I know a blacksmith who makes shapes out of 16 ga sheet steel. Like a
banana, for instance. When he welds the sides (the "peels") together
and grinds down the welds, the thing looks kinda flat, not "fat". So,
he welds a 1/8" pipe coupling to the end, fills it absolutely FULL of
water and caps it.
Puts it in the freezer and it comes out looking beautifully
"fattened". He then removes the pipe plug, cuts off the coupling and
welds on a stem.
The thing is, you have to have it FULL and the end sealed up Tight
for this to work, I think.

Pete Stanaitis

_ wrote:
Won the battle to remove motorcycle header pipes from the "slip-on" (yeah
right) 2-1 collector - multiple applications of penetrating oil,
electrolytic derusting, fitted wooden clamping blocks, finally used a
propane flame to get the outside pipe red hot and then they shifted.

Two of the header pipes have not-so-small dents in them. Right now they
are outside, filled with water, and it's supposed to drop below -10
centigrade tonight.

I'll have a look in the morning and let you know what, if anything,
happened.