Piping and Valves Knowledge: [Daily Question] 10-12-18
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This post was last edited by security on 2010-12-18 22:44. The value after DN indicates millimeters (mm), but no unit is specified. 1) All participants will receive a reward ； :):victory: 2) Please hide your replies; the method for doing this is: http://bbs.hcbbs.com/thread-492556-1-1.html. Do not edit the replies after posting them. 3) Answer: Correct. Refer to the Implementation Guidelines for GB/T 20801-2006 \"Code for Pressure Piping – Industrial Piping\"
Because the number after DN is neither the inner diameter nor the outer diameter
Reply 1# security is correct; DN: a size designation that is a combination of letters and numbers used for pipeline system components. It consists of the letters DN followed by a dimensionless integer, which is directly related to characteristic dimensions such as the bore or outer diameter of the end fitting (expressed in mm).
DN refers to the nominal diameter, which generally denotes the inner diameter. For units, mm is generally used. So, I think the wording of this question is incorrect.
Error: Nominal diameter, also known as mean outside diameter. It refers to the standard diameter after standardization, denoted by DN, in millimeters.
The nominal diameter does not necessarily represent the actual size of the pipe fitting. It’s just a standard interface. That’s what I think
This post was last edited by crjgood on 2010-12-18 08:18; the error means it is not exactly equivalent to the mm value. According to GBT 1047-05 \"Definition and Selection of DN (Nominal Size) for Pipe Fittings,\" DN is defined as \"a size designation that is a combination of letters and numbers used for pipe system fittings.\" It consists of the letters DN followed by a dimensionless integer. This value is directly related to characteristic dimensions such as the bore diameter or outer diameter of the end fitting (expressed in mm). ”Therefore, the number after DN is merely an integer value that is approximately equal to the same mm value; it is not equivalent to mm itself.
By extracting a sentence from the rules alone, outside of its specific context, it becomes ambiguous to make a judgment; it is recommended that moderators improve upon this shortcoming when creating questions in future.