by Chad Thomas, RegO VP of global engineering and quality, email@example.com
While developing stainless steel globe valves for handling cryogenic liquids such as LNG, RegO incorporated several design features to help ensure that valves have a tight seal when closed, superior flow rate when open, simplified maintenance and a longer service life.
For example, RegO’s SK Series cryogenic valve designs feature a conical seat that is preferred over the flat design used in conventional globe valves. This feature delivers up to a 39 percent higher flow coefficient (Cv) for cryogenic liquids by enabling a higher volume of liquid to pass through; and in turn results in a 10 percent reduction in refill time for both trailers and bulk tanks.
The one-piece conical seal design opens wider to enhance the Cv, shuts more securely to reduce waste and eliminates seal damage due to over-torquing. It also has more contact area between the seat and seal, and reduces the probability of debris or contaminants in the seat with fewer parts to wear out. These features combine to deliver up to 15 percent more durability for valves with severe usage.
RegO additionally specifies PCTFE (polychlorotrifluoroethylene) material for seals used with its SK Series cryogenic valves, therein providing superior dilation and expansion coefficients when compared to alternate materials, such as PTFE (poly-
tetrafluoroethylene). In addition, PCTFE seals require significantly less torque to achieve a complete reseal after use.
While considering the design of the seal assembly itself, RegO has adopted a one-piece design that does not use nuts and washers to retain the seal. Such components can be subject to loosening due to vibration, which can affect other equipment in the system, such as strainers, flow meters, pumps and compressors. A single-piece seat assembly requires only a single wrench to remove the bonnet’s nut, compared to several different sized wrenches for conventional multi-piece seat assemblies.
Other LNG serving devices include RegO’s ergonomic handwheel design, bonnet pressure relief system and weld-in-place valves. The ergonomic handwheel design enables faster opening/closing times for more efficient operation, while also reducing both the stress for operators and carpal tunnel syndrome occurrences. A symmetrical handwheel design is also up to 50 percent stronger, with more durability and lower maintenance costs.
Additionally, RegO’s proven bonnet pressure relief system increases the life of the valve’s packing system by avoiding overpressure in the bonnet area.
Conventional bonnet valve designs employ a “weep hole” technology that releases more gases into the work environment and is inherently less safe. And such conventional bonnet valve designs also result in more leakage of liquid and gas into the packing system, requiring more frequent replacement, while involving recurrent and scheduled adjustments of the bonnet nuts.
Through careful design, RegO’s bonnet valves significantly reduce leakage around the packing system, requiring less frequent bonnet nut adjustment and eliminating deformation of the bonnet tube. Through the use of a perforated ring built into the valve as a pressure relief mechanism, pressure is allowed to expand into the valve stem and quickly equalize with pipe pressure, ensuring safer operation than a cryogenic system without bonnet pressure relief.
Conventional valves often do not employ “live load” packing, resulting in gas/liquid leakage over time as the system components wear out. RegO’s next generation valve designs feature live load packing to ensure a tighter, safer seal with reduced leakage.
Unlike many conventional valve designs that require disassembly before welding to protect internal components from damage due to conducted heat from the welding operation, RegO’s weld-in-place valves can be welded in place without disassembly to provide faster, easier installation. www.regoproducts.com ■