The world's largest galvanizing kettle recently
hot-dipped the heaviest single item ever in North America--and maybe even
the world.
On Jan. 10, a single bridge tower anchor fabricated from
50-gage steel and weighing 86,000 lb was gently raised from the "super
kettle" at the A-Plus Galvanizing Inc. plant, Salina, Kan. This tower
anchor will eventually be a key component in the construction of a new
cable-stayed bridge in Columbus, Ohio.
The event was all in a day's work for Brian Morgan,
operations manager for A-Plus. Morgan said the whole process began a while back
when A-Plus was contacted by PDM Bridge, a contract bridge fabricator from
Wausau, Wis. According to Morgan, they were in need of a galvanizer with
significant capacity. PDM Bridge had heard of the Salina firm through sources
in the industry.
"I dealt with PDM Bridge directly before the product
was ever built concerning specifications about our capacity. In the beginning,
once I was shown the drawings and knew the dimension and weight requirements, I
was able to assist them with information about our capabilities and capacity
concerning galvanizing."
As you can imagine, there was a lot of communication between
A-Plus Galvanizing, PDM Bridge and the bridge designer before the part was
fabricated in Wisconsin and transported to Kansas for galvanizing.
The 31/2-hour process started with the 43-ton steel
anchor being dipped into a cleaning solution. Then two rinses were followed by
a sulfuric acid bath that cleans the steel. The anchor went through two rinse
tanks before heading to the flux tank, which was filled with a zinc ammonium
chloride solution that removes oxides and prevents oxidation prior to
galvanizing. The final phase was the dipping into the A-Plus Galvanizing super
kettle which was filled with molten zinc at around 830°F.
After being completely submerged for approximately 10
minutes in the kettle, the piece was lifted out by one of the four 50-ton
cranes at A-Plus. The galvanized part then spent between 6-8 hours cooling,
going through inspection and preparation for transportation back to Wisconsin.
"The capabilities and the capacity of this kettle and
our facility to handle beams such as bridge structures opens up the market for
large items to be galvanized by single dipping," said Morgan. "In
the past, items this size would normally be painted for limited protection
because it would not fit the physical capacity of the galvanizing industry. Any
time you can single dip an item, it's better quality."
Ray Iesalnieks, project manager for PDM Bridge, is a bridge
contractor with considerable experience in fabricating complex bridge
structures. He worked in conjunction with structural engineer and bridge
designer Dave Jones of Jones-Stuckey Ltd., Columbus, Ohio, to develop the tower
anchor, which required galvanizing.
"In the beginning, we had two options supplied by the
designer, and that was to either galvanize or metalize," said Iesalnieks.
"We were not able to metalize, which requires a spray-coating process. It
wasn't feasible in this situation. We had heard about A-Plus Galvanizing
but this was the first major project we had tried with them. Due to the weight
of the item it required a galvanizing operation with a lot of crane capacity
and a big kettle."
The cable-stayed bridge will be the gateway entrance for the
Ohio State University campus crossing over the Olentangy River in Columbus.
According to bridge designer Dave Jones, the bridge is a
two-span cable with the tower at the middle. It has a 387-ft span and is 165 ft
above the roadway.
The tower anchor will be used where the cables are tied off
at the top of the tower. The two pieces of galvanized steel, standing 40 ft
tall, will be encased in concrete. Jones said, "We felt concrete alone
wouldn't withstand the forces. So we solved this problem by going to
steel. The reason we galvanized it was because the bridge owner, Franklin
County Ohio, wanted a life span of over 100 years. We could have metalized it,
but felt that the steel could be galvanized. At the time, I didn't know
that the anchor would be the heaviest item to be hot-dipped galvanized. This
was a complete surprise to me. We knew it was heavy but we didn't know it
was the heaviest.
"We designed the project, then put it out on bid. The
contractor who got the bid ($15.4 million) then had PDM Bridge work on the steel
fabrication for the tower anchors. They found A-Plus Galvanizing with the
needed kett-le and crane capacity. This galvanizing project went a lot smoother
than a lot of them. I've heard from PDM Bridge that these parts are
fitting up very well."
Tom Langill, technical director of the American Galvanizers
Association, was at the A-Plus plant to witness the dipping event.
"To my knowledge this was the heaviest single item to
be hot-dipped galvanized in North America," he said. "In many
galvanizing operations, you couldn't do that size of piece because you
had to consider a bath and crane capacity large enough to accommodate that size
of piece.
"The features worked out by the designer, fabricator
and galvanizer allowed this piece to be galvanized very smoothly. In the past,
a project of that size and weight wouldn't have been considered for
hot-dip galvanizing. You may have had to paint that size of piece and therefore
all the surrounding pieces that went with it. The fact is, we can now galvanize
larger and heavier items."
With a kettle that measures 82 ft long, 10 ft wide and 12 ft
deep, one can imagine the possibilities for the next record to be broken.
