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Gaskets for fertilizer, ammonia and hydrogen plants
Ammonia, urea and nitric acid plants combine high-pressure synthesis loops, hot hydrogen and strong acids. Green hydrogen adds electrolysers, compressors and storage at high pressure. Every one of these services punishes a poorly chosen gasket. We supply QGER gaskets matched to pressure class, temperature and media for each unit.
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| Representative image | Gasket / seal | Fertilizer / ammonia / hydrogen use | Typical construction | Representative plant applications | Typical standards / specifications |
|---|---|---|---|---|---|
 | Spiral Wound Gasket - QSW4 | Severe high-pressure/high-temperature flange sealing where hydrogen, synthesis gas or ammonia service demands an inner ring to protect the winding and control inward buckling. | Profiled metallic winding with graphite, PTFE or mica filler plus metallic inner and outer rings. | Hydrogen compressor discharge/interstage piping; ammonia synthesis loops; high-pressure syngas; high-class reactor and converter connections; pressure-vessel piping; ammonia transfer where raised-face high-pressure flanges are used. | ASME B16.20; mating flanges ASME B16.5 / B16.47; ASME B31.3 for process piping; ASME B31.12 for hydrogen industrial piping where applicable; ASME PCC-1 or project bolted-joint procedure for assembly. |
| Spiral Wound Gasket - QSW3 | General raised-face process-piping sealing with centering and compression control across fertilizer, ammonia and hydrogen balance-of-plant systems. | Profiled metallic winding with graphite or other compatible filler and metallic outer centering/compression ring. | Sulfuric/phosphoric-acid utilities; steam and condensate; cooling water; low-to-medium pressure ammonia auxiliaries; hydrogen balance-of-plant; process air and general plant piping. | ASME B16.20; ASME B16.5 / B16.47 for mating flanges; ASME B31.3 for chemical/fertilizer process piping; hydrogen lines may additionally invoke ASME B31.12. |
 | Camprofile / Kammprofile Gasket | Severe-service sealing with high recovery where temperature, pressure, thermal cycling or limited bolt load makes a grooved metal-core gasket advantageous. | Grooved metallic core with graphite or PTFE facing; guide ring depending on flange arrangement. | Ammonia converters and synthesis equipment; hydrogen process vessels; high-pressure heat exchangers; sulfuric/phosphoric-acid units; reformer/syngas auxiliaries; cyclic process equipment. | 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; equipment/OEM drawing governs specials. |
| Urea-Grade Kammprofile / PTFE-Enveloped Camprofile Gasket | Severe corrosion-resistant flange and equipment sealing in high-pressure urea synthesis service, especially where hot ammonium carbamate, ammonia, CO2 and concentrated urea solutions create exceptionally aggressive corrosion conditions. | Precision-machined grooved/serrated metallic core in licensor-approved urea metallurgy such as 316L Urea Grade (UG) or 25-22-2 / 310MoLN / UNS S31050 / EN 1.4466. Soft sealing may use PTFE/ePTFE or a full PTFE envelope to isolate the metallic core from aggressive media, strictly as specified by the urea licensor or equipment OEM. | Urea reactors; high-pressure strippers; carbamate condensers; high-pressure scrubbers; high-pressure synthesis-loop vessel connections; carbamate/urea equipment flanges; selected stripper and condenser nozzles where the licensor specifies a camprofile-type seal. | Urea-licensor / OEM specification governs (Stamicarbon, Saipem/Snamprogetti, Urea Casale, thyssenkrupp Uhde, TOYO or project-specific requirements as applicable). ASME B16.20 for grooved-metal gaskets with covering layers where applicable; ASME B16.5 / B16.47 for flange interfaces; ASME B31.3 at process-piping level; ASME BPVC Section VIII for applicable pressure equipment. Urea-grade stainless may also require licensor-specified corrosion qualification; ASTM A262 Practice C is a nitric-acid intergranular-corrosion test used for austenitic stainless steels where specified. |
