VALVES AND TURBINES’ SEALS FOR HYDRO POWER PLANTS

Scenario

River water, even when clear, contains a high amount of debris that remain solid despite filtration systems work. This is a problem for valves and turbines’ mechanical components

Challenge

An important manufacturer of hydroelectric plants asked us to study a sealing system that could improve their lip seals’ life, generally used in turbines and valves

Solution

Analysing operational and technical data, ATP designers identified the main problem in debris. Seals were used in various points of the system, but they were exposed to not particularly heavy pressure levels (between 1bar and 36 bar). Moreover speed conditions were largely within range of use of a great number of materials that can be used for both rubber and polyurethane seals. The temperature could vary from 40 C to about 0 C in winter.

Analysing river water after filtering, our technicians found out that debris were composed of mixes of both soft and abrasive materials, such as mud, and hard and sharp materials, such as sand and rocks’ pieces.

Seal material had to have good resistance to both wear and low temperatures. By using our tribometer ATP technician could compare wear rates of various materials initially selected for this application. Especially, tribometer allows tribological analysis and thank to it is possible to identify, using defined standards, both friction coefficient and wear rate for specific combinations of speed and load. In view of the results obtained, our technicians proposed to use SINTEK HTPU LT PLUS, a hydrolysis resistant polyurethane with excellent wear resistance and elasticity proprieties even at low temperatures. Therefore it is usable even in particularly cold climatic conditions during winter.

Innovation guided our profile’s choice. Thanks to FEM analysis, ATP designers studied a new solution with a customized lip seal with multiple sealing points. FEM results were indispensable for correct points’ sizing and to simulate the wear effect by increasing the seals’ life.

We recommend to use OKS 1110, special lubricant based on silicone with consistency class NLGI 3, to assembly seals. It further improved the the sealing system performance.

Testimony

Thanks to the innovative multiple point solution proposed by ATP, we have significantly increased our seals’ life, reducing the number of interventions on the system.