Welded pipes

Currently, welded pipes account for almost half of pipe production. Used in most industries.

Manufacturing materials

The raw material for the manufacture of a welded pipe product is sheet steel, up to 5 centimeters thick, or steel tape, of different thicknesses.

Rolled steel is obtained from:

– carbonaceous. The type of carbon steel is determined by the amount in the composition of the main element. With this in mind, it can be low carbon, medium carbon and high carbon. A high carbon content provides high strength products, but significantly reduces its elasticity and makes it quite brittle when used at low temperatures;

– low-alloyed. The welded pipe, made of steel with alloying additives, the proportion of which does not exceed 2.5%, has a significantly higher strength, independent of operating conditions. In addition, such products are distinguished by lighter weight, better resistance to corrosion, high wear resistance and longer service life. Pipe products made of low-alloy steel are somewhat more expensive, but this is fully compensated by its properties.

Stainless products are made from steel with an even higher content of special additives that determine their properties. Stainless steel pipes are light in weight and attractive in appearance, easy to process and highly resistant to corrosion.

Pipes welded from stainless steel can be cold or hot rolled. The first are produced with a wall thickness of 0.4 to 5 millimeters, and the second – from 2 millimeters to 5 centimeters.

Product types

Pipe products with a straight longitudinal seam are made by welding the edges of a steel sheet rolled to the shape of the final product. Structures of especially large diameter have two seams, since they are welded from two sheets with a limited width.

Products with a spiral seam are produced and steel sheet rolled. The advantage of this method is the ability to produce welded pipes with a diameter of up to 2.5 using a workpiece that has an equal width. The ratio of wall thickness to diameter in these pipes can exceed 100.

The technology for producing spiral-seam pipe products requires the use of less complex mechanisms than straight-seam products. At the same time, it is characterized by high precision of execution.

The advantages of spiral rolled products include the impossibility, in the event of an accident, of the occurrence of longitudinal main cracks, which are considered the most dangerous deformation for pipes. This greatly simplifies the process of eliminating the consequences of an accident.

A disadvantage is that such a welded steel pipe is long, which requires a large investment in welding operations.

Production methods

There are several ways to obtain welded pipes. The most relevant technologies include:

– furnace welding, which involves exposure to high temperatures on a steel billet (strip). In this case, the metal strip is heated up to 1300 degrees in a tunnel furnace, after which it acquires the desired shape on a molding machine programmed for the desired diameter. After that, the edges of the workpiece are welded;

– electric welding, which is the most common, allowing to obtain steel welded pipes of significant diameter and with thin walls, high-quality seam and high-quality surface. This method involves cold forming with special rolls or a press mold, if necessary, it will receive half-cylinders for two-seam products. Strips for spiral products are obtained using a bushing and roll-arboring machine. To connect the edges of workpieces, different types of welding technologies are used. But, for products intended for main pipelines, submerged arc welding is used;

– welding in shielding gases, used to produce stainless steel and high-alloy steel products. A protective environment of carbon dioxide, helium or argon avoids the carbidization of alloying components, which can degrade the quality of the weld. The technology allows the use of both electric and gas welding.

Applications

Welded pipe, which can be bought with different characteristics, has found wide application in the energy, oil and gas industry, construction, and the utilities sector. Stainless products are used in the pharmaceutical, food and light industries.

Where can I buy

It is always possible to purchase welded pipe products with the required characteristics from A-Sintez, which offers rental from leading domestic and foreign manufacturers.

You can buy welded pipes in any required volume and at the most affordable prices.