Welding Tips and Tricks

Hi, I was hoping to get a few tips on making a T joint weld on 3/4 to 1/2. I've welded lots of half and under but never above half inch. I'll be welding with a miller bobcat 225, I currently have 5/32 7018, 5/32 6010 & 1/8 7018. I've cleaned up both areas to be joined real well, my plan was to make a root pass with the 6010, cover with mulitpass stringer beads 7018 to achieve a fillet 1/2 in. Does this sound acceptable? Do I need to preheat? Any tips? What am I forgetting?
Thank you in advance.

Pre-heat probably isn't required, but it is nice to hit the metal with a torch and sweat out any moisture. Depending on where and how long it has been stored there can be quite a bit.

A 6010 root isn't exactly necessary, but if there isn't anything saying whether you should or shouldn't, it's up to you. For the sake of simplicity, I'd probably just go with 7018 through out. Just be mindful of the effects of heat. It may be bigger/thicker, but it will still move and distort.

Thank you Pete. Would you use the 5/32 or just the 1/8 7018?

Since they're on hand, the 5/32. That will help the weld move along a little quicker.

PeteM wrote:Pre-heat probably isn't required, but it is nice to hit the metal with a torch and sweat out any moisture. Depending on where and how long it has been stored there can be quite a bit.

I would respectfully have to disagree with your statement.
Steel does not absorb moisture during storage and then need to be heated to get it out.

MinnesotaDave wrote:

PeteM wrote:Pre-heat probably isn't required, but it is nice to hit the metal with a torch and sweat out any moisture. Depending on where and how long it has been stored there can be quite a bit.

I would respectfully have to disagree with your statement.
Steel does not absorb moisture during storage and then need to be heated to get it out.

How do I have that wrong or in some way mixed up?

I've sweated a lot of steel pre-weld, and a good bit of moisture comes out.

No, Pete, it doesn't.

You're using a torch who's primary by-product is H2O on a metal surface whose temperature is well below the dewpoint of your gas flame, so you get instant condensation which doesn't disappear until the metal is nearing 212F.

Steve S

Oh? I always just took for granted that there was moisture in the metal. I guess that makes sense though.

Sorry for dispensing bad info. If you think its a good idea, I'll edit that part about sweating it out.

This is how we judge our lower preheat temp. Apply flame and watch the condensation form and then evaporate and that's reasonably close to the required temp.

weldin mike 27 wrote:This is how we judge our lower preheat temp. Apply flame and watch the condensation form and then evaporate and that's reasonably close to the required temp.

Exactly. This is good practice any time one is welding metal below 50F, and advisable on any metal to be sure it's above the local dew-point and is dry.

Steve S