Hi Rolly, I have been doing some research on the latest parameters governing the use of copper tubes in boilers, and it is a bit worrying to say the least, rulings by Lloyds Register, and similar from ASME, state that copper tubes in boilers may not be worked at more than 200 C, and as you probably know this equates to around 230 PSI. At best most calculations are done with the asumption the tubes are round, are they?.
In the "Copper book" the collapsing pressure for solid drawn copper tube 1/2" Dia. X 1/16" wall is 1325 PSI. ( in old money) but this is at ambient not at the temperatures we operate at, it is a little less for annealed tube say 1300.
Coincidentaly the 200 deg. limit is about at the "Knee" on the stress graph where copper strength starts to deteriorate quickly, taking the above information and as boiler design calls for 5 to 8 as a safety factor you can understand my preference for steel tubes, I accept the "stories" about boilers working at 1000 PSI but this is all down to the design AT THAT TIME I wonder what size and gauge the tubes were on the 1000 PSI boiler,and the tales of deliberately destroying a boiler (Stanly's) (different rules in those days)I know you will check all this so look forward to your comments regards Les

The ASME code is not a government document, it is written and decided upon by a private group of engineers and belongs to them exclusively unless you pay for its use, and in its entirety is not totally used by the national board that issues license. Most States in the US adopt parts of it for their inspectional authority and have to put only parts of it into law for regulation. But in the end it’s the insurance companies that regulate what is acceptable.

In 1999 the ASME revised there Code section 1 (power boilers) and section VIII division 1 (pressure vessels) to amend the 1998 edition issued in July 1999 to contain allowable stress values based on material design to a facture of 3.5 rather then 4 as used for over half a century. Technologies in steel making has made this long over do.

That said Stanley boilers do not meet the ASME code in there design. The minimal plate thickness as required by the ASME code is 3/8 inch for any fire tube boiler less then 42 inches in diameter. The ligament spacing is much too small in a Stanley boiler. Wire wrapping is not allowed for a fired pressure vessel. It is my opinion that it is impossible to build a Stanley boiler to meet the ASME code and still power a Stanley car.

The copper tube used in a Stanley boiler does not get the total heat of the burner as the gases going up a tube are in lamer flow and do to the venturi affect only fill 60% of the center of the tube. With a good radius on the edge of the tube you can get this to 75% and the work done in the tube is more radiant from the gases them flame impingement, the water in the tube being at the saturated temperature holding the tube temperature at a more constant.

This does not mean a Stanley boiler is un-safe. My little EX boiler I built has an A106 shell. Mill cert. good for 2500 lb hydro. A106 is an expectable tube for fired pressure vessels, the top and bottom plates are 3/8 SA516-G70 boiler plate per the code. The welding of the plates to the shell is an ASME approved weld. PW-16.1(a) The non ASME parts is the ligament spacing and the use of 0.049 wall copper tube. The cold-water hydro was 1000 PSI and I run at 400 PSI.

One day I may build a test rig and do a cold-water hydro to collapse a tube and then do it using steam and see just where it is. Till then it’s not worth the argument as Stanley boilers have been running safely for the last 100 years. Subject closed.

Rolly

Thank you Les and Rolly for your comments on Copper and Steel boiler tubes.

I have now found time to start drilling out my boiler tubes and I think I have found the reason for them leaking. My boiler has only two blowdowns, (at the front). As I removed the tubes, starting in the centre of the boiler I could see the bottom tube plate was fairly clean and also towards the front of the boiler was fairly clean. BUT the further towards the back of the boiler I get there is more and more crud. Please see attached photos.

I have always given my boiler a blowdown every morning and night when steaming but never seem to get much out. I must admit that up to now I have rarely blown the boiler down completely. I have only owned this Stanley for two years and the boiler has only been in service for six years. I know that the previous owner would blow down regularly and also used tanning in the boiler and so did I till I started to have problems. I can not believe the amount of muck in this boiler.

While I have the tubes out I intend to have two more bosses welded on the boiler shell for two more blow downs but I still don’t see how this muck can get out through 90 degree bends and needle valves. Has any one ever fitted larger blowdowns than ¼ NPT.?

Don

Dear Donald, In blowing down a boiler after a run, after about 5 minutes with all fire out, I always blow my boiler down until there is just dry steam coming out of the blow downs. That is when I shut the blow down valves off. Then I usually have between 150 and 200 pounds left of steam on the steam gauge at this point, plenty enough pressure to move the Stanley about the shop for storage. On the 23" diameter boilers and larger, 4 blow downs using 1/4" pipe street elbows is usually enough to keep things clean inside. The 1/8" pipe blow down elbows, if used on the tube sheet, get plugged with sediment too easily. Also use schedule 80 stainless elbows. I have used sechedule 40 steel elbows in the bottom of the tube sheet before and they rusted out on me way too soon. Blow downs should always be evenly spaced around the boiler perimeter. For boiler treatment, I use TSP (washing soda) Tri-sodium-phosphate. I only put enough into my feedwater so that during blow down I can just feel just a little slippery action on my finger tips. It is amazing how much better my water pumps work with a little TSP added into the feedwater. About two table spoons of TSP to about 30 gallons of water is what I have been using in our water here-abouts. TSP disolves the solid minerals so that they can be blown out with the water. What type of water that you have, is what determines how you treat it. I like to aim for a Ph of about 8 in my boilers.



Edited 1 times. Last edit at 12/11/10 02:43AM by SSsssteamer.

Dear SSsssteamer.

Thank you for your speedy reply.
What kind of “life expectancy” would you expect to have with a Stanley boiler/ boiler tubes?

When I get all of my tubes out I will need to clean the inside of my boiler shell some how, has anyone any ideas what to use?

Don

Don, very nice photos. Shows the need for water treatment weather in a condensing or non-condensing system.

As Pat stated I also have always used TSP in the past. Now I am trying LSB8000
I try for a PH of 10 or 11 though.

To clean your shell after your tubes are removed find a large tub and sock the whole thing in a solution of water and soda ash.
Rolly

Just about what I would expect in a boiler with only two blow downs , I recommend two blow downs and NOT needle valves, ball valves with PTFE seals are ok, these will give full flow and not block with sediment , I have been through the needle valve scenario and one in particular was for ever blocking with crudd , 1/4 BSP are quite big enough as they have thro bore, 1/8 BSP are useless.

Les
A lot of men thought the same way early in the game. That’s why they came out with the seatless blowoff valve. The Yarway blowoff valve was used on the condensing cars, how earlier then that I’m not sure. This is a very nice design with acme threads and very easily maintained, no drip. They came with a spout or a threaded hub on the outlet.
Rolly
See attached

The needle blow down valves are what came on my 1914 and earlier Stanleys and that is what I will always use. I use the Stanley 650-1 needle valve on the front of these cars for their blow downs. During the past 25+ years I have had several occasions to have the boiler blow downs plugged with what I thought could have been rust scale (?). While under pressure, completely removing the valve stem and then probing the stem hole with a stiff wire, quickly clears the obstruction. I always carry a short length of bailing wire in my tool box for all kinds of emergency uses. Usually the gas cars need the wire for an emergency tail pipe bracket, or the wire gets chopped up to make cotter pins for their shifter linkage. I once had to wrap a split out perch rod pole with wire so that I could finish a 500 mile tour. Wire works well to repair many things, including plugged fuel lines too.

further to this thread I made a mistake in my earlier message I said " I recommend two blow downs" of course I meant to say 4--- FOUR not two blowdowns Les