Diameter of metal pipes
The thickness of the wall of the steel pipeline, its length, outer and inner diameters are all geometric parameters, more detailed information about which can be read in the established GOSTs. In these normative documents, certain values in mm are indicated, as well as their permissible deviations in the percentage ratio.
Let's take a closer look at what each of the above parameters is.
The outer diameter of the steel pipe( dn) is considered to be the distance between two points located oppositely on the outside of the product. The internal diameter of the metal pipes( dv) is the distance between two points located oppositely on the inside of the product. The difference between them is the wall thickness of the steel pipe. If you round out the outer dimension in inches or millimeters, you will know the conditional diameter of the pipe.
To date, there are only four ways of manufacturing a steel pipeline:
- "cold" and "hot" rolling;
- welded product with straight and spiral seam.
Based on GOST, the diameter and length of the metal pipeline are related to the method of their manufacture. Ie, each of these manufacturing technologies has its own specific product range. Next, we will try to briefly cover the whole range of rolled steel tubes.
The range of cold rolled steel pipes includes products with a diameter of 5 to 250 mm. According to GOST 8734-75, similar products are about 70. If you take into account, such a parameter as( dв), then the figure 70 will change to a three-digit number. This is due to the fact that the thickness of the walls of this type of pipeline can reach from 0.3 to 24 mm.
The assortment of the steel pipeline "hot rolled" includes pipes, whose diameter is from 20 to 550 mm( considering only the outer diameter).According to the second GOST 8732-78, their quantity also reaches up to seventy, and( dв) of such pipes will be different due to different values of the wall thickness. So, for example, a pipeline with a diameter of 25 mm has 15 different types of products, the wall thickness of which varies from 2.5 to 8 mm.
Welded products with a straight and spiral seam. Dimensions of diameters and their importance
In the normative document GOST 10704-91 you will find a special table in which the parameters of a steel pipeline with a straight seam are indicated. This pipe diameter table starts at 10mm and ends at 1420mm. The document describes more than eighty different products. Due to the gradation in the thickness of the wall of the product from 1 to 32mm, this pipeline has twelve more types of pipes in 60mm.
Normative document GOST 8696-74 gives the definition and data for welded pipes with a helical-type seam. It contains 21 products, the diameter of which varies from 159 to 2520mm. The list includes steel pipes of large dimensions, but the thickness of their walls is relatively small. That is why, the number of products is much smaller than that of previous GOSTs.
Naturally, having read all the information, the question arises: "Why is diameter so important?"The answer is quite simple - on this parameter depends the strength of the product and its throughput. Not knowing it or not taking into account in the calculations, you can call on irreparable trouble. So, for example, if you design a sewage system and apply a pipeline with a diameter that is not suitable for a large volume of transported liquid, the pipe simply will not have time to fulfill its function of tap and all dirt will spill over the neighborhood, causing environmental damage.
Strength is also very important and depends on the size and shape of the section. Therefore, in the calculations it is necessary to take into account both external and internal pressure on the pipeline.
