Did you review ASME B16.5?? The answer to your question can be found in Table 3 (Permissible Imperfections in Flange Facing Finish for Raised Face and Large Male and Female Flanges) on page 61 of ASME B16.5.
I did review ASME 16.5, The radial projection of imperfections is where I am looking for reassurance of my interpretation. If you had an imperfection the full cicumference of the gasket surface that never exceeded the maximum radial projection in width and was not in excess of the allowable depth would it be acceptable? PS sorry about the post in the wrong thread.
According to what you have presented in your post and information in Table F3 of ASME B16.5, yes. The circumferential length of the imperfection does not apply.
Agree with metengr, and if you think about it, its logical, because, what you have to be concerned about is a potential leak path. If an imperfection within the allowable limits ran around the entire circumference, it would not present a leak path.
There are two type of groves purposely machined in to flange faces, a phonographic, helical, and concentric rings.
This paper has some further information on the merits and disadvantages of each and other good information on bolted joints.
