Because highway barrier pins will be exposed to the elements they are often required to have a protective coating. Hot-dip galvanizing is the most commonly specified protective coating for this purpose. After undergoing prepatory baths in caustic soda solution, sulfuric acid, and flux solution, the barrier pins are submerged in a tank of molten zinc which metallurgically bonds the zinc to the steel. This provides long-term protection against weather exposure and corrosion.
Commonly used specifications for hot dip galvanizing include:
- ASTM A153 – Iron and steel hardware
- ASTM F2329 – Threaded fasteners
- ASTM A123 – Steel shapes and plates
- AASHTO M232 – Corresponds to ASTM A153
- AASHTO M111 – Corresponds to ASTM A123
For more information on galvanizing you can visit the American Galvanizers Association.