This study evaluated reuse of lime softening sludge, generated from drinking water treatment utilities, as an environmental sorbent for capturing SO2 and heavy metals in wet scrubbers of coal-fired power plants. Specifically, Part III evaluated viscosity and metal corrosion as practical issues in the transition from limestone to lime sludge at power plants. Results of Marsh funnel viscosity experiments conducted at different solids contents and temperatures indicated the limestone and lime sludge slurries and their gypsum counterparts had similar flow characteristics. Carbon-steel, stainless-steel, and Hastelloy coupons were tested for corrosion by lime sludge and limestone slurries. Both stainless steel and Hastelloy were resistive to corrosion in slurries made from lime sludge or limestone samples or their gypsum counterparts. A considerable but similar amount of corrosion was observed for carbon-steel coupons exposed to lime sludge and limestone slurries. Adding 5000 ppm of Cl to slurries considerably increased the corrosion rate of carbon steel. This dataset is associated with the following publication: Dastgheib, S., J. Mock, H. Salih, and C. Patterson. Utilization of Water Utility Lime Sludge for Flue Gas Desulfurization in Coal-Fired Power Plants: Part III. Testing at a Higher Scale and Assessment of Selected Potential Operational Issues. ENERGY AND FUELS. American Chemical Society, Washington, DC, USA, 33(11): 11536-11543, (2019).