Seamless cold-rolled pipe is a type of pipe metal, the distinguishing feature of which is the absence of welds.
This product integrity provides seamless pipes with the following benefits:
- strength and resistance to high internal pressure;
- resistance to corrosion, chemical and mechanical stress, to aggressive environments and temperature extremes;
- precise dimensions and a smooth, even surface;
- long service life;
- slight elastic deformation regardless of diameter.
Peculiarities of production
The method of cold production of seamless steel pipes involves the processing of hollow sleeves obtained by hot rolling on special machines.
The sleeve is repeatedly crimped between the rolls of rolling mills until it acquires the specified parameters. The production cycle is reciprocating.
This production method is time consuming and energy intensive. But the product at the same time has accurate characteristics, shiny and smooth inner and outer surfaces, free from cracks and pits.
The whole cycle of cold rolled tube production can be divided into 5 main processes:
- 1. Selection of a monolithic billet. As a rule, a finished hot-rolled seamless steel pipe is used, followed by annealing.
- 2. Pretreatment. Consists of knitting, pickling, washing, rinsing, neutralizing, drying and applying lubricants.
- 3. Phosphating and copper plating (if necessary) to give increased strength to the future product.
- 4. Cold working - rolling or drawing.
- 5. Finishing. Includes heat treatment of finished products, axis correction, sampling, manual inspection, hydraulic testing, lubrication, packaging, storage.
Classification
The classification of this type of rolled product was based on the ratio of the outer diameter and wall thickness:
- with an indicator of 6 units. the pipe is extra thick-walled;
- from 6 to 12 - thick-walled;
- from 12 to 40 - thin-walled;
- more than 40 - extra thin-walled.
Requirements
Seamless cold rolled tube is a standardized product. The requirements for its quality, as well as the assortment are prescribed in GOST 8734-75. Rolled products are produced in diameters from 5 mm to 250 mm with a choice of wall thickness from 0.3 to 24 mm.
Deviations in outer diameter and wall thickness should not exceed the values prescribed in GOST.
Cold-rolled tubular products are produced in random lengths - from 1.5 to 11.5 m; measured length - from 4.5 to 9 m. It is possible to cut the ends at an angle of 90 degrees, but at the same time with a well-cleaned surface.
< /p>Application
Cold-rolled tubular products have a fairly wide range of applications:
- Hydraulic systems - due to the absence of seams, the lines easily cope with high loads.
- Installations for the generation of energy and heat - often used, as rolled products easily cope with temperature changes.
- Oil and gas industry - due to its strength, it is widely used as casing pipes.
- Chemical industry - as a material for laying pipelines for the transportation of aggressive chemicals.
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