Procedure for Steel Boilers at the end of the running day

[martyn1936]

We are having a debate at our club as to the best way to dispose of our steel boilered locomotives at the end of a running day.
One proposal is to turn the injectors on and leave them on until they knock, with the glass normally full or there abouts.
The other proposal is to turn the injectors on as before and when they finally knock off fill the boiler with the hand pump until the safety valve dribble a bit of water, i.e. the boiler is completely full.
In both cases the fire is left in to cool slowly and only cleaned out at the next firing when the tubes are also blown and brushed through. The boiler is blown down at the next firing when the pressure is around 30 psi.
In full size I believe they use the first proposal but of course they don't have the option of another way of filling the boiler.
What do other clubs do?

[ettingtonliam]

I always understood that there were 2 procedures for steel boilers. One was the one you use, which is to fill it right up to the top, so there is no air in the boiler. Downside is, this makes the loco very heavy to move, with a boiler full of water. I wouldn't leave the ash and clinker in the firebox though. Full size boilers which have been left for extended periods of time with the remains of the last fire in the grate, have often been found to have the firebox plates badly corroded just above grate level.

The other way is to let the pressure down, drop the grate and then blow down, while the boiler is still warm so there is no water left, and the interior is dry.

[suctionhose]

The full-of-water storage technique requires the oxygen removed from the water presumably with a water treatment product. An injector is capable of adding air to the water - you can hear them sucking at the overflow. Many fullsize injectors have a valve to close the overflow once operating to prevent this happening.

Personally, having built, owned and operated mini steel boilers for decades - admittedly in drier climes than UK - the ONLY way is dry storage. (In fullsize, there is an expense to dump such a quantity of water and treatment down the drain not to mention the work of opening and closing the boiler - horses for courses).

Blow down at 10psi more or less. The vital part is to open the boiler up top and bottom to let the vapour out as it dries using remaining heat in the metal. My boilers are designed with this practise in mind. However, once in storage, steps must taken to prevent condensation occurring due change of ambient temperature.

An incandescent globe in the firebox or other gentle source of warmth to elevate the boiler temperature a couple of degrees will do it. Here in Sydney, I store the engines in an enclosed box with some desiccant crystals to absorb moisture from the air trapped inside the box.

Ash and cinders must be removed as noted above. They are acidic, absorb moisture and are highly corrosive left in contact with the steel.

Treatment while steaming is mandatory. I use Veolia Water Hydrex 1922 which is a combined oxygen scavenger / corrosion inhibitor / descaler for boilers. The concentration must be adequate though to much and priming can occur. Concentration is monitored by sampling the boiler water. pH 11 is a common marker for correct concentration. For boilers in use for extended periods, the Total Dissolved Solids is a better indicator. For a few hours steaming, I add a known amount of treatment directly to the boiler. Add it to the tender if several boiler volumes are going to be evaporated during the run.

[Jim]

I follow the same method as described by Ross for the Burrell's steel Briggs boiler and have had no problems whatsoever. The secret as Ross says is to use a water treatment to inhibit rust and to ensure the boiler is well ventilated when not in use. 

On the Burrell I leave the inspection plugs out of the smoke box tube plate and the the blow down valve open to enure the boiler remains dry.

Jim

[tenor]

I go with what Ross says. With a tannin based boiler treat, all the plates will become tannin coated.

IMHO the "fill it solid" approach sounds good, but is wrong. It does nothing to control crevice corrosion or electrolytic action around bronze fittings.

Martin