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CRYOGENIC VESSEL NDT IN-SERVICE INSPECTION

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ferchuvicente

Mechanical
Feb 4, 2004
20
HI, Iam Fernando Vicente and i am mechanical engineer and i have some doubts in a work that i have to do.
We have to take some thickness measure from the DEMETHANIZER TOWER , the problem is the tower is in service and it has a COLD INSULATION whose thicknes is 180 mm from PIR material(polyisocianurate).The operating temperature is -95C(-200F).
The shell material is SA-240-TP304(SATINLESS STEEL),THICKNES=35mm.
My questions is, if i try to get insulation out to reach the shell to take contact with ultrasonic sensor on the shell, the material could be sufer a violent expansion,and ice formations?


regards

fernando
 
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I am going to ask an obvious question - if the tower is fabricated of SA-240 Type 304 ss why do you need to obtain thickness measurements on line for this process?
 
hi metengr,thanks for you reply this meessage. the tower never was inspectioned in 5 yeasr , and we want to know the shet plate integrity.
What is your opinion, do you say that is imposibe that corrosion exist?


regard
fernando
 
If you have no known or expected corrosion problems, a UT for thickness will serve no purpose. I would wait until a scheduled outage of the tower, and perform an internal visual inspection of the tower. At that time you can decide if UT is required.
 
193.2639 Maintenance Record – Corrosion Controls - (retain for life of facility)
193.2639 Maintenance Record – Miscellaneous - (5-year minimum retention)
 
have you considered pereforming an IR survey of the tower. it may not be conclusive but if there are sufficient corrosion instances the thermal view should indicate differences in the overall scan.

then as was mentioned wait til the tower is out of service for the visual/UT inspection.
 
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