Hazards crevice corrosion

Solid centre shafts are heavy relative to their strength, compared with tubes hence solid shafts tend to be used only on short feed screws. Bolted-in end shafts, a fairly common form of construction for some standard ranges of screw conveyors, are rarely used for feeder screws, as these are less strong than welded-in end shafts and present hazards relating to hygiene, cross-contamination, crevice corrosion, and fatigue failure. 

A freeze-drier intended for processing hazardous products should ideally be fabricated from stainless-steel since this metal displays excellent corrosion resistance to a wide range of sterilants. The freeze-drier chamber should be smooth and crevice-free to facilitate topical cleaning. 

---