Brittle Failure of Vessels
Brittle Failure of Vessels
(OP)
The most excellent (but now closed) thread, number thread135-145412 , contained a discussion about the depressurizing of a tank containing a liquified gas (CO2). In the thread, Mr. Montemayor presented a scenario in which a full depressurizing of a vessel caused the steel temperature to drop to the contained fluid's boiling point (-78oF in that case). He then implied that the tank was essentially useless, having been rendered so by exposure to low temperatures.
Some unanswered questions followed about whether the steel's properties weren't restored when it returned to ambient temperature. A second question arose concerning the possibility of restoring the vessel through some means such as stress relieving. Can anyone address these issues?
Some unanswered questions followed about whether the steel's properties weren't restored when it returned to ambient temperature. A second question arose concerning the possibility of restoring the vessel through some means such as stress relieving. Can anyone address these issues?





RE: Brittle Failure of Vessels
Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
RE: Brittle Failure of Vessels
Suggest that you repost in the Boiler & PV forum.
There are many engineering texts available that describe the dangers of brittle failure (fracture) in boiler and pressure vessel operations.
Most of the design codes (incuding ASME VIII)force both the designer and operator to ensure that the materials selected do not operate in the brittle range. Some materials, of course (austenitic stainless steels) do not have a brittle range.
-MJC
RE: Brittle Failure of Vessels
http://en.wikipedia.org/wiki/Fracture
The field of knowledge that is devoted to these effects is called "Fracture Mechanics"
You could post your question on another website that may be much better equipped to answer it:
www.hghouston.com (The Hendrix group)
Please complete the thread and let us know what the final answer is..
Regards:
-MJC
RE: Brittle Failure of Vessels
I'm sure the tecnical understanding of brittle fracture resides in the forums you've suggested, but I think it is important that knowledge of the phenomenon of brittle fracure be widely known.
Operational people need to know of it. It shouldn't be secreted away in a specialist arena.
I too would like to know the answer to the original query -does a steel vessel satisfactorily recover from a cold embrittlement excursion, when it returns to warm temperatures? Or has it been permanently damaged?
John.
J.
RE: Brittle Failure of Vessels
Steel does not "embrittle" at low temperatures. True it may have lower toughness, but that is a temperature dependednt problem. The steel's metallurgy is not permanently altered. When the steel warms back up, its just the same as it was previously to the cold temperature excursion.
Joe Tank
RE: Brittle Failure of Vessels
Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04