1. what salt does to steel - corrosion in slow motion and fast-forward
Corrosion on steel is essentially an electrochemical process: iron loses electrons and reacts with oxygen to form iron oxides - rust. Pure water accelerates this process. Salt water accelerates it dramatically because chloride and sulphate ions close the electrolytic circuit that drives oxidation.
In practice, three forms of corrosion are particularly common:
- Surface corrosionUniform material removal, often on exposed, unprotected steel surfaces.
- PittingLocalised corrosion attacks, often in areas with local salt accumulation or contamination.
- Crevice and contact corrosionAt joints, flanges, behind brackets - anywhere where brine does not dry out and concentrates.
Three practical consequences:
- Salt deposits must be removed before they dry up or become encrusted.
- Cleaning must be carried out in such a way that no new capillary salt films form afterwards.
- Corrosion protection starts with cleaning - not only during the coating process.
2. what cleaning products for offshore applications need to do
The corrosion mechanism and the regulatory framework result in four requirements that no product can avoid:
2.1 Effectiveness against salt-related soiling
The product must reliably dissolve chlorides, sulphates and stubborn salt crusts - even in thin layers on heavily exposed surfaces. Pure water is often not enough: it removes loose salts, but not the fine films and incrustations that settle in crevices and micro-scratches.
2.2 Material compatibility
Steel, aluminium, stainless steel, paint, coatings, rubber, plastic: in the offshore environment, cleaning agents come into contact with a whole range of materials. Aggressive acidic or strongly alkaline cleaners can even promote corrosion instead of preventing it. Modern offshore cleaners therefore have a neutral to slightly alkaline pH value.
2.3 Biodegradability
What is used on board can theoretically end up in the sea - deliberately or accidentally. Products for offshore applications must therefore be readily biodegradable in accordance with OECD 301 (or an equivalent standard). Persistent, bioaccumulative or toxic (PBT) substances are generally ruled out.
2.4 Safe storage and transport
Storage space on platforms and ships is limited, ventilation is often restricted and personnel change regularly. Cleaning agents without CLP hazardous substance symbols and without ADR dangerous goods status are not a luxury here, but a real operational relief.
3. cleaner classes in offshore use
The most important product groups for maritime applications can be roughly categorised into four families:
3.1 Salt Remover
Cleaners formulated on a neutral to slightly acidic basis that dissolve chloride and sulphate deposits without attacking steel, aluminium or coatings. Often with an inhibitor effect, which provides short-term corrosion protection after cleaning.
Application: Platform structures, railings, decks, helideck areas, tools. (In preparation in the Green4Clean portfolio - enquiries via the contact form).
3.2 All-purpose and deck cleaner
Surfactant-based, biodegradable cleaner for general soiling - salt films in combination with dirt, fuel splashes, lubricant residues. pH value mostly neutral to slightly alkaline, gentle on materials.
3.3 Bitumen, oil and grease cleaner
Water-based speciality cleaners, such as those based on plant-based surfactants, for spilled mineral oils, fuels and lubricants on decks and in technical areas. In the Green4Clean portfolio focussed on traffic route construction, this role is assumed by Bituclean Extra - also for workshop areas on land.
3.4 Liquid oil binding agents
Instead of classic granulate, biosurfactant-based liquid products are used. They bind leaked oils and fuels and then support their biodegradation - without producing hazardous waste granulate. Example: Anti Slip Eco, which can also be used in offshore and harbour environments.
4. routine concept for offshore cleaning
Effective cleaning stands and falls with routine. Three time horizons that should be covered in every offshore maintenance concept:
4.1 Daily visual cleaning
- Spray water and salt films from easily accessible decks, railings, maintenance areas Rinse with fresh water or mild detergent.
- Tools Dry after use, oil if necessary.
- Clean up spillages (fuel, oil) immediately, before they are distributed over large areas.
4.2 Weekly/bi-weekly deep cleansing
- Salt remover application on particularly exposed steel surfaces: Railings, access aids, helideck edges, cranes.
- Inspection of gaps, flanges, weld seams - where brine is favoured.
- Control of the coatings: Mark and document the first centres of corrosion and include them in the maintenance plan.
4.3 Planned maintenance and conservation campaigns
- Major cleaning campaigns before painting or coating work.
- Combined cleaning with high pressure, if necessary with warm water, where permitted and compatible with the material.
- Repainting or preservation on a prepared, salt-free surface - a coating on residual salt will not age.
Three rules of thumb for your routine:
- Do not allow the cleaner to dry. This is especially true in direct sunlight on board.
- Rinse with clear water. Cleaner residues can become deposits or centres of corrosion in the long term.
- Document centres of corrosion. What is not systematically recorded becomes expensive later on.
5. oil spills on water and harbour areas - the special challenge
A spilled litre of diesel on a pier, a trail of oil on a port roadway, a slightly dripping hydraulic connection on the helideck: dealing with mineral oil spills is part of everyday life in the offshore and port environment. At the same time, the requirements are strict - discharges into harbour basins or the sea are clearly regulated.
Classic granular binding agents have limitations here: although they bind the oil, they must be disposed of as hazardous waste. They can only be used on water in certain authorised areas. Liquid, biosurfactant-based oil binding agents such as Anti Slip Eco offer an alternative route here:
- Immediate effectThe surface quickly becomes non-slip.
- Biological degradationInstead of producing a mass of hazardous waste, the biosurfactants and nutrients it contains activate the natural microbial degradation of the oil compounds.
- Easy to useCan be applied with standard sprayers or pump spray bottles - important on decks and platforms where complex application equipment is out of place.
Important: Use on water is always subject to the specific authorisation situation. Harbour operators and the responsible authorities set the framework - we will be happy to advise you on whether and how Anti Slip Eco fits in your specific case.
6 Corrosion protection begins before coating
An observation from many offshore maintenance projects: Coatings often last shorter than planned because the underlying surface was not completely free of salt. Residual chlorides, overlooked in the blasting phase or newly introduced by spray water shortly before painting, trigger corrosion under the new coating long before it visibly fails.
The consequence for practice:
- Check that there is no salt before coatingWith wipe tests or Bresle patches.
- Schedule cleaning stepEven with „only slight corrosion“, a salt remover treatment before blasting or grinding.
- Respect time windowsCoat as soon as possible after cleaning and drying - otherwise new films will form.
The cleaning agent is not an auxiliary material here, but a component of the corrosion protection concept.