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Technical Discussions
N.DHANASEKARAN
R & D
WELDING RESEARCH INSTITUTE, BHEL, India, Joined Jun 2005, 3

N.DHANASEKARAN

R & D
WELDING RESEARCH INSTITUTE, BHEL,
India,
Joined Jun 2005
3
02:31 Jun-17-2005
sensitivity in ut

hello,
I have a query about the sensitivity possible by conventional UT ( Pulse echo - A scan ). Requirement of resolving power quantitatively like for a specific thickness and sensitivity , what is the minimum resolving power required?
N.DHANASEKARAN


 
 Reply 
 
S.V.Swamy
Engineering, - Material Testing Inspection & Quality Control
Retired from Nuclear Fuel Complex , India, Joined Feb 2001, 787

S.V.Swamy

Engineering, - Material Testing Inspection & Quality Control
Retired from Nuclear Fuel Complex ,
India,
Joined Feb 2001
787
06:12 Jun-19-2005
Re: sensitivity in ut
----------- Start Original Message -----------
: hello,
: I have a query about the sensitivity possible by conventional UT ( Pulse echo - A scan ). Requirement of resolving power quantitatively like for a specific thickness and sensitivity , what is the minimum resolving power required?
: N.DHANASEKARAN
------------ End Original Message ------------

Dear Shri Dhanasekaran,

Your question will be answered by the designer for a given application. Resolving power depends, as you are no doubt aware on the wavelength of the ultrasonic wave used. The shorter the wavelength, the better is the resolution obtainable, keeping all other conditions same. However, the wavelength which one can use depends on the material, processing history, surface condition, thickness etc. Keeping all these factors in view, the designer is expected to specify the minimum size of a discontinuity to be detected.

With best wishes,

Swamy




 
 Reply 
 
Ed T.
Ed T.
01:07 Jun-19-2005
Re: sensitivity in ut
----------- Start Original Message -----------
: : hello,
: : I have a query about the sensitivity possible by conventional UT ( Pulse echo - A scan ). Requirement of resolving power quantitatively like for a specific thickness and sensitivity , what is the minimum resolving power required?
: : N.DHANASEKARAN
: Dear Shri Dhanasekaran,
: Your question will be answered by the designer for a given application. Resolving power depends, as you are no doubt aware on the wavelength of the ultrasonic wave used. The shorter the wavelength, the better is the resolution obtainable, keeping all other conditions same. However, the wavelength which one can use depends on the material, processing history, surface condition, thickness etc. Keeping all these factors in view, the designer is expected to specify the minimum size of a discontinuity to be detected.
: With best wishes,
: Swamy
------------ End Original Message ------------

You must keep in mind that there are distinct differences between resolving power and sensitivity. Your ability to detect a flaw of a given size is a function of your wavelength, type, shape and orientation of the flaw.
Resolving power or being able to resolve the indication from other reflectors (resolution)is another story.
That is a function of your wavelength as well as your pulse length, pulse repetition rate and damping.
These settings must be finely tuned to optimize the resolution of your UT system.
This is all theoretical, however. It all depends on the type, shape, orientation and frequency response obtained from the flaw(s).
Just because you interrogate a flaw with a given frequency does not mean that is the frequency that you will receive back from the flaw.



 
 Reply 
 
Philippe Rubbers
Engineering
SCM, South Africa, Joined Nov 1998, 22

Philippe Rubbers

Engineering
SCM,
South Africa,
Joined Nov 1998
22
05:24 Jun-20-2005
Re: sensitivity in ut
A common comment is that frequency determines the resolving power. A more accurate comment would be to say it is the bandwidth (in Hz) that determines resolving power. However, since bandwidth ranges from 60% to 120% of the centre frequency, yes the centre frequency indirectly determines resolving power.
Note that Phased array probes have very poor bandwidth at the lower end of the scale (typically 70% only).
If there is a supplier of broadband PA probes, please let me know.

Best regards

----------- Start Original Message -----------
: : : hello,
: : : I have a query about the sensitivity possible by conventional UT ( Pulse echo - A scan ). Requirement of resolving power quantitatively like for a specific thickness and sensitivity , what is the minimum resolving power required?
: : : N.DHANASEKARAN
: : Dear Shri Dhanasekaran,
: : Your question will be answered by the designer for a given application. Resolving power depends, as you are no doubt aware on the wavelength of the ultrasonic wave used. The shorter the wavelength, the better is the resolution obtainable, keeping all other conditions same. However, the wavelength which one can use depends on the material, processing history, surface condition, thickness etc. Keeping all these factors in view, the designer is expected to specify the minimum size of a discontinuity to be detected.
: : With best wishes,
: : Swamy
: You must keep in mind that there are distinct differences between resolving power and sensitivity. Your ability to detect a flaw of a given size is a function of your wavelength, type, shape and orientation of the flaw.
: Resolving power or being able to resolve the indication from other reflectors (resolution)is another story.
: That is a function of your wavelength as well as your pulse length, pulse repetition rate and damping.
: These settings must be finely tuned to optimize the resolution of your UT system.
: This is all theoretical, however. It all depends on the type, shape, orientation and frequency response obtained from the flaw(s).
: Just because you interrogate a flaw with a given frequency does not mean that is the frequency that you will receive back from the flaw.
------------ End Original Message ------------




