boiler explosion. what not to do.

[Bentwings]

There was a question asked a while ago about welding the boiler.
my boiler is aluminum . I had considered steel but4130 tube the size I was considering just was not available.
now even TIG welding aluminum softens or annuals the aluminum so it would have seriously compromised the boiler. I had a catch tank explode right next to me in a race car in the shop the tank was well made an nicely welded. Pat on back. It exploded so violently it ripped the metal outside of all welds. Everything came apart. It was returned to kit form as we say. This was a fuel air explosion not just pressure of boiler or compressor I’ve never seen anything like it . I blew about a two square foot hole in the Fiberglas body right next to where I was sitting it was a crankcase vent tank. Apparently a stuckintake valve allowed fuel air mix to be blown back into the tank. Then the stuck valve caused the push rod to gall up the socket in the rocker arm it got red hot igniting the fuel air in the connection tube to the tank which unloaded itself pretty scary it’s a good idea not to be close to running race cars that use nitromethane for fuel there was no fire that I saw just parts flying all over and a deafening noise . So this in mind I decided not to weld the aluminum . My eyesight is not good but I’ve been practicing welding the tablet lines and I’m getting to where I can follow them even around corners and curves. I honestly don’t know how this is working in real life but I’ll soon find out . I know the procedure and I’m redeveloping the eye hand coordination . I can’t even describe how I’m doing this some times having the drive to do something is what is needed.
hours in the batting cage allowed me to hit one of the few out of the park home runs in senior baseball . How I could still throw strikes yet hardly be able to see the plate is beyond me even the coach couldn’t believe it when I tried out. So I’m going to give welded steel a try. 4130 is easy steel to weld. It’s hard to mess it up unless seriously over heated. My new lighted magnifying glass may help . We will see .
Byron

I did not progress as far as I had planned yesterday as I ran into holes that I couldn’t get screws into some went in easy others just refused to start m 3 is pretty small stuff if you are vision limited. I have 3 m3 taps but I could not get either to start. I had my magnifying glass at full pier. I could see that the rap threads were trying to engage but just were being held up I didn’t want to cross thread or mess threads up. Finally I got one to start. I think dust or possibly pain got in the threads. Anyway I had to fiddle with the tap and got all me holes retapped there are a lot of them so a lot of Turing both ways . I didn’t take any metal out but the tap was dirty on every hole there was even some brass that had tight threads. So maybe I’ll have better results today. There are so many small screws and parts. It’s truly amazing the quality of machine work on this littl engine. Now I find I have to change the spacing between each engine. Fortunately I’ve allowed for this and it’s just a matter of unbolting the engines. I’ll make a drawing of the new bolt pattern so I can transfer it to the new mount plate . I have to go to a piece of ground tooling plat as it is dead flat. It cast aluminum and hard enough to tap larger holes but m3 are a real challenge I don’t have a clutch driver tunable for tiny m 3 taps so it’s hand twist all the way. This stuff doesn’t tap well en on larger sizes on a good day . More snow so I have to shovel a bit

byron

 

[kaolsen1728]

Is this a copper boiler or steel? Do not overstress the boiler when doing a hydrotest. ASME notes that the water should be at 70 deg F. Obviously it can be a little more than this, probably up to 100 deg. Then the pressure is raised slowly. Just like we do or should do when steaming up. If it is a steel boiler, 1 1/2 times the calculated maximum allowable pressure for the weakest component is to be used. If a copper boiler, I would not go much over 125 psi. If there is a bad joint, it will let you know. Once the boiler has been put into service, unless it has been modified and or repaired, there is no ASME requirement to hydro unless it has been modified and or repaired. However, on run days that you do steam up, check for any obvious signs of failure. The weakest component of a model boiler is the crown sheet. The problem here is that even a hydro on a cold boiler will show any problems. However, if the water while under steam gets below the crown sheet, the hot metal will loose its strength. The engineer will experience a lot of steam coming out of the firebox and firebox door. The boiler will be garbage! Be sure that the bottom of the sight glass is above the top of the crown sheet and test it prior every run. If you need any help on doing the calculations, let me know, I can help you do this. Ken Olsen

 

[Bentwings]

The external superheater will be 4130 seamless steel tube 3/16 or 1/4” wall what ever I can get. This stuff is very tough easy to weld not too har to machine I’ve worked a lot with it . Actually 1/8” wall would be enough but it would require bungs for threaded openings they are readily available but a lot more work than drilling and tapping this is what axel hosing tube on race cars use I’m going to go to a friends shop where my TIG welder is located and see if I can still see well enough to weld quality welds. If not another friend can help me out .
byron

 

[Bentwings]

The external superheater will be 4130 seamless steel tube 3/16 or 1/4” wall what ever I can get. This stuff is very tough easy to weld not too har to machine I’ve worked a lot with it . Actually 1/8” wall would be enough but it would require bungs for threaded openings they are readily available but a lot more work than drilling and tapping this is what axel hosing tube on race cars use I’m going to go to a friends shop where my TIG welder is located and see if I can still see well enough to weld quality welds. If not another friend can help me out .
byron

im pretty sure I have all the stuff for pressure testing as we do this on some race car things too we have a pretty strong hydraulic pump. Most of what we have to test deals with fuels like alcohol and nitro. We don’t pressurize any directly but use water most of the time . Even some oils will detonate under pressure so water works best . The only thing we use air on is tires. They go to about 6-7 psi so not dangerous even mounting we don’t need much air as they generally slip on with hand tools or tire machine
I’m unclear on how a condenser can work inside the superheater tube I suspect that just having the inlet discharge near the top of the round tube would cause water vapor to condense out or be heated enough to become dry steam . Then there would need to be a drain or some sort . This is a bit confusing to me . I searching internet I did run across something like this but it was a very short more comment than how it works. I’m studying steam tables a bit each night to try and get a better handle in what is going on. .
Byron

