heat exchanger welding

[123hotchef]

what are the chances of me repairing a oven heat exchanger successfully with my mig?

pics of cracks to follow oh and I have 4 of these to fix.

 

[123hotchef]

 

[Brad93]

Next to no hope sealing that properly with a MIG in the state that's in.

A good clean up, all cracks ground out and tigged is what that needs.

Stainless too by the look of it.

Give me a PM if you want them tig welded - I'm only the other side of the water.

 

[500e]

Interesting job agree with JB TIG, not that my welding would be up to it.
What are they out of ? the level of damage failed material would suggest there is another problem that wants addressing.

 

[dobbslc]

Looks like they've missed the joint and welded right on the edge of it.

 

[123hotchef]

Interesting job agree with JB TIG, not that my welding would be up to it.
What are they out of ? the level of damage failed material would suggest there is another problem that wants addressing.

they are heat exchangers out of my big 20 grid oven, they have had 8 years of abbuse you know heating them to silly hot for the oven then they get sprayed with cold water and turned onto the steam setting well it has taken its toll on them, now they need fixing and the chefs told not to spray them with cold water as I am sure that is the cause

 

[Brad93]

Looks like they've missed the joint and welded right on the edge of it.

That heat exchanger has cracked in the HAZ of the weld. In all fairness to the welder that weld is probably perfectly fine for the application. It looks to have been purged properly as there is no 'sugaring' on the inside.

Id say its probably either a 321 stainless or 400 series to deal with that heat.
If the latter some can be quite crack sensitive.

I doubt it is Inconel but you never know.

Unlikely to be duplex as I don't think that would take all that heat?

 

[123hotchef]

That heat exchanger has cracked in the HAZ of the weld. In all fairness to the welder that weld is probably perfectly fine for the application. It looks to have been purged properly as there is no 'sugaring' on the inside.

Id say its probably either a 321 stainless or 400 series to deal with that heat.
If the latter some can be quite crack sensitive.

I doubt it is Inconel but you never know.

Unlikely to be duplex as I don't think that would take all that heat?

I am not sure on the material type but the welds do look good.
Like I said they have been abused a bit which is no supprise they cracked.

 

[ronan]

We were told in tech, while getting coded in tig, that anything made of stainless steel that has anything to do with heat, eg ovens, kilns etc, is usually 310 stainless.

That may have changed over the years though.

Edit, Seems not.

https://www.azom.com/article.aspx?ArticleID=4392

 

[8ob]

Mr Chef I think you should incorporate some short stainless bellows in the cracked areas to allow for expansion/contraction. Those corners are being subjected to a lot of stress which is causing fatigue .

Bob

This sort of thing.

 

[123hotchef]

Mr Chef I think you should incorporate some short stainless bellows in the cracked areas to allow for expansion/contraction. Those corners are being subjected to a lot of stress which is causing fatigue .

Bob

This sort of thing.

that was something that crossed my mind too Bob,

 

[Brad93]

It’s not to do with the repeated heating the material is specced for that. It’s stress corrosion creaking

 

[Badger1bear]

 

[123hotchef]

It’s not to do with the repeated heating the material is specced for that. It’s stress corrosion creaking

it will be the thermal shock of being super cooled with water from 500 deg C

 

[Richard.]

it will be the thermal shock of being super cooled with water from 500 deg C

Unlikely.
If the rapid cool was to cause that to crack it would of almost certainly happened on the first instance. What’s more likely the cause is the water and heat have caused excessive corrosion over time just like an exhaust system and this has probably been the culprit for the crack. Either way it’s very repairable with the right process in skilled hands.

 

[123hotchef]

That's what I like to hear thanks Richard. I won't attack it with the mig then

Unlikely.
If the rapid cool was to cause that to crack it would of almost certainly happened on the first instance. What’s more likely the cause is the water and heat have caused excessive corrosion over time just like an exhaust system and this has probably been the culprit for the crack. Either way it’s very repairable with the right process in skilled hands.

 

[Richard.]

That's what I like to hear thanks Richard. I won't attack it with the mig then

No.
Give it to brad if he’s local.

 

[123hotchef]

No.
Give it to brad if he’s local.

yes he aint a million miles away we have been exchanging messages he just needs to speak to his colleague to make sure it is repairable.

I cant see why not, it could also be sleeved if necessary

 

[123hotchef]

Just so u can see the whole unit

 

[123hotchef]