This paper discusses novel applications of anodic protection, weld overlay, and thermal spray coating for corrosion protection of carbon steel batch and continuous digesters. Anodic protection now offers the possibility of protecting behind screens and blank plates. Stainless steel weld overlay can be applied behind headers for protection against erosion-corrosion. Thermal spray coatings can be applied over circumferential weld seams for protection against stress corrosion cracking. Also discussed are the advantages and disadvantages of each protection mode as well as their compatibility with each other.
Keywords: acid cleaning, anodic protection, clad plate, digesters, duplex stainless steel, erosion-corrosion, intergranular attack, pitting, pulp and paper, stress corrosion cracking, thermal spray, weld overlay