CoatingsPro Magazine

MAY 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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Page 52 of 92

52 MAY 2018 COATINGSPROMAG.COM platform required constant coordination with the Coast Guard and local sightseeing vessels due to extremely tight vertical clearance constraints. e existing clearance of the bottom of the bridge to the average water level was 40 feet [12.2 m], and some commercial vessels that travel the A llegheny require 38-foot [11.6 m] clearance. Our Safespan support cables and chains had to be installed to the perfect height, and water levels had to be constantly monitored during abrasive blasting when spent abrasive could accumulate on the platform and reduce the vertical clearance," explained Skaroulis. A lthough much of the work was done from the Safespan platform, there were other areas above deck where scaffolding was erected or pneumatic lifts were used by the crew. In these areas, fall protection was one of the primary safety concerns. e crew used harnesses with double lanyards in conjunction with rope grabs to maintain 100 percent tie-off. "Because the Safespan platform had handrails and was a self-contained platform, fall protection wasn't needed while we were blast- ing and coating," stated Skaroulis. However, regardless of whether the work was taking place on the Safespan platform, on scaffolding, or on lifts, the crew wore personal protective equipment (PPE) during abrasive blasting, including Nova and Bullard supplied-air hoods. During coating application and mixing, the team wore 3M half- and full-face respirators. Hard hats, safety glasses, high-visibility vests, gloves, and steel-toed boots were worn at all times. Contain and Monitor One of the most important, if not the most important, aspects of the job was abrasive blasting the structural steel to NACE No. 2/Society for Protective Coatings (SSPC) Surface Preparation (SP)#10: Near-W hite Blast Cleaning. During Southern Road and Bridge's first mobilization, all structural steel was blasted using ARS S6 blast/recycle units, each paired with two 1600 CFM (45.3 m³/min.) compressors and an ARS DC-45 dust collector. During the second mobilization, the crew blasted the exposed buckle plate steel using an ARS S-2 blast/recycle unit, one 1600 CFM (45.3 m³/min.) compressor, and a 20,000 CFM (566.3 m³/ min.) dust collector. "Many people don't know what buckle plates are, and in fact, I had to look it up myself when looking at the specifications of the job. Simply put, buckle plates support the rebar and concrete of the bridge deck," said Skaroulis. For both mobilizations, containment was a critical part of the abrasive blasting process. e overwater, downtown location is in close proximity to many businesses and heav y pedestrian/automotive traffic. "is necessitated an extremely secure containment during abrasive blasting," said Skaroulis. Impermeable tarps manufactured by Eagle Industries were used to completely contain the Safespan platform. According to Skaroulis, the containment material went from the bottom of the platform to the sidewalk and over the top of the handrails. e same impermeable material was also used on the scaffold- ing and in areas where the crew used pneumatic lifts to access the blast area. "Containment was always a priority on this job," stated Skaroulis. In addition, Southern Road and Bridge had third party high-volume total suspended particulate (TSP) monitoring at five locations during the abrasive blasting, with two locations always in use simultaneously during each phase of the blast- ing process. (e location of the two TSP monitors in use at a particular time depended upon the location of the blasting.) "e TSP monitors looked like metal bird houses and measured the particulates in the air. MB Environmental Consulting installed calibrated, collected data and sent samples to the lab for analysis. We successfully maintained emissions to below the A llegheny County daily allowable TSP-Lead of 10 ug/m3 [0.3 ug/ ft.³] as an 8-hour concentration and 25 ug/m3 [0.7 ug/ft.³] at any time," said Skaroulis. Complex Coating Job Once the abrasive blasting was completed, it was time for the crew to apply the Sherwin-Williams coatings. Much of the struc- tural steel, including the eyebar chains, towers, floor beams, and girders, received the same system: Zinc Clad III Organic Zinc-Rich Epoxy Primer, Macropoxy 646 Fast Cure Epoxy, and Acrolon 218 HS Acrylic Polyurethane. A ll of these coatings were In addition to wearing hard hats, safety glasses, gloves, and steel- toed boots at all times, the crew also relied on a Safespan platform for below deck work. The platform spanned 58,000 square feet (5,388.4 m²). Wearing 3M respirators, the crew coated the steel with an epoxy primer, epoxy intermediate coat, and polyurethane topcoat. The cells on the girders also received the primer and two coats of the epoxy. Andy Warhol Bridge

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