Welding 304SS Headers

[MEAN_SBC]

I'm building a set of 304SS headers and I'm using a Diversion 165. I've been practicing quite a bit, but my question is if I only use enough filler rod to keep my puddle going, is the weld going to be strong enough??? I dab a little push the weld a ways and then dab a little more... I can make the weld look very pretty with this method, but I want it to be strong as well...

Another question, if the butt weld joints are perfect with absolutely no gaps, is filler rod even required????

Thanks in advance!!!!

[Bodybagger]

It depends. The throat of your weld should be as thick as the base material. If it's thinner, it will crack from thermal strain.

As for "perfect fitup," you can make autogenous welds from the outside edge (imagine welding the seam of a box-you weld from the outside) pretty readily because you are welding the root. But with headers, the root is inside the tubing. You should leave enough gap to have a keyhole going and fill it with rod. Otherwise, you will not fuse the root and it will seed cracks through.

[FATFAB]

I would add back purge or Solar Flux type b.

http://www.solarflux.com/

[FusionKing]

I would add back purge or Solar Flux type b.

http://www.solarflux.com/

What a pityful website.

[allessence]

the weld bead is best if it can be slightly raised from the surface. The 304 will expand and contract quite a bit and is prone to cracking especially in high heat applications like turbo's.

I have seen some on Nissans and other last 6 months if luck and these are factory made units like HKS and such.

I have made several out of mild steel and have held up very well. One is 2 years old on a turbo charged car. Schedule 40 1.25" mild steel weld els with 1.25 mild steel pipe for the straights. 3/8th flange on head and 1/2 flange for turbo.

[Laiky]

I would go with the backpurge if your going for a full penetration (keyhole) weld. In my experience getting the solar flux in the puddle causes trouble.

[4sfed]

It depends. The throat of your weld should be as thick as the base material. If it's thinner, it will crack from thermal strain.

As for "perfect fitup," you can make autogenous welds from the outside edge (imagine welding the seam of a box-you weld from the outside) pretty readily because you are welding the root. But with headers, the root is inside the tubing. You should leave enough gap to have a keyhole going and fill it with rod. Otherwise, you will not fuse the root and it will seed cracks through.

I butt the ends, but bevel to approximately half the thickness of the tubing and back purge. I've used the Solar Flux, but the puddle develops a film that makes it sluggish and you get a hard coating of flux on the inside.

When welding a "bend", the tubing is much thicker on the inside of the radius, so adjust the bevel accordingly.