Hi Ketan,

According to ASME B16.5 2003, Table 6, column 6, ASME allows a maximum 3.5" opening (< 4") at center of 24" std blind. This B16.5 coverage will help to skip calculation of blind thickness as well as reinforcement of opening on blind.

From 4" opening onwards, hub requirement will be started (need compliance to hub diameter X), become a flange rather than blind.

Please read footnote 1 for explanation.

Wish this help.

S K Tan