Tyseley: Oil, Tubes and Flues...

Hi all. Today was another volunteer Shed Day at Tyseley Loco Works. I arrived at just before 10am and immediately sought the warm sanctuary of the cabin where some of the other volunteers were already gathered. Work during the morning was simply to move some of the loco's around in an effort to keep them well oiled, rather than letting them root to the spot during their Winter rest period. The BR Green Class 47 was therefore soon roaring into life, coughing smoke up into the blue skies. Having warmed up and made air, the 47' moved forward and coupled to the stalwart pair of Great Western 4-6-0s: 5043 and 4965. Having been well oiled, the Western pair were moved outside into the chilly morning air for a push-pull working up and down the yard...

With the locomotives having blown away a few cobwebs and been returned to the cover of the shed, the 47' was shut-down. After Lunch, work continued on the boiler of 7029 "Clun Castle". Today we were starting to slide in the Flue tubes.

A super-heated steam boiler contains two types of tubes: Smoke Tubes and Flue Tubes. The smoke tubes are the numerous small tubes, there to allow heat drawn from the firebox to boil the water in the barrel efficiently before the gases then leave the smokebox end for ejection up the chimney. The Flue Tubes are much larger as they contain the superheater elements. The elements are basically pipe-work which provides a longer steam circuit for steam leaving the boiler at the regulator. The steam enters the superheater elements where it is taken back through the boiler within the elements which are fitted inside the Flue Tubes. Eventually the steam enters the steam chest for admission via the valves into the cylinders. This process raises the temperature of the steam further, thus drying it, and providing superheat. (A non super-heated engine is known as a saturated type). 7029's boiler is typical of a GWR main line 4-6-0 in terms of general construction but there were variations between the 171 sisters of the Castle Class. "Clun" for example carries the final development of the boiler, with 28 Flue Tubes spread over 4 rows, the larger superheater being provided for the double-chimney engines. 5043 also has this arrangement, though I believe that the other 6 preserved Castle's are all the single chimney type with lower superheating capacity. The flues are very heavy and are threaded into the firebox tubeplate. Therefore, when fitting, lugs are tagged onto the smokebox end and the flue is then fed gently into its chosen hole in the tubeplate. Once threaded in, an adapted fitting is used with a large rachet to drive the flue into the firebox tubeplate on its thread. Once firmly in place, attentions turn to fitting the next flue. Naturally, once all the flues are in place, they will be expanded and beaded where necessary. The smoke tubes will also be expanded and beaded.

Its very interesting helping with boiler work as it provides an astonishing learning exercise into the design and construction of steam locomotives as a whole. All the best, Sam...