Next Question from novice with a Model M Boiler

[CannonFodder]

Hello Gentlemen,

Tube bending (for superheater and waterheater) has become the next question (or questions, as I know nothing of the field).

I have three lines of thought:

First, after watching This Old Tony on Youtube easily bending steel tubing flawlessly with only the most basic of tools (roller wheels from an automatic gate system), and another guy making some nice bends in steel tubing after packing them with sand and using no proper dies at all, I set out to bend my own tubing. For me it hasn't been that simple. I made some pretty good dies to investigate with, using HDPE. I got some fair bends. I was going to continue with some steel dies, and my question is: Is this a reasonable approach? Can a novice end up with a proper set of superheaters, et al, pursuing it with shop-made tooling, or am I wasting my time?

The second question concerns the size of the tubing. My blueprints call for 5/8ths tubing throughout. This seems to be difficult for the vendors in the Phoenix area. I have been repeatedly offered 1/2" and 3/4" because they don't carry 5/8ths. If I can't get the 5/8ths, what do you think is a good way to go?

The third question follows the uncertainty of the first questions. Does anyone just weld up the superheater and waterheater from pipe? I quess there is some inefficiency through the thickness of the pipe, but it beats not being able to fabricate the units at all? If this were my new path, what size pipe would be good? What do you think?

Thank you for considering these questions. Any advice on these or other suggestions are all appreciated.

CannonFodder (Robert)

[TahoeSteam]

Shop made tooling is what started and perpetuated the industrial revolution, so with attention to detail and trial and error anything is possible.

They make "u"-bends that would make making an economizer very convenient and easy.

[DetroiTug]

Quote: "using HDPE. I got some fair bends."

It really depends on the radius. Plastics would not be suitable for concave forming dies. The load on the sides are horrendous and it takes a very strong material (steel) to counter them. The heavier the tubing wall, the less likely it is to collapse when bent in to a radius. Generally by changing the design with little consequence, difficult to form radii can be avoided.

The diameter is not very critical. As long as you have sufficient steam flow. If you have a 1/2" NPT steam supply line, then 1/2" NPT super heater will work just fine. I use a superheater in my Locomobile made from 1/2" Sch 80 A106 seamless and it works just fine, and that is with a much-hotter kerosene fire than wood, coal or propane. It's just threaded together and sealed with Jomar "Green Stuff" pipe dope. The main thing to remember with a super heater is to situate the throttle before it.

Bending steel, an acetylene torch makes the job much easier. And too, it anneals the material to prevent work hardening.

-Ron

[CannonFodder]

Thank you so much for your responses. I always learn good stuff here!
But it also generates some more questions for me.

I'm afraid I'm not sure of "They make "u"-bends that would make making an economizer very convenient and easy." Does this mean that there are manual tube benders available that would make it easy to fabricate a superheater? Sorry!

Here is a photo of the path that I am on for tube bending. This is Harbor Freight hardware with my prototype dies done up in HDPE. As I continue to steel dies, am I on a path with a reasonable chance of success, or is there something I should change right away?



Would I be trying to fabricate a large serpentine superheater all at once, or merely U shapes that are welded together with some kind of sleeve or union?

Thanks,

CannonFodder (Robert)

[TahoeSteam]

Here are a few pictures of the economizer we made for our Worthington boiler utilizing 3/4" pipe and u-bends threaded together.
The economizer has about 50sqft of heating surface now.

[CannonFodder]

Wonderful, now I get it. Thanks for the photos. I probably won't be purchasing all those U-bends, but I can now see that my superheater and waterheater can be built with the skills and tools I have. Thanks.

CannonFodder

[barts]

So where did you find 180 return bends? These are hard to find
for 200 psi steam.

- Bart

[TahoeSteam]

Bart,

It has been some time, but I *think* it was mcmaster carr.

The economizer John York built for the Ben My Chree is built up with u-bends also.