What is the difference between hot-dip galvanizing and pregalvanized steel?
Pre-galvanized tubing is typically thin walled, high strength steel tubing with the interior surface painted for protection and exterior surface coated with a thin zinc coating. During fabrication the tubing is cut to length and welded. A zinc rich paint is used to cover the area that was burned off through the welding process. This results in poor protection for the painted exterior and no protection on the unseen interior of the tube in the area of the welding heat. Hot dip galvanizing to ASTM A-123 occurs after fabrication when completed assemblies are immersed in a molten zinc bath. In this method, both the inside and outside surfaces of the material are galvanized and the protective zinc coating is generally many times thicker than on pre-galvanized tubing. This method of producing a zinc coated truss insures protection inside and out for many years with a service life that is more predictable.
Related Questions
- I’m interested in specifying hot-dip galvanizing for reinforcing steel. Are there any concerns with fabricating rebar after galvanizing?
- Are there any special design and fabrication considerations required to make steel ready for hot-dip galvanizing?
- What is the difference between hot-dip galvanizing and pregalvanized steel?
