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Valve Techbook 2017

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26 | September 2017 | VALVE TECHBOOK: CASE STUDIES O wners and operators of offshore platforms, floating production storage and offloading units (FPSOs) and floating liquefied natu- ral gas (FLNG) facilities face important challenges due to valve size, weight limitations and high levels of corrosion in the marine environment. Boosted by the constant need for higher production capaci- ties, offshore applications require more robust and compact products. Emerson's Vanessa triple off- set valves (TOVs) have proven effective in address- ing these issues due to innovative product designs and material selection with a history of successes in this industry dating back more than 20 years. Three brief case studies that validate the effectiveness of Vanessa TOVs for offshore applications are included in this article. Why triple offset valves for offshore? Significant technological developments have been made in the butterfly valve segment over the past 40 years--the reduction or complete elimination of rubbing during rotation is part of the evolution of this type of valve. These relatively new designs (double offset, also known as high performance, and triple offset) ensure longer life cycles, require lower mainte- nance and provide an improved leakage performance compared to concentric types. Nonetheless, the differences in terms of capability and functionality between double offset valves and triple offset valves are still somewhat confused. The Vanessa valve was the first to provide a triple offset valve capable of performing zero leakage by using a non-rubbing design across the entire 90° rotation (differently from double offset valves), delivering a sin- gle, instantaneous contact between sealing elements only when a closed position is achieved. (Zero leakage means no visible leakage when tested at high pressure with water and low pressure with air according to existing international standards.) Vanessa TOVs are able to handle bidirectional flow and tightness in both sealing directions up to ASME class 1,500 pressure due to the combination of such non-rubbing rotation with torque seating (a key difference with position seated concentric butter- Triple Offset Valves Can Replace Ball, Gate and Butterfly Valves By Marco Ferrara and Sergio Casaroli Emerson Automation Solutions Emerson's Vanessa Series 30,000 triple offset valves address the need for higher production capacities and more robust, compact designs for offshore applications. (Images courtesy of Emerson Automation Solutions) They are proving effective across a wide range of offshore applications.

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