That’s an interesting question. I’m no expert on boiler management so you will have to wait for those in the know. However blowing down a boiler when in steam is an effective way to remove scale and sludge using the existing pressure in the boiler itself especially if the blowdown valves are appropriately positioned so the main flow is from areas where sludge collects. Observation in my youth of a local factory boiler house showed that blow down was part of the daily routine and done each shift.

As to historical practice on loco’s high pressure water is easy enough to obtain by siting a water tower up hill or even from simple hydraulic accumulators. As to if that is actually what was done or not is another question.

regards Martin

Depends on how early! The early builders had to sort out a lot of problems and develop new materials and methods as they went.

Early boilers were low pressure, and they leaked! Cow-dung is often mentioned as a gasket sealant, mixed with horse hair, with leather or paper padding etc. This sort of gasket may not last long, but they're cheap and easy to replace even in primitive circumstances.

Blowing down uses the pressure of the boiler itself to remove gunk, not necessarily doing a good job, and of course wasting a lot of coal. Had to be done very frequently at sea because marine boilers ran on salt water. The boiling point of salt water rises as it gets more salty, to the point the fire damages the boiler plates. Marine boilers had to be blown down much more often than land-based boilers.

At first no-one paid much attention to water purity, and this persisted on mainline rail because it was cheaper to fix boilers than to treat water. Pretty crude compared with marine steam, where water quality and treatments got attention. Running a marine engine for few months at sea with no easy access to fresh-water, coupled with a pressing need for fuel economy and high reliability meant better technology was introduced earlier. A locomotive breaking down between Paddington and Swindon is a tiny dirt cheap problem compared with a steamship breaking down between Perth and Suez. So ships usually had high-pressure pumps, condensers, water treatment, multi-stage and superheat before the railways. Easier to do on a ship because they have the space, even for a well-equipped workshop.

On land, the need for high-pressure steam soon asserted itself, and this led to the demise of cow-dung, in favour of factory made seals, and the need for clean water, and furnaces designed to burn cheap coal. High-pressure led to huge numbers of boiler explosions, so these too went up-market.

Road and rail locomotives remained something of a special case, because weight and size limitations restricted what could be done. Boiler inspections relied on men poking burning paraffin rags and mirrors through mud-holes well into the 20th century.

Not sure when high-pressure water was first used to clean boilers on the railways. Maybe early, though it's not mentioned in any of my books. An ordinary water tower requires something like a 25psi feed, and steam force pumps existed long before railway locomotives. Whether they were used or not on locomotives I don't know. My impression is they may have relied on a mix of high-pressure blow downs and/or rinsing out at ordinary water pressures.

The story is complicated by wide variations between different railways. Some were forward looking, properly equipped, and well-run, whilst others were sloppy in the extreme. The Wikipedia account of the 1876 accident near Radstock speaks volumes about the dreadful state of the Somerset and Dorset Railway at the time!

Dave

One thing I do know for certain, the steam threshing contractors avoided lifting water from ponds with ducks on if at all avoidable.

regards Martin

I’d like to see the pond that didn’t have ducks on it!

I've fired and driven industrial/shunting locos which had one injector and one Weir pump (as in the company, who are still making weird pumps for odd requirements today), which had certain advantages for being efficient with steam when the boiler pressure was low and having much greater suction head which allowed it to be used for re-filling the tender in less than ideal circumstances…

But the auxiliary outlet used to fill the tender (with an auxiliary input) could also have a nozzle attached to the end of the hose, providing a jet of alarmingly high pressure water for washing things down.

I do recall that when the pump broke down it was really quite awkward to work on, but good whilst it was going.

In any case, I'm not sure how common those were, or when they came into use, but it would provide any maintanance depot a mobile source of high-pressure jetting equipment, just hook up to a shunting engine which is still in steam and you're away.

To answer the question about seals on mudhole doors, you can male the joints using a mold and molten lead, so I imagine that is what was done. The lead can be re-melted to make a new joint, as you don't want to re-use them. When I have seen this done, they are rdged rather than flat, the mold is round, then to male them oval theu were run down a tapered piece.of wood, where the bottom was the oval required.

Baldric

Yes, seagoing vessels are much like power stations and industrial boiler plants, they run on some kind of distilled or reverse-osmosis purified/demineralised water to make up for any condensed steam that is lost each cycle. But water treatment is still needed to some extent. Not so much because of solid sediments but because of pH balance, sulfites, condensate corrosiion inhibitors and other factors. There can be quite a bit of contamination comes back with the condensate into the hot well, from leaky condenser tubes as discussed, or corroded pipework etc.

My grandfather went to sea on a Grimsby trawler as a lad and he told me they went out for a couple of weeks at a time, running on pure seawater, then when they got back to port, the boilers were opened up and the salt scraped out.

Some industrial boilers I worked on needed a good scraping/water blasting internally once a year, even with good water treatment. It was the apprentice's job to crawl inside the top drum of the water tube boiler and run a high pressure water hose down and back each of hundreds of 2" diameter water tubes and blast the scale out. Mostly it was a thin layer about 1mm or less thick of a hard glass like scale. Some old 1923 vintage fire-tube hospital boilers I worked on in America, we had to crawl in through the manhole once a year and clean the tubes with chipping hammers and wire brushes. They had no evaporators or RO unit, just mains water filtered and treated, so they were pretty horrible inside. Still in use up into the 21st century!

Manhole doors (sorry, person access covers) and handhole and mud doors I think would have always had gaskets of some sort. If no new gaskets were available, the old ones could possibly be reused, or you made your own by laying asbestos packing rope in there carefully, with the ends spliced together. Or cut gaskets out of flat sheets of thick asbestos-laced jointing paper. Good old Bell's Asbestos jointing. It's a wonder any of us survived. (Some didn't.)

Edited By Hopper on 09/03/2023 10:47:33