Mobile access system for essential maintenance

Paul Boughton
Access and scaffolding contractor Harsco Infrastructure has designed and installed two bespoke mobile access systems to allow contractors to carry out essential maintenance work at Peterborough Power Station in the UK.

Centrica, which operates the 360MW gas-fired power plant, has enlisted industrial painting specialist East Coast Industries to carry out the work which involves cleaning and re-painting the air cooled condenser (ACC) units. This has involved working on the ACC's enormous horizontal steam pipes with obscure angles that made the ACC units inaccessible by conventional means. Also with the pipes reaching a surface temperature of 65°C SGB had to make sure that the access system could withstand these high temperatures and still be functional.

East Coast Industries awarded Harsco Infrastructure with the contract to design, manufacture and install a mobile access system, which would afford a safe means of access to and from the working area. The system was also required to provide a safe means of evacuation in the event of emergency.

Harsco Infrastructure's design uses powered self-propelled work platforms suspended from a steel framework. The rig travels along the pipes on a series of wheels which are specially angled to accommodate the cylindrical surface of the pipes. Users of the system gain access to the work platform via a cradle suspended from an electric hoist attached to the frame.

One challenging task for Harsco Infrastructure was to find a way for the system to traverse the steel flanges which project around the circumference of the pipe sections. This was solved by providing a jacking system which lifts the wheels clear of the flanges as they pass.

"Because of the location of the ACC units, a traditional access method was unfeasible and would have taken double the time, " comments Bill Murdoch. "This required a completely different approach" he adds. "Harsco Infrastructure designed a mobile access system which was far superior to any of the other companies involved" comments Harry and Ben Lee, Owners of East Coast Industries. "The service which Harsco Infrastructure provided from concept to delivery was of a very high standard."

The inaccessible location of the jobsite required the use of a high-capacity mobile telescopic crane to lift the two access rigs into position on top of the ACC pipes. East Coast Industries commenced work in early September 2009 and is due to complete the contract before Christmas.

Peterborough Power Station uses 'grey' water supplied by the local sewage works to generate steam for its turbines, reducing the consumption of potable water. The condenser is air-cooled rather than water-cooled to further reduce water consumption.

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