# What is the OD, inner diameter, nominal diameter of steel pipe?

May 15, 2018
###### Spiral steel pipe manufacturing process
May 16, 2018

What is the outer diameter, inner diameter, nominal diameter of steel pipe?

The diameter of steel pipe can be divided into outer diameter, inner diameter and nominal diameter.

The outer diameter of the pipe with the antiseptic spiral steel pipe is denoted by letter D, followed by the size and wall thickness of the outer diameter.

For example, the anticorrosive spiral steel pipe with an outer diameter of 108 has a wall thickness of 5mm, which is expressed by D108*5. The plastic pipe is also expressed by the outer diameter, such as De63. Others such as reinforced concrete pipes, cast iron pipes, and galvanized pipes are indicated by DN. Design drawings are generally expressed in terms of nominal diameters. The nominal diameter is a standard that is conveniently and artificially specified for design, manufacture and maintenance. It is also a nominal diameter and is the specification name of a pipe (or pipe fitting).

The nominal diameter of the pipe is not equal to its inner diameter and outer diameter.

For example: a nominal diameter of 100MM spiral steel postal mail 102 * 5, 108 * 5 several, 108 is the outer diameter of the pipe, 5 is the pipe wall thickness, therefore, the inner diameter of the pipe is (108 * 5-5) =98MM, but it is not exactly equal to the difference between the wall thickness and the wall thickness. It can also be said that the nominal diameter is a specification of a pipe diameter that is close to the inner diameter but does not equal the inner diameter. With nominal diameter, the purpose is to determine the pipe size, pipe fittings, valves, flanges, gaskets and other structural dimensions and connection dimensions according to the nominal diameter. The nominal diameter is denoted by the symbol DN. If the outside diameter is used in the design drawings, it should also be made. The pipe specification table shows the nominal diameter and wall thickness of a certain type of pipe.

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