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embrittlement of stainless steel by hydrogen - lining solution

embrittlement of stainless steel by hydrogen - lining solution

embrittlement of stainless steel by hydrogen - lining solution

(OP)
Dear all:

I am currently in the process of setting-up simulations for retrofitting of a natural gas pipeline for hydrogen transport. The operating conditions will be 100 bar hydrogen pressure, temperature -50 to + 50 degrees Celsius.

Because of the embrittlement of stainless steel (e.g. 304, X-65) when exposed to high pressure hydrogen, an internal polymer lining is expected to be required. A well performing polymer lining will keep the hydrogen concentration at the stainless steel surface at a minimum (however this depends on the barrier properties and liner thickness, we assume that glass reinforced polyamide 11/12 will do the job rightly).

To describe the improvement in pipeline life in a quantitative manner, I am in search of a quantitative reference of ageing of stainless steel under the exposure of hydrogen at high pressures (the process itself is rather clear to me:  hydrogen diffuses with a simultaneous chemical equilibrium reaction into the metal followed by surface Griffith like cracks).

Many thanks in advance!
Best Regards

RE: embrittlement of stainless steel by hydrogen - lining solution

Hi diffusion,
We've installed systems in hydrogen to 7000 psi from -420 to ambient and have used austenitic stainless for these without issue.  I'm sure if there was an issue, our corporate metalurgists would have screamed foul a long time ago.  

I also did a brief internet search and found some information that seemed to support that 300 series stainless is not affected by hydrogen.  Precipitation hardened steels and high strength carbon steel is a different story.

Also, I can't imagine a polyimide or any kind of plastic being able to significantly reduce hydrogen penetration.  I would think hydrogen would fairly quickly penetrate any surface treatment like that.  

I'm not an expert on this, so perhaps the question is best posed to the metal and metallurgy engineering forum here:
http://www.eng-tips.com/threadminder.cfm?pid=330

RE: embrittlement of stainless steel by hydrogen - lining solution

(OP)
Many thanks Iainuts for your quick and very valuable reply!!!

Kind Regards,

http://www.diffusion-polymers.com

RE: embrittlement of stainless steel by hydrogen - lining solution

Austenitic SS will not hydrogen embittle.  There are some cases where the ductility goes down slightly under hydrogen charging, but these are highly non-standard and usually related to weld composition.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

RE: embrittlement of stainless steel by hydrogen - lining solution

(OP)
Dear All:

Further to your replies, we carried out multilayer diffusion simulations for hydrogen at 100 bar pressure and 298 Kelvin. We simulated the following configurations:

1. 10 mm glass reinforced polyamide on top of 12.7 mm
   stainless steel (16 inch diameter pipeline).

2. 10 mm glass reinforced polyamide on top of 12.7 mm high
   strength carbon steel (16 inch diameter pipeline).

In the first configuration, the liner keeps the hydrogen surface concentration in the stainless steel much lower than without. However, the kinetics of stainless steel embrittlement are so slow, that the liner appears to be rather useless.

In the second configuration, the hydrogen permeation properties of the high stength steel are much better than most/any of the available plastics today (you were right Iainuts). Hence, instationary and stationary diffusion simulations show, that again, the liner is useless.

Case closed, I would think...

Thanks for the support!

Diffusion

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