News, engineering notes and stories from the Dadhivala Iron Craft team.
Hot-dip galvanizing (HDG) protects steel for roughly 20-70 years, pre-galvanized (mill-galvanized) sheet for about 10-25 years, and electro-galvanized (EG) steel for only 5-15 years before red rust appears.
A galvanizing kettle is a welded rectangular tank that holds molten zinc at about 445-465 °C. Good design comes down to three things: the right steel (low-silicon, low-carbon boiler-quality plate), the correct wall thickness (typically 40-60 mm depending on kettle size and heating method), and accurate sizing (internal length × width × depth matched to your longest product plus adequate freeboard). Get these right and a kettle commonly lasts 8-12 years; get them wrong and premature wall erosion or bulging can end its life in a few years.
Setting up a hot dip galvanizing plant is not a machinery purchase. It is a process project - and the decisions you take in the first four weeks, long before any steel is cut, will decide your cost per tonne for the next fifteen years.
