Leningradsky Metallichesky Zavod has manufactured a pre-turbine disc gate valve intended for technical re-equipment of hydroelectric power plants, where similar equipment has exhausted its service life.
The service life of the designed gate valve is at least 40 years, and the service life between overhauls is at least 7 years, provided that the gate valve is operated in an area with seismicity up to 8 points.
The pre-turbine gate valve provides shut-off of the pressure pipework and its opening both in operation conditions and in case of emergency. The internal diameter of the water conduit for which the gate valve is made is 5 meters, the maximum design head is 230 m. For such dimensions, the pre-turbine gate valve guarantees the possibility of safe work in the turbine scroll under the cover of the gate valve only. For this, the gate valve is equipped with two rows of seals (operational and repair).
To ensure tightness and to increase the operational reliability of the gate valve, Power Machines engineers developed and applied their own patented innovative repair seal design. The main advantages of the new equipment include ease of operation and minimization of the effect of the gate valve disc elastic deformations, that occur when the water conduit is shut off, on the performance and reliability of seals.
The prototype model of the gate has been shipped to the customer. The equipment weight is over 90 tons; the equipment is delivered by rail.
The pre-turbine gate valve acts as a locking mechanism for shutting off the water flow from the HPP dam headwater, which is supplied to it through a pressure water conduit. Shutting off occurs both for scheduled inspections and repairs of the wheel space parts of hydraulic turbines, and in emergency situations.