Hot Moist Hydrogen Chloride - Rate of Attack on Mild Steel
Hot Moist Hydrogen Chloride - Rate of Attack on Mild Steel
(OP)
Does anyone have or know of any data for rate of attack of hot moist hydrogen chloride gas on mild steel?
Conditions are pressure up to 100 psig; temperature up to 300 °F; mass fraction HCl up to 0.98 with balance water vapour and traces of air.
We are considering temporary use of mild steel for a reactor emergency depressurization line. Under normal conditions, the line is isolated from the reactor by a rupture disk assembly. In twenty years of operation, there has never been an emergency depressurization.
In the event that a rupture were to occur, it is estimated that the depressurization would occur in about 3 minutes. The question is, would a mild steel line stand up to the hydrogen chloride for this time - if necessary, adding a suitable corrosion allowance. A second issue would be generation of hydrogen and whether this would be signficant.
If the line were ever used, we would be prepared to replace it after a single use.
Conditions are pressure up to 100 psig; temperature up to 300 °F; mass fraction HCl up to 0.98 with balance water vapour and traces of air.
We are considering temporary use of mild steel for a reactor emergency depressurization line. Under normal conditions, the line is isolated from the reactor by a rupture disk assembly. In twenty years of operation, there has never been an emergency depressurization.
In the event that a rupture were to occur, it is estimated that the depressurization would occur in about 3 minutes. The question is, would a mild steel line stand up to the hydrogen chloride for this time - if necessary, adding a suitable corrosion allowance. A second issue would be generation of hydrogen and whether this would be signficant.
If the line were ever used, we would be prepared to replace it after a single use.





RE: Hot Moist Hydrogen Chloride - Rate of Attack on Mild Steel
RE: Hot Moist Hydrogen Chloride - Rate of Attack on Mild Steel
Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
RE: Hot Moist Hydrogen Chloride - Rate of Attack on Mild Steel
Thanks for your quick reply - and it was useful to know that you had thought along similar lines.
I'm not sure though, if perhaps there was a misunderstanding - the gas stream is almost 100% HCl, not 2%. Even so, I'm inclined to think it will hold up under these conditions for the very short time involved, but I'd feel more comfortable if I had something to back up that feeling!
RE: Hot Moist Hydrogen Chloride - Rate of Attack on Mild Steel
Many thanks for your response - that's really helpful and gives me at least a basis for evaluating this proposal.
And yes, it will be junked if there is an event or even before. We are moving equipment from an existing plant where the lines are PTFE-lined steel; once the existing plant is shut down, the PTFE-lined pipe can be reused - the possible use of the carbon steel is only a stop-gap measure for about 6 months.