Gaskets for pulp and paper mills

Where our gaskets are used

Representative image	Gasket / seal	Pulp & paper use	Typical construction	Pulp & paper applications	Typical standards / specifications
	Spiral Wound Gasket - QSW3 / QSW4	High-pressure and high-temperature flange sealing for steam, recovery-boiler auxiliaries and pressurized process services.	Profiled metallic winding with graphite, PTFE or mica filler; QSW3 has an outer ring and QSW4 has both inner and outer rings.	Recovery-boiler steam and condensate; digesters; evaporator steam systems; sootblower/steam auxiliaries; high-pressure process piping; pressure vessels.	ASME B16.20; mating flanges ASME B16.5 / B16.47; ASME B31.3 for process piping. ASME BPVC Section VIII may apply to associated pressure equipment.
	Camprofile / Kammprofile Gasket	Severe-service flange and exchanger sealing where pressure, temperature cycling, vibration or limited bolt load requires high recovery.	Grooved metallic core with graphite or PTFE facing; optional fixed or floating guide ring.	Digesters; evaporators; black-liquor concentrators; heat exchangers; recovery-area pressure equipment; large process nozzles and cyclic hot-service flanges.	ASME B16.20 for grooved metal gaskets with covering layers; ASME B16.5 / B16.47 flange interfaces; EN 1514-6 where EN/PN flanges are specified.
	Metal-Jacketed / Heat-Exchanger Gasket	Seals heat exchangers, evaporators and large equipment where a metallic shell protects a resilient filler.	Thin metallic jacket enclosing graphite or another resilient filler; single/double-jacket and ribbed exchanger configurations.	Multiple-effect evaporators; condensers; liquor heaters; bleach-plant exchangers; black-liquor and white-liquor heat recovery; process coolers.	ASME B16.20 where applicable; TEMA exchanger requirements; ASME BPVC Section VIII where the exchanger is pressure equipment; OEM drawing controls geometry.
	Solid Metal / Metal-Core Gasket	Extreme-pressure/temperature or special-equipment sealing where conventional soft gasket materials are unsuitable.	Solid metallic gasket or rigid metal core, optionally faced with expanded graphite or ePTFE.	High-pressure digesters; recovery-plant pressure equipment; specialty valve or vessel covers; turbine/compressor auxiliaries; custom OEM joints.	ASME B16.20 where applicable; purchaser/OEM drawing for special geometries; ASME BPVC Section VIII if part of pressure equipment.
	Flexible Graphite Gasket	High-temperature static sealing with strong recovery and resistance to steam, hot liquors and many mill process fluids.	Flexible/expanded graphite, with or without reinforcement or metallic insertion; ring or custom-cut shape.	Recovery boiler auxiliaries; steam and condensate; hot black-liquor service; valve bonnets; evaporators; digester auxiliaries; hot process flanges and manways.	ASME B16.21 for nonmetallic flat gaskets where applicable; EN 1514-1 for PN flanges; ASME B31.3 for connected process piping; OEM drawing for custom covers.
	PTFE / ePTFE Flat Gasket	Chemically resistant sealing for bleach chemicals, acids, caustics and oxidizing or corrosive process media where PTFE is compatible.	Virgin/filled PTFE, restructured PTFE or 100% expanded PTFE flat gasket.	Bleach plants; chlorine-dioxide systems; causticizing chemicals; chemical preparation and dosing; stock-treatment additives; corrosion-sensitive piping and equipment interfaces.	ASME B16.21; EN 1514-1 for PN flanges; ASME B31.3 at process-piping level. Chemical compatibility, oxidizer service and permeation requirements govern final material selection.
