24.07.07
Scientifics go Forth
Bridges are one of the most striking aspects of the UK’s rail network, none more so than the 2.5 km. (1.5 mile) Forth Railway Bridge, the world’s first major steel bridge.
Completed in 1890, it ranks as one of the great feats of engineering and is Scotland’s biggest ‘listed’ building. It is also one of the landmark contracts for Scientifics.
The coatings team carry out regular paint inspections and surveys on the Forth Bridge. They visit every six weeks to give Network Rail an independent assessment of work carried out on the bridges and make recommendations on future work to be carried out.
This work is all part of the £40m refurbishment package which began in 1998 after the HSE undertook a structural and maintenance assessment of the structure. Indeed, this is exactly the kind of work that Scientifics undertakes not just for Network Rail but also for major suppliers such as Carillion, May Gurney and Balfour Beatty.
It is not just paintwork that needs testing and analysing. The bridges, tunnels, stations, cuttings and embankments that bind the railway network together, as well as aggregate beneath the track itself, all need investigation by engineers and technicians to comply with safety and operating legislation.
Scientifics have a specialist UKAS accredited team that does this job. So far this year, they have carried out over twenty structural investigations just for Birse Rail. The works involve mobilising PTS qualified, structural investigation engineers and technicians in order to inspect and sample from concrete, masonry and steel structures. In some cases, it might be necessary to carry out borehole works using their own track mounted, multi-functional unit that is capable of gaining access to difficult locations over rough terrain.
Once the site assessment work is completed, a variety of physical and chemical tests is carried out on the removed samples. Then they combine the findings of the site works to prepare a detailed report. But let’s go back to the Forth Bridge.
The work Scientifics’ coatings team is doing is supporting Network Rail. The new paint system employed for the steelwork requires blast cleaning to bare metal; an application of zinc based epoxy primer to prevent corrosion (35 microns); a glass flake epoxy intermediate coat providing a barrier (400 microns); and a polyurethane gloss top coat to give an attractive “Forth Bridge red” finish (50 microns) on all of its estimated 400,000m².
The system was developed for Railtrack in the mid 1990's and has been extensively tested in Scientifics’ Derby laboratories and in natural weathering site trials which are now entering their 10 years of exposure. The glass flake epoxy system is designed to give a minimum 25 year service life which means the bridge may be free of its legendary painters sometime in 2012.
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