Cracking and corrosion performance of composite tubes and air port designs in a kraft recovery boiler

Alternative composite tube systems fabricated into two different port designs were installed in a kraft recovery boiler to evaluate their effectiveness in solving a composite tube cracking problem. Test ports have been examined for cracking and corrosion of the cladding/overlay every six months since the time of their installation. Test ports with co-extruded modified A825/carbon steel composite tubes, and port design designated "B" were the only one where no cracking or corrosion was found on any of the tubes after 30 months of exposure.