	Low-Load PTFE / GYLON Gasket for FRP & Plastic Flanges	Provides chemical resistance and high sealability on fragile or low-bolt-load FRP, plastic and lined flanges common in corrosive mill areas.	Soft/compressible restructured PTFE or engineered low-load gasket; full-face or ring form matched to flange design.	Bleach-plant FRP piping; chlorine dioxide and hypochlorite systems; chemical storage/transfer; low-load nonmetallic equipment flanges.	ASME B16.21 where flat-gasket dimensions apply; ASTM D5421 or project/OEM specification for FRP flange interfaces; ASME B31.3 at piping-system level. Bolting limits of the nonmetallic flange govern.
	PTFE Envelope Gasket	Combines a chemically inert PTFE wetted surface with a compressible core for aggressive chemicals and corrosion-sensitive equipment.	PTFE envelope around compressed non-asbestos fibre or flexible graphite core; standard or custom geometry.	Bleach chemical systems; chlorine-dioxide and caustic service; filters; glass-lined/FRP equipment; chemical tanks; specialty process flanges.	ASME B16.21 where standard flat-gasket dimensions apply; EN 1514-1 for compatible PN flanges; equipment/OEM drawing for proprietary geometry.
	CNAF / Compressed Fibre Gasket	General-purpose sealing for water, air, oils, low-pressure steam and mild chemical/utility service.	Compressed non-asbestos fibre sheet using synthetic/inorganic fibres, fillers and elastomeric binder.	Cooling and process water; compressed air; lubrication systems; low-pressure steam; stock-preparation utilities; pump and valve flanges; maintenance services.	ASME B16.21; EN 1514-1; ASME B31.3 at process-piping level; purchaser/OEM material specification.
	EPDM / NBR / FKM / Rubber Flange Gasket	Flexible low-to-medium pressure sealing for water, stock, selected liquors, oils and mill utility services.	Full-face or ring elastomer gasket in EPDM, NBR, FKM/Viton, neoprene, SBR or reinforced rubber, selected for chemistry and temperature.	White water and stock systems; cooling water; seal water; lube-oil auxiliaries; pump connections; low-pressure liquor service; rubber-lined piping.	ASME B16.21; EN 1514-1; ASME B31.3 for associated process piping. Elastomer compound must be verified against liquor chemistry, temperature and oxidizers.
	ePTFE Gasket Tape / Joint Sealant	Form-in-place sealing for large, irregular, damaged or non-standard equipment flanges and covers exposed to aggressive process media.	100% expanded PTFE tape or cord compressed in place around the flange, manway or housing cover.	Digesters and large vessel manways; bleaching towers; tank covers; ductwork; washer/filter housings; large non-standard process-equipment flanges.	Equipment/OEM drawing and bolted-joint procedure govern; ASME PCC-1 may guide bolted-joint assembly where applicable; ASME B31.3 applies to connected process piping.
	Graphite / PTFE / Pulp-Service Compression Packing	Controls leakage around pump shafts, valve stems, agitators and other rotating/reciprocating mill equipment.	Braided graphite, PTFE or reinforced fibre packing; preformed graphite rings where appropriate.	Continuous digesters; stock pumps; white-water fan pumps; washers and deckers; filters; agitators; black-liquor pumps; valve service; rotary sludge equipment.	Pump/valve OEM specification and FSA/ESA packing installation guidance. API 622 / ISO 15848-1 may apply only where fugitive-emissions valve qualification is specified.
	Mechanical Seal	Controls leakage around rotating pump and mixer shafts in stock, liquor, water and chemical service.	Stationary/rotating seal faces with springs and secondary seals; single/dual arrangements and materials selected for solids, chemicals and temperature.	Black- and white-liquor pumps; stock pumps; bleach-chemical pumps; condensate/water pumps; chemical dosing; evaporator and process circulation pumps.	API 682 / ISO 21049 where an API-type sealing system is specified; otherwise ISO 5199 / ISO 9905 and pump-OEM requirements may govern.
