Heat Transfer Fluid (HTF) Expansion Vessels are component parts of a solar power plant and are designed to hold the HTF, which transfers energy from solar collector arrays (SCA’s) to steam generators.

These vessels undergo extreme thermal cycling in their daily operation. The vessels begin to warm up at sunrise as energy becomes available and quickly reach maximum operating temperatures and remain there until the solar energy starts to fade and the vessels cool off. Shorter, less service, thermal cycles also occur during the day when passing clouds partially obscure the sun and reduce the day when clouds partially obscure the sun and reduce the amount of solar radiation available.