My earliest encounter with zinc was in my grandma’s basement. She had a wringer-washer with an assortment of rinsing tubs, all galvanized. I didn’t know they were coated with zinc, but I was pretty sure the shiny, grainy-looking coating kept them from rusting. The semi-dark, clean-smelling wonder of wash day was something special, rather like the smell of laundry freshly hung outside on the clothesline to dry. For younger readers, a clothesline is…oh, never mind.
In grade school, my next encounter was also memorable. We went to high school football games, not to watch the game, but to play our own brand of football behind the bleachers using a bunched-up paper pop cup as our football. I somehow got my foot caught under the chain-link fence and…there it was again, that funny-looking metal on the chain-link fencing. It was also capable of putting a hole in my sock and making my ankle bleed. This is when our fathers came behind the bleachers and told us, “Quit screwing around and watch the game!” Good advice, but there was nothing galvanized on the field.
High school chemistry class. Boring. Small high school. There were seven of us that took chemistry that year. Occasionally I passed the time staring in wonderment at the periodic table of the elements posted in all its glory on one wall. It was very close to the shelf of chemicals. There was the infamous bottle of potassium (K), immersed in liquid in a sealed glass bottle. NEVER EXPOSE THAT TO THE AIR OR YOU’LL ALL DIE. Refocus. Zinc (Zn), is between Copper (Cu) and Gallium (Ga). Zinc’s atomic number is 30. It has a filled d-shell, and knowing this allows me to sleep at night.
It is interesting that adjacent elements, copper and zinc, when combined, form brass. These metals are used extensively in the electric utility industry. And trombones.
The civil engineering program at Nebraska required a materials science course. The textbook had a multi-colored cover, so the class became “Rainbow.” In Rainbow, the wonders of zinc when galvanized onto steel became better understood. It was not just any ordinary coating slapped onto steel. With the correct process, metallurgy and temperatures, galvanizing creates a strong steel-zinc bond at a microscopic level that resists corrosion. Zinc blocks corrosive substances from reaching the underlying steel. It also sacrifices itself and will corrode before steel, so even if the galvanizing coating is compromised, the remaining zinc will still protect the steel.
As I began my electric utility career, galvanizing soon became a well-known material in my utility engineer toolkit.
Power-installed screw anchors – galvanized. Various hardware fittings – galvanized. Substation structures and fences – galvanized. All of these components used in the industry were designed to provide important, long-lasting value.
On one of my first tubular steel pole transmission lines, a contractor used chains instead of fiber slings to move the poles. They severely scratched the zinc coating. My initial reaction to this was NEVER EXPOSE THAT TO THE AIR OR YOU’LL ALL DIE. But because it was galvanized, it did not need any additional action. The poles are still in the air, and everyone is still alive.
On a line upgrade project, we removed some 69kV galvanized lattice structures to make room for the new circuit. The structures were in perfect shape…after more than 70 years of service. It was impressive. Galvanized steel continues to serve the industry very well to this day in a whole host of applications.
As with everything, things change. Galvanizing has been with us for at least 175 years, yet the industry continues to make improvements. Here are some trends to watch:
- The American Galvanizers Association is researching ways to produce galvanizing that provides a Grade B slip coefficient. In other words, if galvanizing can provide a slip-resistant surface, it can be used in an increasing number of applications.
- Another study is looking at ways to hot-dip A490 bolts without creating hydrogen embrittlement. For those of you who are concerned about your A490 galvanized bolts, you should watch for the results of this study. I am of an age where I’m more concerned with snapping a hip, but that may just be me.
- LEED rating systems are evaluating galvanized steel as a highly-sustainable building material. It is durable, has low life-cycle cost and is 100% recyclable.
As industry professionals, we have the obligation to design facilities that will successfully perform for decades. Galvanized steel is one material that we can use with confidence. Thank you #30!