 | Metal-Jacketed / Heat-Exchanger Gasket | Seals shell-and-tube exchangers and large process equipment where a metallic shell protects a resilient filler and pass-partition ribs may be required. | Thin metallic jacket enclosing graphite or other resilient filler; single/double-jacketed and ribbed configurations. | Ammonia synthesis and refrigeration exchangers; syngas coolers; condensers; phosphoric/sulfuric-acid heat exchangers; waste-heat boilers; evaporators; process coolers and reboilers. | ASME B16.20 where applicable; API 660 / TEMA for shell-and-tube exchangers where adopted; ASME BPVC Section VIII for pressure-vessel exchangers; equipment drawing controls geometry. |
 | Ring Type Joint (RTJ) - R / RX / BX | Metal-to-metal sealing for very high-pressure/high-temperature connections where ring-joint flanges are specified. | Precision-machined metallic R, RX or BX ring in carbon, alloy or stainless steel selected for service conditions. | High-pressure hydrogen compression; ammonia synthesis loops; syngas and reformer compressor systems; high-pressure reactors; specialty valves; storage/compression systems using ring-joint flanges. | ASME B16.20; API 6A / ISO 10423 where API ring-joint interfaces are used; mating flange specification governs; ASME B31.3 / B31.12 at piping-system level as applicable. |
 | Solid Metal / Metal-Core Gasket | Extreme pressure/temperature or special-equipment sealing where conventional soft gasket materials are unsuitable. | Solid metal or rigid metal core, optionally faced with expanded graphite or ePTFE. | Ammonia converter and reformer equipment; compressor/turbine casings; high-temperature hydrogen/syngas equipment; pressure-vessel covers; specialty reactor joints and OEM equipment. | ASME B16.20 where applicable; special designs controlled by purchaser/OEM drawings; ASME BPVC Section VIII where used on pressure equipment; material compatibility must be verified for hydrogen duty. |
 | Flexible Graphite Gasket | High-temperature static sealing with strong recovery and broad chemical resistance for steam, hot process gas and many fertilizer-plant media. | Flexible/expanded graphite with or without reinforcement or metallic insertion; ring or custom-cut shape. | Steam and condensate; hot ammonia-process auxiliaries; sulfuric-acid plant utilities; valve bonnets; manways; compressors; heat exchangers and high-temperature process flanges. | ASME B16.21 for nonmetallic flat gaskets where applicable; EN 1514-1 for PN flanges; ASME B31.3 at process-piping level; purchaser purity/oxidation requirements may also apply. |
 | Graphite Pressure-Seal / Cover-Seal Ring | Self-energizing sealing for pressure-seal valve bonnets and other self-sealing covers under severe pressure and temperature cycling. | Preformed high-density flexible graphite ring or cover-seal profile compressed by system pressure and bonnet geometry. | High-pressure ammonia/hydrogen valves; synthesis-loop isolation valves; high-pressure steam and process services; self-sealing covers on pressure equipment. | ASME B16.34 and valve/OEM specification for pressure-containing valve assemblies; API 600 / API 623 where those valve types are specified; ASME B31.3 or B31.12 at piping-system level. |
 | PTFE / ePTFE Flat Gasket | Chemically resistant sealing for strong acids, caustics, fertilizer chemicals and low-stress flanges where PTFE compatibility is appropriate. | Virgin/filled PTFE, restructured PTFE or 100% expanded PTFE flat gasket. | Phosphoric and sulfuric acid systems; chlorides/chemical dosing; demineralized-water and electrolyzer auxiliaries; alkaline-electrolyzer balance-of-plant; glass-lined/FRP interfaces; aggressive cleaning systems. | ASME B16.21; EN 1514-1 for PN flanges; ASME B31.3 at process-piping level. Hydrogen-generator system safety may invoke ISO 22734-1:2025; material compatibility/permeation requirements govern final selection. |
