The project So Far
Steam Tunneltug Hasty

 

Monarch's Boiler

The FMC Steamer Monarch was converted to diesel in 2005 and the VFT boiler was removed. This was made by Classic Steam in 1992, it is 38" diameter and 43" high with 275 x 1" tubes and 41 stays. Monarch was oil fired but the boiler was designed for coal firing which is how I intend to use it.

 

The Boiler

This is the boiler stripped down with the tube ends ground off ready for tube removal to begin. The rust has been removed and a coat of "Rust Curing" primer has been applied.

The boiler being removed from SN Monarch in Spring 2005. The weight is approximately one tonne

The lagging consisted of a stainless steel jacket (Painted black) covering a layer of what appeared to be domestic pink fibre glass loft insulation.

 

The extent of the corrosion on the exterior was revealed once the lagging had been removed. This was caused by condensation which soaked into the lagging and stayed wet for long periods whilst Monarch was not in steam.

 

Ultrasonic examination found that in some areas the shell had reduced from 12.7mm to 11.9mm but this was not caused exclusively by  the exterior rust as there was obviously corrosion on the inside as well, but all things considered, the shell was in pretty good condition.

At some time in the past leaks had developed around the crown plate end of the tubes. This seems to have been remedied by welding them up.

 

These welds had to be ground off before any tubes could be removed.

 

Care was taken not to reduce the thickness of the crown plate but as it is 5/8" thick this wasn't critical.

Unfortunately Monarch had been non condensing for many years and running on canal water without treatment the tubes also suffered from corrosion.

 

All of the 273 tubes had to be replaced but the stays which were 1/4" thick walled tubes were considered good for a few more years and the decision was made not to replace them at this time. This decision was later over ruled by the boiler inspector John Glaze

The finished boiler minus lagging. It has passed it's hydraulic test and as you can see the smoke box and ash pan have both been fitted. Originally it was oil fired but now the iron fire door has been mounted on the hinge that Terry Statham welded on for me, previously, the oil burner was mounted in the fire door opening. The ash pan is made from 10mm thick steel and has an opening flap vent which is very close fitting so when closed will starve the fire of oxygen. The smoke box is 5mm plate and has the gasses vented out the back where the funnel will be connected, a bit like a loco boiler turned up on end. This configuration allows full access to the tubes for cleaning.

 

I will post more pictures soon

 

 

 

 

 

 

 

After Ultrasonic Crack testing, and installation of new stay tubes by Terry statham of TRS in Derbyshire the boiler was returned to a safe location where the re-tubing work could be carried out.

 

Some time in the past the 275 boiler tubes had been welded to the crown plate I guess to eliminate leaking however this has a very destructive effect on the tube holes. The problem was caused by the passage of water between the tube plate and tube. Welding the tube to the plate on the fire side did indeed plug the leak but only on the very outer edge of the union between the two and so the corrosion in the tube hole caused by the presence of water continued un-noticed for many years. Once the welds were ground off and the tubes hammered out the extent of the corrosion was evident and so a lot of reaming was going to be needed to get the holes back into a state that the new tubes could seal against.

 

Another noticeable thing was the miss alignment between corresponding holes in each end of the plates, as much as 1/2" in some cases which over the 21" between the plates is quite significant.

 

The final problem with the tube holes was the presence of little nicks caused by an oxy-acetylene torch which were presumably put there during a previous re-tubing exercise. Some of these nicks were as much as 1/32" deep and bridged the hole face from the inner to the outer making a true seal impossible. Luckily Terry Statham was able to carefully fill these nicks up with weld and dress them up to be as good as new because to have reamed them out would have been unrealistic.

 

 

 

 

 

 

End

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Being moved from storage and in situ on the boat

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