The galvanized pilings in the tidal
area had suffered extensive loss of steel thickness. The loss occurred in the
entire tidal zone and about 1 foot [0.3 m] above the high-tide mark. Even in
areas where the galvanization hadn’t failed, it was heavily weathered,” said
John Griffin of Grace Coatings.
Grace Coatings specializes in
coatings jobs with areas of rusted steel where environmental issues limit
blasting and coating options. With the knowledge gleaned from previous
and his team were ready to accept the challenge to clean and coat the pilings.
They proposed using a specialized hot water pressure washer to prepare the
surface of the pilings, priming the steel with LifeGuard Active Rust Primer,
and coating the substrate with two coats of PPG’s polysiloxane PSX 700 to
provide long-term coatings protection.
According to Griffin,
the Carolina Yacht Club wanted real-life proof that Grace Coatings’ plan was
the right solution for its dock pilings. During the month of September, a
single piling was hot water pressure washed and the LifeGuard primer and the
PSX 700 coating were applied. After five months, the piling was inspected and
the results were more than favorable. The Carolina Yacht Club gave Grace
Coatings the green light to proceed with the job.
The team, which numbered between two
and four men, started the job in early March. On one hand the timing was great,
considering it was the offseason, so the dock area wasn’t crowded. On the other hand, Mother Nature was less
than cooperative at times. “Cold and rainy days limited work a bit during the
two-month duration of the project,” said Griffin.
Inclement weather was not the only
consideration when it came to timing. Work on the pilings could only take place
during low tide, so the hours were very limited. “We started painting one hour
before low tide to ensure plenty of dry time. Luckily, the LifeGuard and the
PSX 700 are both fast-cure coatings. This made securing the pilings at low tide
easy,” stated Griffin. All in all, the Grace
Coatings crew cleaned, primed, and painted 50 pilings, each 2 feet (0.6 m) in
diameter. According to Griffin, depending on the
condition of the galvanized steel, the crew worked on a range of 6 to 8
feet (1.8–2.4 m) in length per piling.
In Hot Water
Working over the water in the Charleston Harbor
required extreme caution — life vests were worn during the job — and compliance
with environmental regulations. “We couldn’t spray any coatings, so both the
primer and the PSX 700 were brush- and roller-applied. Most significantly, we
couldn’t use any cleaning detergents or solvents. We could only use fresh water
for the surface preparation process,” said Griffin.
This is where the Cam Spray MCB7042H
CB Series oil-fired hot water pressure washer came into play. As stated by Griffin, this pressure washer is an indispensable piece of
equipment for jobs such as the one at the Carolina Yacht Club. The hot water
pressure washer is portable and requires no electricity as the water is heated
by an oil-fired burner that uses diesel fuel or kerosene to achieve 140° F (60°
C). “It is 7,000 psi [48.3 MPa] with a turbo nozzle to remove all loose rust
and scale. The pressure washer provides a unique combination of high pressure
with heat in a small portable package that can reach most any job,” said Griffin. And since hot water acts as a natural emulsifier,
no detergents were used, making the surface prep method compliant with
environmental regulations and containment unnecessary.
Just in Time
Once a piling was pressure washed (and hand tooled
where needed), it was time for the crew to apply the LifeGuard Active Rust
Primer. LifeGuard Active Rust Primer is a water-borne, acrylic primer with
natural tannins that allow it to adhere directly to a clean steel surface. “It
has a high tolerance for salt and is suitable for harsh marine and industrial
environments. It also dries to the touch in 15 minutes and is fully cured in 2
hours. This made it the perfect choice for the dock pilings,” said Griffin. In addition, the primer is biodegradable and
Working around the tide cycle, the
crew brush-applied two coats of the LifeGuard primer at 2–3 mils (50.8–76.2
microns) wet film thickness. The two
coats were typically applied in one day, with the crew coming back the next day
to brush-apply the PPG PSX 700 polysiloxane coating at a wet film thickness of
4–5 mils (101.6–127.0 microns). The PSX 700 is a fast-drying epoxy that is
long-lasting, ultraviolet (UV)-resistant, and slick, an important property for
standing up to the friction of the dock moving up and down with the tide
cycles. A second coat of the PSX 700 was applied again at a wet film thickness
of 4–5 mils (101.6–127.0 microns) the following day at low tide. It also should
be mentioned that the crew rinsed the pilings with fresh water between tide
cycles and before applying the next layer of coating.
According to Griffin,
the job at the Carolina Yacht Club was a success because of many factors, not
the least of which was strategic planning on the part of his crew. They also
used the right tools and materials for the project.
“Coating products that offer
long-term protection are a must when dealing with galvanized steel in and
around marinas, docks, and harbors. With both the LifeGuard primer and the PPG
PSX 700, we know that the coatings are manufactured especially to endure the
harsh marine environment. And they cure very fast, which was very important
when working around the tide cycles. Also, using the Cam Spray hot water
pressure washer was huge on this job — we were able to properly prep the
pilings and be compliant with the environmental regulations that exist anytime
you are working over water,” stated Griffin.