Chemical Processing Gaskets & Seals
Sealing for aggressive media, elevated temperatures, and strict emission controls across the chemical process industries.
From the Kwinana strip in Western Australia to the Botany industrial precinct in New South Wales, Australian CPI plants run corrosive acids alongside high-pressure steam — often on the same flange. A single joint failure can shut down an entire process train, or release hazardous media to atmosphere. We supply gaskets and seals matched to your specific chemical and thermal profile, from PTFE envelope gaskets for glass-lined reactors to FFKM (perfluoroelastomer) O-rings for reactor instrumentation.
Applicable Standards for CPI Sealing
These are the standards your engineering team and our team are both working to — flange dimensions, gasket design, emission limits, and assembly. Abbreviations used below: SWG = Spiral Wound Gasket, RTJ = Ring-Type Joint, CNAF = Compressed Non-Asbestos Fibre.
Conventional vs. Engineered Approach
CPI Applications
These are the applications we see most often in Australian chemical plants. Each carries its own sealing challenge and material answer.
Shell-and-Tube Heat Exchangers
Large-diameter flanges with high thermal cycling. Kammprofile gaskets with graphite facing handle the differential expansion between shell and tube bundle, typically 150–350 °C at Class 300–600.
Glass-Lined Reactor Gaskets
Low bolt-load flanges with fragile glass lining that cracks under point loading. Expanded PTFE (ePTFE) envelope gaskets seal at minimal stress without damaging the lining surface. That matters for pharmaceutical intermediates and fine chemicals.
Distillation Columns
Dozens of flanged joints per column, each at different temperature and pressure. Spiral wound gaskets with PTFE or graphite filler — matched to the service at each elevation — keep volatile organics contained.
Acid Piping Systems
Concentrated sulphuric, hydrochloric, and nitric acid lines demand full chemical resistance at every joint. PTFE envelope gaskets on ASME B16.21 faces, or PTFE-lined SWGs where bolt loads allow metallic recovery.
Chlor-Alkali Cells
Brine, caustic soda, and wet chlorine at 80–90 °C. PTFE gaskets resist both acid and alkaline sides of the cell. FFKM O-rings seal instrumentation taps where FKM would swell in hot caustic.
Tank Nozzles & Manholes
Oversize flanges with low bolt density and uneven surfaces. Full-face soft-cut gaskets in PTFE or CNAF seal reliably at low stress, sized from our stock sheet or cut to your drawing, typically within one business day on standard materials.
Pump & Valve Gaskets
Bonnet gaskets, case gaskets, and lantern rings for chemical-duty pumps and valves. SWG or Kammprofile in 316L/graphite for process pumps; PTFE packing and lantern rings for valve stems handling corrosive media.
Scrubbers & Off-Gas Treatment
Wet scrubber flanges, absorber columns, and quench tower joints. PTFE-lined gaskets resist the acid condensates and chlorinated off-gases that destroy conventional elastomers within weeks.
Lined Pipe Flange Gaskets
PTFE- and rubber-lined piping uses raised-face or flat-face flanges with limited bolt load to protect the lining. PTFE envelope gaskets match the corrosion resistance of the lining without overloading it.
Key Materials for Chemical Processing
Wrong material in a CPI joint means unplanned downtime at best and a reportable release at worst. These are the materials we specify most for chemical plant service, each matched to a specific combination of media, temperature, and pressure.
PTFE / ePTFE
Three forms, each for a different CPI problem. Virgin PTFE for flat and envelope gaskets in acid piping. Expanded PTFE (ePTFE) tape and sheet for low bolt-load flanges, glass-lined reactors, and irregular surfaces. Filled PTFE (glass, carbon, or stainless steel) for improved creep resistance under sustained load. We stock sheet from 0.5 mm to 6 mm in all three variants.
Temp: -200 °C to +260 °C
Media: Near-universal; resists most acids, caustics, and solvents. Not for elemental fluorine, chlorine trifluoride, or molten alkali metals.
FKM (Viton)
Broad chemical resistance rated to 205 °C continuous. Standard for hydrocarbon service, mineral acids, and chlorinated solvents. For high-pressure gas service with rapid pressure cycles (CO₂, ethylene, propylene, chlor-alkali), specify RGD-resistant grade. Standard FKM blisters under explosive decompression.
Temp: -20 °C to +205 °C
Media: Hydrocarbons, most acids, chlorinated solvents
FFKM (Kalrez / Perlast)
Rated to 325 °C continuous with near-total chemical resistance. Specified where FKM fails on amines, hot concentrated acids, and steam-chemical cycling.
