Recommended Materials for Vessels with High Chlordies

What is your pH, what are the associated cations and is the given concentration chloride ion or total chlorides, and are there any oxidisers or reductants in the composition? These details make a huge difference.

316L is a chloride resistant material, not chloride proof. It has been found to show pitting and crevice corrosion in seawater (design, finish and flow rates can have a big impact on this). My personal recommendation would be against using it at this elevated temperature.

As far as the carbon steel/ paint combination, no comment as this is a pressure vessel. Speak to your material supplier, provide more info on the protective coating or follow Tornado's advice.

Follow Tornadoes (:-) advice. And while your are at it have a complete list of process parameter and fluids involved at hand.

Also make sure you know how long it needs to be acceptable and by whom.

What coating?

316L SS is not holding up for long in certain environment to 60000 ppm Chlorides!

It is fortunate that you are asking this question before your expensive vessel design is complete !

It is not complete....is it ?

All of the people above offer good advice. Your 316L is not a good choice for your high chloride/high temperature environment.... it will form pits.

Your carbon steel shell may fare worse than the 316L..... It will all depend on the quality and type of the internal coating.

I suggest that you procure the services of a corrosion professional.

The Hendrix Group is very knowledgeable and experienced in chloride corrosion issues

http://hghouston.com/home.aspx

Please let us know of your final decisions.....

Tantalum has good resistance to chlorides. Get out your wallet.

• Plastics
• Rubber lining
• Glass lining
• etc.

Make the vessel smaller. "What you don't have, cannot leak." - the late Dr. Treevor Kletz, globally-recognised process safety guru.

There is one recommendation to use Glass Flake Reinforced Vinyl Ester Coating for Immersion Service at Temperature up to 90°C. but this internal coating is not recommended when steam out cleaning will be utilized. and in this case what about the internals, SS 316L internals will also be provided with coating?

PTFE.

At our company we use very aggressive chemicals (Acrylic acid, among others) in 304 SS reactors. So far, the best linings we have found to protect the vessels are: glass, Teflon and Plasma coating. From the latter, the only process that may be suitable for your vessel (due to it´s internal configuration) seems to be a Plasma Coating, as it it directly sprayed to the surface, requiring no subsequent melting as Teflon (250ºC) or glass (about 600ºc) do. Before hiring a company for doing these processes we sent them some sheets of metal, got them coated and eventually left these samples submersed in the chemicals to simulate an ageing process. Samples were later on analysed to determine the degree of the chemical attach (if any). Good luck in your project!

What is the major kations? NaCl solotion (brine) is stored at concentrations of about 180g/L as Cl or 300g/L as NaCl. HCl you need a ...... I do not know. Talk to some one at a Cl2 plant.

Good Day

You going to have a problem with cracking (Chloride Stress Corrosion Cracking) in the 316 ss, especially if your PH is more than 2. Low Alloy steels will be functional in such a vessel, but I think you have a corrosive environment, you will have to use materials with a high nickel content in the region of 35% nickel they are highly resistant but not totally immune, but material with 45% nickel are virtually immune, but these materials are expensive, but will last much longer, I am speaking of experience.

Did you really mean if pH is more than 2, or did you mean to say less than 2?

I agree that chloride, acid solutions, along with any heat stress will crack 316 within possibly even minutes, not hours.