Calculation of required flange thickness (App. 2) 2

Kelly,

The required flange thickness may be based on either the calculated stresses or the flange rigidity. In re-rating calculation mode ("Get Pressure Rating&quot the flange stresses are calculated and reported based on the actual flange thickness. The required flange thickness is also reported (at top of report) but no details are provided. You can confirm that the value reported is accurate by changing the actual flange thickness to the required thickness reported by COMPRESS; in that case either of the following should occur: (1) one of the calculated flange stresses for operating or gasket seating will equal its corresponding allowable stress, or (2) the flange rigidity Index "J" will equal 1.0 (flange rigidity is now a mandatory Code requirement with the A05 Addenda, previously this was an optional calculation).

Similarly, the flange report shows the flange MAWP without details. This pressure may be limited by the flange stresses, flange rigidity, or the required bolt area. Changing the flange's design pressure to the reported MAWP should result with one of these three criteria meeting its corresponding Code limiting value.

Tom Barsh
Codeware Technical Support

kll777:
If you are making a repair/replacing a portion of an existing vessel you can replace "like for like". The new rigidity calculations will produce a thicker flange than an original CODE, before 2004 A06. Design using the original code.