Tyseley: A Boiler Washout...

Hi all. Today I was over at Birmingham-based Tyseley Loco Works taking part in another Saturday working party. Throughout the day I was gainfully employed on a periodic boiler washout for 4965. For those not in the know, I thought it might be interesting to talk a little bit about the process and the background to it. During evaporation of water into steam, certain deposits are created from the impurities of the water. These deposits don't leave the engine during normal working, but settle within the boiler. Of course locomotive owners will tend to opt for boiler water treatments which help to keep the 'solids in suspension' before they can be removed from the boiler. No boiler treatment can prevent the requirement of a washout however, it is simply used to ensure that the water causes the least damage to the boiler between water changes and washouts.

Boiler washouts tend to be carried out, depending on the railway in question, at intervals of anything between 14 and 21 steaming days, although engines at 84E are often washed out more regularly than that. At this point the engine is removed from service, the water drained to empty the boiler and then the various mudhole doors and plugs removed. Water is then injected at high pressure in order to washout the harmful deposits that have collected during steaming. Starting at the top of the firebox, you can wash over the crown before continuing around the boiler washing everything downwards. Your aim is basically to wash everything down towards the lowest point in the boiler: the foundation ring: where the open mudholes at the lowest point will allow the water to gush out, taking with it any accumulated scale or muck. A thorough wash is undertaken both through the water space between the inner firebox and outer wrapper as well as through the boiler barrel itself. It's a process which involves getting very wet as a water jet sprayed in through one hole tends to find its way out of the next but it's the only way to thoroughly wash out scale.

Whilst the locomotive is being washed out the various mudhole doors and plugs can be checked, cleaned and readied for refitting. The fusible plugs are also generally checked during a boiler washout for condition. Eventually, once boxed back up again, the locomotive can be refilled with clean water and the process begins again. In 14-21 days time (depending on the railway in question) it will be time to washout again. All of this helps to keep the level of harmful scale down within the boiler, particularly between the inner box and outer wrapper. I've seen outer wrappers cut away during 10-year overhauls to reveal a pile of solid scale several inches thick; just imagine what that does to your stays! But yes, in short, the washout is not unlike descaling your kettle at home and is the staple of steam locomotive maintenance regimes. Cheers all, Sam...