What kind of corrosion would you call this? 1

[StoneCold]

I have an older reactor that is made of 316Lss. It has been exposed to acid numerous times. It is developing these black areas with pits. I wonder what you call them?
Obviously the tank needs replaced. I get that, but from a pursuit of knowledge aspect. What is happening there? Why is it turning black? Is some element being leached out?
I put a bunch of pictures in a pdf, hopefully you can download it.
Please tell me what you think.

Regards
StoneCold

 

[mrfailure]

150C might not be enough to kill the bacteria if present. If the bacteria are anaerobic, they would not be killed because they have burrowed into the matrix of the material, where the tetrahydrofuran could not reach them.

Since the reactor is being scrapped, it would be a good idea to get a metallurgical analysis of the damage to identify failure mechanism. Tough to take corrective actions (including material and fabrication changes) without first knowing what happened.

Aaron Tanzer

http://www.lehightesting.com