I need to complete the casing of my "Plan B" boiler which is of the Lune Valley type. As I was planning to use coal rather than oil firing, it would seem likely that the tubes will need reasonably regular cleaning. Given the fact that the "plumbing" all comes off the drum end caps, taking off the whole side panel does not look like an easy task.
Below is the state of the boiler so far and yes, there are no supports for the drums just yet!
Looks like the boiler I had in 'Silkie 1'. I never cleanmed the tubes - the soot burned off. Tom Peebles who also has a water tube boiler only cleans his tubes during the winter refit. WTB people seem to stay that little bit cleaner.
Gudmund
I would recommend retractable steam soot blower for this duty. Small holes (about 1/2 inch diameter 12mm) in the casing at a few points, to insert a steam lance which can blow tubes while underway or in hot standby condition. The steam lance is a piece of steel (or stainless steel) tube, about 20 inches (500mm) long x 3/8 (10mm) diameter, with a small nozzle in the end at 90 degree angle, hole diameter about 0.08 inches (2mm). A small whistle valve, and about 7 feet (2 meters) of high pressure steam hose completes the assembly.
The lance is inserted through the casing hole into the top of the furnace, and HP steam is blown onto the heat transfer tubes above, cleaning them as the lance is moved along the tube bank. Inserting into another hole, perhaps in the middle of the tube bundle cleans the intermediate tube areas. These small holes in the casing are then plugged with some insulation, and a metal cap if you like.
For safety, a self closing valve is necessary, such as a whistle valve, the operator has to hold open the lance valve for steam to flow. One good short length steam hose can be had from common teflon lined, stainless braided high pressure compressed gas hose. The hose I have available is rated for 6000 PSI (420 Bar), and will be safe with steam PROVIDED the hose material is good enough for your steam temperature. Teflon is good to 380F (190C), rubber to 340F ((170C). PVC lined hose, or other materials could be wrong here, if the steam temperature melts the lining under the braided stainless.
When blowing tubes, soot issues from the stack, so be aware of yourself, your passengers, and other neighbors during the process.
I agree with Fred a lance is nice for that and cleaning off your hull after a trip scummy water like the hudson river near Albany...Fred knows where I am talking about., broke his boat twice there....if was fun though. I also have a strong liking to Creasote destroyer in a pint sized plasic tub, when firing up and had a decent but not roaring fire I would scoop about 1/2-1 teaspoon of it onto a piece of wood and toss it in the firebox, a few minutes later open the blower and watch the soot fly. woked great but it is caustic. I used it for about 13 years in Adelaide which was roberts type WTB
A high pressure steam lance is an amazing cleaner, for anything that needs cleaning, except sometimes it will take off the finish of a part, or take paint off the hull, etc. A 100 PSI (7 Bar) steam lance works so much better than a 2000 PSI (140 Bar) water pressure washer, and the pressure washers generally work pretty well too!
Four things I have seen that can clean off a surface better than a steam lance: 1. A sandblasting rig, which of course is way too much for anything like normal cleaning duties. 2. Air blasting with Walnut shells, this is used to clean burned-on oil deposits in oil fired gas turbines, and does the cleaning without damaging the turbine blades, which are a special grade of stainless steel. 3. Liquid CO2 blasting, the very cold Carbon Dioxide (a few hundred degrees below zero) thermally shocks the surfaces, and most deposits come off, without harming the base metal. This is used to remove rust from steel surfaces, and leaves the parent metal undamaged. 4. A hot acid bath is what might be called an extreme solution, and requires an industrial setup for large operations. I once saw an old cast iron radiator (very rusted and having several coats of paint on the outside) dipped into a hot acid bath for about 30 seconds, and when lifted out of the bath it looked like a new iron casting that had just been shaken out of its mold.
Of course, burning coal, rather than high resin wood (US boilers mentioned above?), especially Welsh Steam Coal, you will produce far less tar, and your fire will be hotter by far- self cleaning as it burns any build-up off the tubes.
Yes the soot will go up the stack, and what goes up will come down.
On the destroyers we had to get permission from the bridge before blowing tubes. Depending on the wind direction, a coarse change may be needed to put the wind to our beam so the soot would be carried over the side and not land on deck. The Knox class had uptakes that discharge almost horizintally, and were equipped with a damper so the discharge could be shifted from side to side so it could be kept to the leaward side.
Though I doubt this was an approved practice, one of my Chiefs told of steaming in a pressurised fireroom, where the boilers didn't have an air casing, they would toss sand through the air registers with the idea that this would help clean the tubes. This may have been a practice on locamotives too. Sand blasting underway?
I need to was the soot off my hands, It's time for dinner.
The 'sanding the flues' as it is called, on locomotive boilers is less abrasive as one might think. The reason being that the fireman watches the stack and stops sanding when the stack clears. Most flue erosion and failure seemed to occur on the outside of the flues near the firebox ends. Hot spots and dreadful water.
On most all 'modern' locomotives there are a number of larger flues with superheater piping within them. Multiple passes in each of these flues. There are usually dampers over the front, or firebox ends of these flues that respond to cylinder back pressure so that the superheater action occurs mostly at higher power settings.
Since most surviving locomotives live an easy life moving tourists back and forth on level track, the dampers seldom open from day to day. Thus a good deal of soot collects in around the superheater piping. This is not a good thing in the long run. Best to clean it out from time to time.
On the logging museum Shay that I fired, we would wait until everyone had left on a Sunday evening and then make a few passes around our loop of track with the brakes applied. At first, it would be impossible to open the throttle very far as the track was greased liberally to cut down the flange squealing. The grease was all over the brake shoes.
After a bit, the brakes would begin to take hold and the throttle could be opened up. The dampers would open and the soot would roll out of the stack! As soon as it began to die back a bit I would hold a shovel full of sand near the peep hole in the firebox door and let the intense draft suck it in. More gouts of carbon in the air!
There was a housing development about a quarter of a mile downwind from the park and as we drove home we would see people out looking at their cars and driveways and scratching their heads. We kept our heads down and said nothing.
Mike
If you think you are too small to make a difference, try sleeping with a mosquito.
Dalai Lama
