Electric Hard-Seated Butterfly Valves

Laminated Stainless/Graphite Class

Engineered for saturated steam, hydrocarbons, and cryogenic applications up to 425°C (Class 150/300). Alternating layers of high-grade 316 stainless steel and flexible graphite rings provide resilient multi-line sealing contact, ensuring bubble-tight ANSI Class VI shut-off with natural self-compensation for thermal piping shifts.

• API 607 & ISO 10497 fire-tested and certified
• Zero seat-to-disc rubbing eliminates galling across 100,000+ cycles
• Field-replaceable laminated seal ring on the disc face

Solid Stellite Metal-to-Metal Class

Built for severe abrasive catalysts, refinery coking, hot flue gases, and thermal power lines up to 550°C+ (Class 300/600). The valve body seat and disc edge are hard-faced with supersonic weld-overlayed Stellite 21/6 alloy, resisting particle impingement, wire drawing, and thermal erosion.

• Withstands severe erosive slurry and particulate fly ash
• Class V metal-to-metal high-pressure shut-off
• Extended high-temperature bonnet keeps electric actuators cool

Friction-Free Triple Eccentric Geometry

By combining shaft axis offset, pipe center offset, and an inclined conical sealing cone, the disc lifts out of the body seat instantly upon the first degree of rotation. Zero rubbing eliminates seat wear and dramatically reduces actuator torque.

Certified API 607 Fire-Safe Security

Because no soft elastomers are used, the all-metal and graphite sealing construction inherently withstands refinery pipeline infernos. Tested and certified to API 607 / ISO 10497 to maintain pressure containment during and after destructive plant fires.

Thermal Stand-Off Actuator Isolation

High steam lines conduct intense heat up the valve stem. DELCO integrates cast heat-dissipation cooling fins and a 150mm stand-off bonnet column that lowers conductive temperatures below 60°C, protecting actuator motor electronics.

True Bidirectional Tight Shut-Off

Unlike older single-direction butterfly valves, our precision-machined conical seat geometry provides tight Class VI isolation regardless of flow direction, allowing flexible installation in reverse-flow district heating and pump discharge lines.

Live-Loaded Graphite Stem Packing

High-density flexible graphite die-formed packing rings are pre-stressed with Belleville spring washers. Dynamically compensates for frequent thermal expansion and contraction cycles, eliminating hazardous fugitive steam or gas emissions.

High-Thrust Intelligent Actuation

Triple-offset valves require precise torque-seating at final shut-off. Paired with industrial electric actuators equipped with mechanical torque limit switches, 4–20mA digital positioners, and handwheels for exact mechanical wedging.

1. What is the difference between concentric, double-offset, and triple-offset butterfly valves?

• Concentric: Center-line disc with rubber liner; continuous rubbing across 90° stroke; limited to low temps (≤ 120°C).

• Double-Offset: Disc cams away from seat early in travel; uses PTFE seats up to 200°C.

• Triple-Offset: Adds a third geometric angle (conical seat geometry). The disc makes contact with the metal seat only at the exact point of final mechanical closure, creating zero rubbing and enabling bubble-tight metal seating up to 550°C+.

2. Why is "torque-dependent seating" essential for triple-offset electric actuators?

Unlike standard butterfly valves that shut off purely by positional limit switches (angle-dependent), triple-offset metal valves achieve zero leakage through mechanical compressive wedge force (torque-dependent). DELCO electric actuators utilize sensitive Belleville spring torque switches that drive the disc into the conical seat until a verified torque threshold is reached, ensuring bubble-tight shut-off regardless of thermal pipeline expansion.

3. Can laminated metal-to-metal seats be serviced or replaced in the field?

Yes. DELCO mounts the laminated stainless steel and graphite seal ring directly onto the disc perimeter, secured by a heavy-duty bolted retaining flange. If damaged by severe pipeline debris, maintenance technicians can replace the laminated ring kit directly without replacing the entire disc or valve body, drastically reducing life-cycle MRO expenses.

4. How does the extended bonnet protect the electric actuator in 400°C+ steam lines?

Electric motors, capacitors, and microprocessors fail rapidly when exposed to temperatures exceeding 70°C. DELCO casts an extended high-temperature bonnet stand-off column (100mm to 200mm high) equipped with convective heat-dissipation fins. This isolates the ISO 5211 actuator mounting platform from the valve body, allowing natural air convection to keep actuator electronics safely within rated limits.