Resources & Extraction

Marine & Offshore Gaskets & Seals

Application-led gasket selection for seawater systems, vessels, offshore process piping, subsea equipment, and LNG service.

Marine joints need the complete corrosion couple, electrolyte, crevice geometry, coatings, cathodic-protection design, service conditions, flange, and project or class requirements reviewed together.

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~19,000 ppm Representative seawater chloride
Certificate-specific Class approval status
Wound Spiral wound construction
Machined or sourced Non-standard RTJ route
Material Selection Warning

Graphite and PTFE Need Separate Review

Graphite-containing gaskets can create a serious galvanic or crevice-corrosion risk against stainless steel in seawater. PTFE is a different case: it can intensify crevice conditions in some joints, but suitability depends on the full flange, gasket, loading, temperature, and water chemistry.

Flexible Graphite

Strong Caution — Stainless Flanges in Seawater

Graphite is electrically conductive and sits at the noble end of the galvanic series. Against stainless steel flanges in seawater, it can accelerate attack of the flange. Review the complete couple, exposed area ratio, electrolyte, coatings, crevice geometry, and cathodic-protection design.

Keep seawater exposure separate from hydrocarbon or exhaust duty. Any retained graphite construction still needs product-specific purity, pressure-temperature, oxidation, and project approval checks.

PTFE Filler

Conditional — Crevice-Corrosion Review

PTFE can create severe crevice conditions on stainless steel flange faces in some test and service configurations. Do not turn that mechanism into a pressure threshold or a blanket material ban; review the actual joint and project-specified construction.

Cryogenic or process use requires separate evidence for the exact PTFE grade, gasket construction, service medium, joint load, temperature, pressure, and cycling.

Correct Alternative

Aramid fibre sheet and selected non-conductive high-temperature constructions may be candidates for defined marine duties. Confirm the named product, flange alloy, electrolyte, temperature, pressure, fire requirement, gasket stress, and project or class acceptance before selection.
Failure Prevention

Plan the Joint Before the Maintenance Window

The planning example below is illustrative. It does not claim a customer, location, cost, or measured outcome; its purpose is to show the records that should be checked before mobilisation.

Illustrative Scenario: A Gasket Missing from the Shutdown Kit

Planning example only: no customer or project outcome claimed

Challenge

A maintenance team opens a flange and finds that the staged kit does not contain the required gasket. The drawing, line class, material specification, dimensions, and documentation requirement now have to be confirmed inside the work window.

Solution

Build the kit from the current flange register and equipment drawings, then verify each non-standard or large-diameter item with the responsible engineer. Confirm whether it will be manufactured or sourced, what evidence accompanies it, and the delivery route at quotation.

Result

The control is procedural: reconcile the kit against current records before mobilisation and identify items with long or uncertain lead times. Do not rely on the previous shutdown kit as the sole dimensional or material authority.

Practical Guidance

Marine Gasket Selection: Workshop Notes

Galvanic Compatibility

Review the metallic gasket components with the flange, fasteners, coatings, electrolyte, crevice geometry, exposed cathode-to-anode area ratio, and cathodic-protection design. A more noble winding is not automatically safer, and alloy name alone does not establish compatibility with a stainless flange in seawater.

Drydock Planning

Reconcile the gasket kit against current flange registers, equipment drawings, line classes, and service conditions before mobilisation. Record the material and construction on the order, then confirm evidence and lead time for each non-standard item.

Vibration on FPSOs

Platform motion and equipment vibration can impose cyclic loads on connected piping. Select inner rings where the current ASME B16.20 requirements, filler, size and class, flange bore, line class, or project specification call for them. Review pipe supports, alignment, bolting, corrosion, medium, and normal and upset conditions before choosing a winding alloy or filler.

IMO 2020 / Tier III Scrubber Sealing

Scrubber and selective catalytic reduction duties must be separated. Record the actual wash-water chemistry, chlorides, pH, temperature, pressure, cleaning regime, flange, and site material specification for each scrubber joint. For urea injection, verify the exact seal compound against AUS 32/urea service rather than prescribing PTFE or banning an elastomer family.

