Side effect of upgrading material 1

[lovescroll]

i'm curious about the side effect of material upgrading.

I currently found that my cooling exchanger was found some severe corrosion material was fabricated from carbon steel, life is less than 6 months. and we try in various way to improve the integrity like water wash injection and corrosion inhibitor injection but still no use. So we will consider upgrading them, but do the corrosion accelerate at the another point at downstream unit instead of this exchanger ?

For example remaining of existing exchanger is 6 months but after I upgrade this exchanger, this 6 months of remaining life might shift to the downstream piping instead or not ?. Actually I think the downstream unit’s corrosion rate shouldn't be accelerate. it should be the same as is. Please share your experience.

 

[EdStainless]

No, upgrading this unit should not impact following units, unless you use it as a reason to stop treatment that is also protecting other equipment.
I wold suggest caution. If you are upgrading alloys on equipment it is very easy to solve one problem but create others. Just because a material will resist the form of corrosion that damaged the CS unit does not mean that it will resist all forms of corrosion in your system.

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P.E. Metallurgy, Plymouth Tube

 

[NBrink]

As is so often the answer: it depends.

If the corrosion is caused by a large amount of moderately corrosive fluid (for instance, a hot oil stream with sulfur), no, upgrading won't cause corrosion to move downstream. It can look like that sometimes, because everything is corroding, but you just upgraded the worst part, and then a few years down the road, the part that was corroding slow and steady is due for replacement.

If the corrosion is caused by a very small amount of extremely corrosive fluid (trace acids condensing is the first thing that comes to mind for me), yes upgrading can absolutely move the corrosion downstream. If the corrodent was all getting used up in the exchanger, and it's no longer being consumed, it'll move downstream and cause problems.

Nathan Brink

 

[sahsanb]

In my experience 6 months of service life is very less even with CS metallurgy. Corrosion on carbon steel tubes on exchangers is not just occurring because of inferior metallurgy but can also be accelerated due to low flows in the tubes and small tube ID. Upgrading SS 304/316L is likely to solve your problem, however as mentioned by the experts above its better to look at the issue in totality before undertaking major investments.

Regards,
SAB

 

[MFJewell]

Don't forget CS and SS have different heat transfer capabilities. If you change the internals to SS but keep the same heat transfer area, you will not get the same performance from the exchanger.

 

[NBrink]

Be very careful upgrading to an austenitic like sahsanb is suggesting. Water wash and corrosion inhibitor injection with a six month life screams a crude unit overhead to me (but that could just be because I'm coming from a refinery background). You'll crack a 300 series in weeks in an atmospheric overhead...

Not saying that's the case here, but definitely watch out for upgrading to a material with other damage mechanisms.

 

[SJones]

Classic corrosion control failure analysis issue - determine the specific corrosion mechanism(s) before developing an holistic solution for the specific system.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.