21st October 2011
Yesterday was spent in Derbyshire, firstly visiting Alton Engineering to view progress on Lewin’s boiler which is now in the repair bay there. Here are some views of progress to date…
Below: This piece is one of the safety valve arms (which links valve to the spring on this Salter type of valve) being machined from round section bar (EN8). Lewin has two of these, one on the dome and one on the steam turret in the cab.
Below: The dome had, at some point in its Seaham days, lost the top ring of the casting. This is above the steam space so a repair has been effected by milling the break true then having this casting made (pattern painted red) to create the required shape and seat. The short ring is a collar to fit inside both pieces of casting at the joint.
Below: An overall view of the boiler with the large dome very prominent at the front (mostly hidden when the saddle tank is in place).
Below: A view inside the firebox where there was a known repair required. Whilst this was being carried out grooving became evident where the wrapper joins the flanging of the doorplate. This will now be attended to.
Below: This area, looking towards the tube nest (or the front right hand corner of the engine if you like) showing the caulking carried out on the seam. Note also the exposed girder stay bolts projecting from the crown – the nuts on these are being replaced at the behest of the boiler inspector having found to be undersize. This will also compensate for some thinning on the crownsheet itself (on the fire side).
Below: An overall view of the inside of the firebox. The chalk marks are the boiler inspectors readings, showing the metal thickness in each area (in mm). The dark splodges are grease used as a conductor for the ultrasonic device used to measure the metal thickness. These readings confirm that in all probability this is a replacement firebox fitted at Seaham, being steel rather than the more usual (for an engine of this age) copper and wrought iron (the latter would not give a clear thickness reading due to the laminated nature of its construction and is not readily repaired, not being weldable).
Below: A view of the dome top showing the regulator valve (which includes a pilot and main valve). This was an encouraging visit and the boiler is not far from a hydraulic test then steam test…
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