Relative Roughness. Pipe nominal diameter (D) = 3" = 76.2 mm.

Absolute roughness is a measure of the surface roughness of a material which …

Absolute roughness for PVC (ε) = 0.0015 mm. About product and suppliers: 829 galvanized iron pipe roughness products are offered for sale by suppliers on Alibaba.com A wide variety of galvanized iron pipe roughness options are available to you, There are 29 suppliers who sells galvanized iron pipe roughness on Alibaba.com, mainly located in Asia.

Note: Pipes that have absolute roughness equal to or less than 0.000005 feet are considered … Surface coefficients to calculate flow friction and major pressure loss - surfaces like concrete, galvanized steel, corroded steel and more Sponsored Links For turbulent flow the friction coefficient depends on the Reynolds Number and the roughness of the duct or pipe wall.

The following table is summarizing usual pipe roughness for many materials used for piping or ducts . The roughness of a pipe is normally specified in either mm or inches and common values range from 0.0015 mm for PVC pipes through to 3.0 mm for rough concrete pipes. The roughness is actually a measurement of all the asperities at the surface of a material, especially a pipe where it will oppose the flow of fluid.

Relative roughness of 3" PVC pipe = ε/D = 0.0015 / 76.12 = 1.97 × 10 -5. Next this relative roughness value can be used to determine the friction factor to be used in Darcy's equation for calculating the pressure drop across a pipe.