That is such nice work.

In your tank, this is kinda one of those real world vs on paper situations. Real world, you are unlikely to have issues with stress corrosion cracking there imo. Many tanks that get anodized will be welded with 5356 to be a good color match post anodizing (there are other fillers you can use here too, but are not as common). In the marine world, this is more of an issue as it is in a very corrosive environment, as well as being susceptible to vibrations and movements that create more stress, add elevated temps in the mix and over time it is much more likely to crack. My experience has been that heat alone isn’t as big of a deal as heat, stress, AND corrosion.

Very nice repair.

A couple things to add that come to mind. Adding filler wire can really help to cool the puddle down a bit each time you dab it. Short arc length helps with heat control as well, it will be easier to move quickly and keep heat down with a tighter arc. If you can, try running a bead and when you stop keep your torch hand as still as possible and take a picture of it showing the angle and arc length, a video is even better. Iit can really help to give you a good perspective on what you’re really doing while welding as sometimes it is hard to realize these things while you’re welding. I see things I’m doing that surprise me when I can see it from that different perspective.

Tell us more about your setup and prep.

It takes a bit of practice to make silly b move how you want it to, don’t get discouraged by that cause it can be cool stuff once you have it dialed in.

Aaron Laughlin yeah, holding a nice tight arc to light up on can keep the HF from zapping you. I have welded with a few machines that would zap you with HF no matter what you did.

Are you saying he was against walking the cup? If that is the case, I don’t agree with it being a problem in general. Any technique can be terrible if it is done incorrectly.

You need to make sure you have enough actual weld size at the beginning and end so that it has enough bulk to be strong enough for the cooling cycle to happen without the weld breaking. Often, it is just a matter of a few extra dabs of filler.

There is reeally no one single answer to this. It all depends. Something like 3x filler diameter is a target some shoot for, but it really depends on a number of things. Typically this will be specified in a wps because it can vary so much.