The outer and inner diameter of the steel pipes."Cold " and " hot" rolled steel pipes

diameter metal pipes

wall thickness of the steel pipe, its length, outer and inner diameter - all these geometric parameters, more detailed information on which may be read in the installed guest.In these regulations, some values ​​are given in millimeters, as well as their tolerance percentage.

Let's look in more detail what is a one of the above parameters.

outer diameter steel pipe (DH) is considered to be the distance between two points located on the outside of the opposite side of the product.The inner diameter of the metal tube (d in) - is the distance between two points oppositely disposed at the inner side of the article.The difference between them is the steel pipe wall thickness.If the round number of external dimensions in inches or millimeters, you will learn nominal diameter of the pipe.

Today distinguish all four methods of manufacturing steel pipe:

• «cold" and "hot" rolled;
• weldment with straight and spiral seam.

From Standard diameter and length of the metal pipe connected to the process of their manufacture.That is, each of these manufacturing techniques has its own particular range of products.Next, try to briefly cover the entire range of rolled steel tubes.

The assortment of steel pipes "cold" rolled includes products with diameters ranging from 5 to 250 mm.In accordance with GOST 8734-75, similar products, there are about 70. If we take into account, such as a parameter (DB), the figure 70 is changed to a three-digit number.This is due to the fact that the wall thickness of this type of conduit can reach 0.3 to 24mm.

The gauge steel piping "hot rolling" includes pipes, which is equal to a diameter of 20 to 550mm (considering only the outer diameter).According to the second GOST 8732-78, their number also reaches up to seventy, and (DB) of such pipes will be different because of the different values ​​of the wall thickness.For example, in a pipeline with a diameter of 25mm, there are 15 different kinds of products, the wall thickness of which varies from 2.5 to 8 mm.

welded products with a seam straight and spiral type.Dimensions diameters and their importance

The normative document GOST 10704-91 you will find a special table, which lists the parameters of a steel pipe with a straight seam.This table pipe diameters starts at 10mm and ends at 1420mm.The document describes more than eighty different products.Due to the graduation on the wall thickness of the product from 1 to 32 mm, in such a pipeline there are twelve varieties of pipe in 60mm.

normative document GOST 8696-74 provides a definition and data for welded pipes with a seam spiral type.It contains a product 21 whose diameter ranges from 159 to 2520mm.The list includes steel pipes of large sizes, but they are relatively small wall thickness.For this reason, the number of products is significantly less than that of the previous guests.

course, reading all the information, the question "Why is it so important is the diameter?".The answer is quite simple - this parameter depends on the strength of the product and its capacity.Without knowing it, or without taking into account in the calculations, it can be fatal self-fulfilling prophecy.For example, if you design a sewage system and apply the pipeline with a diameter not suitable for a large amount of the fluid, pipe simply does not have time to do its job removing all dirt and spill over the neighborhood, causing environmental damage.

strength is also very important and depends on the dimensions and shape of the cross section.Therefore, the calculations must take into account both external and internal pressures on the pipeline.