Large Diameter Penstock Condition Assessment & Replacement: Two Case Studies

Many existing hydroelectric penstocks that were placed into service 80-90 years ago are showing signs of deterioration. As a result, Owners are more concerned about the dependability of these important assets that generate revenue 24 hours per day, 365 days every year. This paper presents the condition assessment investigation on two large-diameter, riveted-steel penstocks and the remediation actions (repair or replacement) offered by the design team along with the ultimate solution that was acted upon by each owner. The first penstock, 96" x 1/4" steel pipe, riveted construction, was partially buried with constructing commencing in 1924. The assessment and design for this penstock was completed in 2011 with construction commencing in 2012. The second penstock was installed in 1924 and consists of a buried, 216" x 3/8" steel pipe, again riveted construction. The assessment and design was completed in 2012 with construction commencing in 2012.