Material for high temperature caustic vessels 2

[msii]

Hi Guys,

I'm designing a pressure vessel with 250 C temperature and 20 barg for caustic soda 50%. Do you have any idea about material selection? I have read a couple of references like "Alloy selection for caustic soda service" and "NACE SP040315" but not applicable for this temperature.

Thanks

 

[metengr]

Look at nickel base alloy options in ASME BPV Code Section VIII Div 1. Ni base alloys are recommended by Dow Chemical literature in area c.

 

[mk3223]

For reference, here is the doc link of the SS and Ni Alloys material review for caustic cracking. Interested to know what is the material selected on your final design. Good luck.

https://e-reports-ext.llnl.gov/pdf/326030.pdf

 

[pradipgoswami]

Hi Mosii,

Earlier this posting was posted in "Corrosion Engineering forum". After getting 2 responses including one from myself, suddenly this posting was removed from the above forum and got reposted here.
Any specific reason?

Thanks.


Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
ca.linkedin.com/pub/pradip-goswami/5/985/299

 

[SJones]

@pradipgoswami - the policy is to post a question only in one forum. Posting the same question across multiple forums usually attracts a report flag from someone. The moderators investigate the report flag and, in general, will attempt to remove all the posts save the one in the most appropriate forum. Frustrating indeed, but the learning point is to check across other forums before making a reply.

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.

 

[metengr]

Well said, SJones. I red flagged the post in the corrosion forum because it was an exact duplicate with the post in this forum - boilers and pressure vessel engineering. The OP dealt with fabrication of a pressure vessel with consideration of corrosion.

 

[msii]

@mk3223
Thanks for your reply. I read this article but corrosion rate is not specified for more than boiling point. it has corrosion rate in 150 C not 230C or more. Do you have any other references?

 

[msii]

@metengr
area C consist of several material from nickel 200 to alloy 800. And as far as I'm aware corrosion rate for different materials in different conditions is not included in asme.

 

[metengr]

Your best bet is to use Ni 200 in this environment.
Excerpt below from Industrial Experience on the Caustic
Cracking of Stainless Steels and Nickel
Alloys - A Review

The best metallic material overall to handle caustic solutions at all concentration and temperatures
is Ni-200 (N02200) (Table 2). Ni-200 can be used even in molten anhydrous NaOH at temperatures
as high as 538°C (1000°F). Figure 1 shows the general corrosion rate by weight loss of several alloys
of interest. 1,19 The higher the Ni content the lower the corrosion rate. Ni-200 may be still slightly
susceptible to caustic cracking but mainly at temperatures higher than 300°C.

Others consider Ni-200 practically immune to caustic cracking.

 

High temperature caustic service is a very difficult problem.
I concur with Ni-200 as the best option.


"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[EdStainless]

The only other alloy used in this service (with long life) is the superferritic E-Brite.
It is not suitable for structures or even clad, but it is used in heat exchanges and evaporators that are built with Ni-200 tubesheets. Typically the tubes outlast the tubesheets by 3-5x because of erosion.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[msii]

@ironic metallurgist
@metengr

The problem of Ni-200 plate is its low yield stress (100 MPa acc. to ASME Sec. II Part B) and consequently leads to high thickness of vessel which seems unnecessary. I've read some articles about Nickel alloys and ASM Handbooks which suggest Inconel 600 and 690 in different cases. What do you think about these two?
Also, another option can be using Ni-200 cladding. But I couldn't find any reference for base material and implementing procedure.

cheers,

 

[EdStainless]

200 is nearly always use as explosively bonded clad plate, usually a medium strength structural steel is the backing.
There is a small group of fabricators that commonly build these units.
690 has been shown to have good resistance, but I don't know of a case where anyone has built a vessel out of it. It is expensive.
600 has noticeably less corrosion resistance in this service, and it isn't very strong either.
See if you can find MTI MS-6 Ammonia and Caustic service (ISBN1-57698-031-6) it has very good technical information in it.


= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[metengr]

600 will eventually result in problems. I would use Ni 200 cladding on carbon steel plate. Both are acceptable for use by ASME Section VIII, Div 1.

 

[pradipgoswami]

Hi Mosii,

You should consider integrally manufactured clad construction, involving C.S backing + Pure Nickel(Nickel 200) cladding. Look at Sec-II, Pt-A, SA-265 for guidelines on plates.
Thanks.

Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
ca.linkedin.com/pub/pradip-goswami/5/985/299

 

[msii]

@EdStainless
According to ASM Metals Handbook Volume 13 C
Alloy 600 (N06600) is used as an alternate to alloy 200 (N02200) in caustic environments, when the latter is not of sufficient strength. Alloy 600 was also used extensively in nuclear steam generators, until superseded by alloy 690 (N06690), which was found to be considerably more resistant to stress-corrosion cracking in pure water, at high temperatures.

Also, I read MTI MS-6 previously as below:
Commercially pure nickel, alloy 200 (N02200) and alloy 201 (N02201) are the best materials for resisting corrosion and stress corrosion cracking in caustic environments. Alloy 400 (N04400) and alloy 600 (N06600) also have excellent stress corrosion resistance. These alloys can however suffer from caustic stress corrosion cracking at caustic concentrations above 70% at temperatures above 290°C (550°F).

Since concentration in my case is 50% and temp. less than 290C, from two above clauses I've concluded Alloy 690 works. But, another question arises what general corrosion rate would be? Please let me know if you have any thought.


@metengr
Do you mean failure due to general corrosion or stress corrosion cracking or caustic corrosion cracking?

 

[metengr]

mosii
Regarding Alloy 600, problems in high temperature caustic solution is IGSCC and IGA. Take your pick.

 

Regarding Alloy 600, problems in high temperature caustic solution is IGSCC and IGA. Take your pick.

For these alloys in aqueous environments at elevated temperatures, the distinction can become almost a matter of semantics, because so many phenomena are activated and interacting. I am thinking of nuclear steam generator tubes particularly.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[msii]

@ironic metallurgist
@metengr

Thank so much. Do you have any reference that i can use?

 

[metengr]

http://files.engineering.com/downlo...0a5a-4dbc-bdb9-227b105f5308&file=Alkalies.pdf

http://corrosionjournal.org/doi/abs/10.5006/1.3581983

https://link.springer.com/article/10.1007/BF03027511