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862 views
09:50 Mar-01-2007

RP Bhan

Engineering,
HPCL Refinery,
India,
Joined Jul 2003
11
NDE technique

I will like to have experts opinion on following :
We have a Column in vacuum service in Refinery . Column bottom section has been provided with SS strip lining over CS base material for corrosion protection . This striplining has tendency to bulge & develops crack in service . We have observed severe corrosion of CS base material under striplining at some locations . We want to ensure integrity of base material .Is there a technique available which will allow us to find out these affected /corroded/grooved locations without removal of strips .-can be from outside on run or from inside during the shutdown of unit . Column operates at about 400deg C .
Thanks .



 
05:18 Mar-02-2007

C Truskolasky

Test Examiner Mil-2132, Level III
Lehigh Heavy Forge,
USA,
Joined Jan 2007
10
Re: NDE technique ----------- Start Original Message -----------
: I will like to have experts opinion on following :
: We have a Column in vacuum service in Refinery . Column bottom section has been provided with SS strip lining over CS base material for corrosion protection . This striplining has tendency to bulge & develops crack in service . We have observed severe corrosion of CS base material under striplining at some locations . We want to ensure integrity of base material .Is there a technique available which will allow us to find out these affected /corroded/grooved locations without removal of strips .-can be from outside on run or from inside during the shutdown of unit . Column operates at about 400deg C .
: Thanks .
------------ End Original Message ------------

I'm assuming CS stands for carbon steel and the column is a shell and the SS is a stainless steel liner that isn't bonded to the shell. The inspection of the CS shell is easily done from outside the shell using a UT wall thickness gage. Calibrate the gage on a sample of the wall of known thickness and take as many measurements required to verify the integrity of the shell. This is a very common procedure and the equipment is very affordable. Be sure to explain as much detail to the sales rep. if you plan to purchase the equipment.


 
09:08 Mar-06-2007
Simon Amallraja
Re: NDE technique ----------- Start Original Message -----------
: I will like to have experts opinion on following :
: We have a Column in vacuum service in Refinery . Column bottom section has been provided with SS strip lining over CS base material for corrosion protection . This striplining has tendency to bulge & develops crack in service . We have observed severe corrosion of CS base material under striplining at some locations . We want to ensure integrity of base material .Is there a technique available which will allow us to find out these affected /corroded/grooved locations without removal of strips .-can be from outside on run or from inside during the shutdown of unit . Column operates at about 400deg C .
: Thanks .
------------ End Original Message ------------

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D.Simon Amallraja.


 
03:10 Mar-23-2007
Ryan Burns
Re: NDE technique I have had some experience with similar application on coker tower. If geometry and access allows, the use of a mechanized rastered scanner to perform 0 degree C-Scan and B-Scan mapping is very effective. This would have to be done off-line, but the data are accurate and reproducable. Depending on the type of corrosion / erosion you are finding, we also used ratered shear wave to give a profile of the void. For example, the failure in the coker clad was very small, <.300" diam., but the void in the cs was huge in comparison. The use of manual UT done online at that temperature would necessitate a probe duty cycle and spot readings would be all you could do. You may not even find the anomalies, and scanning to size the void is not feasable.

Regards,

Ryan.

----------- Start Original Message -----------
: : I will like to have experts opinion on following :
: : We have a Column in vacuum service in Refinery . Column bottom section has been provided with SS strip lining over CS base material for corrosion protection . This striplining has tendency to bulge & develops crack in service . We have observed severe corrosion of CS base material under striplining at some locations . We want to ensure integrity of base material .Is there a technique available which will allow us to find out these affected /corroded/grooved locations without removal of strips .-can be from outside on run or from inside during the shutdown of unit . Column operates at about 400deg C .
: : Thanks .
: I'm assuming CS stands for carbon steel and the column is a shell and the SS is a stainless steel liner that isn't bonded to the shell. The inspection of the CS shell is easily done from outside the shell using a UT wall thickness gage. Calibrate the gage on a sample of the wall of known thickness and take as many measurements required to verify the integrity of the shell. This is a very common procedure and the equipment is very affordable. Be sure to explain as much detail to the sales rep. if you plan topurchase the equipment.
------------ End Original Message ------------




 


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