Allowable scratch depth on flange sealing surface

0.2 mm Before flange installation, check whether the flange surface is damaged, such as scratches, nicks, mud, corrosion, burrs, etc. The depth of dents and scratches on the sealing surface of the flange that radially pass through the waterline shall not exceed 0.2 mm. Flange is a part between connecting shafts, which is used to connect pipe ends.