Flange Ventilation Butterfly Valve | DN50-3000 High Temp 900°C Factory

A Flange Ventilation Butterfly Valve is a non-hermetic (non-sealing) centerline disc butterfly valve specifically designed for ventilation, gas transportation, flue gas, and dust-laden gas applications - adopting a centerline disc structure welded with short-structured steel plates, featuring compact design, light weight (50-70% of similar products), easy installation, while effectively avoiding the impact of high-temperature thermal expansion and ensuring smooth operation even in harsh high-temp/dusty conditions, with DN50-3000 (custom to DN6000), PN2.5/6/10 (≤1.0MPa), -10~900°C (per material: ≤450°C, ≤600°C, ≤900°C), wear-resistant sealing ring, leakage ≤1% (ventilation non-seal - not for liquid sealing), Q235A/16Mn/Cr-Mo/Cr-Ni-Ti steel body, manual/worm gear/electric/pneumatic drive, for power plant boiler flue gas, chemical flue gas, metallurgy dust removal, environmental waste gas treatment, cement/glass building materials - a reliable high-temp large-bore ventilation butterfly valve for gas/flue/dust pipelines. The core highlights are: (a) Ventilation-specific non-hermetic design (core): (i) NOT a sealing valve - designed for gas/ventilation where zero leakage is NOT required (leakage ≤1% acceptable); (ii) lightweight steel-plate welded body (not heavy casting) - for large-bore low-pressure gas lines; (iii) centerline disc - simple, low torque, large flow; (iv) short structure - compact, saves space; (b) Ultra-large bore: (i) DN50-3000 standard (2"-120"); (ii) custom to DN6000 (240" / 6 meters - one of the largest butterfly valves); (iii) for large ventilation ducts, flue gas stacks, dust collection mains; (c) High temperature to 900°C: (i) -10~900°C (depending on material selection); (ii) ≤450°C (Q235A carbon steel standard); (iii) ≤600°C (16Mn / heat-resistant steel); (iv) ≤900°C (Cr-Mo steel / Cr-Ni-Ti stainless / heat-resistant alloy); (v) for boiler flue gas, hot air, furnace gas; (d) Low pressure PN2.5/6/10: (i) PN2.5 (0.25MPa), PN6 (0.6MPa), PN10 (1.0MPa); (ii) ventilation/gas lines are typically low pressure; (iii) lightweight body suitable for low pressure (not for high pressure); (e) Optimized thermal gap: (i) gap between disc and body designed to accommodate thermal expansion/contraction; (ii) prevents jamming/seizure at high temp (common failure in high-temp butterfly valves); (iii) stable operation across wide temp range; (f) Wear-resistant for dust-laden gas: (i) wear-resistant sealing ring (hardfaced / heat-resistant alloy); (ii) disc/stem materials for dust/abrasion; (iii) for flue gas with fly ash, cement dust, metallurgical dust; (g) Multiple drives: (i) manual (handwheel/lever, small DN); (ii) worm gear (large DN, labor-saving, self-locking); (iii) electric (IP68 protection, F-class insulation motor, double limit switch, overheating protection - for remote/automated); (iv) pneumatic (fast, for automated/dust collection); (h) Flange connection: (i) double flanged (GB/T9113, ASME B16.5, ASME B16.47 for large DN); (ii) easy install/removal; (iii) compatible with standard duct flanges; (i) No internal rods/bolts: (i) disc welded to stem (no internal fasteners that can loosen in high-temp/dust); (ii) reliable, no secondary maintenance; (j) Standards: JB/T8692 (ventilation butterfly valve design), GB/T12221 (face-to-face), GB/T9113 (flange), GB/T13927 (test), API 609, API 598; (k) Applications: power (boiler flue gas, hot air, dust collection), chemical/petrochemical (flue gas, chemical gas, dust-laden gas), metallurgy (ventilation, dust removal, furnace gas), environmental (waste gas treatment, dust removal, ventilation), building materials (cement, glass, hot air/flue gas), HVAC, mining ventilation; (l) Leakage ≤1%: non-hermetic - acceptable for ventilation (not for liquid or hazardous gas sealing); (m) Cost-effective: steel-plate welded = cheaper than cast for large bore, lightweight = lower transport/install cost. This is the reliable high-temp large-bore ventilation butterfly valve solution for gas/flue/dust pipelines.

