Improved Cage Design–Drilled-hole cages, offering excellent strength and additional resistance to destructive vibration, are standard. Special materials of construction are readily available.
Piping Economy–The availability of expanded end connections on EH valves may eliminate the need for line swages while accommodating oversized piping arrangements.
O-ring Seat Ring Gasket Construction–Use of O-ring construction provides excellent shut-off with minimal seat ring installation torques for temperatures up to 232C (450F). O-ring construction is standard on EHT valves. The flat sheet seat ring gasket construction is available for elevated design temperatures and/or NACE constructions where a suitable O-ring material is not available.
Increased Pressure/Temperature Ratings–Steel EH and EHA valves with buttwelding end connections have Intermediate Standard Ratings. With nondestructive testing, these valves can conform to ASME Intermediate Special Ratings, which allow even higher pressure/temperature applications. See table 7 for specific ratings.
Long Trim Life–Hardened materials of construction for the cage, valve plug, cage guiding, and other trim parts are standard for all applications, providing excellent wear resistance. In all applications, rugged cage guiding provides increased valve plug stability. Increased stability results in reduced vibration and other mechanical stresses, which contributes to long trim life.
Control of Low Flow Rates/Tight Shut-off– Micro-Form or Micro-Flute valve plugs (figure 5 or 6) provide superb rangeability in high-pressure, low-flow applications. A choice of several restricted port diameters helps match valve capacity to required flow, helps provide necessary control with full travel, and helps prevent throttling near the seat.
High-Temperature, Class V Shutoff–Use of the metal C-seal (see figure 17) permits Class V shutoff up to 593C (1100F) for up to 4-3/8 inch port in CL2500 rated valves and 5-3/8 inch port in CL1500 rated valves. The metal Bore Seal will permit Class V shutoff up 593C (1100F) for 5-3/8 inch ports and larger.
Excellent Stem Sealing–HIGH-SEAL packing systems provide excellent sealing to conserve valuable or hazardous process fluid and to protect against the emission of hazardous or polluting fluids to atmosphere. This system (figure 1) features graphite packing material and heavy-duty live loading.
High Capacity–Careful consideration of aerodynamic and hydrodynamic principles in the design of the flow stream passages results in 30 to 40 percent higher capacity than conventional valves with comparable port sizes and travels.