FRP marine offshore non-magnetic non-sparking lightweight topsides
The corrosion case for FRP on offshore platforms and marine installations is well established. But corrosion resistance is not the only reason FRP is the correct specification in marine and offshore environments. On an operating oil and gas platform, corrosion resistance is necessary but not sufficient. The non-magnetic property that keeps FRP clear of sensitive navigation and safety instrumentation, the non-sparking property that eliminates ignition risk in hydrocarbon atmospheres, and the weight advantage that directly improves topside payload capacity are three properties that matter as much as corrosion resistance, and that are often underweighted in the FRP specification case for marine and offshore applications.
Published by Reinforce Technology | 19 August 2026
The North Sea Transition Authority estimates total UK offshore decommissioning costs at approximately £40 to £45 billion, front loaded toward the 2025 to 2040 window as a large tranche of mature fields reach cessation of production (NSTA, 2026). New offshore wind foundations, floating offshore wind platforms, and the ongoing new build and life extension programmes for production facilities simultaneously represent active construction and modification programmes across UK offshore infrastructure. Each of these programmes, whether new build, life extension, or decommissioning preparation, involves secondary structural specification decisions for topsides walkways, grating, cable management, handrail, and equipment supports. And in each of these programmes, the case for FRP secondary infrastructure extends well beyond corrosion resistance into properties that are specific to the offshore operating environment and that steel cannot match.
At the Forties Alpha platform in the North Sea, GRP has been integrated into topside structures and walkways. The use of GRP significantly reduced component weight, easing installation and cutting transportation costs (Engineered Composites, 2025). This is not a novel or experimental application. GRP and FRP have been specified in offshore topside secondary infrastructure since the 1980s, with an established track record across North Sea oil and gas platforms, floating production storage and offloading vessels, and offshore wind installation vessel crew decks. The properties that drove initial adoption, weight reduction, non-sparking behaviour, and non-conductivity, remain the primary specification drivers, with corrosion resistance providing additional whole life value on top of those primary operational properties.
This blog covers the three offshore FRP properties beyond corrosion resistance that matter most for secondary infrastructure specification on marine and offshore assets: non-magnetic behaviour, non-sparking performance in hydrocarbon atmospheres, and topside weight reduction. It is the specification case for FRP in offshore environments where the operating conditions, not just the weather, determine what secondary materials are acceptable.
Non-Magnetic: Why It Matters Offshore
Steel is ferromagnetic. It generates a local magnetic field in its vicinity and responds to external magnetic fields by becoming magnetised, distorting the magnetic environment around it. On offshore platforms and marine vessels, this magnetic behaviour creates specific operational problems for the navigation, safety monitoring, and scientific instrumentation systems that offshore operations depend upon.
Marine magnetic compasses, which remain required navigational instruments on all vessels under SOLAS, are affected by the proximity of ferromagnetic materials. The deviation between a magnetic compass reading and true magnetic north, caused by the ship's own steel structure and any ferromagnetic secondary materials in the compass vicinity, must be measured, recorded, and corrected in a compass adjustment procedure. Secondary steel structural elements installed near compass locations increase this deviation and may require additional compass adjustment and deviation card updates. FRP secondary structural sections near compass installations contribute zero magnetic deviation, simplifying compass management and eliminating the contribution of secondary structure to compass deviation errors (PowerGrate, 2021).
On offshore production platforms, the instrumentation most sensitive to magnetic interference includes subsea pipeline inspection gauges, magnetic flow meters in process piping, electromagnetic position reference systems for dynamic positioning vessels, and the degaussing systems used on naval vessels and certain specialist offshore support vessels. In each of these applications, ferromagnetic secondary structural materials in proximity to the instrument create measurement errors or interference that FRP materials eliminate entirely. The non-magnetic property of FRP is not a passive advantage that shows up only in specialist applications. It is a practical operational benefit on every marine and offshore installation where navigation and positioning instruments are in the vicinity of the secondary infrastructure (GRP Grating Systems, 2025).
On floating offshore wind platforms, which use dynamic positioning or mooring systems with precise position monitoring equipment, and on geophysical survey vessels that tow sensitive magnetic survey equipment, the non-magnetic property of FRP secondary structural sections in areas near navigation and survey equipment is a specific and actively specified requirement. GRP and FRP are the standard secondary structural specification in these non-metallic zones on vessels and platforms where magnetic field management is a documented operational requirement.