The ventilation-specific non-hermetic design, ultra-large bore (to DN6000), high temperature to 900°C, low pressure, dust/abrasion resistance, optimized thermal gap, and multiple drives make this valve a specialized large-bore high-temp ventilation butterfly valve - distinct from sealing butterfly valves (for liquid/gas tight shutoff) - designed for ventilation, flue gas, hot air, dust-laden gas pipelines where large flow, high temp, dust resistance, and low pressure are priorities (zero leakage NOT required). Compared to other butterfly valves: (a) vs Electric Flange Butterfly Valve (first): that one is electric + flanged + soft/hard seal (zero leakage) + DN50-2000 + general liquid/gas; this one is ventilation non-hermetic (≤1% leak) + DN50-3000/6000 + high temp 900°C + dust-laden gas + low pressure - ventilation gas-specific vs general sealing; (b) vs Fire Signal Butterfly Valve (second): that one is fire-protection signal + soft seal + DN50-400 + fire water; this one is ventilation + non-hermetic + large bore + high temp + gas/flue - completely different; (c) vs Extended Flange Hard Seal (third): that one is triple-offset metal hard seal (zero leakage) + expansion joint + DN50-2000 + high temp 650°C + steam/oil; this one is centerline non-hermetic + DN50-3000/6000 + 900°C + ventilation gas + low pressure - ventilation non-seal large-bore vs hard-seal high-pressure; (d) vs Stainless Steel Handled Clamp-on (fourth): that one is all-stainless + lever + wafer + sanitary + small/medium + food; this one is steel-plate + flange + large bore + high temp + industrial ventilation - completely different; (e) vs Worm Gear Flange (fifth): that one is worm gear + flanged + soft/hard seal (zero leakage) + DN50-2200 + general; this one is ventilation non-hermetic + DN50-3000/6000 + 900°C + dust + low pressure - ventilation-specific vs general sealing; (f) vs Stainless Steel PTFE Wafer (sixth): that one is all-stainless + PTFE chemical seal + wafer + DN40-350 + chemical; this one is steel-plate + non-hermetic + flange + large bore + high temp + ventilation - completely different; (g) vs Flange Telescopic (seventh): that one is butterfly + telescopic expansion joint 2-in-1 + flanged + DN32-3200 + thermal compensation + water; this one is standard ventilation + non-hermetic + DN50-3000/6000 + 900°C + gas/flue - ventilation high-temp vs telescopic water; (h) vs Pneumatic Wafer (eighth): that one is pneumatic + wafer + soft/hard seal (zero leakage) + DN50-1200 + PN10-40 + automated general; this one is ventilation non-hermetic + flange + DN50-3000/6000 + 900°C + dust + low pressure - ventilation large-bore high-temp vs pneumatic compact sealing; (i) vs general butterfly valve: general = sealing (zero leakage), liquid/gas, medium temp; this = non-hermetic (≤1%), ventilation gas, high temp 900°C, large bore, dust. Ventilation butterfly valve principle detailed: (a) Centerline disc: (i) disc centered on stem axis, rotates 90°; (ii) when open (0°), disc parallel to flow - full bore, low resistance; (iii) when closed (90°), disc perpendicular - contacts seat (but non-hermetic, ≤1% leak); (iv) simple, low torque, large flow; (b) Non-hermetic seal: (i) NOT designed for zero leakage - gap between disc and seat allows small leakage (≤1%); (ii) for ventilation where small leak is acceptable; (iii) wear-resistant sealing ring (hardfaced alloy) - for dust/abrasion; (iv) no soft rubber/PTFE (would fail at 900°C); (c) Steel-plate welded body: (i) body made of steel plates (Q235A/16Mn/Cr-Mo) welded - not cast; (ii) short structure (face-to-face shorter than cast); (iii) lightweight (50-70% of cast similar); (iv) large bore feasible (to DN6000 - casting would be too heavy/expensive); (v) flanges welded to body; (d) Optimized thermal gap: (i) at high temp, disc/body expand; (ii) gap designed so expansion doesn't cause jamming; (iii) at low temp, gap doesn't cause excessive leak; (iv) critical for 900°C service; (e) No internal fasteners: (i) disc welded to stem (no bolts/nuts inside that can loosen at high temp/dust); (ii) reliable, no maintenance; (f) Large bore design: (i) DN>1000 uses truss/reinforced disc (prevent deflection); (ii) body reinforced ribs; (iii) worm gear/electric drive for large DN (manual impossible); (g) Drive options: (i) manual: handwheel/lever for DN≤300; (ii) worm gear: gear reduction for DN300-1200, self-locking; (iii) electric: motor + gear, IP68, F-class insulation, double limit (open/close), overheating protection, remote control; (iv) pneumatic: fast, for automated dust collection/ESD; (h) Flange: double flanged, GB/T9113/ASME B16.5 (standard), ASME B16.47 (large DN >DN600). High-temperature material selection: (a) ≤450°C: Q235A carbon steel (standard, cheap); (b) ≤600°C: 16Mn steel / heat-resistant carbon steel; (c) ≤900°C: Cr-Mo steel (12Cr1MoV), Cr-Ni-Ti stainless (1Cr18Ni9Ti), heat-resistant alloy (e.g., 310S, 2520); (d) disc: same as body or upgraded; (e) stem: 20Cr13 (420) stainless, Cr-Ni-Ti stainless (high temp); (f) sealing ring: wear-resistant hardfaced (Stellite / heat-resistant alloy). Dust-laden gas design: (a) wear-resistant sealing ring - hardfaced to resist dust erosion; (b) disc surface - smooth/hardened to reduce dust adhesion; (c) stem bearing - dust-proof (prevent dust entering bearing); (d) no internal cavity - dust doesn't accumulate; (e) purge port optional - air purge to clear dust. Electric actuator details (for this valve): (a) IP68 - dustproof + waterproof (submersible, for outdoor/dusty/humid); (b) F-class insulation - motor withstands 155°C (for high-temp ambient near flue); (c) double limit - open + close limit switches (prevent over-travel); (d) overheating protection - thermal sensor in motor (cuts power if overheat); (e) torque switch - overload protection; (f) manual override - handwheel for power loss; (g) voltage AC220V/380V (specify); (h) control - on-off (standard), 4-20mA modulating (optional). Testing: (1) body strength (1.5×PN - but for ventilation low pressure, may use air test); (2) seat leak (1.1×PN - ≤1% acceptable, not zero); (3) high-temp test (sample - verify no jamming at rated temp); (4) operation (open/close, torque); (5) flange dimension; (6) weld inspection (NDT - for steel-plate welded body, critical); (7) material cert; (8) electric actuator test (if equipped). Maintenance: (1) periodic exercise (prevent disc seizure from dust); (2) inspect welds (cracks - high temp cycling); (3) lubricate worm gear/stem bearing; (4) check sealing ring wear (replace if excessive); (5) clean dust from disc/body; (6) electric actuator: check motor, limit switches, wiring; (7) high-temp - inspect for thermal deformation/cracks annually. Important: (a) NOT for liquid or hazardous gas (non-hermetic ≤1% leak - would leak); (b) NOT for high pressure (max PN10/1.0MPa - lightweight body); (c) temp per material (Q235A only 450°C - don't use at 900°C); (d) large DN >1000 - need worm gear/electric (manual impossible), reinforced disc, pipe support; (e) dust-laden gas - use wear-resistant ring, purge optional; (f) flange standard - ASME B16.47 for large DN; (g) weld quality - steel-plate welded body needs NDT (critical for high temp/large bore); (h) leakage ≤1% - ventilation acceptable, not for sealing; (i) installation - horizontal (stem horizontal recommended for dust), support large bore; (j) warranty: 18 months (valve), 12 months (electric actuator). The valve is manufactured under strict quality control with 100% weld inspection, 100% operation test, material cert, JB/T8692/GB/T12221/GB/T13927/API609/API598. With an 18-month warranty and OEM/ODM customization (size to DN6000, material for 900°C, drive, flange, wear-resistant ring, electric/pneumatic), this valve is a reliable high-temp large-bore ventilation butterfly valve for gas/flue/dust pipelines.

1.Ventilation Non-Hermetic + Large Flow

Non-hermetic (non-sealing) centerline disc design specifically for ventilation/gas/flue gas/dust-laden gas - leakage ≤1% acceptable for ventilation (not for liquid/hazardous gas sealing). Centerline disc provides full-bore low-resistance flow when open, large flow capacity, small driving torque, ideal for large ventilation ducts and flue gas stacks. Steel-plate welded short-structure body - compact, lightweight.

2.Ultra-Large Bore DN50-3000 (Custom DN6000)

Standard DN50-DN3000 (2"-120"), customizable up to DN6000 (240"/6 meters) - one of the largest butterfly valve sizes, ideal for large ventilation mains, flue gas stacks, dust collection systems, and industrial ducting. Steel-plate welded construction makes large-bore feasible and cost-effective (vs heavy casting). Large DN uses reinforced truss disc and worm gear/electric drive.

3.High Temperature to 900°C + Thermal Gap

Operating temperature -10°C to 900°C depending on material: ≤450°C (Q235A carbon steel standard), ≤600°C (16Mn heat-resistant steel), ≤900°C (Cr-Mo steel / Cr-Ni-Ti stainless / heat-resistant alloy). Optimized gap between disc and body accommodates thermal expansion/contraction - prevents jamming/seizure at high temperature, ensuring stable operation across wide temp range. For boiler flue gas, hot air, furnace gas.

4.Dust/Abrasion Resistant + Low Pressure

Wear-resistant sealing ring (hardfaced heat-resistant alloy) for dust-laden gas (fly ash, cement dust, metallurgical dust) - resists erosion and extends service life. Low-pressure design PN2.5/PN6/PN10 (0.25/0.6/1.0MPa) - suitable for ventilation/gas lines (typically low pressure). No internal connecting rods/bolts (disc welded to stem) - reliable, no loosening at high temp/dust, no secondary maintenance.

5.Multiple Drives + Electric IP68

Manual (handwheel/lever, small DN), worm gear (gear reduction, self-locking, DN300-1200), electric (IP68 protection, F-class insulation motor, double limit switch, overheating protection, torque protection, manual override - for remote/automated high-temp/dusty environments), pneumatic (fast, for automated dust collection/ESD). Electric models safe and reliable with simple external circuits.

6.Flange Connection + Standards + Warranty

Double-flanged connection per GB/T9113, ASME B16.5 (standard), ASME B16.47 (large DN >DN600) - compatible with standard duct flanges, easy install/removal. Design: JB/T8692 (ventilation butterfly valve), GB/T12221 (face-to-face); test: GB/T13927, API 609, API 598. 100% weld inspection (NDT), 100% operation test, material certificate. For power, chemical, metallurgy, environmental, building materials. 18-month warranty, OEM/ODM customization (size, material, drive, flange).

