Special rail grades and profiles - welding problems and solutions
10th IoRW Technical Seminar
And now for something completely different...
Although, at around 50, the number of attendees did not match the dizzy heights of the previous seminar (around 120), the presentations were excellent and there was a lively discussion on the topics raised.
It was also a first for Keith Flavell of Vital Rail who had volunteered to chair the proceedings. Keith ably kept the ship afloat despite one or two 'leaks' like IT malfunction and a missing speaker!
The scene was set by Paul Hooper from the Office of Rail Regulation (ORR) who outlined the regulations affecting light rail systems. Paul was able to report on a number of key changes driven by the EU Railway Safety Directive, Interoperability Directive and Amendment Directive. The new statutory process now is the Railways and Other Guided Transport Systems (Safety) Regulations (ROGS). For non-mainline systems, this requires the duty holder to establish a Safety Management System (SMS) by March 2007, but does not require certification and/or authorisation. For tramways and light rails SMSs must describe high level arrangements and are inspected as part of the intervention process.
Some areas for future interest for light rail and tramway systems were highlighted and extensive guidance is available on the ORR website.
Grooved rails are a key feature of tramways and welding problems and solutions were covered by Mick Wainwright of Thermit Welding GB Ltd. The 'SRZ' process has been developed specially for such rails which employs a special sand plug for the groove. This process has been used successfully on Blackpool tramways, Manchester Metrolink, Sheffield Supertram and Croydon Tramlink.
The same company has also developed techniques for welding dissimilar grooved rail sections. An upsetting device is used in order to compress the rail end foot of the deeper profile in order to match the two rail ends.
Finally, methods of refurbishment by submerged arc welding and grinding were described.
The slightly mysterious world of crane rail welding was the subject of a well-illustrated presentation by Warwick Faville (Consultant). As they are mainly used as a wear element, crane rails are generally bigger, harder and stronger than conventional rails. Crane rails are welded into continuous lengths by either enclosed arc welding or aluminothermic welding. Flash butt welding is sometimes used. In some site conditions there is a strong reluctance to use aluminothermic welding because of the undesirability of having several kilogrammes of melted steel pouring from a crucible at 20m above the works! An article on the welding of crane rails will appear in a future issue of Welding Lines.
Restoration of grooved rails was covered by Paul Norbury of Corus Rail Technologies. This was in the form of a case study of applying a submerged arc welding technique, developed by Jinpo in the Czech Republic, to the Sheffield Supertram system. The main advantage of this technique is that preheating, which would cause damage to the rail surround, is not required. However, cracking was found after initial trials and an alternative approach had to be devised. It was found that a technique involving localised rail 'chill removal' and modified welding parameters and consumables solved the cracking problem. The modified technique has been employed successfully on significant sections of the Sheffield Supertram track.
The Sheffield Supertram also featured in the next presentation (given by Paul Norbury in the absence of Jay Jaiswal, also from Corus Rail Technologies).
Rail grinding is an essential maintenance tool to minimise and manage the growth of corrugations in a cost effective manner. In tramway networks, the requirement to identify a cost effective solution is made even more challenging because of the need to minimise metal removal from top of the rail as the height difference between the rail and the road surface is the life determining criterion.
With these challenges in view, Stagecoach Supertram asked Corus Rail Technologies to undertake a controlled assessment of a range of grinding techniques and the expertise offered by four companies: Speno International, Schweerbau, Mecno, and Thermit (GB). An interim report has been submitted and it is hoped that an external publication can be made while respecting the commercial confidentiality of the participating companies.
The two final presentations covered light rail systems outside the UK. René Feuler, SECO-Rail, highlighted the key features of a number of projects which included welding, grinding and milling of tramway welds in countries throughout Europe. One conclusion was that milling has significant advantages over grinding in terms of quality, cost and safety.
Mike Bullen of Balfour Beatty Rail Projects Ltd went even afield further and presented the welding carried out, in association with the construction of the track and conductor rail systems, on the Santiago Metro in Chile. The scope of the work included:
The welding methods employed for each of the above processes was described, followed by a description of some of the particular welding problems encountered during the work.
Feedback from the delegates was that the day was interesting and informative.