Compatible Materials For Chloride and PH of 5
Compatible Materials For Chloride and PH of 5
(OP)
I would like to confirm my ideas on material selection.
I will be running a water/glycol (basically a 50/50) mix through a vessel and filter. The solution will have approxiametly 100 ppm of chloride and a worst case scenario of ph 5. Maximum temperature of 235°F and psi 55.
I am planning to passivate 316 SS for the housing and all piping (after welding). Flanges will be used as well with a graphite (graphonic) gaskets.
A disposable polyester filter with a 316ss core. As the cartidge will not be in place for long periods (more than 2-4 weeks) I do not see a problem?
Does anyone see any problems with material compatibility. Advice on packaging for valves? Any advice would be appreciated.
I will be running a water/glycol (basically a 50/50) mix through a vessel and filter. The solution will have approxiametly 100 ppm of chloride and a worst case scenario of ph 5. Maximum temperature of 235°F and psi 55.
I am planning to passivate 316 SS for the housing and all piping (after welding). Flanges will be used as well with a graphite (graphonic) gaskets.
A disposable polyester filter with a 316ss core. As the cartidge will not be in place for long periods (more than 2-4 weeks) I do not see a problem?
Does anyone see any problems with material compatibility. Advice on packaging for valves? Any advice would be appreciated.





RE: Compatible Materials For Chloride and PH of 5
RE: Compatible Materials For Chloride and PH of 5
RE: Compatible Materials For Chloride and PH of 5
The best economical choice is using the standard ferritic-austenitic steel type "Duplex" (2205) with a minimum level of nitrogen of 0.15 %.
RE: Compatible Materials For Chloride and PH of 5
Your pressure and temperature are both relatively modest. What about FRP or lined carbon steel pipe, valves and housing? Depending on a variety of parameters, either of these options may give you a less expensive system than doing the same in 2205. And the result will not only be resistant to SCC- they'll be immune to it. PFA-lined ductile iron plug valves (Xomox, Durco etc.) are surprisingly inexpensive compared to what you may find in 2205 etc.
Doubt you'll have problems with your filter internals given the duration of service. But 316 for the housing is definitely out of the question for this chloride level and temperature. SCC is a serious concern.
RE: Compatible Materials For Chloride and PH of 5
RE: Compatible Materials For Chloride and PH of 5
RE: Compatible Materials For Chloride and PH of 5
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Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdo/
RE: Compatible Materials For Chloride and PH of 5
Craig's paper is based on the absense of Oxygen in the media and it is well documented that the potential for SCC in similar environments without oxygen is essentially nil if no chloride concentrating mechanisms are available. If Oxygen is present, there is a much greater potential for SCC in the water/glycol environment described. Also, if there is a potential method for chlorides to concentrate, SCC could easily result.
With the filter replacement and environment as described, I can not believe that Oxygen would not be introduced if not already present; therfore, I stand my recommendation not to use 316 SS.
RE: Compatible Materials For Chloride and PH of 5
Seriously, I wouldn't worry about CSCC at 1000ppm in 316. It will fail from pitting even if it dosen't crack.
Look at the duplex grades. If the chloride level will not any higher than 1000ppm you might consider a lean duplex.
= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.
http://www.trenttube.com/Trent/tech_form.htm
RE: Compatible Materials For Chloride and PH of 5
A petro plant not far from here installed a sea water fire water system in their tank farm. The ring mains were stainless steel. One week after they started up the pumps, leaks sprung up in multiple locations. CSCC!
A lined or duplex stainless vessel seem the way to go.
Cheers
Rob
RE: Compatible Materials For Chloride and PH of 5
Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdo/
RE: Compatible Materials For Chloride and PH of 5
As Sjones mentioned there are a lot assumptions being made. Unfortunately, I am dealing with a new client and they do not have all the ducks in a row as of yet. I was asked to submit a bid on the application.
Thank for all your assistance and pointing me in the right direction. I have researched it in depth and made my proposals based the original request. I did note all the issues that you brought to my attention. It's a starting point.
For example, I am still waiting on the particulars of the water/glycol solution as well as the exact form of chloride.