A Flange Ventilation Butterfly Valve operates on the principle of a quarter-turn rotating centerline circular disc in a steel-plate welded short-structure flanged body - the disc (welded to stem, centerline) rotates 90° via manual/worm gear/electric/pneumatic drive; when the disc is parallel to flow (0°), the valve is fully open (full-bore, low resistance, large flow); when rotated 90° to perpendicular, the disc contacts the wear-resistant sealing ring to shut off flow (non-hermetic, leakage ≤1% - acceptable for ventilation); the optimized gap between disc and body accommodates thermal expansion/contraction at high temperature (to 900°C) to prevent jamming; with DN50-3000 (custom DN6000), PN2.5/6/10, -10~900°C, Q235A/16Mn/Cr-Mo/Cr-Ni-Ti steel body, wear-resistant sealing ring, flange connection - a reliable high-temp large-bore non-hermetic ventilation butterfly valve for gas/flue/dust pipelines. The valve consists of a steel-plate welded body (Q235A/16Mn/Cr-Mo/Cr-Ni-Ti, with flanges welded), a centerline circular disc (Q235A/16Mn/Cr-Ni-Ti SS, welded to stem - no internal bolts), a stem (20Cr13/420/Cr-Ni-Ti SS, anti-blowout), a wear-resistant sealing ring (hardfaced alloy, non-hermetic), bearings (dust-proof), and a drive (manual/worm gear/electric/pneumatic). Centerline disc principle: (1) fully open (0°): disc parallel to flow - medium flows through full bore; very low resistance (K~0.1-0.3), large flow capacity; (2) fully closed (90°): disc perpendicular - disc edge contacts sealing ring; non-hermetic - small gap allows ≤1% leakage (acceptable for ventilation, NOT for liquid/hazardous gas); (3) intermediate: disc at angle - throttles flow (for ventilation regulation); (4) 90° rotation = fast on-off; (5) bidirectional (centerline symmetric). Non-hermetic seal principle: (a) NOT zero leakage - designed for ventilation where small leak is acceptable; (b) wear-resistant sealing ring - hardfaced (Stellite/heat-resistant alloy) to resist dust erosion; (c) no soft rubber/PTFE (would fail at 900°C); (d) leakage ≤1% of rated flow (per JB/T8692 for ventilation valves); (e) gap designed to balance sealing vs thermal expansion. Steel-plate welded body principle: (a) body made of steel plates (not cast) - cut, rolled, welded; (b) short structure - face-to-face shorter than cast butterfly (compact); (c) lightweight - 50-70% of cast similar (less material, lower transport/install cost); (d) large bore feasible - to DN6000 (casting would be too heavy/expensive/impractical); (e) flanges welded to body ends (double-flanged); (f) reinforced ribs for large DN (prevent deformation); (g) weld quality critical - 100% NDT (radiographic/ultrasonic) for high-temp/large bore. Optimized thermal gap principle: (a) at high temperature, disc and body expand (thermal expansion); (b) if gap too small → disc jams against body (can't operate); (c) if gap too large → excessive leakage; (d) gap calculated based on material coefficient of expansion × max temp rise; (e) ensures: at max temp - no jamming; at min temp - leakage ≤1%; (f) critical for 900°C service (common failure = thermal seizure). No internal fasteners principle: (a) disc welded to stem (not bolted); (b) no internal bolts/nuts that can loosen at high temp/dust vibration; (c) no internal rods/linkages; (d) reliable, no secondary maintenance; (e) simple structure. Large bore (DN>1000) design: (a) truss/reinforced disc - internal ribs to prevent deflection under flow/pressure; (b) body reinforced - external ribs; (c) double stem (upper + lower bearing) for stability; (d) worm gear/electric drive (manual impossible for large DN/high torque); (e) pipe support - valve not load-bearing, support duct on both sides; (f) ASME B16.47 flange for large DN (standard B16.5 only to DN600). Drive principle: (a) Manual: handwheel/lever → direct stem rotation (DN≤300, low torque); (b) Worm gear: handwheel → worm → worm gear → stem (gear reduction 40:1-100:1, labor-saving, self-locking - holds position, DN300-1200); (c) Electric: motor → gear reducer → stem; (i) IP68 - dustproof + waterproof (submersible, for outdoor/dusty/humid near flue); (ii) F-class insulation - motor withstands 155°C (high-temp ambient); (iii) double limit - open + close micro-switches (stop motor at full open/close, prevent over-travel); (iv) overheating protection - thermal sensor in motor winding (cuts power if >155°C); (v) torque switch - overload protection (if jammed, cuts power); (vi) manual override - declutch handwheel for power loss; (vii) voltage AC220V/380V; (d) Pneumatic: rack-pinion/scotch-yoke actuator → stem (fast 0.5-5s, for automated dust collection/ESD, fail-safe optional). High-temp material principle: (a) Q235A (carbon steel) - ≤450°C (oxidation above 450°C); (b) 16Mn - ≤600°C (better high-temp strength); (c) Cr-Mo (12Cr1MoV) - ≤650-700°C (Cr/Mo improve high-temp strength/oxidation); (d) Cr-Ni-Ti (1Cr18Ni9Ti) - ≤800-900°C (austenitic stainless, excellent oxidation); (e) 310S/2520 - ≤1000°C+ (heat-resistant alloy, premium); (f) select based on actual max temp (don't over-specify = cost, don't under-specify = failure). Dust-laden gas principle: (a) wear-resistant sealing ring - hardfaced (HRC≥50) to resist dust particle erosion; (b) smooth disc surface - reduce dust adhesion; (c) dust-proof stem bearing - labyrinth/purge seal (prevent dust entering bearing); (d) no internal cavity - dust doesn't accumulate (centerline disc, flat body); (e) purge port optional - compressed air purge to clear dust from disc/seat; (f) periodic exercise - prevent dust bonding disc to seat. Flange connection principle: (a) double-flanged - flanges welded to both body ends; (b) GB/T9113 (Chinese standard, PN series); (c) ASME B16.5 (American standard, Class series, to DN600); (d) ASME B16.47 (large diameter, DN650-1500+ - Series A/B); (e) gasket between valve flange and duct flange (non-asbestos graphite, high-temp); (f) bolts - carbon steel/alloy (per pressure/temp); (g) easy install/removal (vs wafer - no need to disconnect pipe? still need, but flange is standard). Testing: (1) weld inspection - 100% visual + NDT (radiographic/ultrasonic for critical welds, especially high-temp/large bore); (2) body strength - 1.5×PN (air or water, per size); (3) seat leak - 1.1×PN (≤1% acceptable, measure flow); (4) operation test - full open/close, torque (verify drive sufficient); (5) high-temp test (sample) - heat to rated temp, verify no jamming/deformation; (6) flange dimension - bolt hole circle, diameter, face flatness; (7) material cert - body/disc/stem/seal; (8) electric actuator test (if equipped) - operation, limit, overheat, IP. Maintenance: (1) periodic exercise (monthly) - full open/close, prevent disc seizure from dust/thermal bonding; (2) inspect welds (annually) - cracks, deformation (high-temp cycling); (3) lubricate - worm gear, stem bearing (high-temp grease); (4) check sealing ring - wear (replace if excessive leak); (5) clean dust - from disc/body (if accessible); (6) electric actuator - check motor, limit switches, wiring, heater (if humid); (7) flange bolts - re-torque (thermal cycling loosens); (8) purge (if equipped) - regular air purge. Troubleshooting: (a) Valve jammed: (i) thermal expansion (gap too small - at high temp); (ii) dust bonding disc to seat (exercise, clean); (iii) disc deformed (high temp - replace); (iv) stem bearing seized (lubricate/replace); (b) Excessive leakage (>1%): (i) sealing ring worn (replace); (ii) disc deformed (gap increased - replace); (iii) thermal contraction (at low temp, gap larger - acceptable if within spec); (c) Weld crack: (i) high-temp cycling (fatigue - repair/weld, NDT); (ii) body deformation (reinforce); (d) Electric not operating: (i) no power (check); (ii) overheat protection tripped (wait, cool down); (iii) limit switch faulty (replace); (iv) motor burned (replace); (v) valve jammed (torque switch tripped - clear jam); (e) Worm gear hard to operate: (i) lack of lubrication (grease); (ii) disc jammed (clear); (iii) gear worn (replace). Important: (a) NOT for liquid or hazardous gas (non-hermetic ≤1% leak - would leak dangerously); (b) NOT for high pressure (max PN10/1.0MPa - lightweight body not for high pressure); (c) temp per material (Q235A only 450°C - using at 900°C = oxidation/failure); (d) large DN >1000 - must use worm gear/electric, reinforced disc, pipe support, ASME B16.47 flange; (e) dust-laden gas - use wear-resistant ring, purge optional, periodic exercise; (f) weld quality - steel-plate welded body = welds critical, require NDT (especially high-temp/large bore); (g) leakage ≤1% - ventilation standard, not for sealing; (h) installation - horizontal (stem horizontal recommended for dust, vertical optional), support large bore; (i) thermal cycling - re-torque flange bolts periodically; (j) warranty: 18 months (valve), 12 months (electric actuator). With proper material selection (per temp), periodic exercise, and weld inspection, this flange ventilation butterfly valve provides reliable high-temp large-bore service in gas/flue/dust pipelines.

• Power Generation Industry

Thermal power plants, boiler systems, flue gas treatment, dust collection, hot air ducts - control/regulate flue gas, hot air, furnace gas, dust-laden gas. High temperature to 900°C (Cr-Mo/Cr-Ni-Ti steel), large bore DN50-3000 for flue gas stacks, optimized thermal gap prevents jamming, wear-resistant ring for fly ash. Electric/worm gear drive for remote boiler control. Reliable for power plant high-temp flue gas/ventilation.

