1600' Penstock Inspection

Some jobs are not glamorous! This penstock was installed more than a century ago and had not been inspected since construction. While the 48” diameter at the top seems roomy, the penstock constricts to two 17” penstock exits at the bottom. Overall, this 1903 penstock is 1,600’ in length and falls some 950’ in elevation between the forebay and the power station. Our scope was to stop at predefined intervals, take UT measurements, and measure rivet section loss. We also inspected the interior coating throughout. Our client asked us to return and inspect three more identical penstocks.

The Authorized Entrants always worked in pairs to affect a rescue, if required. During the inspection, the crew was in the penstock inspecting for 7 hours. An Entry Supervisor was on hand at all times, monitoring the Confined Space in accordance with the Confined Space permit. In addition to the UT and rivet inspections, all visible surfaces and members of the penstock were subject to inspection. Particular attention was paid to all riveted connections, areas of corrosion, observed deformations and damaged components.