Materials in wet flue gas desulfurization (WFGD) air pollution control systems are exposed to aggressive corrosive conditions. In the past many of these systems were constructed of low grade stainless steel which has suffered significant attack. As a result these systems require repair and upgrade. This can be accomplished by overlay cladding with super-austenitic stainless steel and nickel-base corrosion-resistant alloy sheet. This process is sometimes referred to as “wallpapering”. This is a well-tested and established process and has been widely used for both new construction and repair of existing systems. However isolated lining leaks have occurred which are difficult to locate and repair. Established procedures are reviewed with emphasis on production of leak free welds with optimum corrosion resistance. Alternative repair methods such as coatings and ceramic overlays are sometimes used but require routine maintenance. By selection of proper base metal/weld metal combinations and diligent use of established cladding procedures a very serviceable and reliable “wallpaper” metallic lining requiring only periodic cleaning can be achieved at an economical price.
Keywords: corrosion, crevice corrosion, Wet FGD (wet flue gas desulfurization), duplex stainless steel, super-austenitic stainless steel, nickel alloy, pitting, chlorides, air pollution control, crevice corrosion, UNS S31277, UNS N08926, UNS N10276, UNS S31603, UNS S31803, UNS S32750, halides, sulfuric acid, wallpaper cladding repair, GTAW, GMAW