Corrosion Allowance on A335 P91 Piping Class supercritical water

[anapaz]

Hi all,

I am having some problems in order to justify why my company dares to use 1.6 mm Corrosion Allowance Thickness in a Piping Class for Supercritical water service for a Power Plant. As good engeneering proctice this is what was defined, but as I do not have any data of the corrosion rate for this specific situation, it is imposible for me to say whether 1.6 mm or 1 mm would be enough. My question here is to know if you have any experienece with this, so I can base my reply on other companies experiences. Below the fluid conditions, steam is pretty clean:

Design Temperature: 588ºC
Design Pressure: 153.3 Bar
Fluid conditions on normal operations:
SiO2 < 20 ppb
Sodium < 3 ppb
Chlorine < 5 ppb
Cation Conductivity < 0.2 µS/cm

In advance, thanks a lot!

Ana

 

[metengr]

The Power company I retired from and others I consult with have P91 material for headers, and select locations of T91 tube material and never had a corrosion allowance because of the 9% Cr.

 

[anapaz]

That is something to start with,

Thanks Metengr!

 

[weldstan]

I know of one Engineering firm that specifies a 0.010" CA. See metengr for generally specified.