You've already read the answer I've given to Mr. Gibbon's question on the same subject. If you definetely need to weld the your beam, you should follow strictly Mr. Johnson's recommendation. It's the best procedure to weld galvanized steel. The zinc rich primer that you'll apply is called (wrongly) "cold galvanization". Actually it's no galvanization at all. Galvanization is obtained in two ways: by eletrolysis and by hot dipping. Anyway, as I said, there's no better way than that to weld galvanized steel.
Now, in your case you want to fix up a 2 x 1,5 inches beam, which is a small piece of steel. Is it that expensive? I'd guess no.
My advice is to do a fine job, buy a new beam and replace the broken one.
Giovanni S. Crisi
Sao Paulo - Brazil