In the list of demanded metal rolling units, the pipe occupies a leading position. The scope of its use is wide: the product is used in construction, industry, agriculture, automotive, household. Such popularity is explained by the versatility of pipes, because they help transport liquids and gases, in addition, serve as the starting material in the production of various parts.
Manufacturers offer dozens of types of pipes, differing in the method of production and operational characteristics. An important place in the catalogs of metal rolling is a longitudinal welded pipe. Why is it so highly regarded and what is it all about?
What is a longitudinal pipe?
First of all, you should deal with the concept itself. An electric welded straight-line pipe is a high-quality hollow metal rolling having a round, oval or rectangular profile.
A distinctive feature of such a product is the presence of a straight seam along the entire length of the pipe (because of this characteristic, the pipe was called electrowelded longitudinal seam). This type of metal rolling differs from seamless seamless analogues in low cost and ease of use.
Production Features
The manufacture of longitudinal welded electric pipe begins with the processing of sheet metal. It is he who is the basis of the future high-quality metal rolling. The thickness of the finished pipes depends on the thickness of the selected sheet steel.
Sheets are cut taking into account the necessary parameters and by special deformation on the machines acquire a rounded pipe shape. Depending on the selected technology, the pipes are:
- hot rolled (hot-rolled) or hot-deformed;
- cold rolled (cold-smoked) or cold-deformed.
After rolling, an open section remains throughout the pipe. It is treated with electric welding, after which the pipe itself and the seam are checked for strength.
Differences between hot rolled and cold rolled pipes
This or that type of product should be selected taking into account the particular application, since hot and cold rolled products have different characteristics.
Cold rolled. Cold-smoked pipes during processing pass only exposure to the press. The advantages of such products are a perfectly flat inner surface and attractive external data. This allows the use of pipes to transport any liquids - smooth internal walls do not allow particles to settle on the pipe, which prevents deposits and blockages. However, such a processing method is suitable mainly for mild grades of low carbon steel (St 10, 15, 20, 25). In addition, the cost of such a pipe is an order of magnitude higher.
Hot rolled. Hot-rolled pipes undergo processing not only by mechanical, but also by heat. Among the advantages of such products can be called low cost and increased resistance to corrosion. Among the disadvantages there is a rough surface of the inner walls and low flexibility. In other words, hot rolled pipes should be used only on straight sections of the pipeline.
Range of electric-welded longitudinal pipes
Manufacturers offer a wide range of longitudinal pipes, which differ in several parameters. The most obvious visual difference is the type of profile. According to this symptom, pipes are divided into:
- inert gas welding;
- plasma welding ;
- HF current welding.
The diameter of longitudinally welded electric-welded pipes can be different; its parameters vary from 10 to 1420 mm. Such a wide range allows you to choose the product that is most suitable for specific project requirements. An important characteristic is wall thickness. The strength and durability of the pipe depend on this indicator, in addition, the thickness affects the weight of the product and the final cost. Pipes are manufactured with wall thicknesses from 1 to 32 mm. Depending on other characteristics, the length of rolled metal reaches 4-12 m.
GOST requirements
The quality of longitudinal welded pipes is controlled by GOST 10704-91 (it determines the assortment). In addition, the requirements for general-purpose pipes prescribed in GOST 10705-80 and GOST 10706-76 are taken into account. If the pipe has an increased diameter (428-1420 mm) and arc welding is used in its production, then the quality is regulated in GOST 10706-76.
For pipes of small diameter, the seam of which is produced by resistance welding by high-frequency current, another GOST applies, namely 10705-80. These GOSTs for longitudinal welded pipes have a certain similarity, but still they have different requirements.
Advantages of longitudinal pipes
Pipes of this type differ from other metal products in a number of advantages:
- increased throughput rates;
- immunity to hostile environment (use such a pipeline at various facilities);
- resistance to contact with the chemical environment (use in enterprises is possible);
- increased tightness (up to 100%) when working with a gas medium;
- low rate of thermal expansion;
- long term of operation and high strength to mechanical influences;
- low price of longitudinal welded pipes (the cost varies from 155 rubles per 1 meter of pipe 57 x 2.5 mm and up to 2795 rubles per 1 meter of pipe 273 x 8 mm).
Scopes of welded pipes
The characteristics of this high-quality metal rolling allow to use it everywhere. Throughput indicators and increased strength make them indispensable in laying engineering networks (even with high pressure). It:
- water pipes;
- heating system;
- pipeline;
- low pressure gas pipeline.
Longitudinally welded electric pipes can withstand water pressure, therefore, they are often used in trunk and local distribution communication branches. Profile pipes are often used in construction. Stiffening ribs provide them with increased flexural strength, so such products become an excellent alternative to I-beams and other types of metal.
So, longitudinal seam welded pipes are metal products that are suitable for solving a number of problems and can reduce costs.