There may be some readers who will be baffled by the frequent reference to our coal fired 'Scotch' boiler. Quite possibly there may even be one or two puzzled by it's significance, or otherwise, dependent on their viewpoint.

While there are many significant components which combine to make the restoration of the 'Daniel Adamson' of such importance, it is probably no exaggeration to suggest that the boiler is principal amongst these. The boiler can be likened to the vessel's 'heart' so that it's condition is critical to the success of the whole project. Rusted hull plates can be replaced, rotted woodwork renewed, even our 'Art Deco' saloon can be restored,  a riveted, three furnace, coal fired 'Scotch' boiler is another matter entirely. Quite simply 'they don't make 'em like that anymore'  Well not exactly, so if at all possible it is our intention to restore the one we've got. To that end we are largely in the hands of surveyors and boiler inspectors, whose responsibility it is to ensure, (a) The boiler is capable of restoration and (b) capable of safe operation.

 

The first illustration gives a simplified view of what a 'Scotch' boiler (in this case a two furnace type) looks like, inside and out. In basic terms, the boiler shell, which is a pressure vessel is filled to operating level with fresh water. The water is heated by burning coal in the furnaces, these are the large corrugated cylindrical tubes extending from the 'fire door' to the vertical box structure or 'combustion chamber' at the back of the boiler. The hot gases from the fires naturally heat the furnace itself which is corrugated along it's length both for strength and to increase the heated surface area (they knew a trick or two in the old days!) The hot gases now pass through the combustion chamber on into the 'smoke' or 'fire' tubes where their heat is used again to boil the water in the pressure vessel. The hot gases exit the boiler via the smoke box and thence the funnel (or stack as in the diagram) where they are dispersed. The funnel itself plays an important part in this process, inducing a natural draught to draw the hot gases through the boiler and improve the combustion of the fuel (coal in our case)  The steam generated in this process is pressurized within the confines of the space above the water level and is drawn off  by means of the main stop valve. From there it is piped to the main engines and auxiliaries. In the case of 'Daniel Adamson' steam at a pressure of 120 pounds per square inch is used. As a safeguard in the event that this 'working pressure' is exceeded, the boiler is fitted with a safety valve, set to operate and release the excess steam, thus averting a potentially 'explosive' situation!!  There is rather more to it than that, but hopefully this may help those not familiar with the system with the basic idea.

 

Right now it is the smoke tubes that are being carefully removed, certainly the lower tiers of tubes were visibly corroded, along with much of the smoke-box structure which will also be dismantled to be replaced in due course.  There is the possibility that some tubes may have been okay (for a while) but then again they might not. By replacing all the tubes we start over, knowing that the smoke tubes are 100 % new. The removal also allows almost free access within the boiler itself and allows a thorough examination of the remaining components and the necessary access to effect other repairs as required.

There are numerous reasons for this comprehensive overhaul, not least of which is to ensure that the restored boiler will be as close to 'brand new' as we can make it. As far as is known no other three furnace, coal fired boiler of this type survives today, so 'spares' are not an option! 

Unlike 1912 when as can be seen from Photo 2 things were a bit different, here we see inside the boiler shop at Harland & Wolff, Belfast and just some of the boilers awaiting installation aboard 'Titanic' (In all she had 24 double ended and five single ended (like ours) boilers in six boiler rooms!) A couple of those 'spare' corrugated furnaces to the right of the picture would be nice!

By all accounts, to get a new corrugated furnace today, we would need to do what 'Titanic' failed to do,  that is get to America!  Seemingly the last place they are manufactured! 

So it can be seen that the boiler restoration is a major task and must be done with great care.  Burning out all these tubes is not for the faint hearted and certainly not for the amateur. In Jim Ash (affectionately known as 'Jimmy the Melt') we have an expert, in the following photographs by Dan Cross, we hope to show the skill required to cut through these steel tubes (from the inside) then to cut the remaining tube ends, still using the same burning gear, so that they can be hammered out without damage to the surrounding tube plate or even the thread of the holes into which the tubes had been secured!