CF8M/HCL Corrosion

[lulunet]

I’m trying to elucidate a weird corrosion problem.
Two CF8M (SS316) parts were in contacts with Hcl solution (low pressure (5psi), 250 ?C, High speed).
First one is a short pipe and is clearly corroded. This corrosion is dissymmetric (vs pipe axe).This corrosion exists all around but looks different at the top than at the bottom. Pipe was installed vertically, No gravity action.
The Second CF8M part is a plate and is quasi brand new.
Both parts has been casts with same procedure. Hardness and PMI give same mechanical characteristic.
If people have idea, I’m interested.
lulunet.

 

[Goahead]

Are you sure it is corroded and not eroded by the high speed solution running inside? How is the plate in contact with the fluid?

http://www.welding-advisers.com/

 

[bigc1304]

I believe you have both an erosion and corrosion problem.
The chlorides will pull the chrome out of the 316 SS.
If you have the capabilities, try placing a clean and weighed 316 sample of your part in your HCl solution at some elevated temperature, say 180F. Heat and move the solution with a magnetic hot plate under a fume hood. Use all safety precautions ..... at given time intervals remove
the sample, rinse well with DI water, allow to dry and come to room temperature. Weigh and compare to original weight.
You should get an idea of the amount of attack on the 316.

The temperature of 250F will increase the rate of attack.