You can check it in the hardware manual. Generally speaking, the diameter of the pipe can be divided into outer diameter, inner diameter and nominal diameter. The outer diameter of a seamless steel pipe is represented by the letter D, followed by the outer diameter size and wall thickness. For example, a seamless steel pipe with an outer diameter of 08 and a wall thickness of 5MM is represented by D08*5. A plastic pipe It is also expressed by the outer diameter, such as De63. Others such as reinforced concrete pipes, cast iron pipes, galvanized steel sheet, etc. are expressed by DN. In design drawings, the nominal diameter is generally used to express it. The nominal diameter is artificially specified for the convenience of design, manufacturing and maintenance. A kind of standard, also called nominal diameter, is the specification name of pipe (or pipe fitting). The nominal diameter of the pipe is not equal to its inner diameter and outer diameter. For example: there are several types of seamless steel pipes with a nominal diameter of 00MM, such as 02*5, 08*5, etc. 08 is the outer diameter of the pipe, and 5 represents the wall thickness of the pipe. , therefore, the inner diameter of the steel pipe is (08*5-5) = 98MM, but it is not exactly 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 is close to the inner diameter, but not equal to the inner diameter. The specification name of a pipe diameter. In design drawings, the nominal diameter is used. The purpose is to determine the structural dimensions and connection dimensions of pipes, pipe fittings, valves, flanges, gaskets, etc. based on the nominal diameter. The nominal diameter uses the symbol DN. means that if the outer diameter is used in the design drawings, a pipeline specification comparison table should also be made to indicate the nominal diameter and wall thickness of a certain pipe.
. Pipe series standards
When designing and constructing pressure pipelines, first consider the selection of standard series of pressure pipelines and their components. Although there are many standard systems applied in various countries around the world, they can generally be divided into two categories.
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