Non-Sparking: The Hydrocarbon Atmosphere Requirement
Offshore oil and gas platforms process and handle hydrocarbons continuously. The combination of hydrocarbon vapour, process gas, and the potential for accidental release from pressurised equipment creates explosive atmosphere zones across the processing areas of every active production platform. These zones are classified under the ATEX and IECEx frameworks as Zone 0 (continuous explosive atmosphere), Zone 1 (periodic explosive atmosphere likely during normal operation), and Zone 2 (occasional explosive atmosphere not likely during normal operation). Secondary structural materials, grating, walkways, and handrail systems in and adjacent to classified zones must not create an ignition source under any normal or foreseeable operational condition.
Steel grating and structural sections can generate sparks under mechanical impact, friction, or contact with other hard metal surfaces. A dropped tool landing on steel grating in a Zone 1 classified area of a hydrocarbon processing platform is a potential ignition event. The probability of ignition from a single spark impact is low, but not zero, and offshore safety cases are built on eliminating ignition sources in classified areas rather than accepting low probability events. FRP grating and structural sections are non-sparking under mechanical impact and friction at all loading conditions encountered in normal and foreseeable offshore operations, eliminating the ignition risk from the secondary structural access infrastructure in classified hydrocarbon atmosphere zones (GRP Grating Systems, 2025).
The non-sparking property is tested under the relevant ATEX standard for non-electrical equipment, EN 13463, which requires demonstration that the material does not generate incendive sparks under the impact and friction conditions of its intended use. FRP moulded grating and pultruded structural profiles tested to EN 13463 requirements provide the documented non-sparking certification that offshore safety cases require for secondary structural materials in classified zones. The test documentation is a specific procurement requirement for offshore clients with formal ATEX zone documentation for their facilities, and FRP products without the relevant test data cannot be accepted for use in classified areas regardless of the material's known physical properties.
On floating offshore wind platforms, which typically do not handle hydrocarbons directly, the non-sparking requirement is less universally applicable than on oil and gas production platforms. However, the battery storage systems that some floating offshore wind designs incorporate for short term power buffering create Zone 2 hydrogen atmosphere classifications in the battery room and ventilation areas that apply the same non-sparking requirement to secondary structural materials in those specific areas of the platform.
Topside Weight: Why Every Tonne on an Offshore Platform Costs Money
The weight of equipment and structures installed on an offshore platform topsides is not simply a materials cost consideration. It is a structural engineering constraint that determines the load carrying capacity of the jacket or hull that supports the topsides, the stability and motion response of floating platforms, the crane capacity required for installation and maintenance lifts, and the vessel capacity required to transport materials and equipment to the offshore site.
On fixed jacket platforms in the North Sea, the topsides weight is constrained by the jacket's structural design capacity. Every additional tonne of secondary structural weight added to the topsides during life extension or modification programmes reduces the available capacity for process equipment modifications, new safety systems, or production enhancement equipment. Weight reduction programmes on mature North Sea platforms, which reduce topsides weight by removing redundant structures and replacing heavy steel secondary infrastructure with lighter alternatives, create payload capacity that enables production and operational improvements that would otherwise exceed the jacket's structural limit. Weight shedding has been shown to present a favourable method for extending the life of offshore installations, with target weight reductions measured in hundreds to thousands of tonnes on individual platforms.
FRP secondary structural sections at 70 to 75% of the weight of equivalent steel sections represent a direct and quantifiable topsides weight reduction for every metre of walkway, every grating panel, every cable tray run, and every equipment support frame replaced with FRP. On a large production platform replacing 500 square metres of steel grating with FRP moulded grating, the weight saving is approximately 15 to 25 tonnes, creating equivalent capacity for process equipment that generates production revenue. The economic value of that payload capacity, on a platform producing oil or gas at current market prices, is typically many times the purchase price difference between FRP and steel grating for the same installation (FRP Platform, 2026).
On floating platforms and FPSOs, the weight advantage of FRP is even more directly connected to operational performance. Floating platform stability is determined by the relationship between the centre of gravity and the metacentre of the hull. Lower topsides weight and lower centre of gravity improve stability margins and reduce the pitch, roll, and heave motions that affect operations, safety, and the fatigue life of mooring and riser systems. FRP topsides secondary structures contribute to lower centre of gravity and improved stability without compromising the structural performance of the walkway, grating, and cable management system.
