Flashbutt welding specification issues for general freight and transit systems

Various issues can arise in the qualification and ongoing production of flashbutt welds for fabrication of long welded rail, sometimes as a result of ambiguities in the governing standard in Australia, AS1085.20, as a result of a gradual decline in the condition of welding equipment, or the introduction of a rail grade that has not previously been welded and which requires some adjustments to the welding cycle. For example, a gradual decline in the condition of welding equipment may result in gradual degradation in bond integrity which may not be evident if qualification tests have not been performed for a long period. Contributing factors can include cumulative damage at electrode contact locations, or gradual degradation in the hydraulic equipment that may not be identified by personnel who are unfamiliar with the detailed operation of the equipment. There are also various issues with the interpretation of the hardness requirements for flashbutt welds, partly due to ambiguities in the standard, but also arising from the increasing diversity of rail grades now in use in Australia. This results in further uncertainty when qualification tests are performed on welds in which two separate rail grades are welded together. Other factors that require consideration are the alignment requirements for welds, and how these may be complicated by any simultaneous issues with variable end straightness in the rails, resulting in some confusion in terms of the acceptability of the alignment of the resulting rail/weld/rail combination.