Corrosion from HCl and Cl2 6

[akfirm]

Hi,

I need to know if the gas with the following composition and in present of HCl and Cl2 is corrosive for the stainless steel.

Composition
H2O (1) 1.47 % vol
N2 81.29 % vol
CO2 16.45 % vol
O2 0.79 % vol
Cl2 2 average / 20 max ppm vol
HCl 2 average / 20 max ppm vol
Total Mass Rate 19159 kg/h
Total Molar Rate 627.75 kmol/h
Mol. Weight 30.52 kg/kmol
Op. Pressure 3.60 / 5.30 bar(g)
Max. Temperature 39°C
Reg. Temperature 230 °C
(1)Saturation Water @ 3.60 bar g and 39 °C

Thanks

 

[micalbrch]

Question: For what kind of stainless steel?

 

[tomwalz]

In my experience something that does not corrode stainless steel may corrode stainless steel welds. Might check that as well.

Tom

Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[akfirm]

The stainless steel is AISI 316

 

[pradipgoswami]

Hi AKFirm,

The data provided by you indicates there is possibility of water saturation at the max operating temperature. Both Cl and HCl,in dry and gasesous form are not so corrosive. But the situation if different when they are wet.
S.S 316 possess adequate corrosion resitance in dry chlorine and HCl environment. However the following engineering guidelines would be of help:-
-Use 316L base metal(Max C-0.03%)
-Use E/ER-316L welding consumable,max "C" as above.
-Use properly qualfied weld procedure,(consumables as above)and interpass tenperature not exceeding 175degC-Avoid Sensitization.
-The above shall be monitored during fabrication.
-Regulate the saturation limits, such that the environment never becomes wet.

If there are concerns on process parameters then upgrading from 316S.S to Nickel based alloys would be advisable.

The following guide from NIDI would provide you good information, on materials selction.

Thanks

Pradip Goswami

 

[moltenmetal]

If PARTIAL condensation is a significant risk, you will be condensing chlorine-containing HCl acid- not much of it, but it doesn't take much to do a fair bit of damage.

Please re-read your post and re-state the normal and maximum exposure temperatures. I presume your "maximum" is a minimum of 39 C (i.e. saturation at your pressure).

316/L SS is insufficiently resistant to survive repeated exposure to this partial condensate long-term in my opinion, regardless how good a job you do during specification/fabrication. You may be able to mitigate this by other means, i.e. by blowing the line out with dry gas when it is cooling down.

 

[rconner]

fyi also

http://www.eng-tips.com/viewthread.cfm?qid=241305&page=11

 

[strider6]

http://www.corrosionsource.com/technicallibrary/nidi/literature/pdf/10020.pdf

hope this can help u

S

Corrosion & Rust Prevention Control

 

[akfirm]

All,
Under saturation condition, the concentration of the chloride in aqueous phase is 0.1% in weight.
So,I think that the 316L is suitable for may plant.
Akfirm

 

[akfirm]

All,
Under saturation conditions, the concentration of the chloride in aqueous phase is 0.1% in weight.
So, I think that the 316L is suitable for my plant.
Akfirm

 

[moltenmetal]

If you don't condense all the water, the concentration of chloride will be a lot higher than that- and it won't be Cl- in water, it would be hydrochloric acid with some chlorine dissolved in it. Condense 10% of the water and what you could be condensing will be near enough to 10% HCl, which will do serious localized damage to 316SS if it's left around to accumulate. Do the partition calcs based on PARTIAL condensation using a simulator that can handle electrolytes and then determine what your course of action may be.

If you can avoid condensation completely by procedures or mitigate it by other means, 316 might still be OK.

 

[strider6]

your analysis reports also oxygen and cl2,two strong oxydant, that will increase the likelihood of corrosion for SS. you should also consider that in some areas you can have also accumulation and concentration of HCl.
also in reg (regeneration?) you'll have a temp of 230°C, and at this temperature you can also have CSCC, chloride stress corrosion cracking on SS 316L..
I'll select a more corrosion resistant alloy like nickel alloys.

S

Corrosion & Rust Prevention Control

 

[EdStainless]

you should seriously consider an alloy with better pitting and SCC resistance than 316.
2205 may be good enough, I would look into corrosion data on this grade and see if it looks like a fit.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[GabrieleB]

I have a reinjnection water with 67000 ppm of clorides.
Wich is the pratically solution for the piping in this case.
Carbon steel or Duplex material?
Wich is the mechanism of corrosion of clorides on carbon steel? If there is an absence of oxigen is the corrosion inhibited? Thank's for your answer.
P.S. Naturally the duplex is the bettere choice, but is carbon steel applicable?

 

[strider6]

Gabriele

Injection water is usually deaerated seawater or freshwater, and this will lower the corrosion rate on carbon steel to a negligible value.
Water is considered deaerated when the oxygen level is, as per Norsok M001, below 20 ppm.

http://www.standard.no/en/Sectors/Petroleum/NORSOK-Standard-Categories/M-Material/M-0012/

in your case seems more a production/formation water, the chlorides conc is very high, and you have to assess the corrosivity considering co2 content and other corrosive.


S

Corrosion & Rust Prevention Control