Materials Performance Supplements

Corrosion Prevention and Control for Tanks 2017

Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.

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19 TANK CORROSION CONTROL SUPPLEMENT TO MP MATERIALS PERFORMANCE MAY 2017 for us on that one," he said. "Once they drained it, we jumped on the inside right away. The focus was on getting the inside done—all hands on deck for the interior." The interior took two days to finish, and the first step was surface preparation. Th e crew blasted most of th e steel to remove any rust and mill scale and to achieve NACE No. 2/SSPC-SP 10, "Near- White Blast Cleaning." They wore blast hoods during this stage. But due to the "hundreds of finger-sized holes in the bot- tom ring of the tank," as Doxey explains, the crew had to take great care in that area. " That's one thing that slowed us down. If we'd done the regular blasting, we'd have blown holes in that and taken finger-sized holes into fist-sized or larger." On the bottom ring, the crew used dual action sanders. " The only reason we had to use that was in the areas that were very thin; we would have just blown that bottom ring to pieces," Doxey explains. "There was a lot of scale and rust that came out from the inside of the tank." The client had a recep- tacle on site for the crew to use. "There was already a lot of scale in the bottom of the tank from settling. Then once we sanded and blasted , more came of f so we just removed that." Stripe, Coat, Repeat Wielding Graco Fusion † guns, the crew applied the primer the next morning and the polyurea a few hours later. They started with a full coat of Rhino Linings' 1500 † primer. They followed that with a stripe coat of the same—with a little extra finesse. This was "not just the typical stripe coat but from all angles," Doxey explains. "Right side, left side, top, and bottom—we stripe coated bolts and rivets from four angles to ensure full encapsulation and full seamless liner." They used the same stripe coat strategy with the polyurea too, which was Rhino Linings' HiChem 11-70 † . The polyurea was applied with a Graco E-XP2 Reactor † and a #01 tip applied at 80 to 100 mils (2,032 to 2,540 µm) on the f loor and 60 to 80 mils (1,524 to 2,540 µm) on the walls. According to Doxey, the system adds structural integ- rity back to the bottom ring. "Once they got the door on and bolted up then the crew focused on the exterior," Doxey says. Remember, time was of the essence! So much so that "in effect they were putting water back on the inside while we were coating the outside," he said. Wearing Tyvek † suits and full-face respi- rators, they used the same primer and poly- urea system to the walls on the outside of the tank. There was no need for forced air. "So in effect, we're sandwiching the heavily corroded and weak substrate in between our rugged and structural coating," Doxey explains. Fulfilling a Need Thi s smal l c ommunity was in dire need of access to its potable water. "From the time they emptied the tank, 72 hours later they had water back in it," Doxey says. Working 10-hour days, the qualified crew completed the ~4,200-ft 2 (390 m²) project on time and met that need. This article article was originally pub- lished on the CoatingsPro Ma gazine web site, ©Copyright CoatingsPro. † Trade name.

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