SS for this water?

[YAHA]

Hello.
We are currently designing some piping to convey sea water for RO plant.
Please help to find an optimal kind of SS for such analysis of water:

Na 6200 mg/l
Mg 45
Ca 40
HCO3 100
Cl 7300
SO4 1200

(temp=2-20 C)
We're examine such variant:SS316L.
Is there any reason to use SS316ti or duplex?
Sea water near Odessa (Ukraine)

 

[HEC]

High chlorides suggest thtat higher grade duplex would be best. Or consider composites, GRP or similar.

Mark Hutton

 

[metengr]

Agreed, I would use a duplex stainless steel for this application. It is stronger and has increased corrosion resistance over conventional 316L.

 

[YAHA]

maybe 317L with PREn = 29 ?

 

[SJones]

If you have to go metallic it will be 25Cr super duplex with a compositional restriction to hit a pitting resistance equivalent number of 40 minimum.

Steve Jones
Materials & Corrosion Engineer

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

 

[strider6]

Usually the limit for SS 316 is approx 1000 ppm of Cl-. It depends also on the max temperature, flow velocity... You can upgrade to a super austenitic like 6 Mo or better to a duplex. I'll consider also copper alloy as a possible solution.

http://www.corrosionist.com/Corrosion_Control_Seawater.htm

http://www.stainless-steel-world.net/pdf/11004.pdf

hope this help

S

Corrosion Prevention & Corrosion Control

 

[EdStainless]

For long term service you should look at concrete and GRP. If you want to use metal you are talking about a 25%Cr super duplex or a 6%Mo super austenitic. A 2205 or even hopped up 317LM will not handle this water for the long term. You will end up with under deposit crevice corrosion.

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Plymouth Tube

 

[ApC2Kp]

YAHA,

The temperatures of the seawater are good for HDPE plastic pipe and the HDPE is also a good choice for underground installations. Look for KWH, Weholite, Polypipe, Rinker, Performance Pipe, Kanalrohrsysteme, and others for polyethylene piping systems. Diameter to 750 mm and larger are available. You might consider some of the plastic / lined valves for these temperatures. Many DI water systems use polypropylene lined steel piping around the resin beds. I would avoid the PVC plastic piping due to brittle material properties at the lower temperatures. If the pressures and temperatures are increased, then the need for duplex stainlesses will need to be evaluated.

 

[HEC]

YAHA/ApC2Kp,
The HDPE pipe is a good option, for above ground high pressure application also consider HDPE lined Steel too. PIHA is a good manufacturer who has got around the problems of the HDPE liner "walking" out of the steel liner due to thermal expansion.

Mark Hutton

 

[antmann2005]

302 stainless steel could be a possibility

 

[rab1944]

What about the use of Duplex 2101 for plate and 2205 for pipe. The 2101 cost is somewhat competitive to 304L.

 

[EdStainless]

2101 will not handle this water, it is too lean.
2205 would work for a while.

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Plymouth Tube

 

[stanier]

I suggest you need UNS 32750 or UNS 32760 material for this RO application if a non metallic does not suit your application. 254SMO is also another choice.

Prices for super duplex materials are very competitive if you buy in quantity. there is spare capacity at the mills.

Be advised that it is not only the materials but the welding and post treatment that will be needed to mee these corrosive conditions. (refer ASTM A380)

 

[YAHA]

Thanks to all!

Now We're examine such variant 1.4410 or 1.4462.
Concentration of hypoclorit (NaOCl) 1 ppm in our water.
What abou this choice?

 

[EdStainless]

The 316 will not work, and the 2205 will pit if there is any dirt or fouling.
Admit defeat and look at 25Cr super-duplex grades.

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Plymouth Tube

 

[stanier]

A plant in Australia on RO was shutdown for months and $millions spent on retrofitting the correct grades of stainless steel.

Read Section 1.2 of the report.

http://www.dip.qld.gov.au/resources...t/letter-and-summary-of-desal-engineering.pdf

 

[HEC]

Stanier
Interesting report, though quite high level. I am currently involved in the Adelaide Desalinatin Plant, so it is particularly relevant.

Mark Hutton

 

[stanier]

HEC

I was responsible for the Durability Plan for Adelaide Desal. Back in Sydney now. Must talk sometime.

What organisation are you with?

 

[HEC]

Own company/contract to APP currently hutton4eng@picknowl.com.au I know posting contact detail on forum is verboten but hey, life is short!

Mark Hutton

 

[stanier]

Google Sandvik's hyper duplex