Have noticed the heat treatment given to the tubes being put in the 487. It appears that the work is intended to harden the tube ends, which in actuality should be to anneal the ends. However, even this work is not necessary since boiler tubes manufactured to the SA-178 grA specification are supplied in the annealed condition as noted by that specification.
If these tubes do not conform to SA-178, what material are they that requires this in house work?
Hardening tube ends is detrimental to their useful life and reannealing under uncontrolled conditions destroys the heat treatment conducted by the manufacturer.
Clarification would be appreciated.

sar24nc@hsengco.com

> Have noticed the heat treatment given to the
> tubes being put in the 487. It appears that
> the work is intended to harden the tube
> ends, which in actuality should be to anneal
> the ends. However, even this work is not
> necessary since boiler tubes manufactured to
> the SA-178 grA specification are supplied in
> the annealed condition as noted by that
> specification.
> If these tubes do not conform to SA-178,
> what material are they that requires this in
> house work?
> Hardening tube ends is detrimental to their
> useful life and reannealing under
> uncontrolled conditions destroys the heat
> treatment conducted by the manufacturer.
> Clarification would be appreciated.

There was an extended discussion of this on another site. The tubes were being annealed,
NOT HARDENED. Heating steel and burying in lime
to cause the cooling to be gradual is an old blacksmith's trick. I have also seen this trick used in repairing large castings. Controlling the cooling reduces the stresses created and avoids
new cracks.
I have never worked flues in a full size engine, but that was the procedure we followed in refluing
a couple of 15" Crowns and the tube material
expanded and beaded beautifully. I do not have the flue specs available, but I do recall that they were furnished by a company that imported them from Germany and I believe someone said they were the same as refinery still tubes.
Jim


rrfanjim@charter.net

Perhaps the tubes were being heated for swaging?

dave

irondave@bellsouth.net