Piping for sea water: Duplex 2205 vs 316L
Piping for sea water: Duplex 2205 vs 316L
(OP)
Hi all.
We are currently designing some piping to convey sea water. At first I thought 316L would be OK, but after reading a dozen of articles, it seems there are mixed experiences with it. I am currently considering Duplex 2205, but I would like to know a couple of things:
1) Is it much more costly than 316L? I just want to know that I am not going to ask the supplier for something outrageously expensive...
2) Is duplex 2205 OK for sea water (35g/l NaCl, 20ºC max), considering that the pipe will only convey seawater around 16h/day? I am concerned about having the water stagnant, although the docs I have read seem to point out that a few hours stagnant is not a problem. For longer stops (maintenance and such), I think we will just wash up the pipe with fresh water.
I welcome your tips. Many thanks in advance.
We are currently designing some piping to convey sea water. At first I thought 316L would be OK, but after reading a dozen of articles, it seems there are mixed experiences with it. I am currently considering Duplex 2205, but I would like to know a couple of things:
1) Is it much more costly than 316L? I just want to know that I am not going to ask the supplier for something outrageously expensive...
2) Is duplex 2205 OK for sea water (35g/l NaCl, 20ºC max), considering that the pipe will only convey seawater around 16h/day? I am concerned about having the water stagnant, although the docs I have read seem to point out that a few hours stagnant is not a problem. For longer stops (maintenance and such), I think we will just wash up the pipe with fresh water.
I welcome your tips. Many thanks in advance.
RE: Piping for sea water: Duplex 2205 vs 316L
Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
RE: Piping for sea water: Duplex 2205 vs 316L
You are correct, you can't expect 316 to work in seawater, especially when it will not be continuous flow.
This may be a problem for 2205 also, but it will hold up better.
When you spec the material make sure that you order S32205, and require the ASTM A923 testing.
What will be done for biological control? chlorination? During the stagnant period I am worried about grow taking over.
= = = = = = = = = = = = = = = = = = = =
Plymouth Tube
RE: Piping for sea water: Duplex 2205 vs 316L
Corrosion of Duplex
Stainless Steels in Seawater
ht
"In all tests, components made of
316L and S31803 were attacked by
severe crevice corrosion after a short
time. The highly alloyed steels
S32760 and S31254 performed in an
excellent way, and so did titanium
and S32550"
http:/
hope this help
S
Corrosion Prevention & Corrosion Control
RE: Piping for sea water: Duplex 2205 vs 316L
@strider6: Actually I had already seen that article, and noticed that they test at least at 30ºC, significantly higher than what we can expect. Nevertheless it is an interesting article, but I don't think the cost of the superduplex steel is assumible.
@EdStainless: Yes, we are thinking about 0.5 ppm chlorination, during 30~60 min a day. We must avoid all possible biological fouling as lead loss is also highly undesirable. According to the article attached, 2205 should do just fine as long as the temperature doesn't increase. Also, MANY thanks for the advice about S32205 instead of S31803 (I didn't even know the difference...). With the stress allowable values, it seems that it may be actually less expensive thanks to reduced thickness.
RE: Piping for sea water: Duplex 2205 vs 316L
Sounds like we're getting out the 12-pound sledgehammer to drive that square peg into that round hole!
Cold seawater is an ideal application for non-metallic piping.
RE: Piping for sea water: Duplex 2205 vs 316L
RE: Piping for sea water: Duplex 2205 vs 316L
= = = = = = = = = = = = = = = = = = = =
Plymouth Tube
RE: Piping for sea water: Duplex 2205 vs 316L
RE: Piping for sea water: Duplex 2205 vs 316L
And at those pressures, the extra strength of the duplex grades WILL be of use to you!
RE: Piping for sea water: Duplex 2205 vs 316L
Freom the pressure you have stated this probably a desalination plant using SWRO.
I have been working on plants for Veolia Water and Acciona Agua over the past 4 years. All use Super Duplex UNS 32507 with a PREN>40 for the sea water and brine services.
The question of stagnation is also a cuase for concern for super duplex. Whether you use SAF 2507 Sandvik or Zeron 100 Outokumpu doesnt matter; they both warn of stagnant conditions.
If cost is an issue why not use carbon steel pipe coated with FBE inside and out? You may have a little more maintenance in the future if the external is damaged but is far simpler than the stainlesses.
RE: Piping for sea water: Duplex 2205 vs 316L
you can select also a cupro nickel alloy but there are limitations on the max velocity...
Sea water System Design
ht
S
Corrosion Prevention & Corrosion Control
RE: Piping for sea water: Duplex 2205 vs 316L
As I said, the plant does stop during several hours a day, but there is only so much maintenance you can do during 6~8 hours. During the weekends, it could be possible to make maintenance at little cost, but that ultimately depends on the market, so it's hard to tell.
@stainer: We do not trust coating solutions a lot, to be honest, my bosses have had rather poor experiences with it
RE: Piping for sea water: Duplex 2205 vs 316L
Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
RE: Piping for sea water: Duplex 2205 vs 316L
Not that GRP pipe couldn't take it, but connections might be a challenge.
Mike Halloran
Pembroke Pines, FL, USA
RE: Piping for sea water: Duplex 2205 vs 316L
Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
RE: Piping for sea water: Duplex 2205 vs 316L
Where can I get GRP pipe and screwed connections for pressure like that?
Mike Halloran
Pembroke Pines, FL, USA
RE: Piping for sea water: Duplex 2205 vs 316L
Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
RE: Piping for sea water: Duplex 2205 vs 316L
Thanks.
Mike Halloran
Pembroke Pines, FL, USA
RE: Piping for sea water: Duplex 2205 vs 316L
RE: Piping for sea water: Duplex 2205 vs 316L
We even had a proposal to make a tunnel-like piping in concrete, with an impermeabilization sheet. I can't find any freely available examples to show you, though. But in any case that option is not my field, and I'm rather clueless about it.
RE: Piping for sea water: Duplex 2205 vs 316L
And yes, for seawater there are special concrete formulations. Not to mention the re-bar.
My opinion is that for a reasonable life and a reasonable cost 2205 would be suitable for handling cold seawater.
= = = = = = = = = = = = = = = = = = = =
Plymouth Tube
RE: Piping for sea water: Duplex 2205 vs 316L
Will the line be stagnant and can the temperature rise above 25C?
CEGB in the UK used to make all their seawater intakes to powerstations in carbon steel powder coated with PE. Flanges may be a problem at 60bar wit the gasket/PE thickness.
RE: Piping for sea water: Duplex 2205 vs 316L
= = = = = = = = = = = = = = = = = = = =
Plymouth Tube
RE: Piping for sea water: Duplex 2205 vs 316L