 

[HMEL]

I received a new short tap tool late yesterday. You make me feel like a professor of steam with your praise thank you!
I realized some insulation ofvthe delivery pipe was required so I looked in my favorite supplier site McMaster Carr. Yes they have a number of fiberglass insulating sleeves that will work. There is even a split type so you can go around joints . It’s also pretty inexpensive. Actually we use this in ou streetrods around headers to keep heat in the pipes and away from other car parts. I’m now thinking of making s more efficient intake and exhaust manifolds. I’m going to make another voyage into the weld shop and see if I can press the envelope of my vision dong some precision welding or brazing . I can get 1/4” copper elbows and we have a nice bender used for stainless steel brake lines so I make longer runs and-neater connections. I don’t like pie fitting connections . I’m used to making flanges and slip fit exhaust systems.
I’m viewing his super heating as a way to “ super charge” the steam engine without the blower supercharger. I’ll be able to have variable @ boost at the turn of a valve.
Yes I’m well aware of the dangers of hot steam . Scares me to death . I’ve even given thought to enclosing my operation in a poly carb cover .
Now my question is how do I calculate the energy available in super heated steam I found a nice chart showing pressure and temperatures so if I know one I get the other. This new book I’m getting should have some of he math I think. I’m pretty sure by testing I’ll be able to plot approximate run times at temp or pressure . I just got a nice Ashcroft pressure gage and fittings to make siphon tube.
I mounted the engine frame yesterday but I made a mistake using particle board. While nice and flat I does not take the thread inserts well . I need some super glue to hold them in. This creates issue as super glue wil invariably get into the thread inserts. Then I’ll have to run a tap into them .
I have not tried using Wd40 on the threaded part so I’ll try that today.
we are supposed to get a foot of snow and blizzard conditions later today so I think I’ll walk up to the auto parts store and get some super glue so I can continue assembly not looking forward to shoveling snow.
Byron

To calculate the energy in superheated steam you will use the tables for superheated steam the values will be in btus per lb mass or if you are using metric they will be given in metric units. Select the pressure and choose the temperature the steam is at. Saturated values will be in its own table.

 

[Bentwings]

To calculate the energy in superheated steam you will use the tables for superheated steam the values will be in btus per lb mass or if you are using metric they will be given in metric units. Select the pressure and choose the temperature the steam is at. Saturated values will be in its own table.

Thank you very much. Now I can plot out some “ guesstimates”
I ran into some assembly issues and got frustrated not being able to see tiny parts so I took a day off. I received a small drill press from my son. It’s got an incredibly well fitting spindle . There is no real play at the chuck it runs very smooth especially for a small unit these are notoriously poorly built things I have to remount one enginge so I see how well I can locate the holes I even have a center to help guide the tap handle I hav a metal baking sheet under the drill press to keep oil and chips where I can vacuum them . Hopefully I’ll have the couplings and shaft collars tomorrow . I’ll then be able to finish assembly . It’s goingvto be below 0 with winter storm watch tomorrow so another winter day.
Byron

 

[Bentwings]

To calculate the energy in superheated steam you will use the tables for superheated steam the values will be in btus per lb mass or if you are using metric they will be given in metric units. Select the pressure and choose the temperature the steam is at. Saturated values will be in its own table.

well another interruption today home nurse came in scheduled visit. Righ in the middle of the day . 2 hours.
So I went back to hobby room and continued on mill engine . I was missing one blind cap screw plug so I folded some copper wire cleaned it dipped in solder flux and soldered it into 1/4” 40 TPI me pipe I pole . It was ugly but the flap wheel grinder cleaned it up nicely I drilled out a 10 32 brass nut and tapped it 1/4” 40 ME AND IT FIT PERFECTLY . Screwed it in and I had air supply to number one engine after screwing around with timing like the instruction picture showed which did not work I managed to mar up the crank shag on both ends with the eccentric set screws skin grub screws that they are . I managed to get some semblance of timing in and it ran for about three minutes . Then stopped . Now what well it’s not locked up by dead stopped I started searching and it seemed that something was bottoming out closer looking and I saw the pistons stopping near the ends of the stroke . So let’s take a look well a couple minutes and I had the heads off then noticed the piston was stopping at or near bdc . I pushed the pistons out of the cylinders and blast it the piston screws are loose this is an m3 rod with only nuts on it the piston nut is barely in full depth of thread but now loose then I see the rod is also loose from the eccentric connecting rod. Well this means both cylinder and piston valve cylinders have to come off . Well it’s all apart now I’ll have to see if I can smooth the crank and maybe grind a flat where the set screw lands . I got my shaft collar fix parts so I think I’ll try and see if that will work tomorrow. It only took about 25-30 psi to run the engine other than scar up the crank no damage . My new ultra quiet compressor is very quiet too . So I’m happy about that the time is 180 deg off from the instruction picture . I got a measurement of the piston valve position before I took it apart so I can at least get it running again pretty easily instead of all the fooling around I had to do. I knew that that was goingvto be an issue . I have another coupling coming tomorrow from McMaster Carr hopefully it will work. My son is making a special pair that he said he would bring over Sunday . I YHINK they will lock the eccentric in place better without damaging the crank any more . Every thing was turning over so smoothly too.

Well tomorrow is another day

Byron