Differences of Short - term Overheating and Long - term Overheating ( for Failure Analysis )
Differences of Short - term Overheating and Long - term Overheating ( for Failure Analysis )
(OP)
Greeting to all eng-tips members,
How do we know the differences of short-term overheating or long-term overheating ? what testing shall I do to examine the differences ? Would you mind to give the literature,too ?
I really appreciate any help you can provide. Have a good day.
How do we know the differences of short-term overheating or long-term overheating ? what testing shall I do to examine the differences ? Would you mind to give the literature,too ?
I really appreciate any help you can provide. Have a good day.
RE: Differences of Short - term Overheating and Long - term Overheating ( for Failure Analysis )
Whereas, long term overheat results in less distortion, relatively speaking to short term overheat, and is driven by creep deformation. In most cases, creep damage occurs in the form of voids and micro-cracking which will be present near final failure or at final failure of the material.
For either damage mechanism confirmation is required using metallograhic examination.
The above are very broad based observations with ferrous materials.
RE: Differences of Short - term Overheating and Long - term Overheating ( for Failure Analysis )
Thank you for your response,
So, we can say Long-term overheating as long as we found voids and micro cracking, sir metengr ? Do you have any literature so I can easily recognize the failure, sir ? Thank you, sir.
RE: Differences of Short - term Overheating and Long - term Overheating ( for Failure Analysis )
You can look up the terms I mentioned above on the Internet. This is what I tried to do so that you can follow up on your own.
Not necessarily, long term overheating can also result in subtle changes to the original microstructure which can degrade it with no obvious creep damage. This is why you need to look up this information. Failure mechanisms must be applied on a case by case basis with an understanding of exposure to service conditions.
Failure analysis requires unique expertise based on experience associated with various processes and evaluation of failures from those processes.
I can't tell you how many labs profess expertise in so-called failure analysis and don't know the difference between a boiler tube and exhaust pipe.
RE: Differences of Short - term Overheating and Long - term Overheating ( for Failure Analysis )
I don't mean to get off subject ,but some unusual failures; In the dark ages, refinery furnace tubes would coke-up and turbine drills could plastic ally expand/thin a tube if not operated properly. And steam /air decoking could drastically overheat a tube. ( only for refinery tubes.)
RE: Differences of Short - term Overheating and Long - term Overheating ( for Failure Analysis )
EPRI has great materials on this subject; you should take advantage if your organization is a member.
RE: Differences of Short - term Overheating and Long - term Overheating ( for Failure Analysis )
I could not agree more, and it is especially true for boilers.
Not having 'grown up' around steam, I have found root cause determination of failed tubes to be often difficult, even when the failure mechanism is fairly obvious. Being a quick study on the environment and process in which the failure occurred (i.e., context) is an essential attribute of a failure analyst.
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"If you don't have time to do the job right the first time, when are you going to find time to repair it?"