New Interior Lining for Welded and Riveted Penstocksby Richard D. Stutsman, Pacific Gas and Electric Co, San Francisco, United States,
Abstract: Pacific Gas and Electric Company (PG&E) has 73 hydroelectric power facilities installed throughout its distribution system. Each of these facilities has at least one penstock, which conveys water from a dam, forebay intake structure, tunnel or canal to a powerhouse. To preserve the structural integrity of these steel penstocks, corrosion protective linings were initially provided. However, due to age, many of these linings have deteriorated. This paper discusses a new interior lining material that PG&E has successfully tested in both the laboratory and the field with older welded and riveted penstocks. This material is 100% solids elastomeric polyurethane applied over a sandblasted steel surface using conventional plural component spray equipment. The polyurethane film exhibits good abrasion resistance as well as good elastomeric properties. These properties are important for penstock applications because of migration of sands and gravels along the penstock inverts and the large temperature differentials that can exist between the watered and dewatered conditions. Since 1986, PG&E has performed test applications of the polyurethane material on penstocks at three powerhouses. Based on the successful performance of the material and the application techniques learned, PG&E plans to apply the lining material on a number of penstocks over the next several years.
Subject Headings: Conduits | Linings | Electric power | Polyurethane | Hydro power | Water intakes | Power plants
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