Brass soft seat retention skirts having high-stress concentrations are susceptible to stress corrosion cracking (SCC) [Refer EIGA Doc. 21/19]. SCC occurs when stresses, corrosive environment & time act together and is observable in gases like Carbon Dioxide and Acetylene in the presence of moisture.

The lower spindle material is constructed from 300 series Stainless Steel to eliminate the possibility of SCC.