Hello again. I have been wondering about some repairs that I have seen on both thresher boilers and locomotive boilers {I know they are the same}. I have seen where the bottom 1/3 of the front flue sheet has been replaced, with a fabricated patch, complete with flue holes and flange. Now this was a welded fabricated "patch" if you will and not a "McCabe" type patch. Being a welder I have always wondered why the throat sheets and both rear and front flue sheets couldn't be fabricated {welded}, versus having the McCabe flanging machine do the job. I am impressed with the McCabe and it's obvious uses. The reason I ask is not everybody has a 3/4 McCabe at there shop or at there disposal. Is it legal by FRA? Or has it been tried and found out the McCabe style of fabricating just works better? I lay awake nites thinking about this stuff. Thanks for your responses and ideas. John.

springfield@tds.net

> Hello again. I have been wondering about
> some repairs that I have seen on both
> thresher boilers and locomotive boilers {I
> know they are the same}. I have seen where
> the bottom 1/3 of the front flue sheet has
> been replaced, with a fabricated patch,
> complete with flue holes and flange. Now
> this was a welded fabricated
> "patch" if you will and not a
> "McCabe" type patch. Being a
> welder I have always wondered why the throat
> sheets and both rear and front flue sheets
> couldn't be fabricated {welded}, versus
> having the McCabe flanging machine do the
> job. I am impressed with the McCabe and it's
> obvious uses. The reason I ask is not
> everybody has a 3/4 McCabe at there shop or
> at there disposal. Is it legal by FRA? Or
> has it been tried and found out the McCabe
> style of fabricating just works better? I
> lay awake nites thinking about this stuff.
> Thanks for your responses and ideas. John.

Steam locomotive boilers need the radiused, formed flange on firebox sheets, as it accomodates the various stresses much better than a square corner. While it is a technique carried over from the days of riveted firebox construction, the later era welded fireboxes continued to use flanged corners for that reason.

The flanging can be done hot with wood mallets ("heat it and beat it"), or cold with the McCabe or other types of power presses and dies. Cold was apparently better, with fewer induced stresses, and less hot, hard work.


hpincus@mindspring.com

> Hello again. I have been wondering about
> some repairs that I have seen on both
> thresher boilers and locomotive boilers {I
> know they are the same}. I have seen where
> the bottom 1/3 of the front flue sheet has
> been replaced, with a fabricated patch,
> complete with flue holes and flange. Now
> this was a welded fabricated
> "patch" if you will and not a
> "McCabe" type patch. Being a
> welder I have always wondered why the throat
> sheets and both rear and front flue sheets
> couldn't be fabricated {welded}, versus
> having the McCabe flanging machine do the
> job. I am impressed with the McCabe and it's
> obvious uses. The reason I ask is not
> everybody has a 3/4 McCabe at there shop or
> at there disposal. Is it legal by FRA? Or
> has it been tried and found out the McCabe
> style of fabricating just works better? I
> lay awake nites thinking about this stuff.
> Thanks for your responses and ideas. John.
Yes its legal by fra. Somethings to think about the old firebox plate that was flanged in no longer made-ie sa30 it was like a31 grade a. Some radis of old flanges were 3x t or less. If you try to flange cold 285c 1/2" or heaver to less than 4 x t you could get some inturnal stress that could lead to an early failer. With the modern code steels you must use today I would anneal any flanged plate .Why not ask what luck operators have with square corners? I think you will find they aren't that bad. regards. rob

Probably a good example of this type of new construction would be the new firebox for the 844.I do not have any first hand knowledge of the design or construction however as I have heard the throat is built up from plate rather than flanged and the box itself has square corners being welded construction. This is all I heard and as I said, IT IS SECOND HAND TALK. Perhaps someone in the know would comment on this type of construction.

Partial tube sheet repairs have been common place for years and is still practiced.

> The flanging can be done hot with wood
> mallets ("heat it and beat it"),
> or cold with the McCabe or other types of
> power presses and dies. Cold was apparently
> better, with fewer induced stresses, and
> less hot, hard work.

One problem you can run into with holding steel at forging temps (orange to yellow color) too long is decarburization. This leaves you with weak surface layer and is characterized by a "checked" or "burnt" surface. When this happens the material cannot be salvaged ...it is scrap. When you forge too cold (red color) you can crack the material internally or externally, once again producing scrap.
Cold forming, at the proper radius, and anneal after will produce the most uniform results.


lamontdc@adelphia.net

Legal yes, provided of course that ASME or some similar code is followed in making the repairs.

Don't forget to also take the stress on braces into consideration. In many cases only the flat areas of the plate are considered as areas to be supported, and creating more flat by eliminating the flange may require additional bracing or a lower operating pressure to compensate.

dave

irondave@bellsouth.net

One thing that has to be considered here is that metal will expand when it is heated. Lets use the front flue sheet that you have used as an example. If you were to weld in the patch to the boiler and the remaining portion of the flue sheet, while the rest of the flue sheet was flanged and riveted in, internal stresses could build up with in the entire flue sheet due to the different types of joints in the same piece when the metal starts to expand as the boiler heats up when it is fired.

If a boiler or firebox were to be totally replaced, then welded corners may be a possibility.

> Hello again. I have been wondering about
> some repairs that I have seen on both
> thresher boilers and locomotive boilers {I
> know they are the same}. I have seen where
> the bottom 1/3 of the front flue sheet has
> been replaced, with a fabricated patch,
> complete with flue holes and flange. Now
> this was a welded fabricated
> "patch" if you will and not a
> "McCabe" type patch. Being a
> welder I have always wondered why the throat
> sheets and both rear and front flue sheets
> couldn't be fabricated {welded}, versus
> having the McCabe flanging machine do the
> job. I am impressed with the McCabe and it's
> obvious uses. The reason I ask is not
> everybody has a 3/4 McCabe at there shop or
> at there disposal. Is it legal by FRA? Or
> has it been tried and found out the McCabe
> style of fabricating just works better? I
> lay awake nites thinking about this stuff.
> Thanks for your responses and ideas. John.


railbreaker@hotmail.com