R707's BOILER
Late in 2005 the boiler on R707 started to develop a series of leaks that kept the locomotive out of operation throughout 2006. To fix the problem we have:
- welded six longitudinal cracks in the right hand side of the inner firebox
- replaced eight flexible stays
- replaced three fire grate support studs the three studs which secure the left hand side blow down valve
The firebox was thickness tested in March 2008 and found to be in basically sound condition with only one small (and replaceable) area of wastage. Despite this, the boiler will need constant attention and it is expected that approximately 70% of the flexible stays will require replacement within 2 to 3 years. Access to many of the stays is very difficult.
In addition, R707’s ash pan is paper thin in places and will require replacement. This can only be carried when the boiler is removed from the frames and will result in the locomotive being out of operation for a long period.
To minimise the time R707 will be out of service we are exploring two options:
- overhaul the boiler from R753 and then fitting this on R707
- manufacture a new boiler for R707
The first step is to make a detailed assessment of R753’s boiler. Before this can be carried out it must be de-tubed and all remaining fittings and attachments removed. The boiler will then be grit blasted inside and out to remove all scale and rust to allow a detailed thickness study to be carried out.
Assuming that no major structural problems are found, the minimum work required will be a complete re-tube, replacement of 90% of all rigid and flexible stays, new super-heater elements and a new main internal steam pipe. The estimated cost of new materials is approximately $150,000.
When the extent and cost of overhaul of boiler 553 is known we will then be in a position to compare the cost effectiveness of the overhaul with the cost of a complete new boiler. Remember, repairing a 50 year-old boiler extends only its life with until more repairs are required. A new all-welded boiler should provide 40 years trouble free service.
And, before anyone asks, 707 Operations has no plan to scrap the current boilers of either R707 or R753!
Lasted Updated: 13 November 2008
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