Surface Conditioning

What is the vessel made of?

What is in the vessel? Its temperature and pressure?

Material is 317L ss. Fluid is 70-90 wt% acetic acid in water. Temperature is 305 F at 30 psig. Function a distillation column seperating acetic acid and water. Corossion occurs when chlorides enter system due to cooling water leaking into tower.

Have you given thought into lining (wallpapering) the vessel?

How complicated/big is the vessel? How many nozzles? .....

......... and just to make sure you understand - "wallpapering" means welding inside thin sheets of a more corrosion resistant metal to completely line the vessel.

Yes we are considering it.

I was just curious if some kind the surface treatment (polishing, shot peaning, etc.) would remove pits before they become sites for future attack during the next chloride excursion.

No, because the pits are so eratic - they are not always "open valleys" and often tunnel in between the two surfaces so you can't even see them. You would be grinding away so much metal that you be beyond ANY hope of safe pressure containment. The only VERY SLIM chance of any success would be to pickle and passivate, however, because it wouldn't remove the pits - there would still be crevice corrosion conditions and negate the effects in those very local spots.

.............. but I guess I will mention it for the sake of mentioning it ............. I have never done it but I have heard of urban legends/myths/dreamers thermal spraying corrosion resistant metal ........... but I will leave it at that, and act like I didn't even talk about it.

Here's your best advice. Suck it up and consult the original equipment manufacturer, get out the equipemnt drawings, ASME boiler and pressure vessel code sections; ASME B31.3 and contact an engineer.

"If you are good at something, don't do it for free." - The Joker, Batman Returns

Yas it is the bwst way to contact the Equipment manufacturer and ask, or refer ASME technique for surfcae coating.

Bhupat Meniya