Specification
Telescopic Double Eccentric butterfly Valve Bidirectional Sealing Metal 4 Inch Double Offset butterfly Valve
Advanced Metallurgy
High-Temp Toughness: Ultra-low S/P CF8M bodies solution-annealed at 1100°C + cryo-treated (-196°C CVN ≥80J per ASTM A370).
Intergranular Corrosion Resistance: 0.15-0.25% nitrogen addition passes ASTM A262 Practice E.
Core Processes
Investment Casting:
Silica sol molds, Ra≤125μin finish, 100% RT per ASTM E192.
Seal Surface Enhancement:
Robotic PTA overlay (≤3HRC gradient) + diamond-ground to Ra≤4μin (flatness ≤0.0004″/in).
Bellows Fabrication:
Electro-polished (Ra≤16μin) with 2nm passive layer; ISO 15848-1 BH certified.
Extreme Validation Protocol
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Test
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Standard
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Condition
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Acceptance
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Thermal Cycling
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API 607 Annex B
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30x 600°C↔25°C shocks
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No seal cracking
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Telescopic Fatigue
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EJMA Section 9
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10k cycles ±15mm
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Zero leakage
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Bidirectional Sealing
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ISO 5208
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42MPa hydro / 6.9MPa pneum
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Rate A zero visible
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Torque Consistency
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MSS SP-67
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100k cycles
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≤±5% variation
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Performance Leadership: Redefining High-Temp Reliability
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Parameter
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NWV Valve
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Conventional Competitor
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Thermal Compensation
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±15mm + ±3°
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Requires expansion joints
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Seal Life
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≥250k cycles @600°C
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≤80k cycles @300°C
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Operating Torque
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180Nm (DN600)
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450Nm+ (DN600)
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Maintenance Interval
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10 years (in-situ seal)
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3 years (full removal)
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System Cost Savings
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30% (eliminates joints)
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Additional compensators
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Product Overview
Nwv Telescopic Double-Offset Bidirectional Metal-Seated Butterfly Valve: Dynamic Compensation Solution for High-Temperature Pipelines
In complex piping systems for petrochemical and power generation applications, thermal displacement compensation and zero-leakage sealing are critical operational challenges. NWV’s telescopic double-offset bidirectional metal-seated butterfly valve integrates dynamic expansion joints, dual-eccentric geometry, and multi-layer metal sealing to resolve stress deformation, seal failure, and maintenance downtime in high-temperature/pressure environments—redefining safety in modern industrial flow control.
Core Innovation: Thermal Self-Adaptation & Bidirectional Sealing
Engineered for extreme service (≤600°C / Class 600), this valve overcomes rigid structural limitations:
Axial Compensation: Stainless bellows absorb ±15mm axial displacement and ±3° angular deflection, eliminating flange bolt shear stress.
Bidirectional Pressure Integrity: Multi-layer seal stacks achieve ≤10⁻⁶ mbar·L/s helium leakage (per ISO 5208 Rate A) regardless of flow direction.
Breakthrough Engineering: Geometry Meets Material Science
1. Telescopic Bellows System
Hydraulic-Formed Layers: 100+ plies of 0.15mm 316L strip (≥20,000 cycles per EJMA).
Dynamic Stem Seal: Laser-welded bellows with high-temp grease (-40°C to 450°C) replace packing glands for zero fugitive emissions.
2. Double-Offset Geometry
Offset 1: Stem behind disc centerline reduces friction 85% during unseating.
Offset 2: 8° stem-to-pipe angle enables progressive metal contact (wear rate ≤0.005mm/10k cycles).
3. Bidirectional Metal Sealing
Disc: ASTM A995 4A duplex substrate with PTA-overlaid Stellite 6 (2.2±0.1mm; HRC 45-48).
Self-Compensating Seat: 12-disc spring stacks absorb 1.5mm wear while maintaining sealing stress.
