Wednesday, June 20, 2012

Re: [MW:14610] CS reactor exposed to temperature run away in presence of H2

As long as the equipment does not cross the lower critical temperature of 723 degree Celcius, its OK.
Metallurgical changes would have occured above 723 degree celcius. The same you can confirm by insitu metallography. There are few labs who do insitu metallography.
There were chances of slight hardness drop but you are telling that it is within accepable limits.
Then dont worry !
 
Regards
 
Prem Nautiyal

From: Tarantula Ghosh ghosh.tarantula@gmail.com
To: materials-welding@googlegroups.com
Sent: Wednesday, June 20, 2012 10:12 AM
Subject: Re: [MW:14605] CS reactor exposed to temperature run away in presence of H2

My dear Hrishi,
In my opinion, for this grade steel this incident has done more good than bad. You have got a tempered steel now, as I can see.
Your metallography results when you have them will surely point it out if you  compare them with the original MTC.
Worry not.
TG


On Tue, Jun 19, 2012 at 4:23 PM, K.M Hrishikesan <hrishikm07@gmail.com> wrote:
 
 
Vessel Description: Reactor
MOC: SA 516 gr 70
Design temperature: 200 deg C
Design pressure: 44.6 kg/cm.sq
Thickness: 36 mm for shell; 50 mm for the dished end
 
Service: Hydrogen environment in the presence of catalyst
 
Above equipment was accidentally subject to temperature run away during Hydrogen sweeping. As a result the temperature shot up abruptly to the range of
700 deg.C. for 15-20 minutes and 450 deg c for approximately a couple of hours.We have checked the hardness which is found to be OK. In-situ metallography is underway.
 
My queries to metallurgical experts are
 
  1. What will be the metallurgical impact on integrity of the vessel due to above incident?
     2. How can we assess the damage/degradation which might have occurred on the  of the vessel in terms of its metallurgy? please suggest some NDE's
 
 
Regards
Hrishi
 
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Tarantula



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