I believe the H21 Formula has straight cross bars and has a 12' beam....maybe its time to convert.
H21 Formula? No such thing AFAIK.
The "problem" with welding (as Dan found out) is that it creates a localized weaker spot in the metal because it removes the heat treatment that makes the aluminum strong to begin with. This treatment increseases the strength by over 30%.
The alloy used in extrusions is 6061-T6. If you've got a metal shop near you with an annealing oven, they may be able to restore the heat treatment after you have it welded up again.
Failing that, you can sleeve the tube, but you have to be careful not to create hard spots - like where the sleeve ends. Ideally, you want the sleeve to look like this:
The fingers prevent hard spots at the ends of the tube. This is probably the best (and least expensive) way to go.