Cracked Aluminium Frame at Seat Post entry....isrepairable??

4kicks

I found a nice Aluminium Frame on the rubbish bins which had been thrown as it had cracked quite deeply at the seat post hole, slightly above the clamp, probably due to overtightening the seat post clamp.
If I get my (competent) metalworker to TIG weld the crack, and possibly weld an aluminium collar round the area, it should be pretty OK, right? Of course its difficult to tell without pictures (dont have a digital camera & phone camera wouldnt work) but Im assuming its a relatively low stress area in comparison to BB or head/down tube as most of the stresses are along the line of the tube, right??

sungod

weld+collar should be ok, maybe combine with an extra long seat post

but the forces aren't in line with the tube...

the tube is angled away from vertical, so even on smooth ground, the riders's weight results in a significant static bending force applied through the seat post to the top of the seat tube, on rough ground dynamic forces will be much higher