| PTFE Envelope / Filter Gasket | Combines broad chemical resistance with a compressible core and low contamination risk in strong-acid, caustic and filtration service. | PTFE envelope around compressed non-asbestos fibre or flexible graphite core; standard or custom geometry. | Phosphoric-acid filtration; sulfuric-acid systems; fertilizer process filters; glass-lined reactors; acid/caustic chemical skids; selected electrolyzer chemical-treatment equipment. | ASME B16.21 where standard flat-gasket dimensions apply; EN 1514-1 for compatible PN flanges; filter/equipment OEM drawings govern proprietary shapes; ASME B31.3 for associated process piping. |
 | CNAF / Compressed Fibre Gasket | General-purpose sealing for water, air, oils, low-pressure steam and mild chemical/utility services. | Compressed non-asbestos fibre sheet made from synthetic/inorganic fibres, fillers and elastomeric binder. | Cooling and process water; compressed air; lubrication skids; low-pressure steam; fertilizer handling utilities; pumps, valves and general plant piping. | ASME B16.21; EN 1514-1; purchaser/OEM material specification; ASME B31.3 at process-piping level where applicable. |
 | EPDM / NBR / FKM / FFKM Elastomeric Gasket | Flexible low-to-medium pressure sealing where water, ammonia-adjacent utility fluids, oils or chemicals require a service-specific elastomer. | Cut or molded full-face/ring gasket in EPDM, NBR, FKM/Viton, silicone, SBR or FFKM; reinforcement may be added. | Cooling water; demineralized water; chemical dosing; hydraulic/pneumatic systems; ammonia refrigeration auxiliaries; electrolyzer cooling and water-treatment systems; pumps and skids. | ASME B16.21; EN 1514-1; ISO 3601 series where O-ring geometry is used. Compound compatibility, temperature, permeability and decompression resistance must be verified for hydrogen/ammonia exposure. |
 | Electrolyzer Stack / Cell Gasket | Separates hydrogen, oxygen and electrolyte/water paths inside electrolyzer stacks while maintaining electrical and fluid isolation under compression cycling. | Precision-cut or molded PTFE/ePTFE, EPDM, FKM/FFKM or other OEM-qualified polymer/elastomer profile; geometry depends on alkaline, PEM or AEM stack design. | Alkaline, PEM and AEM electrolyzer stacks; bipolar-plate/perimeter sealing; water/electrolyte manifolds; hydrogen and oxygen separation interfaces. | Electrolyzer-OEM drawing/material specification is primary. ISO 22734-1:2025 applies at hydrogen-generator system safety level. ISO 3601 may apply only where O-ring geometry is used. Hydrogen permeation, purity and electrochemical compatibility must be qualified. |
 | ePTFE Gasket Tape / Joint Sealant | Form-in-place sealing for large, irregular, damaged or non-standard equipment flanges exposed to aggressive fertilizer chemicals. | 100% expanded PTFE tape or cord compressed in place around the flange, manway or equipment cover. | Large acid tanks; fertilizer reactors; phosphoric/sulfuric equipment; glass-lined vessel nozzles; filter housings; large process flanges and manways; non-standard maintenance repairs. | Equipment/OEM drawing and pressure-vessel requirements govern geometry; ASME PCC-1 or project bolted-joint procedures may govern assembly; ASME B31.3 applies to associated process piping. |
 | Flange Insulation Kit / Insulating Gasket | Electrical isolation of flanged assemblies to control galvanic interaction or support cathodic-protection/isolation requirements. | High-strength insulating gasket plus full-length sleeves, insulating washers and steel washers for each bolt. | Hydrogen and ammonia transfer pipelines; storage/terminal piping; buried lines; dissimilar-metal interfaces; plant battery-limit isolation points and cathodically protected piping. | ASME B16.5 / B16.47 or other applicable flange dimensions; AMPP/NACE SP0286 where electrical isolation of cathodically protected piping is required; project corrosion-control specification governs. |
| Graphite / PTFE Compression Packing | Dynamic/static sealing around valve stems and selected pump or agitator shafts, including fugitive-emissions-sensitive ammonia and hydrogen-adjacent duties. | Preformed graphite rings or braided graphite/PTFE packing selected for temperature, chemical exposure and stem/shaft conditions. | Ammonia and hydrogen isolation/control valves; toxic process valves; sulfuric/phosphoric acid pumps; mixers; agitators; steam valves and chemical-service equipment. | API 622 for process-valve packing type testing; API 624 for rising-stem valves with graphite packing; API 641 for quarter-turn valves; ISO 15848-1 for industrial-valve fugitive-emissions qualification; OEM specification governs dimensions. |
