Welding Tips and Tricks

After much practice with my TIG welder I finally got my bead neat enough to tackle the stainless rail work on my boat. On the final weld on up of the bow pulpit I have hit a problem. The top rail is continuous with 4 stanchions. Three lower rail pieces are saddle teed into the stanchions. On the very last saddle, about 1/16" from closing up the weld the puddle suddenly split and a hole formed. Nothing I did would close the hole. Ground out the bead, rewelded and the hole appeared again! What's happening?

I'd be willing to bet the air inside the tubing is expanding and, as this is the last joint, has no place to go, so it's blowing out your weld. you're going to need to drill a pressure relief hole somewhere inconspicuous, and that should solve your problem!