• Chemical + Petrochemical Industry

Chemical plants, petrochemical refineries, waste heat recovery, flue gas systems - control chemical gas, flue gas, dust-laden gas, hot air. Corrosion/heat-resistant materials (Cr-Ni-Ti stainless), non-hermetic design for ventilation gas, large bore for process ducts, wear-resistant ring for catalyst dust. Pneumatic/electric for automated process control. Reliable for chemical/petrochemical flue gas/ventilation.

• Metallurgy Industry

Steel mills, smelters, iron works, foundries - ventilation, dust removal, furnace gas, hot air systems. High temperature (furnace gas to 900°C), dust-laden gas (metallurgical dust), large bore for dust collection mains, wear-resistant sealing ring, optimized thermal gap. Worm gear/electric for large DN. Reliable for metallurgy high-temp dust-laden ventilation/dust removal.

• Environmental Protection Industry

Waste gas treatment, dust removal systems, bag filters, cyclone separators, ventilation projects - control/regulate waste gas, dust-laden gas, hot air. Large bore for dust collection ducts, wear-resistant ring for dust, non-hermetic acceptable for ventilation, pneumatic fast actuation for bag filter cleaning/automation. Reliable for environmental waste gas/dust removal ventilation.

• Building Materials + Other Industries

Cement plants, glass factories, ceramic, lime kilns - regulate hot air, flue gas, kiln gas in production processes. High temp (kiln flue gas), dust-laden (cement/glass dust), large bore for kiln exhaust. Also HVAC systems, mining ventilation, tunnel ventilation - reliable gas flow control. 18-month warranty, OEM/ODM customization (size to DN6000, material for 900°C, drive, flange). Reliable for building materials high-temp dust ventilation.

Our Flange Ventilation Butterfly Valves are manufactured under an ISO 9001:2015 certified quality management system, with every valve undergoing rigorous inspection and testing at each production stage - because these steel-plate welded large-bore high-temp ventilation butterfly valves are used for power plant boiler flue gas (to 900°C), chemical flue gas, metallurgy dust removal, environmental waste gas, cement/glass kiln gas where weld failure (body cracking at high temp), thermal jamming (disc seizure), excessive leakage, material oxidation (wrong material for temp), dust erosion, or drive failure can cause process disruption, unsafe flue gas release, dust emission (environmental non-compliance), boiler inefficiency, and costly downtime (the steel-plate welded construction and high-temp service make weld quality and material selection critical additional quality points beyond standard butterfly valves).

Raw material control: every body/disc/stem material batch comes with material certificate (chemical + mechanical per heat); Q235A carbon steel verified (C, Mn, Si, S, P - for ≤450°C); 16Mn steel verified (Mn content, for ≤600°C); Cr-Mo steel (12Cr1MoV) verified (Cr, Mo, V - for ≤700°C); Cr-Ni-Ti stainless (1Cr18Ni9Ti) verified (Cr, Ni, Ti, for ≤900°C); heat-resistant alloy (310S/2520) verified (for >900°C); stem 20Cr13/420 verified; wear-resistant sealing ring (hardfaced alloy - hardness HRC≥50, chemical); fasteners verified (high-temp alloy for high-temp service). Body manufacturing - steel-plate welding (critical): (a) steel plate cutting - CNC plasma/laser cutting (precision); (b) rolling/forming - plate rolled to body cylinder; (c) welding - (i) flange-to-body weld (full penetration, critical); (ii) body longitudinal seam (full penetration, 100% NDT); (iii) stiffener/rib weld (for large DN); (d) weld procedure - WPS (Welding Procedure Specification) + welder qualification (WPQ), preheat for Cr-Mo/alloy steel, post-weld heat treatment (PWHT) for Cr-Mo (relieve stress); (e) 100% visual inspection of all welds; (f) NDT - (i) 100% radiographic (RT) or ultrasonic (UT) of critical welds (body seam, flange weld) for high-temp/large bore; (ii) penetrant (PT) or magnetic particle (MT) of surface welds; (g) dimensional check - body diameter, roundness, flange bolt hole circle, face-to-face; (h) flatness - flange face (≤0.5mm per meter); (i) wall thickness (per design); (j) stress relief - for large bore/high-temp (vibratory stress relief or heat treatment); (k) surface treatment - high-temp paint (silicone aluminum, for ≤600°C) or no paint (for >600°C - paint would burn); (l) nameplate (stainless, engraved - DN, PN, temp, material, standard, date).

Disc manufacturing: (a) steel plate cut/formed; (b) welded to stem (full penetration, no bolts - critical); (c) truss/reinforcement for DN>1000 (internal ribs); (d) machining (sealing edge, stem hole); (e) hardfacing (wear-resistant sealing surface, if specified); (f) dynamic balance.

Stem: (a) 20Cr13/420/Cr-Ni-Ti stainless machined; (b) anti-blowout collar; (c) surface treatment (nitriding for wear); (d) straightness.

Sealing ring: (a) hardfaced alloy (Stellite/heat-resistant) - hardness HRC≥50; (b) machined; (c) dimensional check; (d) replaceable design (if applicable).

Bearings: (a) dust-proof design (labyrinth seal); (b) high-temp grease (for high-temp service); (c) bronze/PTFE composite (self-lubricating).

Assembly: (1) install stem + bearings + dust seal; (2) install disc (welded to stem - verify alignment); (3) install sealing ring; (4) mount drive (manual/worm gear/electric/pneumatic); (5) full stroke test (0-90°, smooth, no jamming); (6) set stops (open/close); (7) verify gap (disc-to-body - per design for thermal expansion).

Pressure/testing: (1) 100% body strength 1.5×PN - air or water (per size), zero external leak (especially welds); (2) 100% seat leak 1.1×PN - ≤1% leakage (measure, ventilation standard); (3) 100% operation test - full open/close, torque (verify drive sufficient, no jamming); (4) high-temp test (sample/type test) - heat to rated temp, operate, verify no jamming/deformation/excessive leak; (5) weld NDT - 100% critical welds (RT/UT); (6) flange dimension - bolt hole circle, diameter, flatness; (7) face-to-face (GB/T12221); (8) material PMI (if stainless/alloy); (9) electric actuator test (if equipped) - operation, limit switches, overheat protection, IP test (sample), insulation resistance; (10) torque test (verify drive torque ≥ valve torque × safety factor).

Traceability system: (a) unique serial number on nameplate; (b) database links: raw material cert (body/disc/stem/seal), heat number, steel plate batch, WPS/welder ID, weld NDT report, hydrostatic test, seat leak report, operation test, high-temp test (if), production date, inspector, order/customer; (c) full batch traceability (quality control, recall).

Coating & marking: exterior - high-temp silicone aluminum paint (for ≤600°C, silver/gray) or no paint (for >600°C - paint burns, bare steel/alloy); interior - bare (gas contact, no paint); valve permanently marked with DN, PN, max temp, body material, disc material, standard, flow direction (bidirectional), manufacturer, year, serial number; nameplate (stainless, engraved, riveted/welded - high-temp resistant).

Documentation: shipped with weld NDT report (critical welds), hydrostatic test report, seat leak report, operation test report, material certificate (body/disc/stem), high-temp test report (if type tested), electric actuator manual/cert (if equipped), installation/operation/maintenance manual (including material-temp limits, thermal gap, weld inspection, maintenance).

Warranty: 18 months from shipment or 12 months from installation (valve body); 12 months from shipment (electric/pneumatic actuator); extended warranty and third-party inspection (BV, SGS, TUV), high-temp material certification, custom size to DN6000 available.

Q: This valve is "non-hermetic" with ≤1% leakage - what does that mean, and can it be used for liquid or hazardous gas?

