Many of the pulp and paper plants in North America are aging – the equipment is old and in need of maintenance and/or repair. Over time the harsh chemicals used in pulping and papermaking degrade the integrity of FRP bleaching towers, pulp retention tanks, J-tubes and FRP chlorine dioxide tanks. Periodic inspection, maintenance, and relining will significantly extend the life of the equipment.
Upon inspection, you may determine that remediation is necessary to maintain the integrity and safety of your pulping and papermaking operation. If the scope of work outlined by your inspector includes FRP relining, you will engage an FRP field services company to do the work for you.
It is important to understand that not all lining veils are the same and the performance will vary depending on the application. The optimal relining solution should provide anticorrosion and abrasion resistance at high temperatures to adequately protect the FRP equipment. It also must meet performance standards and regulatory requirements.
In side-by-side comparison tests of ECTFE, C-glass and polyester veils in sulfuric acid (98% at 250ₒF/121ₒC), sodium hypochlorite (13% at 200ₒF/93ₒC), sodium hydroxide (50% at 250ₒF/121ₒC), and nitric acid (20% at near boil), ECTFE veil performed very well. Only slight discoloration (due to a processing additive that does not deteriorate the ECTFE polymer) and only slight loss of strength in sodium hypochlorite was observed (whereas the others failed or completely dissolved). These tests were performed on veil fabrics, not composite samples, and were immersed in chemicals for 30 days.
For many years ECTFE meltblown was not available on the market. HTAC™ Veil – High Temperature Anti Corrosive meltblown veil – is now being manufactured by Monadnock Non-Wovens (MNW). HTAC is an apertured veil that is easy to laminate and wet-out in the relining process. It may be applied by hand lay-up and roll/tape winding, in an ortho winding or filament winding process.
Learn more about HTAC.
If you are a mill engineer, an FRP inspector or FRP field services company and you are interested in talking to us about HTAC, please don’t hesitate to reach out to Ray Whitby at MNW.
