High-performance butterfly valves are widely used for equipment isolation and other on/off applications in a variety of chemical and petrochemical processes.
Common applications
A high-performance butterfly valve can be utilized in a number of scenarios, but it is ideally suited for equipment isolation and on/off applications that require bubble-tight, zero-leakage cutoff.
These valves are typically less expensive and need significantly less space than plug or ball valves. There are numerous butterfly valve designs on the market, with substantial differences in sealing performance and long-term durability.
Sealing and packing designs
When assessing a high-performance butterfly valve, users should consider the disc and seat design. Some butterfly valves wedge the disc into a soft seat and rely on process pressure to ensure a consistent shutdown. Such valve designs are only effective with pressure on one side of the valve and function poorly in bi-directional applications. Other valves have seat designs that wear constantly as the valve moves, resulting in leakage after only a short period of use and early seat failure.
Better designs incorporate a double offset, which raises the disc off the seat within a few degrees of motion while still allowing the disc to wedge snugly into the seat when closed, independent of system pressure. These innovations maintain bubble-tight sealing while reducing wear for a longer service life. Designs with a self-adjusting seal constructed of durable materials increase valve life even further.
Current environmental rules mandate low emissions, which usually necessitates high-compression packing. Live-loaded packing washers and innovative sealing ring materials provide customizable compression to reduce emissions while allowing for easy stem movement and decreasing component wear.
Body design considerations
User-friendly valves should have standard face-to-face proportions, an enlarged stem to accommodate insulation, and a mounting base that accepts the majority of actuators without the need for coupling or additional brackets. Some valve designs have a low-profile stem/disc to increase flow capacity.
Ease of maintenance
While a high-quality butterfly valve can survive for years, seat and packing wear is unavoidable, thus these components should be simple to repair or replace without removing the valve stem and disc. Though such repairs should be infrequent, ease of maintenance lowers overall lifecycle costs.
Key advantages
High-performance butterfly valves provide good sealing for equipment isolation and other on/off applications at a reasonable cost and in a tiny form factor when compared to other valve body types. Features like double offset sealing, improved disc seat designs, and low emission packing greatly improve performance, resulting in extra lifecycle cost reductions.
Visit the Butterfly Valves section of newzelindustries.com to learn about the whole variety of butterfly valves, from general purpose to heavy duty and high performance types.
