Blow-downs, or not ...

[JonL]

I recently saw a 5" boiler in which no blowdowns were fitted. It's quite an old boiler which has previously passed inspection (though out of ticket now).

Other than being an inconvenience, is there any problem with this? I glanced through the code to see if they were mandatory but couldn't see any reference to them, and in retrospect couldn't think of an emergency requirement for them. All the same it must be a terrible inconvenience.

[runner42]

Blowdown valves are mandatory requirement of the AMBSC Code Part 1 which of course is the Australian boiler code and doesn't apply to your situation, but the point is made on the basis that it a necessary means of maintaining the boiler in good working condition. I suspect that the rationale for such a requirement is that the accumulation of particulate matter if bridging the small spaces between tubes and flues can affect water circulation and cause hot spots which are detrimental to the safe operation of the boiler. 

Brian 

[davewoo]

A few years ago I helped a fellow club member get a LBSC " Miss Ten To Eight" back steaming, the boiler was built by his father pre war and had no blowdowns fitted. The boiler failed its test and a new one was built by CRB boilers to the same dimensions as the old one (and fitted absolutely perfectly)out of interest we cut the old boiler up and the firebox legs were absolutely solid with scale and general crud, there wasn't much room for water in there. The engine had spent it's entire life in a hard water area and had been very well used but the amount of scale and deposit was quite shocking. Although I'm sure scale would have accumulated even with blow downs fitted, the amount of sediment would not have settled so permanently, and it would have been much easier to de-scale at regular intervals.
The new boiler and pistons with some packing in them transformed the old engine from a shy steamer into a very good engine, I often wonder where it ended up as it was sold by the family on the members death.
Dave

[JonL]

I guess they can be added retrospectively, as the silver solder isn't going to melt around the joint where you fit the bush, but it would be a heart stopping thing to drill....

[delaplume]

Hi matey

Use the fine manual down feed on a vert. miller............... small, ratchet straps and blocks of wood are ideal for holding the boiler still...

[delaplume]

Hi runner42,

" I suspect that the rationale for such a requirement is that the accumulation of particulate matter if bridging the small spaces between tubes and flues can affect water circulation and cause hot spots which are detrimental to the safe operation of the boiler. "

yes,that's exactly the reason, especially on top of the foundation ring between the inner and outer sheets....