tank welding advice

[cascadia]

I acquired some old stainless steel tanks that I would like to use as fermentation vessels. At some point in their history legs were welded onto them. The welds were not back gassed or fluxed. So, there is some sugar on the inside of the tank.

1. Can I sand the problem areas and passivate?
2. If sanding causes a crack or hole to open, can it be repaired? If so, how?

I have a weldor that I am confident can do whatever I ask, I just want to have some information before I go to him.

Thanks all.

 

[BrewMoreBeers]

sand and passivate. that is how my kegs were made.

 

[Ohio-Ed]

IMO, the fermentation side of brewing is the only one that really needs sanitary welds. I'm learning to TIG but it will be a while before I'm comfortable welding on a fermentor.

I do think you can get around the sanitary weld requirement depending on your configuration. For instance... If you can sanitize the fermentor with heat/steam I think you can get away with less than perfect welds. If your only choice is to slosh around some chemical like starsan, then I think your welds need to be near perfect.

I ferment in a sanke and just add some water, cover the opening loosely with aluminum foil, toss it on a burner and steam it for 20 or 30 minutes.

Good luck,
Ed

 

[cascadia]

Hmm, it will be difficult to heat it to get the steam. Would transferring boiling water be sufficient?

 

[Ohio-Ed]

Hmm, it will be difficult to heat it to get the steam. Would transferring boiling water be sufficient?

To sanitize with heat/steam, you really have to maintain the temp for a period of time. If you transfer boiling water into a SS tank, the water will cool pretty quickly and you will have a hard time maintaining the heat required to sanitize.

That said, your best bet may be to see if you can get get the tank repaired with sanitary welds.

Ed

 

[cascadia]

Fair enough, thanks Ed. I have followed your threads closely over the years and trust your input.

I will talk to my welding guy and see what he has to say. Like I said before, I am just trying to get some other perspectives.

 

[critch]

my commercial fermenting tanks are sanded along the welds (used a grinder actually!) ive never had a problem in two years. as long as you clean em right itll be fine

+1 for grinding them back and then passivating

 

[Dog House Brew]

How does one passivate after grinding?

 

[dmfa200]

If you use new clean abrasives you don't need to passivate. Passivation is only needed if stainless has been contaminated. Clean abrasives do not contaminate.
Stainless steels oxide layer will reform after it has been disturbed. No need for passivation

 

[wyzazz]

You can help the passivation process along by using an acid on the freshly ground stainless. Bar Keepers Friend seems to work well.

 

[critch]

i use peracetic acid to repassivate my stainless