Material Compatibility for Industrial Water Service

[Pavan Kumar]

Hi All,

I have been asked to check the compatibility of Lean Duplex Steel for Industrial water, spec give below. I wanted to know how I can check this. On checking this forum I found that there is Langelier index which tells you if Caco3 will precipitate or not, but then how do you check if the material is suitable for this spec.

Demin Water on carbon steel - Water treatment and distribution

I need advise how to deal with demin water (chemical additive??) so that it will not be too harse on carbon steel piping, without using stainless steel as an option?

www.eng-tips.com

Thanks and Regards,
Pavan Kumar

 

[EdStainless]

Normally with a scaling index (any of them) the water either scales or it dissolves metal.
However, with SS there is little risk of dissolving metal.
The issues in SS are pitting or crevice corrosion.
So you look at Cl (+F), pH, and temperature.
There are a number of handy sources for pitting limits for various SS alloys.
Considering that lean duplex grades are generally equal-to or slightly-better than 316L.
Though unless you are doing this for strength reasons, if this water will never scale 304L might work just fine.

 

[pierreick]

Hi,
On top of the comments from Specialist, you may want to perform indexes calculation and validate the quality of the water (corrosive) .
Underneath you will find link to support your knowledge on SS steel.

Library - SSINA

www.ssina.com

Pierre

 

[georgeverghese]

There appear to be 3 grades of lean duplex SS (S32101,S32202,S32304) - may be good to know which one you've got, even if PREN appears to be the same for all 3 at 26.
How is chloride so low at <<50ppmw here - is this industrial water sourced from city mains potable water?

 

[EdStainless]

No one really uses 2304 any more.
LDX2101 is the workhorse lean duplex.
There is also 2001, 2003, 2202, and 2011.
These all have similar PREn and strength.
I often see them mixed-and-matched because if you need sheet, plate, and bar you may need to deal with three different mills.

 

[georgeverghese]

At these low chloride levels, looks like the major contributor to corrosion is microbial growth - MIC.

 

[Pavan Kumar]

Hi georgeverghese and EdStainless,

The water is drawn from river and Cl- is 3.5 ppm. The water after pre-treatment ( solids removal) needs to be stored in a tank for which I am checking the compatibility of Lean Duplex Steel. I need to tell the vendor if Lean Duplex Steel is acceptable or not. I know if it is expensive, but given the composition will Lean Duplex Steel work?. They might eliminate Duplex steel for cost reasons but we must at least know if it is acceptable corrosion wise. What factors should I look at and check the limits. What REFERENCES can I look for these limits. Kindly suggest.

Thanks and Regards,
Pavan Kumar

 

[pierreick]

Hi,
Probably a good candidate: Uranus 45N if 316 L not suitable for your application

https://www.steelmillsoftheworld.com/products/ss/hotrolledplates/duplex_stainless_steel_URANUS_45N.pdf

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Pierre

 

[SJones]

Resistance of Stainless Steel to Corrosion in Naturally Occuring Waters (1262)

nickelinstitute.org

 

[EdStainless]

Part of your pre-treatment will some form of biological control, won't it?
This needs to be considered.

 

[Pavan Kumar]

Part of your pre-treatment will some form of biological control, won't it?
This needs to be considered.

Yes

 

[EdStainless]

Make sure that everyone knows that this will require periodic cleaning and inspection regardless of the material of construction.
You could do this with internally coated carbon steel, like they use in water towers.
The coatings are durable but still have a finite life and require replacement periodically.
You could consider a lower grade SS such as 304L.
But any upset in water condition (spike in Cl) or treatment (biological growth incident) could cause rapid pitting failure.
A lean duplex gets you higher corrosion resistance without ridiculous cost.
The publication that SJones listed is good, but from 1980 so it does not include newer alloys.

Ur45N is 2205, and is overkill for this application.

 

[georgeverghese]

It is very likely that hypochlorite injection into the river water tank and "industrial water" stream ( both batch and continuous dosing) will be necessary for obvious reasons - this will have a strong influence on materials selection. This probably will justify lean duplex SS with PREN=26 ( dont know if Mo content variability in these grades is a concern - the second link recommends S1.4362 with higher Mo as a minimum ). But you may need higher alloys at the point of hypo injection and several feet downstream.

https://nickelinstitute.org/media/8daa6b24158653f/10087_stainlesssteelforpotablewatertreatmentplants.pdf

Duplex Stainless Steel Profiles in Water Treatment - Montanstahl

Stainless steel profiles are exposed to special circumstances in water treatment. But duplex stainless steel presents itself very resistant there.

www.montanstahl.com

 

[pierreick]

Hi,
We have no idea about the size of the tank, the residence time.
These are key factors for the costing.
Why don't you consider plastic (PE or PP) tank or CS lined, even concrete coated for Industrial water?
Too little information,
my view only.
Pierre

 

[pierreick]

Hi,
If you want confirmation about the metallurgy, select a few samples of metal coupons and put them in contact with your water in an accelerated test.
Good luck
Pierre

 

[Pavan Kumar]

Hi,
We have no idea about the size of the tank, the residence time.
These are key factors for the costing.
Why don't you consider plastic (PE or PP) tank or CS lined, even concrete coated for Industrial water?
Too little information,
my view only.
Pierre

Hi Mr. Pierre, EdStainless, georgeverghese,

I donot have any idea of the tank too. I have suggested to the client what while Lean Duplex Steel is good for this service, SS304 is also acceptable. I have let you all know what decision is taken.

Thanks and Regards,
Pavan Kumar