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Technical Discussions
Terry Walls
Terry Walls
04:28 Aug-02-2000
Thickness Monitoring Surveys

We are seeking information concerning inspection methods for monitoring corrosion/wall loss in a 3m dia. x 25m high insulated column. Inspection points (100mm ø) have been cut out of the insulation at one metre intervals (around 100 points in total)and we wish to monitor wall thickness whilst the vessel is in service. Vessel is 65 - 100mm thick and operates at 104°C.

Any suggestions?


    
 
 
Joseph Pascente
Engineering
Lixi, Inc., USA, Joined Nov 1998, 39

Joseph Pascente

Engineering
Lixi, Inc.,
USA,
Joined Nov 1998
39
04:43 Aug-02-2000
Thickness Monitoring Surveys
Lixi's Profiler with high energy isotope will measure
the total wall thickness of this insulated column
without the removal of the insulation. The equipment
could be lowered via a pulley system.


    
 
 
Terry Walls
Terry Walls
05:08 Aug-02-2000
Re: Thickness Monitoring Surveys
I wish to add to my previous posted message that we wish to monitor the column thickness on a continuos basis and record data remotely.




    
 
 
Tom Nelligan
Engineering,
retired, USA, Joined Nov 1998, 390

Tom Nelligan

Engineering,
retired,
USA,
Joined Nov 1998
390
05:18 Aug-02-2000
Re: Thickness Monitoring Surveys
: We are seeking information concerning inspection methods for monitoring corrosion/wall loss in a 3m dia. x 25m high insulated column. Inspection points (100mm ø) have been cut out of the insulation at one metre intervals (around 100 points in total)and we wish to monitor wall thickness whilst the vessel is in service. Vessel is 65 - 100mm thick and operates at 104°C.

: Any suggestions?

I assume this is made of a steel alloy? Based on your description, it should be readily possible to measure remaining wall thickness using many commercially available ultrasonic corrosion gages. From my company's product line, you could use any of the Panametrics 26-series gages or a Model 36DL PLUS with a D797-SM transducer (2 MHz, 25mm diameter)to optimize measurement of a 100 mm maximum thickness. The temperature is no problem for this transducer. You can find a link to our Australian office on our web site.

--Tom Nelligan




    
 
 
John O'Brien
Consultant, -
Chevron ETC , USA, Joined Jan 2000, 278

John O'Brien

Consultant, -
Chevron ETC ,
USA,
Joined Jan 2000
278
05:27 Aug-02-2000
Re: Thickness Monitoring Surveys
There are a number of approaches depending on what you really need to achieve. Is there a definite corrosion problem i.e. are you monitoring reductions in thickness close to a remmnant life assessment or are you simply interested in corrosion activty as it occurs and then go and check those locations. Also what form is the corrosion, general, lake type, pitting, MIC etc.

You could use AE sensors installed which would monitor activity and you set a threshold level. These are hooked up to a Local Area Monitor wired back to control room or even into your plant DCS system. when you get activity you know the location and you go out and measure thickness. Been done a lot on Buried Vessels, Ammonia Tanks, Process Coloumns. Safe Intrisic certified systems available.

Direct thickness measurement - place UT probes on permenently and daisy chain them through a multiplexer and a processing system back to control room or even internet download - possible problems, fixing probes (a French company does a magnetic attached probe), data transmission method, questions on intrinsic safety. Has been done in Nuclear Industry and at least one place in the USA on Petrochemical Plant.

PVDF Strips - Glued to surface and hard wired to a plug in point or through a data transmission system. This system has worked well in some applications, surface temperature is close to upper limit. Intrinsic safety questions.

Field Signature Method - not direct thickness measurement and I think small area systems still at development satge, likely expensive and not sure about instrinsic safety issues.

As far as my thinking goes without more input. Please contact us if you need further assistance.



    
 
 
David Hermanutz
Consultant,
Hbndt.com, China, Joined Jul 2012, 85

David Hermanutz

Consultant,
Hbndt.com,
China,
Joined Jul 2012
85
05:35 Aug-02-2000
Re: Thickness Monitoring Surveys
: : We are seeking information concerning inspection methods for monitoring corrosion/wall loss in a 3m dia. x 25m high insulated column. Inspection points (100mm ø) have been cut out of the insulation at one metre intervals (around 100 points in total)and we wish to monitor wall thickness whilst the vessel is in service. Vessel is 65 - 100mm thick and operates at 104°C.

: : Any suggestions?

: I assume this is made of a steel alloy? Based on your description, it should be readily possible to measure remaining wall thickness using many commercially available ultrasonic corrosion gages. From my company's product line, you could use any of the Panametrics 26-series gages or a Model 36DL PLUS with a D797-SM transducer (2 MHz, 25mm diameter)to optimize measurement of a 100 mm maximum thickness. The temperature is no problem for this transducer. You can find a link to our Australian office on our web site.

: --Tom Nelligan

Hi Terry,

When and where would you like the min thickness alarm to go off? I've set up several systems in high erosion / High danger areas with remote alarming systems. I've also been extensively involved in condition monitoring in petrochem and mining industries.

Feel Free to call me on Oz time at 0411 879 064

David Hermanutz
Panametrics Melbourne




    
 
 
Jamie Gauthier
Jamie Gauthier
01:37 Aug-02-2000
Re: Thickness Monitoring Surveys
RTD Quality Services uses a piece of equipment called Incotest. It can measure the remaining wall thickness without removal of any insulation. It is fast, cost effective, and in use all over the world. It is an excellent tool for this type of work. For more information call 800-661-0066 and ask for someone to discuss with you the tools specifications.


    
 
 
Rob Wilkins
Rob Wilkins
06:04 Aug-22-2000
Re: Thickness Monitoring Surveys
: We are seeking information concerning inspection methods for monitoring corrosion/wall loss in a 3m dia. x 25m high insulated column. Inspection points (100mm ø) have been cut out of the insulation at one metre intervals (around 100 points in total)and we wish to monitor wall thickness whilst the vessel is in service. Vessel is 65 - 100mm thick and operates at 104°C.

: Any suggestions?
Have you looked at a System called Rightrax,this system is a permanent installation using ultrasonic flexible senors so it can monitor thickness constantly.
I am the Far East agent but look at the UK website www.rabco.co.uk




    
 
 
Godswill Chiorlu
Engineering
Willy Oil Services, USA, Joined Aug 2001, 6

Godswill Chiorlu

Engineering
Willy Oil Services,
USA,
Joined Aug 2001
6
07:52 Aug-13-2001
Thickness Monitoring Surveys

Hi everyone

Please does anyone know of a UT tool used in measuring the wall thickness of pipes coated with wraps.





    
 
 
Art Leach
Sales
GE Inspection Technologies, USA, Joined Apr 2001, 12

Art Leach

Sales
GE Inspection Technologies,
USA,
Joined Apr 2001
12
07:45 Aug-15-2001
Re: Thickness Monitoring Surveys
What kind of wraps? If it is a hard plastic type material, with good mechanical bonding to the pipe, you can use a A-Scan thickness gauge, like the Krautkramer DMS 2 instrument.

Art.

: Hi everyone
.
: Please does anyone know of a UT tool used in measuring the wall thickness of pipes coated with wraps.
.
.
.
.
.
.
.



    
 
 

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