of both spiral and longitudinal joints. In the latter case, the design of the machine includes the following elements:
receiving and loading device;
unwinder;
the right car;
scissors for cutting the ends of the strip;
oven for heating the strip;
molding, welding and calibration mills;
flying saw etc.
Before welding, the workpieces pass through a special molding press or rollers.
The spiral pipe mill consists of the following elements:
There is a process of pipe formation in such a mill at a speed of up to 1.1 meters per minute. The quality of the weld in modern enterprises is checked using ultrasound. The manufactured cut pipes after the mill go to calibration.
Thus, you now know how electric steel pipes are made and what they are. The assortment of GOST defines these products in accuracy. We also figured out what standards are provided for in the manufacture of seamless pipes. Exact adherence to manufacturing technologies allows to obtain high-quality and reliable products of this type, used in many areas of the national economy.