Fire-Test Scope

Map SOLAS, IACS, class, and project requirements to the exact vessel, system, component, and paragraph. IACS UR S6 concerns hull steel grades, UI F42 was deleted, and UR P2 is not a loose-gasket certificate. API 589 directly evaluates piping flange gaskets; API 6FB covers tested end connections and API 607 or 6FA cover their stated valve scopes. Evidence belongs to the exact tested configuration and report.

Cathodic Protection

Install a flange isolation kit only at locations defined by the cathodic-protection and electrical-isolation design. Check sealing duty, insulation level, bonding, surge, static and lightning control, hazardous-area requirements, installation, and commissioning for the complete assembly.
Material Selection

Metallic and Elastomeric Materials for Marine Service

PREN (Pitting Resistance Equivalent Number) is a comparative screening index, not a survival calculation. Final selection also depends on temperature, chlorides, oxygen, pollutants, microbiological activity, crevice geometry, surface condition, weld and heat treatment, product form, coatings, area ratio, and cathodic protection.

Alloy Selection by PREN

PREN = %Cr + 3.3(%Mo) + 16(%N). Higher PREN = better pitting resistance in chloride environments.

Alloy
PREN
Screening Position
Checks Before Selection
304 SS
~19
Lower PREN
Do not infer seawater suitability; complete a corrosion review
316L SS
~24
Crevice-sensitive
Check temperature, crevices, surface, welds, chlorination, and exposure
Duplex 2205
34–36
Higher PREN
Verify product form, heat treatment, welds, crevices, and service conditions
Super Duplex 2507
>40
Higher PREN
Still requires temperature, crevice, surface, weld, and CP review
Inconel 625
~51
High PREN screen
Check environment, product form, galvanic couple, temperature, and specification
Monel 400
N/A
PREN not applicable
Use alloy-specific seawater, velocity, aeration, and galvanic data
Incoloy 825
~34
Higher PREN
Check sour or acid environment, product form, condition, and project limits
Hastelloy C-276
~76
High PREN screen
Verify mixed chemistry, temperature, product form, couple, and project specification

Elastomers for Marine Service

EPDM

Selected EPDM compounds are common candidates for water and weather duties. Check seawater chemistry, temperature, pressure, swelling, compression set, and any hydrocarbon contamination.

Compound-specific Deck seals Cooling circuits Hatch seals

Neoprene (CR)

Neoprene compounds may suit selected weather-sealing and water duties. Verify grade, fluid, temperature, movement, weathering, and expected service interval.

Verify grade limits Hatch covers Weather sealing Cable transits

NBR (nitrile)

NBR compounds are often screened for mineral-oil hydraulic, fuel, and lubrication duties. Confirm the exact oil package, temperature, pressure, motion, and compound.

Compound-specific Hydraulics Fuel systems Lube oil

FKM (Viton)

FKM is a compound family, not a single process-fluid rating. Use the compound code and manufacturer data for the exact chemical, gas, temperature, pressure, and exposure cycle.

Verify formulation Process fluids High-temp fuel

HNBR

Selected HNBR compounds may have NORSOK M-710 or ISO 23936 test evidence. Match the compound code, report, medium, temperature, pressure, decompression schedule, geometry, and offered product.

Named compound only Subsea Sour gas Match test report

Aramid Fibre Sheet

Selected aramid fibre sheet products may be candidates for seawater cooling, ballast, or firewater duties. Check the exact binder, product data, flange, water chemistry, pressure-temperature envelope, and project acceptance.

Product-specific Seawater Ballast Firewater

Cryogenic Service (LNG)

LNG service near -162 °C needs a material set selected under the governing code and project specification for the design minimum metal temperature. Verify the exact seal compound, metal components, product form, toughness or low-temperature data, flange, bolting, cool-down rate, and thermal cycles; do not prescribe PTFE, PCTFE, or stainless steel by family name alone.
Compliance

Standards and Classification

Marine gasket selection involves classification society rules, international maritime conventions, and application-specific standards. NOPSEMA does not prescribe specific standards; operators must demonstrate ALARP (As Low As Reasonably Practicable) through their safety case.

ASME B16.20-2023

Metallic gaskets for pipe flanges: spiral wound, ring joint, and metal jacketed. Core standard for offshore process piping.

API 6A / API 17D

Wellhead and subsea tree equipment. Match the applicable R, RX, BX, SRX, or SBX ring-joint profile, pressure-temperature class, groove, dimensions, material, and performance requirements to the exact equipment and project documentation.

