CoatingsPro Magazine

JAN 2013

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 78 of 100

"I remember the moment I went topside and told the plant managers there was bad news and good news," says Zaharias. "The bad news is that we were only doing one section an hour. The good news is that there was 30 to 40 mils (762 to 1,016 microns) of old epoxy on the pipe, and were still doing one section an hour. Needless to say, a change order was issued." Using Rozek's blast cart, the Sponge-Jet # 30 silver oxide knocked the old epoxy off and gave the concrete an ICRI CSP-3 surface profile. The Structural coatings crew then brush rolled a single 3 - 5 mil (76.20 - 127 micron) (DFT) pass of Structural Technologies V-Wrap 700 epoxy, formulated to also act as a directto-concrete primer. The two-part 100 percent solids epoxy is mixed by first using a mechanical mixer to premix Part A for two minutes. Part B is then added to the full contents of the Part A pail. Smaller batches may be created by mixing equal portions. After blending Part A and Part B for three minutes until uniformly blended, V-Wrap 700 delivers an approximate pot life of three to six hours at 68°F (20°C). After the primer cured, the crew hand troweled in one pass a 20-mil (508 micron) (DFT) coat of V-Wrap 700 thickened with fumed silica. A 32-ounce composite structural fabric was then wetted with V-Wrap 700 and installed over the trowel coat. Installing the fabric was a three-man job. One man wetted, rolled, and cut to length. Another installed the fabric. A third used a steel-ribbed roller to press the fabric into the epoxy. After allowing the coating to set up, the crew hand troweled a single 130-mil (3,302-micron) (DST) pass of silica-thickened V-Wrap 700. Immediately thereafter, Structural mechanically installed a 208-mil (5,283.20-micron) diameter steel wire into the still wet coating. The wire was installed utilizing a wheeled, cartbased machine that slowly moved inside the pipe. The cart was fed via a topside spool equipped with turntable and gooseneck that ultimately dished approximately 3.4 miles (5.47 km) of wire into the pipeline to fortify the pipe restoration. The machine's rotating arm moved at about 4 rpm to bury the wire, in hoop fashion, into the coating to achieve 2.5 wires per inch (2.54 cm). Once wire was in place, the crew troweled another 20-mil (508-micron) (DFT) coat of fumed silica-thickened V-Wrap 700 to cover the wire. The trowel coat was covered with another layer of 32-ounce composite structural fabric. Dessert cart As though this crazy-strong epoxy sandwich wasn't enough, project managers had another course in mind. Polyurea, ordered off the dessert cart! So they tapped the brains of another Wisconsin-based robot cart inventor, Mike Kronz, who runs Remote Orbital Write in Reader Inquiry #222 78 coatingsPro g January 2013

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