 | Mechanical Seal | Controls leakage around rotating pump shafts in ammonia, hydrogen-plant auxiliaries, fertilizer chemicals and utility services. | Precision stationary/rotating seal faces with springs, secondary seals and single/dual arrangements selected for the process fluid. | Liquid ammonia pumps; process condensate; boiler-feed/cooling water; phosphoric/sulfuric acid pumps; chemical-transfer pumps; electrolyzer water/cooling systems; selected hydrogen-plant auxiliaries. | API 682 / ISO 21049 where an API-type pump shaft-sealing system is specified; API 610 / ISO 13709 for applicable heavy-duty centrifugal pumps; ISO 5199 / ISO 9905 or pump-OEM specification for other chemical-process pumps. |
 | Expansion Joint / Flexible Coupling | Absorbs thermal movement, vibration, pressure surges and misalignment in process piping and duct systems. | Engineered non-metallic/fabric or elastomeric flexible joint with flanged ends; metallic bellows may be used in other designs. | Sulfuric/phosphoric acid plant ducts and utilities; reformer/furnace and process-air systems; ammonia plant utilities; pump/compressor discharge; cooling-water headers; large-diameter process systems. | ASME B31.3 at piping-system level; FSA guidance and purchaser specification for non-metallic expansion joints; ASTM F1123 where arch-type rubber expansion joints are used; EJMA standards where metallic bellows are used. |
 | Pump Diaphragm | Flexible pumping barrier for acids, caustics, fertilizer additives, contaminated liquids and controlled chemical dosing. | ePTFE wetted face bonded to reinforced elastomer backing, or OEM-specific PTFE/elastomer diaphragm construction. | Acid/caustic transfer; antiscalant and chemical dosing; phosphoric/sulfuric acid auxiliaries; water-treatment skids; fertilizer additives; metering and filter-feed applications. | Pump OEM dimensional/material specification governs. API 675 applies to controlled-volume metering pumps where specified; it does not universally apply to air-operated double-diaphragm pumps. |
 | Precision O-Rings / Molded Elastomer Seals | Compact static and dynamic sealing in instrumentation, valve actuators, dosing equipment, compressors, pumps and hydraulic/pneumatic systems. | Precision-molded EPDM, NBR, FKM/Viton, silicone, FFKM or other specialty elastomer; backup rings may be added at higher pressure. | Hydrogen/analyzer systems; ammonia valve actuators; instrument fittings; dosing pumps; compressor auxiliaries; hydraulic/pneumatic skids; electrolyzer balance-of-plant and cooling systems. | ISO 3601-1 for O-ring dimensions/tolerances; ISO 3601-2:2025 for housing dimensions; ISO 3601-3 for quality acceptance; ISO 3601-4 for backup rings. Hydrogen/ammonia material compatibility and decompression/permeation qualification must be project-specific. |
 | 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. | Ammonia refrigeration and cooling; electrolyzer cooling and heat recovery; demineralized-water systems; fertilizer-process heating/cooling; water/glycol loops and utility exchangers. | Heat-exchanger OEM drawing/specification governs geometry and compound. API 667 may apply where adopted for plate-and-frame exchangers in petroleum/petrochemical-style service; otherwise project/OEM requirements control. Elastomer compatibility is service-specific. |
These are typical starting points. Final selection depends on your service conditions and is confirmed with QGER engineering before manufacture.
Points to watch
- For hydrogen service, state the design pressure and temperature. Hydrogen leaks through joints that hold other gases.
- With a PTFE filler, a spiral wound gasket needs an inner ring to prevent inward buckling.
- Give the exact acid and its concentration. The same acid at two strengths can need different materials.
Get the right gasket for your plant
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