How Do I Use the AGA Progressive Dip Charts?

The AGA Progressive Dip Charts are available to estimate the maximum article length which can be galvanized if the article height and galvanizing kettle dimensions are known. There are four charts which provide the output of maximum article length for articles of 1 ft, 2 ft, 3 ft, or 4 ft in height when considering a range of typical galvanizing kettle lengths and depths. 

These charts assume the article width is less than the kettle width and that 1 ft of the kettle depth is unused between avoiding the bottom dross layer and to account for a small gap between the zinc height and kettle height.

In order to use the charts, you will need to obtain the following information:

• Kettle Length in feet
• Kettle Depth in feet
• Article Height (rounded up to the nearest foot)

For example, let’s envision we have a wide flange beam (W24) to be hot-dip galvanized in a kettle sized 40 ft long, 5 ft wide and 6 ft deep. The properties needed to determine the maximum length of W24 beam that can be galvanized is:

• Kettle Length in feet = 40 ft
• Kettle Depth in feet = 6 ft
• Article Height (rounded up to the nearest foot) = 2 ft

Because the article height is 2 ft, we can use Chart No. 2 entitled Progressive Dip Galvanizing (Articles 2 ft in Height). First locate the kettle depth on the horizontal axis, and draw a line up to the curve associated with a kettle depth of 6ft (see Figure 3).

The chart indicates the maximum length of W24 beam that can be progressive dipped within a 40 ft long by 6 ft deep kettle is approximately 61 ft. Again, these charts assume an article’s width is less than the kettle width and that the galvanizer is avoiding immersion of the part in any bottom dross layer.

Note: Even if the article can be progressive dipped, the maximum height of articles above the bath, available rigging height, and maximum crane capacity varies widely by galvanizing plant and should be confirmed directly with the galvanizer ahead of time.

For additional resources on progressive dipping, check out the AGA Progressive Dip Calculator to determine if an article with more specific dimensions can be hot-dip galvanized within a galvanizing kettle of known size.