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Thermoplastic coatings protect metal and investment

Patrick Benson, technical and marketing director at Plascoat Systems Limited, explores the benefi ts of using thermoplastic coatings for a wide range of applications within the rail industry.


ost pressures on the rail transport industry have never been greater, resulting in an

urgent need to increase asset life time, reduce maintenance costs and achieve the best whole- life outcome for investment.

Within these fi nancial constraints, the rail industry has major responsibilities towards the health and safety of its customers and employees, and to the environment. Equipment needs to be built to last, to require minimal maintenance, to be safe, to be environmentally friendly – all within a static budget.

If equipment and parts are to last they must be protected and anything made of metal needs to be coated. Surface fi nishing methods include galvanising, anodising, liquid and spray paints, and powder coating, each suited to different requirements. Chosen appropriately, a coating will provide excellent protection together with other properties such as texture, grip, ‘warm to touch’ and fume output on burning. Thermoplastic coating offers the greatest longevity, lowest whole-life cost and the widest range of benefi ts.

A suitable thermoplastic coating adheres strongly to the underlying metal. It is tough and durable, with good impact resistance and it doesn’t chip or crack. It is a thick fl exible coating with long-term corrosion protection and UV resistance, retaining a smooth glossy appearance over many years.

Thermoplastics can withstand immersion in water and low temperatures (to -70C) without cracking, making them ideal for underground installations. The expected working life of a piece of metal covered in a thermoplastic

powder can be up to 70 years. Maintenance costs are minimal and minor repairs can often be dealt with by re-melting and resealing. These qualities are exceptional and there are more, of particular relevance to the rail industry.

Apart from PVC, the fumes on burning from many thermoplastic coatings have very low toxicity and a low rate and density of smoke generation, making them safe for use in London Underground stations. The coating has high electrical and thermal resistance, suitable for cable conduits around underground rail tracks. Inside train carriages, thermoplastics have been used to coat small items such as brackets for coffee fl asks and fi re extinguishers, the qualities of fi re resistance being equally relevant here.

Thermoplastic coatings present little risk to the environment since they are entirely free of VOCs, heavy metals, BPA and halogens. A small but essential part of the rail track is the track fastener, and increasingly thermoplastics are being used as the coating for these vital components. By minimising the maintenance needs of these and other trackside assets, maintenance and track closures can be kept to a minimum too.

Although other coatings will almost certainly be cheaper at the outset, none can match the thermoplastic powder coating whole life value. Galvanised metals and anodised surfaces improve corrosion resistance in the short term but corrosion is inevitable where the metal is exposed to moisture or chemicals. Wet-painted surfaces can fl ake and crack and maintenance and replacement costs can soon negate initial savings.

Access hand rails need to provide grip and to be ‘warm to touch’ (DDA regulations). Thermoplastics have these credentials and can be seen on access hand rails within many stations including recent additions to Paddington and Tottenham Court Road London Underground.

Around £400m a year is spent on repainting or replacing railway infrastructure damaged by vandalism. Not only do thermoplastic coatings protect from impact without cracking but they are also impermeable to paints and non-reactive, making graffi ti removal easy and inexpensive. Train operating companies including South West Trains, East Midlands and Network Rail are using thermoplastics to coat and protect chairs and other structures on station platforms.

Finally, improving overall customer experience keeps the railways in business. The wide range of colours and textures of thermoplastic powders gives designers a broad scope, creating bright and pleasing station environments and train interiors.

Plascoat Systems is the world leader in thermoplastic powder technology and its best selling product is PPA 571. Almost all of the items mentioned above are coated in this product. By protecting structures within the rail transport infrastructure, Plascoat’s PPA 571 ensures durability, an aesthetically pleasing appearance and signifi cant long term cost savings.


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rail technology magazine Dec/Jan 13 | 75

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