A: Non-hermetic (non-sealing) means this valve is NOT designed for zero leakage - it allows a small amount of leakage (≤1% of rated flow) when closed, which is acceptable for ventilation and gas systems but NOT acceptable for liquid or hazardous gas service. What "non-hermetic ≤1% leakage" means: (a) Leakage rate: when fully closed, up to 1% of the valve's rated flow capacity may leak through (e.g., if rated flow is 10,000 m³/h, up to 100 m³/h may leak); (b) Why non-hermetic: (i) ventilation/gas lines don't require zero leakage (small leak is harmless - gas is already in duct, leak to atmosphere or adjacent duct is acceptable); (ii) high temperature (to 900°C) - soft seals (rubber/PTFE) would burn/fail; metal-to-metal seal cannot achieve zero leakage; (iii) thermal expansion - gap needed to prevent jamming, gap = leakage; (iv) dust-laden gas - dust particles prevent tight sealing; (v) low cost - non-hermetic = cheaper than zero-leakage hard-seal; (c) Standard: JB/T8692 (ventilation butterfly valve) specifies ≤1% leakage for non-hermetic type. What it CAN be used for: (a) ventilation air (HVAC, building ventilation, tunnel ventilation); (b) flue gas (power boiler, industrial furnace - flue gas is ducted to stack, small leak acceptable); (c) hot air (drying, heating ducts); (d) dust-laden gas (dust collection, cement/metallurgy - gas with dust); (e) non-hazardous gas (air, nitrogen, CO2 - non-toxic, non-flammable); (f) waste gas (environmental treatment - before/after treatment, ducted). What it CANNOT be used for: (a) liquid (water, oil, chemical liquid - would leak liquid, dangerous/waste); (b) hazardous gas (toxic gas: chlorine, H2S, ammonia; flammable: natural gas, LPG, hydrogen; corrosive concentrated - leak = safety/environmental hazard); (c) high-pressure gas (max PN10/1.0MPa - lightweight body); (d) vacuum service (leakage would ingress air); (e) precise flow metering (leakage affects accuracy); (f) tank isolation (leakage would empty/fill tank). If you need zero leakage for gas: (a) use sealing butterfly valve (soft seal EPDM/NBR/PTFE - zero leakage, but temp limited ≤200°C); (b) use hard-seal triple-offset butterfly valve (metal seal, zero-ish leakage Class IV/V, to 650°C, but higher cost); (c) use gate valve / ball valve (for hazardous gas, zero leakage); (d) use bellows seal valve (for toxic gas). If you need high temp + zero leakage: (a) triple-offset hard-seal butterfly valve (metal seal, to 650°C, Class IV/V leakage - very low, but not zero); (b) high-temp gate valve (Cr-Mo steel, to 600°C+, zero leakage); (c) but for 900°C + zero leakage - very difficult/expensive (special alloy, bellows seal); most 900°C flue gas systems use non-hermetic ventilation butterfly (leakage acceptable). Selection guide: (a) ventilation air / flue gas / hot air / dust-laden non-hazardous gas → this valve (non-hermetic) - cost-effective, high-temp, large-bore; (b) natural gas / LPG / toxic gas / liquid → sealing valve (soft/hard seal butterfly, gate, ball) - NOT this valve; (c) high temp (>200°C) + need low leakage → triple-offset hard-seal butterfly (to 650°C, Class IV/V); (d) 900°C + flue gas → this valve (only practical option - zero-leakage at 900°C is impractical). Common mistakes: (a) using this non-hermetic valve for natural gas (leak = explosion risk - WRONG); (b) using for water (leak = water waste/damage - WRONG); (c) expecting zero leakage (it's ≤1% by design - don't specify for sealing); (d) using Q235A at 900°C (oxidizes - use Cr-Ni-Ti); (e) using at PN>10 (body not rated). This valve's positioning: it is a ventilation-specific non-hermetic butterfly valve - the ≤1% leakage is by design, not a defect; it is the right choice for ventilation/flue gas/hot air/dust-laden non-hazardous gas where zero leakage is unnecessary and high temp/large bore/low cost are priorities. Important: (a) confirm medium before ordering - if hazardous/liquid, this valve is NOT suitable; (b) leakage ≤1% is per JB/T8692 standard (we test to confirm); (c) if lower leakage needed (but still ventilation), we can offer enhanced seal (closer gap, better sealing ring - leakage ≤0.5%, but still not zero); (d) for zero leakage, use a different valve type (we can recommend); (e) we can advise based on your specific medium/temp/pressure.

Q: What temperature can this valve handle, and how do I choose the right material (Q235A vs 16Mn vs Cr-Mo vs Cr-Ni-Ti)?

A: This valve handles -10°C to +900°C depending on material selection - the body/disc/stem material must be matched to the maximum operating temperature (using wrong material = oxidation, deformation, failure). Material-temperature guide: (a) Q235A carbon steel (standard, cheapest): (i) max temp ≤450°C; (ii) above 450°C, carbon steel oxidizes rapidly (scale formation, thinning, strength loss); (iii) use for: ambient air, low-temp flue gas (<450°C), HVAC, general ventilation; (iv) advantages: cheap, widely available, easy to weld; (v) limitations: oxidizes >450°C, not for high-temp; (b) 16Mn steel (heat-resistant carbon steel): (i) max temp ≤600°C; (ii) Mn improves high-temp strength and oxidation resistance vs Q235A; (iii) use for: medium-temp flue gas (450-600°C), hot air drying, waste heat recovery; (iv) advantages: better than Q235A, still relatively cheap; (v) limitations: not for >600°C; (c) Cr-Mo steel (12Cr1MoV / 15CrMo): (i) max temp ≤650-700°C; (ii) Cr (chromium) improves oxidation resistance; Mo (molybdenum) improves high-temp creep strength; V (vanadium) improves strength; (iii) use for: high-temp boiler flue gas (600-700°C), furnace gas, power plant; (iv) advantages: excellent high-temp strength/oxidation; (v) limitations: more expensive, requires preheat/PWHT when welding; (d) Cr-Ni-Ti stainless (1Cr18Ni9Ti / 321): (i) max temp ≤800-900°C; (ii) austenitic stainless steel - Cr (18%) for oxidation, Ni (9%) for toughness, Ti (titanium) for carbide stabilization (prevents intergranular corrosion); (iii) use for: very high-temp flue gas (800-900°C), furnace exhaust, corrosive high-temp gas; (iv) advantages: excellent oxidation to 900°C, corrosion resistant; (v) limitations: expensive, lower strength at high temp (vs Cr-Mo), thermal expansion high (need larger gap); (e) Heat-resistant alloy (310S / 2520 / HK40): (i) max temp ≤1000-1100°C+; (ii) high Cr/Ni alloy (25Cr-20Ni etc.); (iii) use for: extreme high-temp furnace gas, incinerator; (iv) advantages: extreme high-temp; (v) limitations: very expensive, custom. How to choose: (a) determine max operating temp (not average - peak/transient); (b) add safety margin (e.g., if max 400°C, Q235A is OK; if max 430°C, consider 16Mn for margin); (c) consider cycling (frequent temp cycling accelerates fatigue - upgrade material); (d) consider corrosion (if gas is corrosive - SO2, HCl, use stainless); (e) consider dust/abrasion (high dust - hardfaced sealing ring, regardless of body material); (f) cost balance (Q235A cheapest, Cr-Ni-Ti 3-5× more expensive - don't over-specify). Selection examples: (a) HVAC ventilation, ambient air, 40°C → Q235A (plenty); (b) boiler flue gas, 350°C → Q235A (OK, <450°C); (c) boiler flue gas, 500°C → 16Mn (Q235A would oxidize); (d) power plant flue gas, 650°C → Cr-Mo (12Cr1MoV); (e) furnace exhaust, 850°C → Cr-Ni-Ti (1Cr18Ni9Ti); (f) incinerator, 1000°C → 310S/2520 alloy (custom); (g) cement kiln gas, 400°C + high dust → Q235A + wear-resistant sealing ring; (h) chemical flue gas, 500°C + corrosive (SO2) → Cr-Ni-Ti stainless (corrosion + temp). Stem material: (a) 20Cr13 (420 stainless) - ≤450°C (martensitic, hard, wear-resistant); (b) Cr-Ni-Ti stainless - ≤900°C (austenitic, for high-temp); (c) match stem to body temp (stem is in gas flow too). Sealing ring material: (a) Q235A/16Mn - ≤450/600°C (general); (b) hardfaced alloy (Stellite/heat-resistant) - ≤900°C, wear-resistant (for dust/high-temp); (c) always use wear-resistant ring for dust-laden gas. Thermal gap consideration: (a) different materials have different coefficient of thermal expansion (stainless expands more than carbon steel); (b) gap between disc and body is calculated per material (stainless needs larger gap); (c) we design gap based on selected material + max temp; (d) if you change material after order, gap may be wrong (confirm material at order). Welding consideration: (a) Q235A/16Mn - easy to weld, no preheat needed (thin plate); (b) Cr-Mo - requires preheat (150-300°C) + post-weld heat treatment (PWHT) to prevent cracking; (c) Cr-Ni-Ti stainless - requires stainless welding (E308L/E347 filler), no PWHT (solution anneal optional), prevent carbide precipitation; (d) weld procedure (WPS) + welder qualification (WPQ) for all; (e) 100% NDT for high-temp/large bore. Coating consideration: (a) ≤600°C - high-temp silicone aluminum paint (silver, heat-resistant); (b) >600°C - no paint (paint burns, bare metal/alloy - will discolor/oxidize but functional); (c) interior - no paint (gas contact). Common mistakes: (a) using Q235A at 600°C (oxidizes rapidly - fails in months); (b) using Cr-Ni-Ti for 100°C ambient (overkill, 3-5× cost); (c) ignoring peak temp (average 300°C but peak 500°C - Q235A fails at peak); (d) ignoring corrosion (SO2 at 500°C + carbon steel = rapid corrosion); (e) wrong gap for material (stainless with carbon-steel gap = jams at high temp); (f) no PWHT for Cr-Mo weld (cracks). Important: (a) specify max temp + medium at order - we recommend material; (b) material cert provided (verify); (c) don't exceed rated temp (voids warranty, dangerous); (d) if temp varies (cycling), upgrade material for fatigue; (e) if corrosive, specify (we recommend stainless + hardfaced seal); (f) we can provide material-temperature chart per request; (g) this valve's max 900°C requires Cr-Ni-Ti or heat-resistant alloy (Q235A is only 450°C - page "900°C" is max with appropriate material, not standard Q235A). This valve = material-selectable for -10~900°C (Q235A ≤450°C, 16Mn ≤600°C, Cr-Mo ≤700°C, Cr-Ni-Ti ≤900°C, alloy >900°C) - specify your max temp/medium, we recommend and certify material.

