Strange corrosion on AISI 304 (1.4301) 2

[dominic82]

Hello,

I am new in this forum, my problem is with one of our vessels. It is used for fermentation of wine. For cleaning we use sulfurous acid 5% water solution at temperature 30-40 degrees and washing with clean water from underground after this.

On the surface inside as you can see on the picture start forming something.

https://onedrive.live.com/redir?resid=9DD0BF74DE0478F7!596&authkey=!AN-_ZZzhDeXAEY8&ithint=folder,

Do you know what is this? Is it some corrosion process, or something else?

Thank you in advance for the answers!

 

[ASMEQC]

what i see in the picture is splatter from somebody cutting metal. It should scrape off.

 

[EdStainless]

Either weld spatter or debris from a grinding wheel.
Either way the area should be cleaned with fresh clean abrasives.
Start fairly coarse so that you can remove this efficiently, then move to finer ones to get a good finish.
After this you will need to clean (passivate) either with nitric acid (25%) or with a commercial pickling paste (RedOne).

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Plymouth Tube

 

[gr2vessels]

dominic,
Seems that you are somewhere in Russia, so you'd be better of using one of the many electro-cleaning process available in Russia. It's quicker safer and you will look good with your superiors.

 

[Guest102023]

Actually it looks to me more like spatter from soldering or brazing.

"If you don't have time to do the job right the first time, when are you going to find time to repair it?"