Double offset butterfly valves are industrial fittings intended for full opening or closing flow. They may be also used for a rough flow control. The valves are designed for operation with very hard industrial conditions demanding safety, reliability and minimum maintenance like for example: nuclear energy industry, water treatment, gas pipe-works, chemical industry, metallurgy, pulp and paper-making industry, shipbuilding industry, oil and petrochemical industry, heat recovery, steam heating, processing hydrocarbons, fuel storage in aviation industry.