I'm trying to figure out the relationship between the absolute roughness of the interior surface of steel pipe and the RMS (root mean square) surface finish number used by pipe manufacturers. I believe the RMS number is given in microns and can therefore be related back to absolute roughness which is given in either ft. or inches. Please let me know if there is a table that correlates the two...thanks.

(1). If you type "pipe roughness" into a web search site, such as yahoo, you will get many websites related to the pipe roughness. (2). One of the place to begin with is http://www.efunda.com/formulae/fluids/roughness.cfm

Thanks, I had been to the efunda web site yesterday but had overlooked that particular table. So I'm now assuming that an RMS surface finish is usually given in a value of microns??? If so, that can easily be equated to an absolute roughness coefficient.