Fifteenth-Year Evaluation of Experimental Test Linings in Shasta Dam Penstock

摘要

Twenty-five protective lining materials were applied during 1949 in short test sections to a 160-ft length of interior of the 15-ft-dia Unit 5 penstock at Shasta Dam on the Sacramento River in California. The purpose was to field test the most promising linings for their resistance to continuous fresh water immersion. Nearly annual inspections disclosed that many paints developed serious defects or failure early in the test; only 10 materials were unaffected at the fifth-year inspection. By the fifteenth year, 7 remained in excellent condition. These included VR-3 vinyl resin paint, a phenolic paint, and 5 somewhat similar phenolic red lead paint systems. VR-6 vinyl resin paint is considered also to have performed with the preceding coatings. Coal-tar enamel is performing well in the remainder of the 5 Shasta penstocks. The deterioration history of paints in this test suggests that defect-free performance by organic coatings in this exposure presages at least 15 yrs of effective protection against corrosion.