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February 21 - February 27, 2016

Alternatives to coal tar epoxies in wastewater/sewage applications have been in service for a number of years. From experience, which coating types with what fillers at what thicknesses (over steel) have performed best?

Selected Answers

From Todd Theis of Gulf Coast Paint Mfg., Inc. on November 7, 2016:
I would recommend a cycloaliphatic epoxy, applied in 3 coats at 7-10 mils DFT per coat.

From Anthony Koontz of Sherwin Williams on October 20, 2016:
I suggest a solvent-free elastomeric polyurethane at 60-80 mils dry film thickness.

From Tom Schwerdt of TxDOT on May 12, 2016:
Why would you switch from coal tar epoxy to coal tar urethane? Coal tar is unpleasant to work with and a carcinogen.

From Robert Olmstead of Olmstead Business Services International (OBSI), LLC. on May 6, 2016:
I am aware of many waste treatment/sewage plants going back to 1989, both domestically and internationally, that have successfully specified and maintained ongoing use of 2 coats of coal tar urethane (CTU) at 10-12 mills DFT per coat, on concrete clarifiers and similar structures. The coating is based on a single-component, moisture-cure urethane (MCU). On steel they use same spec over a MCU zinc or MIO Zinc (micaceous iron oxide) combination primer, at 2-4 miles DFT. They also use the same zinc primer under a MIO-rich intermediate (3-5 miles DFT) with an aliphatic MIO-rich MCU topcoat (2-4 miles DFT) for areas above the water/sludge line for severe chemical and abrasion resistance. The  material is conventionally applied. It must be high solids (>62% solds by volume) and VOC-compliant in all 50 states. These systems are well established and readily available in the marketplace.

From bart de cremer of acotec on April 25, 2016:
i suggest a solvent-free epoxy with a DFT of 1000 microns, a proven one-layer coating system to be applied by brush and airless spray with single- or plural-pump type Graco or Wiwa.

From Feng Min of Andritz Hydro on April 22, 2016:
I suggest a vinyl ester resin with glass flake filler at 300-1500um.

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Tagged categories: Asia Pacific; Coal tar epoxy; Coating Materials; Coating types; EMEA (Europe, Middle East and Africa); Latin America; North America; Sewer systems; Steel; Wastewater Plants

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