AutoPIPE contains a multiplier of the density defined in the pipes. This multiplier is defined for each Analysis Set and therefore allows calculating each analysis set with a different density, either because the product changes density with temperature or because the piping system will work with different products.
Thermosolar plants use Thermal Oil (HTF Heat Transfer Fluid) to bring the heat from the solar collectors to the steam generators or HTF-MS heat exchangers, where the heat will be stored in Molten Salts (MS).
The density of HTF varies a lot with temperature, in the minimum temperature range in which it has a viscosity that it can be pumped, up to the maximum of operation, its specific gravity changes from 1 to 0.65.
When the thermosolar plants began to be designed, the pipes had a small diameter and the effect of the change in fluid density was less. Currently with large diameter pipes its influence is great and we must consider it when calculating the springs or the loads on the equipment.