Installation in the Offshore Environment: Why Weight Saving Is Amplified
The weight advantage of FRP secondary infrastructure is amplified in the offshore installation environment in ways that do not apply to onshore installations. Offshore crane operations are constrained by vessel motion, weather windows, and the crane capacity of the installation vessel or platform crane. Every item of equipment and structure lifted by a platform crane represents a crane time allocation from a limited pool, and crane time on an offshore platform is a scarce and expensive resource.
FRP grating panels, structural sections, and cable tray components at 70 to 75% less weight than steel equivalents can be handled manually by offshore installation teams in many configurations without crane support for individual panel or section placement. A two person installation team can carry, position, and secure FRP grating panels and cable tray sections across a topsides walkway installation without the crane lift that steel sections of equivalent structural function would require for every placement. The reduction in crane lifts across a topsides secondary infrastructure installation programme directly reduces the crane time cost of the installation, which on an offshore platform can be measured in tens of thousands of pounds per crane hour (MEP Solutions, 2025).
The transportation advantage operates at the same ratio. FRP secondary infrastructure shipped from a fabrication yard to an offshore installation site occupies the same volume of supply vessel cargo space as equivalent steel infrastructure, but at 70 to 75% less weight. The weight saved per vessel voyage translates to additional cargo capacity for other materials and equipment, reducing the number of vessel voyages required to complete the installation programme and the associated vessel charter cost and fuel consumption.
Fire Retardant FRP for Offshore Applications
Standard FRP formulations are combustible, and offshore platforms have strict fire safety requirements under international conventions including SOLAS and the MODU Code, and under UK regulatory requirements enforced by the Health and Safety Executive under the Offshore Installations and Wells regulations. Secondary structural materials on offshore platforms in occupied areas must meet the fire performance classifications specified in the facility's fire and explosion risk assessment and the applicable regulatory framework.
Fire retardant FRP formulations incorporating halogen-free flame retardant additives are available for offshore applications requiring specific fire performance classifications. FRP decking systems manufactured using fire retardant resin achieve a Class 2 fire rating under BS 476 Part 7, ensuring the material limits flame spread and maintains its structural integrity during exposure to heat. The combination of non-sparking properties, low smoke emission, and electrical insulation in FR-grade FRP makes it the secondary structural specification for offshore occupied modules, accommodation areas, and emergency evacuation routes where fire performance classification is a regulatory requirement alongside the operational properties that make FRP the correct material for the offshore environment.
The selection between standard and fire retardant FRP formulations for offshore applications is determined by the area classification of the specific installation location within the platform's fire zone documentation. Open topsides process areas in non-occupied zones may accept standard FRP under the applicable risk assessment. Occupied accommodation modules, muster stations, escape routes, and areas classified as temporary refuge in the platform's emergency response arrangements require FR-grade FRP to satisfy the fire performance requirements of the regulatory framework. The project's fire and explosion risk assessment and the facility's area classification documentation are the definitive reference for this selection, and the FR grade specification should be confirmed against those documents before procurement.
The Offshore FRP Specification Summary
In marine and offshore environments, FRP secondary infrastructure is specified for four properties that steel cannot provide simultaneously: corrosion immunity in saltwater and marine atmospheric exposure, non-magnetic behaviour near navigation and safety instrumentation, non-sparking performance in hydrocarbon atmosphere zones, and 70 to 75% weight reduction that directly improves topside payload capacity and installation efficiency. Each of these properties has a quantifiable operational value on every offshore platform and marine vessel where secondary infrastructure is being specified, replaced, or upgraded as part of a life extension, modification, or new build programme.
The North Sea decommissioning pipeline, the floating offshore wind new build programme, and the ongoing life extension activities across UK Continental Shelf production infrastructure all create active secondary specification decisions where these four properties determine the correct material. FRP vinyl ester, in FR-grade formulations where fire performance classification requires it, is the specification that satisfies all four properties across the 25-year design lives that offshore assets demand from their secondary infrastructure.
