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:
- 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.
A post trip inspection of R707 following its double-headed run with R761 to Bendigo on 09 October 2010 for Steamrail found two broken flexible stays at the top of the firebox on the fireman's side. When these stays were removed a boroscope examination revealed significant wastage of the inner firebox wall and necking of the flexible stays on both sides of the firebox in line with the top two rows of stays. A subsequent untrasonic examination of the full firebox indicates†significant wastage was confined to this area and therefore relatively easy to repair.
An area of the inner firebox wall was cut out on both sides of the firebox. It extended vertically down from the top radius to between the 2nd and 3rd rows of stays and horiziontally from the back plate to almost the combustion chamber. New plate is currently being fitted and the remaining cladding removed to allow the outer firebox to be crack tested.
In addition to the stays where the inner firebox is being replaced, a number of other stays were found to be cracked or leaking at the flexible stay cups. At this stage is is believed that a total of approximately 120 stays will require replacement.
As a result of these detailed examinations of the boiler condition we are now confident that, with regular inspection and minor maintenance, the boiler has many years service left before it will require major overhaul or replacement. To avoid R707 then being out of service for a prolonged period when this happens we are taking preliminary steps for the overhaul the boiler from R753 with the aim of fitting this on R707.
The first step is to make a detailed assessment of R753ís 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. This work will be programmed when funds are available.
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 at least†$150,000.
Lasted Updated: 23 February 2011