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Dissimilar Metals and FRP Galvanic Corrosion Solutions
Overview
This Tech Talk Tuesday session explains the risks created when dissimilar metals are used together in the presence of moisture or another electrolyte, with a focus on galvanic corrosion in industrial access structures. The webinar discusses where dissimilar metal issues commonly occur, why they matter for maintenance and structural durability, and how FRP can help by acting as a non-conductive material within the system.
Galvanic corrosion occurs when different metals are in electrical contact in the presence of an electrolyte, causing one metal to corrode faster while the other is protected. Authoritative corrosion references describe this as an electrochemical process involving dissimilar metals, electrical contact and an electrolyte such as water, saline water or other conductive moisture.
The session applies this principle to real site conditions, such as stainless steel fixings on mild steel structures, aluminium handrails on coated steel supports, stainless cable ladder hung from mild steel framing, or FRP grating fixings installed on galvanised or coated steel. It then explains how Treadwell uses FRP and purpose-designed clip isolators to reduce electrical contact, avoid coating damage and simplify long-term maintenance.
Key Benefits
Clear understanding of galvanic corrosion risk
The webinar explains that dissimilar metals can create a corrosion risk when they touch in the presence of moisture, including moisture in the air. Salt water and saline process water can make this risk worse because they act as stronger electrolytes.
Reduced maintenance demand
Galvanic corrosion can increase the need for inspections, cleaning, recoating, cathodic protection and replacement of isolation materials. By reducing dissimilar metal contact, FRP can help support lower maintenance access structures.
Lower risk of premature failure
Accelerated corrosion at metal interfaces can weaken components and reduce the service life of structures, fixings and connections. The session highlights that corrosion is not only a maintenance issue, but also a structural and operational risk.
Non-conductive FRP simplifies isolation
FRP is non-conductive, so it does not create the same galvanic pathway as metallic components. This can simplify installations where stainless steel, aluminium, galvanised steel or coated mild steel would otherwise need careful isolation from one another.
Useful around handrails, cable ladder and grating
The webinar gives examples such as aluminium handrail on mild steel, stainless cable ladder on coated steel and stainless fixings on mild steel structures. FRP handrails, FRP cable tray, FRP cable ladder and FRP grating can reduce the number of metallic interfaces that need isolation.
Reduced coating damage during grating installation
Direct drilling into galvanised or coated steel can damage the protective coating and may be difficult to remediate properly on site. Treadwell’s clamp-based fixing approach avoids drilling into the support structure, helping preserve coatings and reduce corrosion starting points.
Stainless fixing durability without direct metal contact
Stainless steel fixings are often preferred for durability and appearance, especially where debris, slurry or dropped material can build up around grating clips. Treadwell’s isolator design allows stainless fixing components to be used while reducing direct contact with the underlying mild steel or galvanised structure.
Purpose-designed poly isolators
The session describes a clamp system with poly isolators that fit snugly over the stainless clamp component. This isolates the clip from the support structure while keeping installation practical and avoiding loose washers or complex multi-part isolation details.
Practical support for high-risk environments
The webinar identifies salt water, maritime structures, jetties, mine processing sites, water treatment and wastewater environments as higher risk areas. These are the kinds of sites where non-conductive FRP and isolated fixing details can help reduce corrosion concerns.
Applications
Grating and decking fixings on coated steel structures
Treadwell’s isolated clamp system is suitable where FRP grating needs to be fixed to galvanised, painted or coated steel without drilling through the protective coating. The system can clamp to the web or flange of members such as UBs, UCs or channels, depending on the support detail.
Stainless fixings on mild steel or galvanised supports
Where stainless steel clips or fasteners are preferred for durability, isolators can reduce direct contact between stainless components and the support structure. This is especially useful where debris, slurry or process material may collect around the fixing and accelerate corrosion.
FRP handrails on metallic structures
Replacing aluminium or stainless steel handrails with FRP handrails can reduce galvanic corrosion risks when the supporting structure is mild steel or coated steel. Since FRP is non-conductive, it reduces the need for metallic isolation at the interface.
