Metso’s revolutionary new control valve

Published: 25th September 2009 | Issue 3

Metso Automation have launched the new Neles® RotaryGlobe control valve, which combines the best features of proven linear and rotary valve technologies in small-bore control valves capable of operating costeffectively up to ASME 1500 pressure class. The flow characteristics of this new valve are just like those of a globe valve. By definition, the globe-style body design leads to a high pressure-recovery factor and, as in globe valves, the interchangeable trim selection includes low Cv, low noise and anti-cavitation trims to meet a wide range of applications with the same basic valve design. These factors, combined with compact size and the low emission characteristics of a rotary valve create a unique design, which offers higher standards of performance in flow-control accuracy and reliability, while reducing lifetime costs and maintenance requirements. Neles RotaryGlobe valves are designed to control a wide range of process liquids, gases and vapours in normal, difficult and even severe service.

Applications for the new valve span the petrochemical, chemical, oil and gas, refining, power generation and pulp and paper industries. Innovative design The Neles® RotaryGlobe valve features a compact, lightweight yet robust construction with a choice of trims. Its one-piece, globe-valve style of body minimises potential leak paths and provides enhanced anti-cavitation performance, whereas the rotary motion stem is employed to provide improved control of fugitive emissions. The modular design offers interchangeability of parts across the size range, a choice of body materials and a range of linear, equal percentage and balanced trims to accommodate even difficult applications; for example, under high-noise conditions, the low-noise trim can reduce noise by up to -20dB. Every aspect of the design has been carefully considered. The thrust bearing, which is isolated from the process fluid to reduce potential corrosion and erosion problems, incorporates a stem anti-blowout device. The new valve, available in the size range ½" 2", operates in the temperature range -80 degrees C to + 425 degrees C and meets all the requirements of both ASME and EN standards. It also fulfils all the latest safety requirements and environmental standards, e.g. ISO 15848-1 Emission control in the Neles RotaryGlobe valve Ever-increasing emphasis on environmental issues, as well as potential product loss, has meant that closer attention is now paid to emissions from control valves. This trend has made rotary valves more attractive, because they have inherently better emission control than linear valves. In linear globe valves, the rising stem tends to move process media into the gland packing area, thereby increasing gland-packing leakage.

By contrast, due to rotary stem movement, rotary valves do not draw dirt into the packing or bearing area. Hence rotary valves are less prone to gland packing leakage than linear globe valves. This is how the design of the Neles RotaryGlobe effectively decreases unwanted fugitive emissions but also eliminates the need for gland packing maintenance and maintenance costs. Other advantages of low fugitive emissions are that potentially costly end-product losses are reduced and, additionally, the danger of explosions, toxic atmospheres and injuries to the people are all lowered.

Metso, Tel: 0870 606 1478

Valmet UK Ltd