309 accident, advice please.

[flyingbrick]

I'm worried.

Short story. I'm not a welder, I'm a turner.

I'm welding a stainless sump to my 70L mild steel fuel tank (new) using 309 rods.

Professional stainless welder buddy comes over and proposes job swap as he needed machine work done.

Buddy decides my wire size is wrong and he completes welding 3 sides (of stainless box to mild steel tank) using 316 wire out of my usual packets.

It is all relatively light gauge.

He thinks it will be OK But since I'm lacking in experience I tend to err on the side of caution.

What are my options?

Grind out the welds and reweld with 309?

Not worry?

Run over all existing welds with 309? (Preferred)

Any help much appreciated.

 

[TechnicAl]

Have they cracked?
If not they might be a bit brittle but its not a certainty. Other than that I would leave well alone

 

[langy]

Just wondering why you used stainless onto mild steel tank ??? As Al said if it ain't cracked already it should be ok but its not something you would normally do

 

[pedrobedro]

Cut the lot off and weld a mild steel one on with mild steel rods ?

 

[Kent]

is this a fuel storage tank? If so it needs to be twin wall, just thought I might mention it as it sounds that way

 

[pedrobedro]

is this a fuel storage tank? If so it needs to be twin wall, just thought I might mention it as it sounds that way

I assumed it was a vehicle fuel tank but he is in New Zealand so the fuel storage tank laws may differ from UK.

 

[the snooper]

I assumed it was a vehicle fuel tank but he is in New Zealand so the fuel storage tank laws may differ from UK.

I would assume the same at 70 litres

 

[flyingbrick]

Sorry, yes it is a vehicle tank.

The guys were just like USE STAINLESS and said it be zero problems with 309 rods.

It will be crack tested with flaw finder spray today.

Would going over it with 309 rods be of no benefit?

 

[Rig Pig]

Stainless and mild steel don't go well together in a corrosive environment, they form a battery with the mild part as the sacrificial anode

 

[flyingbrick]

Thanks guys.

So basically my only option is to cut it off and start again...gutted.

When grinding the old part off should I cut the welded material (tank)off completely or will it be OK just to grind down flat (there may still be stainless wire in the material)

 

[Kent]

I assumed it was a vehicle fuel tank but he is in New Zealand so the fuel storage tank laws may differ from UK.

I missed that bit, it was just the talk of box section that alerted me to it being a storage tank

 

[Richard.]

Sorry, yes it is a vehicle tank.

The guys were just like USE STAINLESS and said it be zero problems with 309 rods.

It will be crack tested with flaw finder spray today.

Would going over it with 309 rods be of no benefit?

No, going over it with a dissimilar rod won't help now as you've already diluted the 316 between the steel/stainless. See how the NDT turns out, if all good then best to leave it as is.

 

[the snooper]

everytime I see this thread pop up I think Peugeot 309 crash

 

[flyingbrick]

Thanks guys. I joined this thread just for this question and you didn't dissapoint!

If the ndt comes back as OK is there a large chance that it will crack later on? Or am I pretty safe to use the tank without worrying

Pretty gutted really as I followed advice from.people that SHOULD know what they are talking about and I did a damn good job.

 

[langy]

Thanks guys. I joined this thread just for this question and you didn't dissapoint!

If the ndt comes back as OK is there a large chance that it will crack later on? Or am I pretty safe to use the tank without worrying

Pretty gutted really as I followed advice from.people that SHOULD know what they are talking about and I did a damn good job.

In my opinion it will be fine if it's been welded correctly, we havnt seen a pic yet ?

 

[flyingbrick]

 

[langy]

Blimey its like deja vu same as how I do them, 1mm A15 rod, I assume it was cleaned back to bare metal before welding ???

 

[flyingbrick]

Your welding is much tidier though!

I'd never seen anyone just make holes as we do- all iv seen online had big pieces cut out which is rediculious!

The big hole let's fuel in, the small holes let air in and out so that it can fill.

Realistically I could have had smaller holes and it still would have let in enough fuel

Definitely cleaned back to bare steel! Just hard to tell because of the dye

Edit.

Oops, forgot this pic! This is what I thought you were talking about!

 

[langy]

Your welding is much tidier though!

I'd never seen anyone just make holes as we do- all iv seen online had big pieces cut out which is rediculious!

The big hole let's fuel in, the small holes let air in and out so that it can fill.

Realistically I could have had smaller holes and it still would have let in enough fuel

Definitely cleaned back to bare steel! Just hard to tell because of the dye

Edit.

Oops, forgot this pic! This is what I thought you were talking about!

Yes I know what you mean, its ridiculous to leave the top of the sump open as fuel will just escape which negates the point of having it in the first place !!! Only ever done sumps this way as it made complete sense to me, my holes are a 1" and a few of them as my 1000gph pump is a little greedy

 

[norlander]

OK-I'm a biker and four wheel thangs are for fetchin the shoppin and big loads of booze for parties, so I'm asking why you do this?.
Both jobs look good to me-but why is it done?