Views:1 Author:Site Editor Publish Time: 2020-11-12 Origin:Site
Generally speaking, the diameter of steel pipes can be divided into outer diameter, inner diameter, and nominal diameter. The outer diameter of the pipe is a hot-dip galvanized seamless steel pipe with the letter D, followed by the size and wall thickness of the outer diameter. For example, the galvanized seamless steel pipe with an outer diameter of 108 has a wall thickness of 5MM, which is represented by D108*5 , Plastic pipes are also expressed by outer diameter, such as De63. Others such as reinforced concrete pipes, cast iron pipes, galvanized steel pipes, etc. are expressed by DN. In the design drawings, they are generally expressed by the nominal diameter. The nominal diameter is for the convenience of design, manufacture and maintenance. A standard artificially stipulated, which is also a standard name for pipes (or pipe fittings), which is more than the nominal diameter.
The nominal diameter of the steel pipe is not equal to its inner diameter and outer diameter. For example, there are several types of galvanized seamless steel pipes with a nominal diameter of 100MM, such as 102*5, 108*5, and 108 is the outer diameter of the galvanized seamless pipe. 5 represents the wall thickness of the pipe. Therefore, the inner diameter of the galvanized seamless steel pipe is (108*5-5)=98MM, but it is not completely equal to the difference between the outer diameter of the steel pipe minus twice the wall thickness. It can also be said that the nominal diameter It is the specification name of a steel pipe diameter that is close to the inner diameter but not equal to the inner diameter. The nominal diameter is used in the design drawings. The purpose is to determine the structure of pipes, fittings, valves, flanges, gaskets, etc. according to the nominal diameter For dimensions and connection dimensions, the nominal diameter is represented by the symbol DN. If the outer diameter is used in the design drawings, a comparison table of pipe specifications should also be made to indicate the nominal diameter and wall thickness of a certain pipe.