Usable volume is not the same as geometric volume
A tank must accommodate the working batch, freeboard, foaming, level-control margins and any displacement caused by agitators, coils or other internals. Filling and discharge behaviour may also require a heel or minimum submergence. The design basis should therefore distinguish gross, working and minimum operating volumes.
Define operating and design conditions
Normal temperature and pressure are not sufficient for mechanical design. Start-up, shutdown, cleaning, blocked outlets, thermal expansion, vacuum during draining or condensation and static liquid head can create governing cases. Each nozzle, support and connected pipe may also introduce loads that need to be considered.
Heating and cooling duty
The required heat-transfer area depends on the batch mass, heat capacity, target temperature change, allowed cycle time, utility temperatures, overall heat-transfer coefficient and heat losses. Jacket type is then selected from pressure, cleanability, fabrication and heat-flux requirements. Agitation often has a major influence on the product-side coefficient.
Wall, jacket and material selection
Shell and head thicknesses must be checked for the specified design code, pressure or vacuum, corrosion allowance, forming allowance, tolerances and external loads. Dimple, half-pipe, roll-bond and conventional jackets have different pressure, cost and heat-transfer characteristics. Material grade is selected from the product and cleaning environment.
Agitation, nozzles and layout
Impeller type, baffles, bottom geometry, nozzle locations, access openings, level instruments and drainage should be developed together. A mechanically adequate tank can still be difficult to operate if product circulation, cleaning access or maintenance removal space is overlooked.
Project data checklist
Specify product properties across the full temperature range, batch size, process sequence, pressure and vacuum cases, utilities, mixing objective, cleaning method, surface finish, nozzle schedule, support arrangement, installation constraints and the governing design standard.