Q: What size can this valve go to, and what do I need to know for DN>1000 large-bore installation?

A: This valve is available in DN50-DN3000 standard (2"-120"), customizable up to DN6000 (240"/6 meters) - one of the largest butterfly valve sizes, designed for large ventilation ducts, flue gas stacks, and dust collection mains. Size range: (a) DN50-300 - small, manual/lever drive, general ventilation; (b) DN300-1200 - medium, worm gear/electric drive, process ducts; (c) DN1200-3000 - large, electric/worm gear drive, flue gas stacks, dust mains; (d) DN3000-6000 - extra-large, custom, electric drive, very large stacks/ducts (requires special design). Large-bore (DN>1000) special considerations: (a) Disc design: (i) truss/reinforced disc - internal ribs/frame to prevent deflection under flow/pressure (flat disc would bend at large size); (ii) lightweight but strong - hollow/ribbed construction; (iii) dynamic balance - minimize torque; (b) Body design: (i) reinforced ribs - external stiffeners to prevent body deformation (roundness); (ii) thicker plate (vs small DN); (iii) double stem - upper + lower bearing (support large disc, prevent wobble); (c) Drive: (i) manual is IMPOSSIBLE for DN>1000 (torque too high); (ii) worm gear for DN1000-2000 (gear reduction, self-locking); (iii) electric for DN>1200 (motorized, remote, IP68); (iv) pneumatic for DN≤1200 (fast, but large actuator); (v) multiple drives for DN>3000 (two electric actuators on one valve, or gearbox with dual input); (d) Flange standard: (i) DN≤600 - ASME B16.5 / GB/T9113 (standard); (ii) DN>600 - ASME B16.47 (large diameter flange, Series A or B) / GB/T13402 (Chinese large flange); (iii) custom duct flange (if non-standard); (e) Weight: (i) DN2000 valve = ~500-1000 kg; (ii) DN3000 = ~1500-3000 kg; (iii) DN6000 = ~5000-10000+ kg; (iv) need crane for installation; (f) Pipe/duct support: (i) valve is NOT load-bearing - must support duct on both sides (valve only connects, doesn't carry duct weight); (ii) support within 1-2× DN on each side; (iii) for vertical duct, support below valve; (g) Installation: (i) horizontal (stem horizontal) recommended (disc weight supported by bearings, dust doesn't settle on seat); (ii) vertical (stem vertical) optional - but disc weight on stem, dust may settle; (iii) any orientation technically, but horizontal preferred; (h) Access: (i) need space for drive (worm gear handwheel, electric actuator) - clearance above/side; (ii) need space for removal (pull disc out - requires duct disconnection or side access); (i) Thermal expansion: (i) large duct expands significantly at high temp; (ii) use expansion joint nearby (or our Flange Telescopic Butterfly Valve if also need compensation); (iii) flange bolts - allow for thermal growth (slip-type holes or spring washers); (j) Wind/seismic: (i) outdoor large bore - wind load on duct/valve; (ii) seismic zone - support design; (k) Testing: (i) large bore may be tested at factory (operation, leak) but hydrostatic may be limited (size); (ii) site test after installation (operation, leak with air). Custom DN6000 process: (a) engineering - custom design (disc truss, body reinforcement, drive sizing, flange); (b) drawing approval - we provide drawing, customer approves; (c) manufacturing - steel plate cutting/welding (large workshop); (d) NDT - 100% critical welds; (e) assembly + test (operation, leak); (f) shipping - oversized cargo (special transport, may be split for transport); (g) lead time - 60-90 days (vs 25-45 days standard); (h) cost - custom quote (based on size/material/drive). Flange connection for large bore: (a) ASME B16.47 Series A (API 605 - larger bolt circle, more bolts, for heavy duty); (b) ASME B16.47 Series B (API - smaller bolt circle, fewer bolts, compact); (c) GB/T13402 (Chinese large steel flange); (d) custom duct flange (if duct has non-standard flange - we match); (e) gasket - non-asbestos graphite (high-temp), spiral wound (for high temp); (f) bolts - high-temp alloy (for >400°C), grade 8.8/10.9. Transport for large bore: (a) DN≤2000 - standard container (40' OT open top) or flat rack; (b) DN2000-3000 - flat rack / break bulk; (c) DN>3000 - break bulk / project cargo (special vessel); (d) may be split (body in halves, assembled on site) for transport; (e) confirm shipping method at order. Common mistakes: (a) ordering DN2000 with manual drive (impossible to operate - must be worm gear/electric); (b) no pipe support (valve carries duct weight - body deforms/flange leaks); (c) wrong flange standard (ASME B16.5 only to DN600 - DN1000 needs B16.47); (d) ignoring thermal expansion (duct expansion breaks flange/valve); (e) no access for drive/maintenance; (f) underestimating weight (installation crane not sized); (g) expecting standard lead time for DN6000 (custom = 60-90 days). Important: (a) DN>1000 requires worm gear/electric (specify drive at order); (b) pipe support is customer's responsibility (we can advise); (c) flange standard - confirm duct flange standard (especially large DN); (d) thermal expansion - use expansion joint if high temp; (e) shipping - confirm transport method for large bore; (f) custom >DN3000 - drawing approval + longer lead time; (g) we provide installation manual with support/thermal guidance; (h) site supervision optional (our engineer supervises installation for large/custom). This valve = DN50-3000 standard, custom to DN6000 - for large bore, we provide engineering, custom design, NDT, appropriate drive (worm gear/electric/multi-drive), ASME B16.47 flange, and installation guidance.

Q: What drive options are available, and what is the electric actuator's IP68/F-class/double limit/overheat protection?

