Wednesday, 6 July 2011

Sentinel 7109 gets a Duvet!

Having passed its first hydraulic test, Sentinel 7109's boiler is now being prepared for repatriation with the loco. Before this can happen, its lagging and outer cladding sheets have to be fitted as they would be impossible to work on once the boiler is lodged within the bijou confines of the loco's cab.

With the boiler at Mendip Steam Restorations, the plan is to take the various bits and pieces to the boiler and assemble them prior to transporting the complete sub-assembly back to Midsomer Norton Station to be dropped straight into the loco. This enables a single crane hire to complete the job.

An earlier post showed the cladding sheets in preparation. The lagging also needed to be cut to size with apertures (in the right place) to fit around the boiler fittings. Fortunately, the cladding sheets can double as templates for locating the apertures.

The ticket office platform at Midsomer Norton station seemed an ideal large flat surface for the cutting out. However, the first problem to overcome was that the wagon containing the cladding was on the far track and there was a train in the way.
Wagon stuck behind 7109 on the far track
Manhandling large floppy sheets between (stationary) trains isn't the first subject I'd mention to a safety inspector but needs must so a ladder was put diagonally between the wagons and the sheets precariously carried across to the platform.
Midsomer Norton's Circus Tricks
The lagging material was laid out on the platform and cut to length. All edges were sealed over using self-adhesive Aluminium foil tape designed for the purpose.
Preparing the templates
The lagging material is a high-spec (expensive) version of the type used for loft insulation. It is Aluminium foil faced on each side and made from ceramic rather than glass fibres so as to handle the boiler's high temperatures. Its trade name is 'Superwool Ceramic Blanket' manufactured by Morgan Thermal Ceramics and supplied to us by Heritage Steam Supplies (HSS). The Aluminium foil is to help avoid condensation being held in contact with the boiler casing and also to reflect heat inwards to the boiler's outer surface. The Aluminium foil tape also came from HSS.

Apertures were cut in the lagging using the cladding sheet templates and a Stanley knife (Why are sharp knives always called Stanley?).
Cutting around a template aperture...
... and removing the waste
The aperture edges were sealed with foil tape to keep it all in place.
Completed Lagging sheets
A good day's work was made possible by the good weather but could have been easier and safer without the manhandling of cladding sheets across the gap between the wagons.
All that was left to do was put it all away again.
More of Midsomer Norton's Circus Tricks
There are one or two small preparation tasks remaining and then the boiler, lagging and cladding can be assembled ready for repatriation with Sentinel 7109.

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