[Aussie Mike]

The trick for doing a verticle up weld is to make little christmas trees. Start in the V of the fillet then move a little to the left side of the fillet then traverse across the center the right side of the fillet. Next move the pool up and into the root of the fillet across to the right side of the fillet then push the pool up and into the V of the fillet then move the torch back to the left side and then traverse back to the right then back up into the V of the fillet. (the drawing will probably make it easier to understand.

You keep working your way up making triangles. What you are doing is building a shelf for the weld pool as you go up and this stops the pool running back down. Traverse quite quickly across over the center of the weld and hold a bit longer on each side. That way you will get good penetration on the sides and maintain a flatter weld. Pushing the pool right into the root of the fillet as you go up is important to making a strong weld.

When the weld is done right it has a nice recuring infinity shaped wave (omega or figure 8 on it's side) as it goes up.

In my opinion this is about the most difficult weld to do. On short runs I can do it OK but after about 8" or 10" I'm starting to loose concentration. Practice makes perfect.

Cheers