A: This valve offers four drive options: manual, worm gear, electric, pneumatic - selected based on valve size, automation requirement, environment, and speed. 1. Manual drive: (a) handwheel (rising stem? no - butterfly is quarter-turn, handwheel direct or via gear) or lever/handle (for small DN); (b) DN≤300 (lever for ≤150, handwheel for 150-300); (c) no power needed, simple, cheap; (d) limitations: not for large DN (too hard), no remote control, no automation; (e) use: small ventilation, occasional operation, no power. 2. Worm gear drive: (a) handwheel → worm → worm gear → stem (gear reduction 40:1 to 100:1); (b) labor-saving (one person can operate DN1000+); (c) self-locking (worm gear holds position - won't drift from flow/vibration); (d) DN300-1200 (typical); (e) no power needed, reliable, cheap; (f) limitations: slow (manual cranking), no remote, no automation; (g) use: large manual ventilation, infrequent operation, no power. 3. Electric drive (most popular for large/automated): (a) motor → gear reducer → stem; (b) features (as page specifies): (i) IP68 protection - Ingress Protection 68: (1) 6 = dust-tight (no dust ingress); (2) 8 = waterproof (continuous immersion in water, per manufacturer depth/time - typically 1m/30min+); (3) suitable for outdoor, dusty, humid, wet, wash-down environments (near flue gas, dust collection, outdoor); (ii) F-class insulation - motor winding insulation rated 155°C (F class = 155°C max winding temp); (1) withstands high ambient temp (near hot flue gas duct, valve body radiates heat); (2) prevents motor burnout in high-temp environments; (iii) double limit switch - two limit switches: (1) open limit - stops motor when valve fully open; (2) close limit - stops motor when valve fully closed; (3) prevents over-travel (damaging valve/disc/stem); (4) also provides position feedback (open/closed signal to control room); (iv) overheating protection - thermal sensor embedded in motor winding: (1) if motor temp >155°C (F-class limit), sensor cuts power; (2) protects motor from burnout (overload, high ambient, frequent operation); (3) auto-reset when cool (or manual); (v) torque switch (additional) - overload protection (if valve jammed, torque exceeds setpoint → cuts power); (vi) manual override - declutchable handwheel (for power failure/maintenance - operate manually); (vii) voltage - AC220V, AC380V, AC110V, DC24V (specify); (viii) control - on-off (standard, open/close), optional 4-20mA modulating (for flow regulation); (ix) position indicator - visual (top of actuator); (c) DN50-3000+ (sized per valve torque); (d) use: remote control, automated process, large DN, outdoor/dusty/high-temp; (e) limitations: slower than pneumatic (5-30s), needs power, more expensive. 4. Pneumatic drive: (a) rack-pinion or scotch-yoke actuator (compressed air); (b) fast (0.5-5s); (c) double-acting (air open/close) or single-acting (spring-return fail-safe); (d) DN50-1200 (typical - large DN needs very large actuator); (e) use: automated dust collection, fast on-off, ESD, hazardous area (ATEX); (f) limitations: needs air supply (0.3-0.8MPa), large actuator for large DN, noise. Drive selection guide: (a) small DN ≤300, occasional, no power → manual; (b) medium DN 300-1200, manual, no power → worm gear; (c) any DN, remote/automated, outdoor/dusty → electric (IP68); (d) fast on-off, automated, air available → pneumatic; (e) large DN >1200 → electric (or worm gear if manual); (f) hazardous area → pneumatic (ATEX) or electric (ATEX). Electric actuator detailed (IP68/F-class): (a) IP68 vs IP65/67: (i) IP65 = dust-tight + water jets; (ii) IP67 = dust-tight + temporary immersion (1m/30min); (iii) IP68 = dust-tight + continuous immersion (best - for outdoor/wet/dusty); (b) F-class vs B-class insulation: (i) B-class = 130°C; (ii) F-class = 155°C (higher - for high-temp ambient near flue); (iii) H-class = 180°C (premium); (c) double limit = open + close (some cheap actuators only have one or none - ours has both); (d) overheat protection = thermal sensor (some actuators rely on torque only - ours has dedicated thermal sensor). Electric actuator accessories: (a) positioner (4-20mA) - for modulating/flow control (optional); (b) heater - for humid/cold environments (prevent condensation); (c) torque switch - overload (standard or optional); (d) local control panel - buttons on actuator (open/close/stop); (e) feedback signal - 4-20mA position (optional); (f) ATEX/IECEx - for hazardous area (optional). Maintenance per drive: (a) manual: lubricate stem bearing, inspect; (b) worm gear: grease gear (annually), inspect; (c) electric: check motor (annual), limit switches, wiring, heater, lubricate gear; (d) pneumatic: FRL maintenance, solenoid, air lines (see pneumatic valve FAQ). Common mistakes: (a) ordering manual for DN1000 (impossible - must specify worm gear/electric); (b) using electric without IP68 for outdoor/dusty (water/dust damages motor); (c) ignoring high ambient temp (B-class motor burns near hot duct - need F-class); (d) no limit switch (over-travel damages valve); (e) no overheat protection (motor burns on overload); (f) pneumatic without air supply (won't operate). Important: (a) specify drive at order (we size actuator per valve torque); (b) electric = IP68 + F-class + double limit + overheat (standard for this valve - not optional); (c) voltage - specify AC220V/380V (matches your power); (d) manual override - standard on electric (for power loss); (e) warranty: electric actuator 12 months (valve 18 months); (f) we can supply valve + drive assembled/tested. This valve = manual/worm gear/electric (IP68, F-class, double limit, overheat)/pneumatic - electric recommended for large/automated/outdoor/high-temp; specify drive + voltage at order.

Q: The valve is steel-plate welded - how do you ensure weld quality, and what maintenance does it need for high-temp/dust service?

