Home: April / May 2012 › Don’t paint it – coat it!
Don’t paint it – coat it!
20/04/2012 | Channel:
Business Improvement, New Products & Services
GEOFF CROWLEY talks about how galvanizing and
powder coating is having an increasing impact on rail
maintenance and improvement
The popularity of steel is easy to understand – it’s strong, versatile and cost effective. Last year, the global crude steel production total hit an alltime high at 1.515 billion tonnes, signalling an increased demand for the material despite a widespread downturn in construction.
The construction industry consumes around half of the world’s steel, while the transport sector is the next biggest user at 16 per cent. It makes sense, then, that a huge portion of our global built environment and infrastructure relies on steel.
But steel corrodes and will only stay useful as long as it’s properly protected. Corrosion is a major problem and one that’s costing the UK four per cent of its annual GNP.
Failure to coat steel appropriately means that around one tonne of the stuff is returning to dust every 90 seconds. In fact, it’s actually been estimated that almost half the tonnage produced around the world every year is made to replace steel that could have been protected more effectively.
Corrosion protection is of particular interest when looking at the rail industry, since huge quantities of steel are used globally – both externally for network infrastructure and internally around trains and stations.
Galvanizing is widely recognised as the most effective way to protect steel from corrosion and involves dipping the metal in a hot molten zinc to form a rust-resistant layer. Part of this coating is 150 per cent harder than the steel itself.
Colour powder coating is the process of applying dry coloured compounds to metals using an electrostatic charge then baking for a smooth finish, offering an environmentally superior alternative to paint. This finish tends to be for decorative purposes or indoor use as it doesn’t offer the level of protection guaranteed by galvanizing, but the processes can be combined for use in harsher environments.
In the UK, rail is actually one industry that does seem to recognise the value of galvanizing external metal assets, such as safety fencing, CCTV posts, car-park street lighting, bollards and cycle sheds, as well as electric track signage and cable supports.
In fact, rail and agriculture really lead the way in terms of responsible use of steel in Britain, but of course there’s more that can be done to avoid needless corrosion and disintegration of kit. One example is the recent Airdrie-Bathgate rail link project, where new stations were set up to serve towns along the route, but for some reason the stairs and walkways between platforms and related infrastructure have been painted rather than galvanized.
This is out of keeping with the general trend within the UK rail sector and can’t simply be explained by the desire for a coloured finish. Admittedly, galvanized coatings come in grey or grey, but colour on galvanizing is much more durable and cost-effective than paint and is used widely across the remainder of the network.
Colour galvanizing involves galvanizing and colour powder coating being used in tandem to give corrosion protection with a coloured finish. Britain suffers its fair share of harsh weather conditions so it’s heartening to see certain sectors taking note and safeguarding assets for as long as possible. Despite that, the UK lags behind most of Europe in the effective use of corrosion protection.
The Forth Road Bridge is another example. ‘Painting the Forth Bridge’ has become a well-known euphemism for a never-ending task, purely because paint doesn’t last. The ongoing cost of this maintenance is phenomenal and the problem is yet to be fully solved. In fact, the new road bridge in construction (the Forth Replacement Crossing) is largely required because of corrosion on the old one.
Of course, there are issues with trying to galvanize a structure of this size, but if it had been designed in sections and galvanized at the outset, this painting debacle need never have begun.
The necessary maintenance is pushing up the true cost of choosing to coat with paint,
which contains harmful solvents in order to dry, thereby directly causing ozone layer depletion. Colour galvanizing is virtually devoid of Volatile Organic Compounds (VOCs) and will stay colourfast for up to 40 years and corrosion-free for up to a century.
Financially trying times over the last few years have undoubtedly brought the issues of longevity and sustainability to the fore in all fields of business, as well as inspiring a
trend of taking care of existing assets. The rail industry has shown its responsible stance by pushing on with extensive and on-going refurbishment programmes for trains.
For example, companies such as Railcare and Railway Projects Ltd work with ScotRail on tight schedules to strip out the interiors of trains and bring each back to the standard of a new vehicle.
Rail refurbishment specialists like these will take delivery of a train every fortnight during a refurbishment project and remove all the accessories – carpets, upholstery, handrails, bike racks; the lot.
When you think about it, quite a bit of what you see and use inside a train is made of metal – either steel or aluminium – so it’s important to protect it all correctly to avoid
unnecessary expenditure down the line. Of course, the protection needn’t be as robust as what’s required externally, where rain, snow, ice and grit have to be considered.
For protection of internal equipment, powder coating is sufficient and also offers a choice of over 250 colours to fit in with branding or to comply with Disability Discrimination Act (DDA) regulations. For example, DDA rules specify that handrails must be very visible, so powder coating is used to achieve the necessary colour contrasts and long-lasting finish.
This move to use powder coating instead of solvent-based paints is a relatively recent development but certainly one that we welcome. It shows a desire within the rail industry to choose fit-for-purpose coatings to protect expensive assets and extend the return on its investment into refurbishment and maintenance.
Recognition of the value in galvanizing and powder coating is beginning to trickle through the ranks of the transport sector, with moves being made by the haulage and shipping industries toward better metal protection. There is also scope for much wider use across construction and engineering as well as emerging markets such as renewable energy.