The AASHTO M232 specification covers zinc coating (hot-dip) on iron and steel hardware.  A newer and more fastener-appropriate specification, designed to replace M232 Class C, approved in 2005 and covering the requirement for hot-dip galvanizing bolts, screws, nuts, washers, and other threaded fasteners is ASTM F2329. It is slowly becoming more widely used and referenced, but many publications and technical manuals are not revised on a regular basis, so it may still be a while before F2329 is widely adopted. AASHTO M111 is a related hot-dip galvanizing specification covering iron and steel products made from rolled and pressed shapes, castings, plates, bars, and strips. This standard is identical to ASTM A153.