A: This valve's body is steel-plate welded (not cast), which makes weld quality critical - especially for high-temperature (to 900°C) and large-bore (to DN6000) service, where weld failure (cracking, leakage) can be catastrophic. Weld quality assurance: (a) WPS + WPQ: (i) WPS (Welding Procedure Specification) - written procedure for each material/thickness (current, voltage, speed, filler, preheat, interpass temp, PWHT); (ii) WPQ (Welder Performance Qualification) - each welder qualified per WPS (test coupon, NDT, mechanical test); (iii) only qualified welders use approved WPS; (b) Material preparation: (i) edge preparation (V-groove, U-groove) per thickness; (ii) cleaning (remove oil, rust, scale - prevent porosity); (iii) fit-up (gap, alignment per WPS); (c) Preheat (for Cr-Mo/alloy steel): (i) preheat 150-300°C before welding (prevent cold cracking); (ii) maintain interpass temp (≤300°C); (d) Welding: (i) SMAW (shielded metal arc) or GTAW/TIG (root) + SAW (submerged arc, for thick plate); (ii) filler material matching base metal (E7018 for carbon, E309MoL for Cr-Mo, E347 for stainless); (iii) full penetration welds (critical - body seam, flange-to-body); (e) Post-weld heat treatment (PWHT) (for Cr-Mo): (i) heat to 600-750°C, hold, slow cool - relieve residual stress; (ii) prevent stress corrosion cracking / brittle fracture; (iii) for stainless - solution anneal (optional, 1050°C) or stabilize (Ti-stabilized 1Cr18Ni9Ti doesn't need); (f) 100% visual inspection - all welds (check surface, size, uniformity); (g) NDT (Non-Destructive Testing): (i) 100% RT (radiographic) or UT (ultrasonic) of critical welds (body longitudinal seam, flange-to-body weld) - for high-temp/large bore; (ii) PT (penetrant) or MT (magnetic particle) of surface welds - check surface cracks; (iii) acceptance per ASME BPVC Section V / JB/T4730 (Grade I/II); (h) Repair: (i) defective welds ground out, re-welded, re-tested; (ii) repair procedure controlled (no repeated repair in same area); (i) Stress relief - vibratory stress relief (VSR) for large bore (if PWHT impractical); (j) Dimensional check - after welding, check body roundness, flange flatness, bolt hole circle (welding distortion corrected). Why weld quality matters for this valve: (a) high temp - welds are weakest point (residual stress + high temp = creep/cracking); (b) large bore - large welds, more distortion, more potential defects; (c) thermal cycling - heating/cooling cycles fatigue welds; (d) pressure - even low PN10, body must not leak (weld leak = gas/dust release); (e) dust/corrosion - weld defects can be corrosion initiation points. Maintenance for high-temp service: (1) Weld inspection (annual): (a) visual - check for cracks, deformation, discoloration (overheating); (b) NDT (UT/PT) of critical welds (every 2-3 years, or after high-temp excursion); (c) flange weld - check for leaks (soapy water for gas); (2) Thermal deformation check: (a) body roundness (large bore - measure); (b) flange flatness (if leak, may be warped); (c) disc gap (if jammed, may be deformed); (3) Flange bolts: (a) re-torque periodically (thermal cycling loosens bolts); (b) check for bolt stretch/creep (high temp - replace if needed); (c) use anti-seize (high-temp); (4) Disc/stem: (a) check disc for warping/cracks (high temp); (b) stem bearing - lubricate with high-temp grease; (c) dust seal - clean/replace; (5) Sealing ring: (a) check wear (dust erosion); (b) replace if excessive leakage; (6) Exercise valve: (a) monthly full open/close - prevent disc bonding to seat (dust/thermal); (b) verify smooth operation (no jamming); (7) Drive maintenance: (a) worm gear - grease; (b) electric - motor, limit switches, wiring, heater; (8) Purge (if equipped) - regular air purge to clear dust. Maintenance for dust-laden gas: (1) Frequent exercise (weekly if high dust) - prevent dust bonding; (2) Clean disc/seat - if accessible, remove dust buildup; (3) Purge system - if installed, regular compressed air purge; (4) Sealing ring - inspect quarterly (dust wears fast); (5) Stem bearing - dust-proof seal, check/replace; (6) Dust collection - ensure upstream dust collector works (reduces dust to valve). High-temp specific issues: (a) Oxidation - carbon steel >450°C oxidizes (scale) - inspect thickness, replace if thinned; (b) Creep - high temp + stress = slow deformation (body/disc) - monitor; (c) Thermal fatigue - cycling causes cracks (welds, body) - NDT; (d) Seal degradation - sealing ring hardfacing may wear/crack - replace; (e) Bolt creep - high-temp bolts lose tension - re-torque/replace. Troubleshooting weld-related: (a) Gas leak at body weld: (i) weld crack/porosity - repair (grind, re-weld, NDT); (ii) if high-temp, may need PWHT after repair; (b) Flange leak: (i) bolts loose (re-torque); (ii) gasket failed (replace - high-temp graphite); (iii) flange warped (machine flat or replace); (c) Body deformation: (i) high temp + low pressure = softening/deformation - reinforce or replace; (d) Valve jammed at high temp: (i) thermal expansion (gap too small - may need to re-machine gap or upgrade material); (ii) disc deformed (replace). Safety for high-temp maintenance: (a) cool down valve before maintenance (don't touch hot); (b) isolate/depressurize duct; (c) PPE - heat-resistant gloves, face shield (for hot work/welding); (d) hot work permit - if welding on site (dust/gas may be flammable - purge duct first); (e) confined space - if entering large duct (atmosphere test, ventilation, attendant). Warranty and welds: (a) weld defects under normal use = covered (18 months); (b) damage from over-temp (exceeding material rating) = not covered; (c) improper installation (no support, wrong flange) = not covered; (d) we provide weld NDT report with shipment (for high-temp/large bore). Important: (a) weld quality is our top priority for this steel-plate welded valve - 100% NDT critical welds, WPS/WPQ, PWHT for Cr-Mo; (b) customer maintenance - annual weld inspection, re-torque bolts, exercise valve; (c) high-temp - don't exceed material rating (Q235A ≤450°C, etc.); (d) dust - frequent exercise + purge; (e) we provide maintenance manual + can offer on-site service; (f) spare parts - sealing ring, stem bearing, fasteners, electric actuator parts. This valve = steel-plate welded with strict weld quality control (WPS/WPQ, 100% NDT critical welds, PWHT for Cr-Mo) - with proper maintenance (annual weld inspection, bolt re-torque, periodic exercise, high-temp grease), it provides reliable long-term service in high-temp/dust-laden ventilation pipelines.

Q: What is the warranty, and what does it cover for this steel-plate welded high-temp valve?

A: Warranty period: (a) Valve body (steel-plate welded body, disc, stem, sealing ring, flange): 18 months from shipment date (or 12 months from installation date, whichever comes first); (b) Electric/pneumatic actuator + accessories: 12 months from shipment date (actuator manufacturer warranty passed through); (c) wear/consumable parts (sealing ring wear, stem bearing, grease, paint, fasteners) - not covered under normal wear. What is covered (valve body): (a) weld defects - porosity, cracks, lack of fusion in factory welds (under normal use/temp); (b) material defects - wrong material, material with internal defects (lamination, inclusion); (c) manufacturing defects - machining error, assembly error, wrong gap; (d) sealing ring - premature failure under normal use (not wear from dust); (e) coating - premature peeling (not damage). What is covered (actuator): (a) electric motor defect, gear defect, limit switch defect, IP68 seal defect (factory defect); (b) pneumatic actuator manufacturing defect. What is NOT covered: (a) exceeding temperature rating - e.g., Q235A used at 900°C (oxidation/failure = not covered - material rating specified); (b) exceeding pressure rating - PN>10 (body not rated); (c) wrong medium - liquid/hazardous gas (non-hermetic valve not for these); (d) normal wear - sealing ring wear from dust, stem bearing wear, paint discoloration at high temp; (e) thermal fatigue from cycling beyond design - if specified for steady temp but used with extreme cycling; (f) improper installation - no pipe support (body deformation), wrong flange, no expansion joint (thermal damage); (g) lack of maintenance - no exercise (disc seized), no bolt re-torque (flange leak), no lubrication; (h) accident/damage - impact, fire, freezing, water hammer; (i) unauthorized repair/modification - non-genuine parts, field welding without procedure; (j) consequential damages - downtime, product loss, labor, duct damage. Warranty claim process: (a) notify us within 30 days of discovering defect (email: Contact@thankfulmaterial.com, phone: +86-15094398934); (b) provide evidence: photos/videos, valve nameplate (DN/PN/material/temp/date/serial), operating conditions (actual temp/pressure/medium), maintenance records, weld NDT if available; (c) we evaluate - may request return (small valve) or on-site inspection (large bore - we may send engineer); (d) remedy: repair (send parts/engineer), replacement (valve/actuator), refund; (e) timeline: 7-30 days (large/custom may take longer). High-temp specific warranty notes: (a) material rating is critical - if you order Q235A (≤450°C) and operate at 600°C, oxidation/failure is NOT covered (we provide material cert - confirm at order); (b) welds - factory weld defects covered; field welds/repairs not covered (unless by us); (c) thermal expansion jamming - if gap is wrong from factory = covered; if due to wrong material (customer specified) = not covered; (d) large bore deformation - if due to no pipe support (customer) = not covered; if due to inadequate reinforcement (factory) = covered. Dust-specific warranty notes: (a) sealing ring wear from dust = normal wear (not covered - replace periodically); (b) disc erosion from high-velocity dust = normal wear (not covered - use wear-resistant ring); (c) stem bearing seizure from dust = if dust-proof seal failed (factory) = covered; if no maintenance = not covered. Extended warranty options: (a) valve 24/36 months - +5-15%; (b) actuator 24 months - +10-20%; (c) specify at order. Service/support beyond warranty: (a) spare parts supply - sealing ring, stem bearing, fasteners, actuator parts, for 10+ years; (b) technical support - material selection, weld procedure, maintenance, troubleshooting (free, lifetime); (c) on-site service - engineer visit for installation/inspection/repair (optional, paid); (d) weld repair - field weld repair procedure + supervision (for large bore); (e) OEM/ODM - custom valves. Important warranty notes: (a) valve vs actuator separate - 18 months vs 12 months; (b) warranty starts at shipment (not delivery/installation); (c) 12 months from installation cap for valve; (d) keep records - installation date, operating temp (data logger), maintenance (exercise, bolt torque, weld inspection) - helps with claims; (e) material cert + weld NDT report - keep (proves factory quality); (f) don't exceed ratings (temp/pressure/medium) - voids warranty; (g) genuine parts - use our spare parts (non-genuine voids); (h) large/custom valves - warranty may have specific terms (specified in contract). This valve = 18-month valve body warranty (including welds, under normal use/rating), 12-month actuator warranty, extendable - with reliable spare parts (sealing ring, bearings, fasteners, actuator) and lifetime technical support (material selection, weld quality, maintenance, high-temp operation). Note: always operate within specified temperature (per material), pressure (≤PN10), and medium (ventilation gas/flue/dust - not liquid/hazardous), perform regular maintenance (exercise, bolt re-torque, weld inspection, lubrication) - this prevents most issues and maintains warranty validity.

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