The classification of steel pipes indicates their purpose

Steel pipes are widely used in domestic and industrial construction. They serve as elements of open and closed systems transporting a variety of liquids and gases. Apply them and as parts of metal.

In everyday life, they are usually used for heating and water supply. At the same time marking of steel pipes will prompt their appointment.

Product division

There are six classes of products described by the following properties:

• the type of material, its homogeneity;
• production method;
• cross-sectional shape;
• destination

Types of steel pipes according to GOST

1. The nomenclature of steel pipes according to State Standards No. 3262 and No. 10705/80 is intended for mounting water and gas pipelines, domestic and industrial heating systems, and creating steel frameworks.
2. Analogs according to State Standard №20295 / 85 are used for arranging main pipelines for gas, oil, strengthening the soil and pits.

Steel grades

In addition to a specific GOST, the choice of products should take into account the steel grade from which the products are made.

It may be:

• St-1;
• St-2;
• St-3;
• St-4;
• St-5;
• St-6;
• Article 7.

Guaranteed qualities of steel are divided into 3 categories:

• Letter A means the mechanical qualities of the material;
• The letter B is its chemical composition;
• Letter B indicates the relationship of the mechanical components of the product with its chemical features.

Grade A always corresponds to the steel types listed above. The instruction notes, if the product is made of so-called "boiling" steel, it is additionally indexed by the letters KP, if from the "semi-quiescent" analogue - PS. When there is no such marking, the metal belongs to the “quiet” type.

Varieties of products in size and method of manufacture

Standard sizes of steel pipes according to their diameter:

• capillary analogs - 0.3 / 4.8 mm;
• products of small diameter - 5/102 mm;
• products with an average cross section - 102/426 mm;
• large diameter pipes have it more than 426 mm.

Sectional shape and wall thickness

The thickness of the pipe walls are divided into:

• especially thin-walled;
• thin-walled;
• normal;
• thick-walled;
• especially thick-walled.

Thin analogues have a thickness of 1 mm, the thickest products - 19 mm.

Note! According to GOST, such a wall thickness of a steel pipe seems to be small. However, such analogues are able to withstand internal and external loads of 20/50 tons.

There are two classes of precision machining products.

1. First-class products trim the ends and remove burrs.
2. The second class is only cut.

The shape of the section profile for steel products is divided into two categories.

1. Shaped (profile) pipes serve as elements of metal structures. They can be rectangular, square, oval, rhomboid, ribbed, segmental, teardrop, triple, hexagonal, octahedral, etc.
2. Round analogues are designed for transportation of various substances.

      Mode of production

According to the method of production of metal pipes are divided into 2 types.

1. Produced using various welding methods: gas-electric; furnace (butt); electric welding using resistance.
2. In the case of a seamless method, the pressed or rolled (deformed) hot and cold analogues are produced.

Characteristics affecting consumer quality pipes

1. The internal roughness of steel pipes leads to the growth of deposits and corrosion products on their walls. This lowers their throughput.

The coefficient of roughness of steel pipes can be different. It depends on the method of their production and condition. Below is a table regarding this issue.

1. When you install your own steel networks, you should take into account the change in pipe length due to thermal expansion due to temperature differences. The coefficient of linear elongation of steel is 0.0120 mm / m • K. Consequently, the pipe from it will expand when the temperature changes by 50 ° to 6 mm.

Note! Linear elongation of metal products is 20 times less than that of plastic analogues. Such a low parameter value is their important advantage.

1. The coefficient of thermal conductivity of steel pipes is quite high - 74 W / m • K. This property is ideal for heating networks and hot water supply. For cold water is bad, because pipes begin to "sweat", get wet and rust.

1. With the same wall thickness, seamless products are stronger than welded counterparts, because the joint is a weak area.
2. Their throughput depends on the size of the internal diameter of products.
3. Wall thickness affects the strength of the pipe and its resistance to high pressure.
4. The outer coating also plays an important role. If the black steel pipe is galvanized, it almost does not rust. The price of chrome-plated counterparts is high, but besides their increased resistance to corrosion, they also look very aesthetic.

Conclusion

If you are well versed in the marking and classification of steel pipes, you can easily get exactly the variety that is needed.

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