Official Answer
Answer
AISI 316 stainless steel is preferred for marine environments due to its molybdenum content ($2-3\%$), which enhances resistance to pitting and crevice corrosion in chloride-rich sea water. Unlike AISI 302, 316 is significantly more stable against corrosion but has a lower tensile strength ($10-15\%$ less). This means the thrust capacity of a 316 ring will be lower than a 302 equivalent. For subsea sensors, the non-magnetic property of 316 (permeability $μ_r < 1.02$) is often essential. Engineers must account for the lower yield strength in their $P_r$ and $P_g$ calculations and may compensate by using a slightly thicker material or a deeper groove to maintain the required safety factor.