FRP cable ladder and cable tray installations
Cable ladder and tray are common areas where dissimilar metal interfaces occur, especially where stainless, aluminium or galvanised components are attached to coated steel structures. FRP cable ladder and tray can reduce these metallic contact points while also supporting corrosion-resistant installation.
Mine processing environments
The webinar highlights mineral processing as a high-risk environment because process water can be highly saline. FRP can help reduce dissimilar metal issues in walkways, grating, cable supports and access structures where moisture and salts increase galvanic corrosion risk.
Marine, jetty and offshore structures
Saltwater environments accelerate galvanic corrosion, making material isolation especially important. FRP grating, handrails and cable supports can help reduce corrosion risk where structures are exposed to sea spray, salt water or maritime conditions.
Water and wastewater treatment plants
Water and wastewater facilities often include high humidity, treatment chemicals, chlorine exposure, hydrogen sulphide and constant moisture. These conditions can increase corrosion risk where different metals are used together, making FRP a useful option for access and support systems.
Closed section structures with added clamp points
Where hollow sections such as RHS or SHS are used, Treadwell notes that tabs or plates may need to be added so clamp-based grating fixings can engage without drilling into the coated member. This should be considered during design.
Sites with limited maintenance access
Locations requiring scaffolding, elevated work platforms, road closures or difficult access can make corrosion maintenance expensive and disruptive. Reducing galvanic corrosion risk at the design stage can help minimise future inspection and repair burdens.
Key Moments
- 00:14 👋 Welcome to Tech Talk Tuesday on dissimilar metals at Treadwell, with Q&A and feedback encouraged.
- 01:25 🔩 Dissimilar metals are alloys with widely different properties that risk galvanic corrosion when contacting moisture or electrolytes.
- 01:51 ⚡ Galvanic corrosion forms a small electrical circuit, accelerating damage beyond normal rates in moist or saline conditions.
- 02:32 📏 Differential expansion between metals can also stress connections, though galvanic corrosion is the main focus.
- 02:47 📍 Risks appear at interfaces like mixed-material flanges, stainless fixings in mild steel, or aluminium handrails on steel.
- 03:44 🔧 Concerns include higher maintenance (inspections, recoating), premature failure, and costly operational disruptions.
- 05:45 🌊 High-risk environments include salt water, mining, wastewater treatment, and humid chemical exposure areas.
- 06:41 🛡️ FRP acts as a non-conductive physical barrier, simplifying installation and reducing long-term maintenance needs.
- 08:31 🔧 Self-drilling screws damage coatings on steel structures; pre-drilled options or clamps avoid this issue.
- 09:54 🛠️ New clamp isolators with poly sleeves enable stainless fixings on grading without coating damage or isolation problems.
Why Treadwell?
Treadwell brings a practical systems-based approach to dissimilar metal risk. The webinar not only explains galvanic corrosion as a theory. It connects the issue to real access structure details such as grating clips, stainless fasteners, coated steel members, cable ladder supports, handrail interfaces and difficult maintenance locations.
Treadwell’s FRP solutions help reduce galvanic corrosion pathways because FRP is non-conductive and does not behave like another metal in the corrosion cell. This makes it useful for handrails, grating, cable ladder, cable tray and access structures where traditional metallic combinations may require ongoing isolation and inspection.
The company also offers practical fixing details, including isolated stainless clamp arrangements with poly isolators designed to preserve coating systems while reducing direct metal-to-metal contact. This allows project teams to keep the durability benefits of stainless fixings while managing galvanic interaction with mild steel, galvanised steel or coated supports.
As an established FRP provider in Australia and New Zealand, Treadwell supports engineers, contractors and asset owners with site discussions, drawings, fixing options, FRP grating, handrail, cable ladder and corrosion-resistant access solutions. For environments exposed to salt water, process water, wastewater, chemicals or humidity, Treadwell can help reduce corrosion risks at the design stage rather than treating them as maintenance problems later.
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*Disclaimer
The information on this page is derived from webinar content and AI-assisted transcription and summarisation. While every effort has been made to ensure accuracy, minor inaccuracies may occur. We recommend viewing the original webinar recording for context.
