Every four days a ship, loaded with LNG, leaves the facility to call at ports around the world. IMI CCI have a partnership with the customer going back more than 25 years with IMI CCI valves installed at all of their major onshore and offshore facilities for critical applications. This facility has over 25 IMI CCI valves installed in critical applications.
The site’s engineering team approached IMI CCI to upgrade the IMI CCI valves supplied in 2003 which were for anti-surge applications. The 18” x 30” and 24” x 32” valves with 16” and 20” DRAG® trim were operated in compressor recycle mode and hot gas bypass mode which was outside the original design of the valve, this caused vibrations in low lift conditions. Such vibrations on valves of this large size can impact the valve and nearby equipment, therefore the need was identified to resize the valves to include the new operating conditions.
IMI CCI rose to the challenge with a custom-designed DRAG® disk stack that has a progressive Cv versus stroke curve and a tri-linear characteristic. The high number of stages during low lift of the valve provides velocity control, high resolution and better controllability of the flow conditions -eliminating the vibrations. The custom-designed DRAG® disk stack could be installed in the existing valve bodies thereby saving the LNG facility significant cost.