Temp: -25 °C to +325 °C
Media: Virtually all chemicals including amines, ketones, esters
Flexible Graphite
Handles saturated steam to 450 °C and maintains seal under high bolt loads without cold-flow. Most CPI plants we work with switch to graphite once PTFE creep becomes a recurring maintenance issue on high-temperature lines.
Temp: -200 °C to +450 °C (inert to +3000 °C)
Media: Most chemicals — not suitable for nitric acid above 20%, chromic acid, concentrated sulphuric acid above 96%, or permanganate solutions. Consult manufacturer compatibility data for specific concentrations and temperatures.
Spiral Wound Gaskets
V-shaped metallic winding with flexible filler — the workhorse for raised-face flanges in CPI. We supply inner ring, outer centering ring, and filler combinations in 304, 316, Monel, or Hastelloy to suit your flange class.
Temp: -200 °C to +650 °C inert / ~450 °C oxidising (filler dependent)
Pressure: To Class 2500 per ASME B16.20
Kammprofile Gaskets
Serrated metal core with soft facing; combines metallic recovery with soft-material sealability. Ideal for heat exchangers and large-diameter flanges.
Temp: Graphite facing to +450 °C, PTFE to +260 °C
Pressure: To Class 2500
Hastelloy C-276
Nickel-molybdenum-chromium alloy with outstanding resistance to wet chlorine, hypochlorite, ferric chloride, and mixed acid environments. Used for SWG windings and Kammprofile cores in the most aggressive CPI services.
Temp: To +650 °C (metallic)
Media: Chlorides, oxidising acids, mixed acids, wet chlorine gas
Monel 400
Nickel-copper alloy resistant to hydrofluoric acid (HF), salt water, and reducing acids. Standard winding alloy for anhydrous HF service (alkylation, fluorochemical plants). For wet HF + air service, Hastelloy C-276 is preferred, since Monel suffers oxidising attack when air ingress is possible.
Temp: To +538 °C (metallic, oxidising atmospheres)
Media: Hydrofluoric acid, fluorine, seawater, caustic alkalies
Worked Example: Selecting for Hot Sulphuric Acid
A chlor-alkali plant needs to re-gasket a 6-inch Class 150 flange on a 93% sulphuric acid line running at 120 °C. Here is how we narrow the material choice:
- Eliminate graphite. Concentrated sulphuric acid above 96% attacks graphite — and at 93% and 120 °C, oxidation rates are borderline. Too risky.
- Assess PTFE. Virgin PTFE resists sulphuric acid at all concentrations and temperatures within its 260 °C limit. But on a raised-face flange, PTFE cold-flows under sustained bolt load. A glass-filled PTFE or ePTFE envelope gasket gives better creep resistance.
- Consider SWG with PTFE filler. A spiral wound gasket with PTFE filler on 316L windings handles the bolt load and provides metallic recovery. Preferred for Class 150+ where bolt stress is sufficient.
- Final call. SWG 316L/PTFE per ASME B16.20. If the plant runs intermittent shutdowns that cause thermal cycling, add a 316L inner ring for gasket centering and blow-out resistance.
Every service is different. This example illustrates the reasoning, not a universal answer. Contact us with your specific conditions for a confirmed recommendation.
Chemical Processing Capability
200+
Chemicals Tested
Compatibility data for acids, caustics, solvents, and gases
325 °C
Max. Elastomer Temp
FFKM perfluoroelastomer continuous service
Class 2500
Max. Pressure Class
ASME B16.20 spiral wound and ring joint gaskets
13
CPI Standards Covered
ASME B16.20/21, B16.5/47, PCC-1, B31.3, EN 1514/13555, TA Luft, AS 1210, AS 4041, NACE, API 622/624
Products for Chemical Processing
Engineering Guides for CPI
Our technical guides and tools cover chemical compatibility, gasket failure analysis, and pressure–temperature ratings: the data CPI engineers need when specifying sealing.
Browse All ResourcesExplore Further
Ready to Discuss Your Chemical Processing Requirements?
We verify gasket materials against your process chemistry and operating conditions before quoting — so the first gasket we send is the right one for the duty.
- Chemical compatibility verification
- Material traceability available on request
- Gaskets stocked to ASME, EN, and AS standards
Disclaimer
This page is provided for general engineering reference only and does not constitute professional advice, specification, or guarantee of performance. Actual results depend on specific application conditions. Universal Gaskets Pty Ltd accepts no responsibility or liability for decisions made based on this information. For full terms, see our Terms & Conditions.
Temperature ranges, chemical resistance ratings, and mechanical properties cited on this page are typical values for standard grades. Actual performance varies with compound formulation, filler package, and service conditions — contact us to confirm suitability for your specific application.