Cold-deformed pipe has found its wide application in construction and in many areas of human activity. With the help of it, parts are made for furniture production, water, gas, oil pipelines, as well as engineering networks are laid, among them those that are designed for pumping aggressive media. The mentioned products have high strength, they have no seam, so the scope also applies to the aviation industry, as well as the automotive industry.
Pipe description
Having become acquainted with state standards, you will be able to understand that a cold-deformed pipe is a hollow rod on which there are no welds and joints. Manufacturing technology can be different, and it can be classified according to several types, among them:
- pressing;
- forging;
- rolling;
- drawing.
The most common way is rolling. As a workpiece, a pipe is used, which is made by hot rolling. Steel is rolled using special equipment. Cold-formed pipe is based on carbon or alloy steel. For the reason that the described products have no seams, this allows them to be used in negative conditions and with mechanical influences.
As for size, such pipes are much smaller than hot rolled or welded. However, one important advantage can be distinguished, which lies in dimensional accuracy. Products have a surface whose quality is much higher in comparison with pipes made using other technologies. Cold deformation allows to obtain pipes with a thin wall.
Main features: classification by parameters
A cold-deformed pipe can be classified by wall thickness and can be thin-walled or thick-walled. Resistance to negative influences and durability depend on this. Thin-walled seamless pipe has light weight. This property is in demand in the construction of custom designs. As for the thickness, it can be equal to from 4 to 6 mm. However, if necessary, the use of a pipe with a wall thickness that differs from the above-mentioned parameters, products can be made in production whose walls reach 12 mm in thickness. They are particularly durable.
The diameter acts as one of the main parameters, it can be equal to a value in the range from 5 to 45 cm. A cold-deformed steel pipe can also have a different cross section, namely:
- oval;
- round;
- rectangular;
- square.
An additional characteristic is also the length. Pipes can be measured or not measured. Measured length is 4.5 or 5 m. If you need pipes of unmeasured length, then you can choose segments from 1.5 to 11.5 m.
State standards
Cold-deformed pipe (GOST 8734-75) can also be classified by the method of use. Such products may have a special or general purpose. The latter option may have an outer diameter ranging from 5 to 250 mm, while the wall thickness is usually equal to a figure from 0.3 to 24 mm.
Pipes can have different wall thicknesses and are:
- especially thick-walled;
- thin-walled;
- thick-walled;
- especially thin-walled.
For these products, there are technical specifications that are prescribed in state standards 8733-74. The documentation mentioned that the products can be divided into separate groups, among them we can distinguish those that are denoted by letters from B to E. The first group is the standardization of the chemical composition, group C is the standardization of mechanical properties. Group D determines the standardization of mechanical properties and chemical composition.
If the pipe belongs to group D, then this indicates the normalization of hydraulic pressure. The mechanical properties are normalized after the heat treatment of pipes that belong to group E. Seamless cold-deformed steel pipes undergo control after manufacture. Validation includes sizing, hydraulic pressure testing and mechanical control. Additional products are checked for bending and flattening, while using GOST 3728-78 and 8695-77.
Additional properties
Cold-deformed pipe is made without the use of welding. Production does not provide for preheating, because the products are obtained from the workpiece. Deviations are standardized by GOST 8734-75. There is a tolerance of 10 mm from the standard. According to the technical conditions, the difference and ovality should not exceed the limit values.
The curvature of the plot is 3 mm, which is true for a length of 1 m. In this case, we are talking about diameters ranging from 4 to 8 mm. The permissible curvature is reduced to 2 mm when the diameter is equal to a figure from 8 to 10 mm.
Properties of capillary products
Capillary pipes are manufactured in accordance with GOST 14162-79. For production, steel grade 12X18H10T is used. Such pipes are compared with steel pipes. Their difference is:
- corrosion resistance;
- mechanical strength;
- longevity.
Such steel seamless cold-deformed pipes, the GOST of which was mentioned above, can be used in an aggressive environment. Manufacturing technology allows you to get pipes with high technical performance. The production is based on sulfuric acid treatment, which relieves internal stress. This increases safety during operation in the gas, chemical and petroleum industries.
Such a steel cold-deformed pipe, GOST, which must be observed, has one important minus, expressed in the complexity of the process. The consequence is an increase in cost and final price, as well as an extension of production time.
Features of a pipe for special purposes
Among cold-deformed seamless products, it is worth highlighting those that are made of stainless steel, as well as a material that can be subjected to high pressure. Another variety is a steel capillary tube with a small diameter. If you are interested in pipes with corrosion-resistant properties, then you should know that they are manufactured in accordance with GOST 9941-81. The documentation indicates the specifications and assortment.
The wall thickness of such a pipe can be equal to a value from 0.3 to 24 mm. As for the outer diameter, its maximum limit is 250 mm. The smallest value is 5 mm. It is based on highly alloyed stainless steel. Products undergo the same tests as general purpose pipes. With their help, laying of pipelines used to transport substances with a high level of aggressiveness is carried out. The pumped medium may have a high temperature. Another area of operation is turbojet and jet engines, which are used to supply oxidizer, fuel and oil.
GOST pressure resistant pipes
Seamless cold-deformed pipes (GOST 11017-80) can be used at high pressure. Their diameter is equal to a figure from 6 to 10 mm. It is based on carbon structural steel. Products are tested different from the above. Pipes are tested for hydraulic pressure and tension, holding time reaches 10 seconds. The area of use is gasoline and diesel engines, which are also called fuel lines.
Finally
On the surface of cold-deformed pipes there should be no cracks and damage, as well as sunsets and other defects. Dross, fine nicks and other irregularities that do not interfere with inspection are permissible. If necessary, the surface is cleaned of scale.
The pipe is cut at a right angle. Burrs are removed from the ends. At the request of the customer, the ends of the pipes can be supplemented with chamfers. This rule applies to pipes whose wall thickness exceeds 5 mm. An important condition is expressed in the presence of an end ring with a width in the range from 1 to 3 mm.