Flanges in and on equipment are calculated according the various calculation codes. The calculation codes such as the ASME VIII div.1, the EN 13445-3 or the EN 1591-1 have a different approach and different assessment criteria. For critical equipment and equipment flanges Red-Bag can execute all these calculations and compare the different results. Based on the strength assessment and the leak tightness assumptions has provided valuable information and suggestions to mitigate troubeled flanges. Manholes on storage tanks have usually a large diameter and a thin flange and cover. The internal pressure is relatively low and the temperatures are ambient. But after years of operation it occurred that the manhole flanges started to show problems. The general assumptions was that the bolt load should be increased but this did not solve the problem. The problem remained and additional problem was that the bolts and manhole were overloaded. Engineering services were provide by Red-Bag resulting in new bolt load and design parameters. (Vopak)