Designing to Prevent Corrosion of Sulfur Storage Vessels
Many chemical process plants produce elemental sulfur from the collection of waste gases containing sulfur. The sulfur is generally stored in its molten state so that it can be more readily shipped to buyers. This can come with its own corrosion problems, as explained in the bulletin.
Molten sulfur is normally stored in either concrete pits or steel tanks. Railcars are often lined with a polymeric or organic spray-applied liner due to frequent filling and emptying. These linings are seldom used in stationary tanks. Temperature is often maintained using steam coils with 50 psig (3.5 bars-g) steam. The saturation temperature of 50 psig steam is just under 300ºF (149ºC), which ensures adequate heating without the risk of overheating the molten sulfur. In railcars, steam jackets are used rather than internal coils.
Corrosion problems have been experienced in both carbon steel tanks and concrete pits that store molten sulfur.
Two design features of sulfur storage tanks that protect sulfur storage equipment are the steam coils used maintain the temperature of the molten sulfur and the steam suppression systems used to extinguish fires.