Reinforce Technology FRP Products for Marine and Offshore Applications
Reinforce Technology supplies FRP moulded grating, pultruded structural profiles, cable trays, and handrail systems for offshore platform, FPSO, marine vessel, and floating offshore wind secondary infrastructure applications. Available in vinyl ester resin systems for saltwater and marine atmospheric environments, with fire retardant formulations tested to BS 476 and relevant offshore fire performance classifications. Non-magnetic, non-sparking, non-conductive, and 70 to 75% lighter than steel across 25-year maintenance-free design lives in the most demanding marine and offshore secondary infrastructure environments in UK waters.
Contact us to discuss your offshore or marine project and the correct FRP specification for your platform, vessel, and operational requirements.
Final confirmation of suitability for any specific offshore or marine application, including ATEX zone classification, fire performance requirement, and structural loading assessment for offshore load cases, remains the responsibility of the appointed project engineer. Reinforce Technology provides technical guidance and material recommendations based on information supplied to us, but specification sign-off should always sit with the qualified professional responsible for the design.
References
Engineered Composites (2025) GRP Construction in the North Sea Offshore Oil and Gas Industry. Available at: https://engineered-composites.co.uk/grp-construction-in-the-north-sea-offshore-oil-and-gas-industry/ [Accessed: 19 August 2026]. [Forties Alpha platform: GRP integrated into topside structures and walkways, significantly reducing component weight, easing installation and cutting transportation costs; GRP non-conductive properties prevent sparking in volatile oil and gas environments; GRP firewater systems high strength, low maintenance, excellent fire resistance].
FRP Platform (2026) FRP Offshore Platform Grating Installation Method: Step-by-Step Guide. Available at: https://www.frpplatform.com/frp-offshore-platform-grating-installation/ [Accessed: 19 August 2026]. [Non-conductive and non-sparking; ease of on-site modification with standard tools; over 20-year service life with virtually no protective coating maintenance versus 3 to 5 recoating cycles for steel].
GRP Grating Systems (2025) GRP in Renewable Energy and Offshore Applications. Available at: https://www.grpgratingsystems.co.uk [Accessed: 19 August 2026]. [Non-sparking reduces ignition risk in flammable gas environments; non-magnetic prevents interference with sensitive monitoring and control systems; GRP Deck 500 panels on offshore platforms].
IntechOpen (2022) 'Fibre-Reinforced Polymer (FRP) in Civil Engineering', in IntechOpen Engineering Series. Available at: https://www.intechopen.com/chapters/84203 [Accessed: 19 August 2026]. [Non-conductive; non-magnetic; non-sparking; 70 to 75% lighter than steel; 25-year design life without maintenance].
MEP Solutions (2025) Fiberglass Reinforced Plastic Cable Tray: Offshore Applications. Available at: https://sfsp-ikk.com/solutions/mep-solutions/cable-management-systems/fiberglass-cable-tray.php [Accessed: 19 August 2026]. [FRP ease of handling reduces hoisting accidents and shipping costs; manual positioning without crane support; reduced crane lift tonnes for same installed metreage on offshore platforms].
NACE International (2016) International Measures of Prevention, Application and Economics of Corrosion Technology (IMPACT). Houston, TX: NACE International. Available at: http://impact.nace.org/economic-impact.aspx [Accessed: 19 August 2026].
NSTA (2026) North Sea Transition Authority: Decommissioning Cost Estimates. Available at: https://www.nstauthority.co.uk [Accessed: 19 August 2026]. [Total UK decommissioning cost approximately £40 to £45 billion in 2024 money; front-loaded 2025 to 2040 window; topsides removal and disposal 15 to 25% of full-field decommissioning cost].
PowerGrate (2021) FRP Phenolic Grating for Offshore Platform. Available at: https://powergrate.en.made-in-china.com [Accessed: 19 August 2026]. [Non-magnetic property allows use in sensitive installations where inherent magnetic properties of metal grating prove dangerous; non-conductive property ideally suitable in electrically hazardous locations].
ScienceDirect (2025) 'Sustainable composites for metal replacement: Environmental assessment and material selection of fiber-reinforced polymer across industries', ScienceDirect, doi: 10.1016/S2667-3789(25)00051-3. Available at: https://www.sciencedirect.com/science/article/pii/S2667378925000513 [Accessed: 19 August 2026].
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