Pit depths of all coupons in rural and urban sites were
still less than 5 µm. Among all sites, coupons of the
same grade and surface finish in marine site had the
highest pit depths. 304 MF had the lowest pit depth
of 13 µm and 430 had the highest pit depth of 32 µm.
Rating numbers of all coupons in rural site were
between 6 and 7. The coupons in marine had the
lowest RN.