	Pump Diaphragm	Provides a flexible pumping barrier for chemical dosing, corrosive liquors and contaminated or solids-bearing fluids.	ePTFE wetted face bonded to reinforced elastomer backing or other OEM-specific PTFE/elastomer diaphragm construction.	Bleach-chemical dosing; caustic/acid feed; antifoam and additive systems; wastewater chemicals; sludge and specialty transfer; metering skids.	Pump OEM dimensional/material specification governs. API 675 applies to controlled-volume metering pumps where specified; it does not universally apply to AODD pumps.
	Expansion Joint / Flexible Coupling	Absorbs thermal growth, vibration, pump movement, pressure surges, settlement and piping/duct misalignment.	Engineered non-metallic/fabric or elastomeric flexible joint with flanged ends; lining and reinforcement selected for liquor, stock and temperature.	Black-liquor and stock pump systems; paper-machine and fan connections; recovery/boiler ducts; bleach-plant piping; large process-water and utility lines.	FSA non-metallic expansion-joint guidance and purchaser/OEM specification; ASME B31.3 at piping-system level; ASTM F1123 where applicable; EJMA for metallic bellows.
	Precision O-Rings / Molded Elastomer Seals	Compact static and dynamic sealing in pumps, valves, instruments, actuators and auxiliary systems.	Precision-molded EPDM, NBR, FKM/Viton, silicone or specialty elastomer; backup rings may be used at higher pressure.	Valve actuators; chemical dosing; hydraulic/pneumatic equipment; pump housings; instrumentation; stock-preparation and paper-machine auxiliaries.	ISO 3601 series for O-ring dimensions, housings and quality acceptance; equipment/OEM chemical-compatibility specification governs compound selection.
	Oil Seal / Bearing Isolator	Retains lubricant and excludes water, fibres, dust and contaminants from rotating shafts and bearing housings.	Elastomeric radial-shaft lip seal or non-contact labyrinth-style bearing isolator; solid or split configurations.	Paper-machine rolls; gearboxes; pumps; refiners; agitators; fans/blowers; conveyors; chippers; debarkers; motors and rotating mill equipment.	ISO 6194 series for rotary-shaft lip seals; equipment/OEM bearing, gearbox and shaft requirements govern bearing-isolator selection.
	Hydraulic Seals / V-Ring Packing	Seals hydraulic cylinders and reciprocating equipment under high load, moisture, fibre contamination and pressure cycling.	Urethane/elastomer V-rings, Chevron packing, plastic-faced seals and related hydraulic sealing components.	Roll presses; calender and reel systems; hydraulic loading equipment; chip handling; bale presses; actuators; mill maintenance equipment.	ISO 7425-1 / 7425-2 for hydraulic-cylinder seal housings; ISO 3601 where O-rings are used; equipment/OEM hydraulic specification.
	Plate Heat-Exchanger Gasket	Seals individual plates and separates process streams in gasketed plate-and-frame heat exchangers.	Precision-molded EPDM, NBR, FKM/Viton or specialty elastomer perimeter gasket clipped or bonded to the plate.	White-water heat recovery; process-water heating/cooling; condensate recovery; lube-oil cooling; chemical and utility heat exchangers.	Heat-exchanger OEM drawing/specification governs geometry and compression. Elastomer compound is selected to fluid and temperature requirements; project pressure-equipment rules may also apply.
	Custom Digester / Vessel Manway & Access Gasket	Custom static sealing for large vessel manways, access doors, inspection covers and non-standard process-equipment openings.	Custom-cut graphite, PTFE/ePTFE, CNAF or elastomeric profile selected for media, temperature, flange condition and compression.	Digesters; bleaching towers; chemical tanks; washers; filters; evaporators; liquor tanks; recovery-area equipment covers and inspection doors.	Equipment/OEM drawing controls geometry; ASME BPVC Section VIII may govern the pressure vessel; ASME PCC-1 may guide bolted-joint assembly. ASME B16.21 applies only where a standard flat flange is used.

These are typical starting points. Final selection depends on your service conditions and is confirmed with QGER engineering before manufacture.

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