01.09.12
Mobile flash butt welding - Network Rail
Source: Rail Technology Magazine Aug/Sept 2012
RTM talks to Sean Heslop, Network Rail’s project manager for MFBW, about progress so far.
As Rail Technology Magazine was going to press, Network Rail was finalising the necessary approvals to roll out its new Mobile Flash Butt Welding (MFBW) service, with the first of four machines hoped to be fully approved for use by the end of August.
Sean Heslop, Network Rail’s project manager for MFBW, told RTM: “Flash butt welding has always been the preferred method for welding rails, ever since we went to continuously welded rail in the UK – but it’s always been done in depots. It’s taken this long to develop a truly mobile flash butt welding system, but the process itself has long been accepted as being far superior to a thermic weld because it doesn’t introduce any other metal, it just uses the existing parent metal.”
Speed is another key benefit of the new mobile system, he said: “For weekend work, it allows us to do re-railing and stressing in one visit. It also allows us to undertake work in shorter mid-week night-time possessions, which previously had to be done on weekends.
“The key comparator is that a pair of stress welds take 40 minutes with a MFBW machine, and they would take about 3.5 to 4 hours with conventional thermic welding.”
Network Rail is currently recruiting teams to man the machines – each will have two teams, with the four based nominally at York, Whitemoor, Rugby, and Eastleigh, but each will in fact serve the whole country: they are not route based.
Together, they will form the Mobile Flash Butt Welding Service, which will be part of National Programmes under the Network Rail service: and, if successful, another six machines could be commissioned.
Heslop told us: “There’s an extensive 12-week training programme for the MFBW teams, which will include, for the first time, a course for RRV drivers and machine controllers, which has been specially developed between Network Rail and AP Webb.”
When RTM spoke to Heslop, approvals were being finalised for the machines, in two parts – the approvals necessary for it to operate as a road-rail vehicle on the network, and those specific to the welding operations.
The vehicle is based on the Dooson 170, but was turned into a bespoke RRV for Network Rail by GOS Engineering in Blaenavon, South Wales. The supplier of the welding head and the weld management system is Holland of Illinois.
Heslop explained: “Its horizontal knuckle boom allows the turret to remain within gauge while the welding operator moves the head from either rail. That allows us to work with the adjacent line open for traffic: no other flash butt welder has that anywhere.
“Also, for safety reasons, when the welder is preparing, he takes control of the RRV vehicle – so the driver cannot move the vehicle once the welder takes control. It’s built to the new 1530 regulations [RIS-1530-PLT], so it has its own hydrostatic service braking.”
Older vehicles were much less mobile, could not stress the rail, and there had been concerns about damage to infrastructure – whereas these RRVs overcome all of those problems and can even work under live OHLE.
If all 10 machines eventually come into service, they should cover around a third of Network Rail’s welding needs.
Heslop explained: “In terms of operations, we’ve minimised the ongoing administration and transport costs by having bespoke trailers built to carry these machines, and with the actual trailers being type specific, they are classed as plant under the STGO rules.”
The target for dealing with a defective rail, from when the machine stops to when it leaves the defective rail fully welded and stress-restored, is one hour: there is a two-hour target to give time to take possession, Heslop said.
He concluded: “In terms of flash butt welding, this is the most modern system in the world.
“But in terms of development of MFBW, in comparison to the car industry, it would be fair to say we’re at about a Model T Ford: there will be tremendous improvements over the next short few years. The knuckle boom itself has already been adopted for two machines that have been supplied to Australia.”
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