A penstock is a group of pipes that transport pressurised water from a reservoir (dam) to the turbines installed in a hydro-electric power plant. Depending on the site’s topography and the technological options available at the time of their construction, penstocks may be located above or below ground and made out of either steel, reinforced or prestressed concrete, composite materials (fibreglass reinforced polyester, HDPE, etc.) or even cast iron.
Steel penstocks, whose sections consist of rolled flat plate, make up the majority of the pipes in operation. Historically, these structures were made out of steel as it was closely linked to the know-how and progress made in the field of metallurgy and compatible with the implementation methods that existed at the time (handling of pipes on the site, in particular). There are several assembly techniques to connect the sections, which can be riveted, water gas welded, flanged, auto-tightened, mechanically welded, etc.
A penstock is generally supported by civil engineering structures: thrust blocks that hold the penstock in place and bear most of the mechanical stress transmitted by it; in the case of an above-ground penstock, small piers bear the weight of the penstock and of the water that it contains between two thrust blocks. Depending on the type of ground, these civil engineering structures require the installation of tensioned or non-tensioned tie rods to channel mechanical stress into the ground.
Hydrostadium is an expert in the undertaking of studies in this field and in the management of penstock repair, renovation or construction projects. Depending on the structure’s location, some work can be particularly technical given the length of the penstock (sometimes several kilometres), access conditions, steep slopes and environmental conditions, etc.