[oburrill]

Hello, a question regarding welding a mild steel fitting onto a mild steel sump/oil pan.
The fitting is 22mm OD, and the end is machined with a step 1.5mm in from the end, with a diameter of 20mm. This 20mm diameter will be through the side of the sump which I will drill for a 20mm hole. The fitting is drilled and tapped for a 1/4" NPT thread, so the wall on the fitting is just over 4mm thick.
The sump is 1 to 1.5mm thick which I will be checking later.
My main question is should I weld both the inside and outside of the fitting?
I was thinking of running a weld on both inside and outside with filler rod.
I do not know if this would have any disadvantages with stress, distortion or chance of cracks? I just want it to be strong.
Any other thoughts? Worth putting a heat sink on the inside?
It is a tig machine with air cooled torch with red tip 2.4mm tungsten, standard argon gas.
I've done a bit of stainless welding with good results, just after a bit of advice before I start welding this new mild steel sump.

Thanks in advance.

[cj737]

I can’t imagine you’d need to weld inside and out for sufficient strength. A good outside filler in a single pass would be my approach.

[motox]

one outside pass as CJ recommended.
no need to put more heat into it then you have to.
craig

[LtBadd]

oburrill, welcome to the forum, just curious, where you are located?

What machine and filler will you use?

[jwmelvin]

I’m about to do this too and I’m thinking to TIG braze it with Al-Bronze rod. Also putting baffles in the pan and thinking the same thing for those. Just to reduce heat input.

[oburrill]

Thanks for the advice.
I'm in England.

[Arno]

Like above.. Welding a fitting on the ouside is fine.

If it's in a nonpressurised sump then you only want it to stay in place and be 'non leaking' as a major design requirement

So focus on drilling a good round hole (eg. use a tapered or step-drill) and make sure the fitting is nice and snug and you have a good fitup so you're not fighting and filling gaps.

Then clean the surface(s) and around the back of the hole well and make sure all the oil and contamination is gone. Otherwise there's a good chance you'll suck the contamination from the back into the weld giving porosity and... leaks...

Do short runs to keep heat input low and stop the fitting and sump from distorting too much.

Bye, Arno.

[lrossini]

Arno, I’m trying to contact you. Have you received my private messages ?

Sorry to bother here.

[jwmelvin]

Why not Al-Bronze braze it?

[oburrill]

I was going to use ER70-S2 tig filler rod.
I have had to get a new sump as they are stuck on, so i'll be modifying the new sump by welding the fitting on and swapping them when I come to the job.
Thanks again.

[cj737]

I was going to use ER70-S2 tig filler rod.

Perfect choice.

[jwmelvin]

Can someone help me understand why this is better welder than Al-Bronze brazed? It doesn’t seem to need the strength of weld and also seems sensitive to distortion.

[cj737]

Can someone help me understand why this is better welder than Al-Bronze brazed? It doesn’t seem to need the strength of weld and also seems sensitive to distortion.

Just because you can use something, doesn't mean you should. The thickness of the material is very close to 0.063, which is plenty thick to tolerate welding. While the internal operating pressures may be low, there's little reason to expect that to be nil. Welding is always the best option when possible as it recreates a solid piece of metal. And welding thin material is a perfectly acceptable and common practice.

Sure, he needs to be mindful of distortion, but that is true any time you weld material, regardless of the thickness. And 0.063 is not so darn thin it can't be welded safely. A 1/16th wire and about 50 amps, and he should get great fusion, a tight bead, and a leak-proof repair. Why fuss with anything else?