Determining and Overcoming the Size Limitations of Hot-Dip Galvanizing

The following excerpt and image were provided by the American Galvanizers Association (AGA).

Authored by Alana Fossa and Brandon Jones

What is the largest item that can be hot-dip galvanized?

Hot-dip galvanizing is a complete immersion process, which means the parts must fit in the zinc bath to be coated. Ultimately, size is limited by the dimensions of the galvanizing kettle, but the kettle dimensions of galvanizers vary.

In North America, the average kettle length is 40 ft (12 m), but there are many 50-60 ft (16-18 m) long kettles. When it comes to galvanizing items over 40 ft in length or over 6 ft in width or depth, the question “will it fit in the kettle?” is an important one. However, the answer is more nuanced than a simple yes or no.

Over the years, the AGA has developed several tools to guide potential customers through the possibilities and alternative solutions when it comes to dipping items seemingly larger than the galvanizing kettle. These tools can benefit projects involving large bridge girders, pedestrian bridges, utility structures, wind towers, trusses, stairways, canopy frames, and more.

On a project specific level and during any phase of a project, AGA offers practical resources to determine whether fabrications can be galvanized due to size, and the options available for larger fabrications.

The remainder of the article outlines practical tips for addressing kettle size constraints during bridge and structural steel projects. It covers common kettle dimensions, the importance of early planning, and techniques such as modular design, progressive dipping, hybrid coating solutions, and direct consultation with galvanizers to accommodate larger or awkwardly shaped components.

Read the full article on the American Galvanizers Association website