Ran a recent tank design per API 650 with bottom plate thickness=10mm per client's specification. The tank is located near an active fault and should be mechanically anchored. API 650 does not require annular plates be equal in thickness or thicker than bottom plates for such tanks. Therefore TANK 3.30 is correctly giving min. annular plate thickness as 9mm per Table 5-1a and calculating the minimum width.

Unfortunately the client's specification is asking for the annular plates to be at least as thick as the bottom plates. To match the client's requirements we are currently adding new explanatory notes to the report and changing calculated weights by hand. It is a cumbersome task to carry out when there are 20 different sized tanks and when we have to do 2 different calculations for each tank (one for hydrotest with tank filled to the top angle without corrosion and the other for operating height taking corrosion into account).

Though we have not been challenged till now, this editing, we think, may rise question marks regarding the dependability of the rest of the output file.

It would be nice if the annular plate thickness and widths could be entered manually, cross-checked with the minimums per the std. and weight calculations be carried out with the higher thickness and width.

It would be even nicer if an optional fluid height entry be added for hydrotest case as extra fill height for hydrotest is quite a common issue we are facing.

These are both good suggestions. I'll add them to the development list.