 
 Reply 
 
N.DHANASEKARAN
R & D
WELDING RESEARCH INSTITUTE, BHEL, India, Joined Jun 2005, 3

N.DHANASEKARAN

R & D
WELDING RESEARCH INSTITUTE, BHEL,
India,
Joined Jun 2005
3
02:41 Jul-02-2005
Re: sensitivity in ut
Hello,
Response for the query is good. But still,to quantitatively measure the resolving power of a given combination of ut parameters,what to do?
N.Dhanasekaran

----------- Start Original Message -----------
: A common comment is that frequency determines the resolving power. A more accurate comment would be to say it is the bandwidth (in Hz) that determines resolving power. However, since bandwidth ranges from 60% to 120% of the centre frequency, yes the centre frequency indirectly determines resolving power.
: Note that Phased array probes have very poor bandwidth at the lower end of the scale (typically 70% only).
: If there is a supplier of broadband PA probes, please let me know.
: Best regards
: : : : hello,
: : : : I have a query about the sensitivity possible by conventional UT ( Pulse echo - A scan ). Requirement of resolving power quantitatively like for a specific thickness and sensitivity , what is the minimum resolving power required?
: : : : N.DHANASEKARAN
: : : Dear Shri Dhanasekaran,
: : : Your question will be answered by the designer for a given application. Resolving power depends, as you are no doubt aware on the wavelength of the ultrasonic wave used. The shorter the wavelength, the better is the resolution obtainable, keeping all other conditions same. However, the wavelength which one can use depends on the material, processing history, surface condition, thickness etc. Keeping all these factors in view, the designer is expected to specify the minimum size of a discontinuity to be detected.
: : : With best wishes,
: : : Swamy
: : You must keep in mind that there are distinct differences between resolving power and sensitivity. Your ability to detect a flaw of a given size is a function of your wavelength, type, shape and orientation of the flaw.
: : Resolving power or being able to resolve the indication from other reflectors (resolution)is another story.
: : That is a function of your wavelength as well as your pulse length, pulse repetition rate and damping.
: : These settings must be finely tuned to optimize the resolution of your UT system.
: : This is all theoretical, however. It all depends on the type, shape, orientation and frequency response obtained from the flaw(s).
: : Just because you interrogate a flaw with a given frequency does not mean that is the frequency that you will receive back from the flaw.
------------ End Original Message ------------




 
 Reply 
 
N.Kuppusamy
Consultant, Level-III
United Testing Co. Pte Ltd, Singapore, Joined Jan 2003, 13

N.Kuppusamy

Consultant, Level-III
United Testing Co. Pte Ltd,
Singapore,
Joined Jan 2003
13
03:28 Jul-04-2005
Re: Sensitivity in UT
Friends,

What for you need to measure resolution quatitatively for a A-scan system? For all practical purposes, it is enough if you are able to discern the echoes from resolution holes (IOW Block) or notches (IIW Block).

Regards,
N.Kuppusamy


----------- Start Original Message -----------
: Hello,
: Response for the query is good. But still,to quantitatively measure the resolving power of a given combination of ut parameters,what to do?
: N.Dhanasekaran
: : A common comment is that frequency determines the resolving power. A more accurate comment would be to say it is the bandwidth (in Hz) that determines resolving power. However, since bandwidth ranges from 60% to 120% of the centre frequency, yes the centre frequency indirectly determines resolving power.
: : Note that Phased array probes have very poor bandwidth at the lower end of the scale (typically 70% only).
: : If there is a supplier of broadband PA probes, please let me know.
: : Best regards
: : : : : hello,
: : : : : I have a query about the sensitivity possible by conventional UT ( Pulse echo - A scan ). Requirement of resolving power quantitatively like for a specific thickness and sensitivity , what is the minimum resolving power required?
: : : : : N.DHANASEKARAN
: : : : Dear Shri Dhanasekaran,
: : : : Your question will be answered by the designer for a given application. Resolving power depends, as you are no doubt aware on the wavelength of the ultrasonic wave used. The shorter the wavelength, the better is the resolution obtainable, keeping all other conditions same. However, the wavelength which one can use depends on the material, processing history, surface condition, thickness etc. Keeping all these factors in view, the designer is expected to specify the minimum size of a discontinuity to be detected.
: : : : With best wishes,
: : : : Swamy
: : : You must keep in mind that there are distinct differences between resolving power and sensitivity. Your ability to detect a flawof a given size is a function of your wavelength, type, shape and orientation of the flaw.
: : : Resolving power or being able to resolve the indication from other reflectors (resolution)is another story.
: : : That is a function of your wavelength as well as your pulse length, pulse repetition rate and damping.
: : : These settings must be finely tuned to optimize the resolution of your UT system.
: : : This is all theoretical, however. It all depends on the type, shape, orientation and frequency response obtained from the flaw(s).
: : : Just because you interrogate a flaw with a given frequency does not mean that is the frequency that you will receive back from the flaw.
------------ End Original Message ------------




 
 Reply 
 

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