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FOMA Bohemia Ltd.
FOMA Bohemia is a traditional producer of industrial radiographic films INDUX and related accessories.

872 views
06:05 Nov-29-2008
farabirazy
Urgent- ToFD for Steam Reformer Tube

Dear Gentlemen,

Does anyone ever involve in research of ToFD for Cast austenitic stainless steel used as ammonia reformer tube? I tried to detect artificial defect in IN 519 material, but I can not distinguish the backwall signal. Can anyone explain why and what should I do to detect the defect in this material by using ToFD? As FYI, I used 2.25 MHz ToFD transducer. Is there any commercial ToFD transducer with frequency below 2.25 MHz?

Please help me...

Sincerely Yours,

Abi


 
00:10 Nov-30-2008

Michel Couture

NDT Inspector,
consultant,
Canada,
Joined Sep 2006
815
Re: Urgent- ToFD for Steam Reformer Tube Abi,

The frequency you are using is too high. ASTM A388 para 8.2.1 states that the prefered frequency for coarse grain austenitic materials is 1 MHz and that in many instances it may be necessary to use a frequency of 0.4 MHz. I know that ASTM A388 is for Ultrasonic Examination of Heavy Steel Forgings, but the reason for freqyency selection doesn't change. You are dealing with a very coarse grain structure and you need to lower your frequency..

Hope this will help.

Cheerio's
Michel

----------- Start Original Message -----------
: Dear Gentlemen,
: Does anyone ever involve in research of ToFD for Cast austenitic stainless steel used as ammonia reformer tube? I tried to detect artificial defect in IN 519 material, but I can not distinguish the backwall signal. Can anyone explain why and what should I do to detect the defect in this material by using ToFD? As FYI, I used 2.25 MHz ToFD transducer. Is there any commercial ToFD transducer with frequency below 2.25 MHz?
: Please help me...
: Sincerely Yours,
: Abi
------------ End Original Message ------------




 
09:53 Dec-02-2008
Ed T.
Re: Urgent- ToFD for Steam Reformer Tube ----------- Start Original Message -----------
: Abi,
: The frequency you are using is too high. ASTM A388 para 8.2.1 states that the prefered frequency for coarse grain austenitic materials is 1 MHz and that in many instances it may be necessary to use a frequency of 0.4 MHz. I know that ASTM A388 is for Ultrasonic Examination of Heavy Steel Forgings, but the reason for freqyency selection doesn't change. You are dealing with a very coarse grain structure and you need to lower your frequency..
: Hope this will help.
: Cheerio's
: Michel
: : Dear Gentlemen,
: : Does anyone ever involve in research of ToFD for Cast austenitic stainless steel used as ammonia reformer tube? I tried to detect artificial defect in IN 519 material, but I can not distinguish the backwall signal. Can anyone explain why and what should I do to detect the defect in this material by using ToFD? As FYI, I used 2.25 MHz ToFD transducer. Is there any commercial ToFD transducer with frequency below 2.25 MHz?
: :Please help me...
: : Sincerely Yours,
: : Abi
------------ End Original Message ------------
Michel is correct. You need to use a 1.0 MHz. Ducer. But it also needs to be a dual focused probe focused for the thickness you are examining with a refracted longitudinal wave mode..
But it can be done.
I would also recomend the use of a UT scope with a strong pulser. That material is tough and some of the grains can be as big as your calibraton reflectors.




 
13:21 Nov-23-2012
jaidev
Re: Urgent- ToFD for Steam Reformer Tube In Reply to farabirazy at 06:05 Nov-29-2008 (Opening).

any success using 1MHz probe

 


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