CoatingsPro Magazine

SEP 2018

CoatingsPro offers an in-depth look at coatings based on case studies, successful business operation, new products, industry news, and the safe and profitable use of coatings and equipment.

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60 SEPTEMBER 2018 COATINGSPROMAG.COM "e JLG operating manual warns not to operate the lift when the wind, including gusts, is above 28 mph [45.1 kph]. But 17 mph [27.4 kph] is scary. W hen the wind is high and the boom is extended, you can really feel it bending, and you just want to bring it down. In those cases, 80 feet [24.4 m] is a good limit to stay under. Better safe than sorry." But to really keep wind from sending this project into a tailspin, company owner McCahill relied on decades of project-sequencing experience and set aside one key component for what he called "filler work." "We held back on the interior of the stairway because we were able to paint a lot of it from the inside," said McCahill. " To be on an 185-foot [56.4 m] lift, you have to be real experi- enced and have a ton of courage. It bounces and moves, so when wind or weather kept us off the lifts, we climbed the stairway and painted." W hen they were on the lifts or other areas at height, the crew members were sure to wear safety harnesses and lanyards. Dust Storm By prepping and coating on the ground as much as possible and using the stairway as hold-back work, the McCahill crew managed to keep on schedule. at is, until they arrived on the jobsite one morning to find the dome covered with thick dust. e additional work order had the potential to push their coating schedule back. "About 75 percent of the dome was covered with dust from a pre-operation procedure," said Bulbucan. "We brought a Honda 2,500 psi [17.2 MPa] pressure washer up on the boom lifts and also harnessed up for rappelling. A lot of people think that when you pressure wash, you're just splashing some water around, but it takes a lot of brush scrubbing. e dust was kind of sticky, so we used an automobile-grade cleanser, the logic being that if it's gentle enough for a car finish, it's gentle enough for the tank 's industrial coating. It was a very difficult cleaning process, but we ultimately got every square inch of it looking like new again." Days lost during the cleanup were partly regained by working extra shifts and weekends, but help also came from the coatings supplier. Much of the structure was held together by galvanized bolts, thousands of them, which are susceptible to corrosion if not properly prepped and coated. According to a 2016 article in International Journal of Scientific and Research Publications, "Corrosion of metals can be disastrous to threaded fasteners. Surface and pitting corrosion attacks threaded fasteners as a result of contact with moisture or other corroding media. Corrosion, coupled with forces in a bolt, tends to accelerate cracking." Rather than stripe coat every nut and bolt on the stairwell and bridge with a brush, the McCahill crew broke out their Graco 395 electric airless sprayer and applied a single, approx- imately 1-mil (25.4 microns) dry film thickness (DFT) coat of Sherwin-Williams DTM wash primer. DTM wash primer helps galvanized steel bond with subse- quent coats, according to Sherwin-Williams commercial paint rep Erick Cavada. "It's an etching primer that chemically reacts to create a paintable surface," said Cavada. "DTM is not a film that sits on top but actually becomes part of the substrate." In lieu of waiting 6 months for the surfaces to weather, McCahill applied a test patch as per Sherwin-William's DTM product data sheet. The crew applied two coats of Sherwin-Williams Macropoxy 646, using spray equipment kept on the ground and brushes and rollers when working at heights. After prepping the steel with a fluidized abrasive blaster to achieve an average 2-mil (50.8 microns) anchor profile, the crew started in on Sherwin-Williams DTM Wash Primer to galvanized surfaces. Steel Coatings

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