CoatingsPro Magazine

JAN 2019

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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COATINGSPRO JANUARY 2019 75 ey started by subbing out the prep work. e subcontractor used waterjetting to get the steel and concrete ready to coat. Before they could get going with the sealer, the coatings crew was sure to mark off the top and bottom edges of the tunnel 's walls to set the coating range. e system started with a penetrating sealer on the concrete surfaces, called Nukote HLT-SR. at was applied with rollers from DULUX to an average thickness of 167 microns (6.6 mils). Next up were the epoxy primers, Nukote EP Prime II and Metal Prime II, which were applied to the concrete and steel surfaces (located at the tunnel 's intake), respectively. ose were spray-applied using Graco GH 300s, gas hydraulic airless sprayers, and then the crew used rollers to ensure the primers were spread evenly. Both of those materials were applied to an average thickness of 100 microns (3.9 mils) and took about four to six hours to cure. en it was time for the workhorse of the system to go down. e crew spray-applied the ST-M polyurea liner on top of the primers. at blue coating was applied using a Graco H-XP2, hydraulic reactors, to an average thickness of 7 mm (275.6 mils). e crew was aware of safety throughout the project. e job required work in man lifts from JLG, which meant the use of access equipment and donning of harnesses. Because the job took place inside the tunnel, the crew also had to use a large blowing machine at the opening and ventilation ducts inside. W hen applying the coatings, the crew was also sure to wear long sleeves, gloves, helmets, and National Institute of Occupational Safety and Health (NIOSH) approved self-contained breathing apparatuses in positive pressure mode with full-face pieces from 3M. ey also had toolbox talks and used safety staff on and throughout the job. A lthough heat was not an issue for the crew on this project — the working temperatures inside the tunnel were between 65 and 80 °F (18.3–26.7 °C) — it had the potential of affecting the coating application. "e difference between [substrate] temperature and dew point should be ≥5 °F [~3 °C] for coating operation," Wang explained. ey used tools to verify those The crew held toolbox talks and had a safety staff member on site. They were able to work around intense typhoons, but there were still delays from the general contractor. Using blowing machines at the opening and ventilation ducts inside, the crew worked on the polyurea topcoat, which was new to the coatings crew. They received training on the product and support from the manufacturer. Taiwan Reservoir

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