Corrosive and Radioactive Resistant Piping 1

[carltogr]

Folks,

I have a recent need to provide piping that is both resistant to corrosives (aqueous solutions of <10% HCL, and <10% HF) as well as have resistance to radioactive materials. We have used stainless steel in the past, but typically it gets "eatin'" within 3 to 4 years. We have tried plastics, but they become brittle due to the radioactivity. Anyone know of a piping material that protect against these? How about a liner, and/or a coating that would protect the piping?

We would like to get protection to at least 6-7 years or double the life of the piping.

thanks,

Carltogr

 

[EdStainless]

The radiation accelerated aging of polymers will make using anything but high grade thermosets difficult.
The only two things that come to mind are either use a higher alloy material. In acid you should use alloy 20 or a Ni based grade. There is a lot of C276 used at Rad Waste sites around the US. I know that Ni prices are through the roof right now, but the stuff works.
There may be epoxy that would work as a liner, but I don't know where you will find durability data. Or how will handle the field coating of the welds.

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Rust never sleeps
Neither should your protection

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[Ashereng]

My apologies, but I do not have any experience with radioactive materials. We try not to use them in my industry unless we have to.


This is a simplistic approach - to double pipe life from 3-4 years to 6-8 years, double the wall thickness. When we design against corrosion, that is what we do. You can either use better material, or more material. Sort of the "When in doubt, make it stout." method. We get the corrosion rate, and after determineing the life of the pipe required, we get the thickness.

Like I said, this is a simplistic approach.

If you want different material solution, I will defer to my colleagues.


"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[STYMIEDPIPER]

I am assuming that you used L grade stainless steel. My previous involvement with nuclear business was 316L.

 

[EdStainless]

If they have been getting failures in stainless it has probably been pitting. With pitting the key is the time until it starts. Making the parts thicker will only add weeks or months to their life. You have to prevent it in the first place.
Making parts thicker only extends their life in general corrosion situations.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[ApC2Kp]

carltogr,
The radiation shield materials that come to mind would be lead or graphite, depending on the type of radiation. The other materials (boron, berylium, depleted uranium?) could be prohibitively expensive. Massive thicknesses of concrete also provide some shielding benefit.
The HCL corrosion of stainless steel could be improved by use of high nickel alloys as recommended by EdStainless. A glass lined piping system might resist the combined HCL+HF exposure, but there would be many flanged joints with PTFE gaskets. PTFE lined steel piping could be corrosion proof, but there remains the carbon steel pipe shell needing shield from radiation.

 

[pwtomlin]

What stainless steel(s) have you tried?

 

[carltogr]

pwtomlin,

We have used 304L and 316L, schedule 80.

Carltogr

 

[EdStainless]

Standard corrosion guides will tell you that these alloys are not suitable for this service.
There are many catches with any material in this service. While I like the idea of epoxy lined piping, getting it installed without damage and making the field joints are major obstacles.
I still suggest that using higher alloys for metallic piping offer the best solutions. You need to select an alloy that will resist corrosion and then use the correct wall thickness based on the mechanical loads. If you can use sch10 the cost may be manageable.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[carltogr]

Folks,

thanks for all of your valuable insight so far....


Sounds like Hastelloy C-276 will be the best fit, although, it runs about 100 bucks per foot.

Hmmmmmm....they probably don't make anything cheaper, do they?

 

[pwtomlin]

I don't know if it would stand up to your application, what the price difference is, or if you already dismissed it but you should follow up on EdStainless's suggestion of Alloy 20. Hastelloy C-276 is one of the more corrosion-resistant alloys but I believe there are alloys that would cost you less but should provide longer life than 304L/316L.

 

[EdStainless]

Unless you are running real high temperatures and pressures there is no reason to be using sch80 pipe. Look at your real design limits and go as light as you can.
Look at some corrosion data on alloy 20, it may be the best bang for the buck in this kind of application.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[unclesyd]

Here is one approach (Sub-One) that I would check into. You can get essentially anything you need to coat the inside of your pipe.

http://www.sub-one.com/index.html

 

[stanweld]

On the first nuclear fuels reprocessing plant in which I was involved more than 30 years ago, Alloy 625 was used for the piping. I believe the operating life of the plant was 5-years.