The mooring was located in an estuarine river subject to regular flows of well-aerated seawater and
the shackle was stated to have been in service for approximately 6 months before the problem was noticed. Grade 316 stainless steel is known to be susceptible to both IGC and to pitting corrosion, and it would have been wiser to have specified
grade 316L with lower carbon content and hence a lower susceptibility to carbide precipitation and the associated grain
boundary chromium depletion