SOLAS Chapter II-2

SOLAS establishes ship fire-safety objectives and system duties. It does not create a generic loose-gasket certificate; map any retained requirement to the exact vessel, system, component, and paragraph.

ISO 15156 / NACE MR0175

Materials for H₂S-containing environments. Three parts covering sulphide stress cracking and hydrogen-induced cracking in sour service.

NORSOK M-710

Qualification evidence applies to a named non-metallic compound, test medium, pressure-temperature conditions, ageing or decompression schedule, specimen geometry, report, and scope. It does not qualify HNBR or FKM as families.

Classification Societies

Check the actual certificate's product and grade, issuing society, manufacturing site, scope, issue and expiry dates, limitations, and vessel or project acceptance. Do not substitute a generic approval cycle or assume a maker's certificate covers a cut gasket outside its stated scope.

API 589 / API 6FB / API 607

API 589 directly evaluates piping flange gaskets and valve stem packing. API 6FB covers tested end connections and API 607 covers its stated valve scope. Evidence remains with the exact configuration, report, and test envelope.

ASTM G48

Laboratory pitting and crevice-corrosion test methods for stainless steel and related alloys. Results depend on method, specimen, product form, surface, temperature, and acceptance criteria; they do not guarantee survival in a marine joint.

AS 1210 / AS 4041

Australian pressure-vessel and pressure-piping standards. Apply them only where the jurisdiction, project basis, equipment boundary, and each standard's scope make them applicable.

MARPOL Annex I / VI

MARPOL imposes pollution-prevention duties at vessel and system level. It does not create a generic leak-free gasket guarantee; cite the applicable annex, system, equipment requirement, and class or project acceptance route.

Products

Marine and Offshore Sealing Products

Flange Isolation Kits

Electrical Isolation for Cathodic Protection

Complete flange isolation gasket sets with insulating sleeves and washers to prevent galvanic corrosion in pipeline systems.

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Metal Gaskets

Spiral Wound, Ring Joint, Kammprofile, Jacketed

Metallic and semi-metallic gaskets for high-integrity flanged connections — Spiral Wound, Ring Joint, Kammprofile, and Jacketed types for petrochemical, refinery, and high-pressure pipeline service.

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Soft-Cut Gaskets

CNAF, Rubber, PTFE, Graphite, and more

Non-metallic gaskets cut to your drawings in compressed fibre, rubber, PTFE, flexible graphite, and other sheet materials.

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O-Rings & Cord

Standard & Custom Elastomer O-Rings and Cord Stock

O-rings and cord stock in Nitrile, Viton, EPDM, silicone, and speciality compounds. Standard metric and imperial sizes plus custom profiles and cut-to-length cord.

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Compression Packing

Braided Packing for Pumps & Valves

Braided packing in PTFE, graphite, aramid, and hybrid constructions for pumps, valves, and rotating equipment.

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Spray Shields

Flange Safety Spray Guards

Safety spray shields for flanged connections to contain leaks and protect personnel from hazardous fluid spray.

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Australian Context

Offshore production, maintenance, and decommissioning work can impose different gasket, certification, preservation, and logistics requirements. Confirm the exact facility, system, class or project basis, documentation package, delivery point, and required date at quotation.
Resources

Related Engineering Resources

Explore Further

Chemical Compatibility Database Check elastomer resistance to seawater, fuels, hydraulic fluids, and process chemicals.
Pressure-Temperature Ratings ASME B16.5 and B16.47 flange pressure-temperature charts for offshore process piping.
Gasket Failure Modes Identify corrosion, extrusion, and chemical attack failures before they cause leaks at sea.
Spiral Wound Gasket Guide Construction, filler selection, and inner ring requirements for SWGs in offshore process piping.
Reverse Engineering Service Capture legacy gasket geometry from a suitable sample, verified dimensions, and equipment records. A photograph alone is not enough for pressure-boundary manufacture.

Drydock Coming Up?

Build the gasket kit from current flange registers, drawings, line classes, and service conditions. Send the required standards, evidence package, quantities, delivery point, and date so the supply route and lead time can be confirmed at quotation.

  • Spiral wound and RTJ requirements checked separately
  • Electrical-isolation duties matched to the CP design
  • Material and fire-test evidence matched to the offered item
  • Availability and logistics confirmed for the named order
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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.