where expertise comes together - since 1996 -

The Largest Open Access Portal of Nondestructive Testing (NDT)

Conference Proceedings, Articles, News, Exhibition, Forum, Network and more

where expertise comes together
- since 1996 -

1262 views
Technical Discussions
LANRE ALAPINI
NDT Inspector,
NDT TRAINING AND TESTING CENTRE HOUSTON TEXAS USA, Nigeria, Joined Nov 2008, 3

LANRE ALAPINI

NDT Inspector,
NDT TRAINING AND TESTING CENTRE HOUSTON TEXAS USA,
Nigeria,
Joined Nov 2008
3
06:49 Nov-18-2008
calibration

this kind of question could be could there be any diferent between the calibration of a single element transducer and dual element transducer


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

Tom Nelligan

Engineering,
retired,
USA,
Joined Nov 1998
390
07:18 Nov-18-2008
Re: calibration
Yes, there will normally be a very significant difference in the zero offset calibration between a single element contact transducer and a dual element transducer of similar frequency and diameter. In the case of a dual, you have to zero out the pulse transit time through the internal delay line, while with a contact transducer you are zeroing out only a very thin wearplate. (Other minor factors like cable length and instrument switching delays wouldn't normally vary with transducer type.)

Material sound velocity is of course independent of tranducer type.


----------- Start Original Message -----------
: this kind of question could be could there be any diferent between the calibration of a single element transducer and dual element transducer
------------ End Original Message ------------




    
 
 
Nigel Armstrong
Engineering, - Specialist services
United Kingdom, Joined Oct 2000, 1094

Nigel Armstrong

Engineering, - Specialist services
United Kingdom,
Joined Oct 2000
1094
00:59 Nov-19-2008
Re: calibration
Lanre

Aside form the technical differences which Tom has outlined, the philosophy of calibration must be the same no matter which tools you are using - namely, traceability, accuracy and repeatability. Before commencing calibration ensure you are familiar with all your equipment's characterisitics (read manufacturer's literature/operating manuals/technical references) and that it is undamaged and in good working order. Both the thickness meter or flaw detector, depending on which you are using) and the calibration block should bear valid calibration certificates and have passed the most recent proceduralised in-house checks as evidenced by a log record. The calibration block MUST be respresentative (very similar sound velocity) of the material which you wish to inspect/measure. You can accept equivalence within but not across material groups, e.g. low alloy steels, austenitics, aluminium, copper. Find yourself a comprehensive table of sound velocities in various materials and get to know the percentage variations.

Now the same applies whether you are calibrating single or twin crystal probes with the keywords in either case being:

TRACEABILITY, ACCURACY, REPEATABILITY.

As always watch out for careless and lazy assumptions creeping in, the major cause of disastrous measurement error.

Cheers

Nigel

----------- Start Original Message -----------
: this kind of question could be could there be any diferent between the calibration of a single element transducer and dual element transducer
------------ End Original Message ------------




    
 
 
LANRE ALAPINI
NDT Inspector,
NDT TRAINING AND TESTING CENTRE HOUSTON TEXAS USA, Nigeria, Joined Nov 2008, 3

LANRE ALAPINI

NDT Inspector,
NDT TRAINING AND TESTING CENTRE HOUSTON TEXAS USA,
Nigeria,
Joined Nov 2008
3
06:21 Nov-20-2008
Re: calibration
nigel, if i get you right, all things being equal theres no different between calibrating with dual element transducer and single element transducer

----------- Start Original Message -----------
: Lanre
: Aside form the technical differences which Tom has outlined, the philosophy of calibration must be the same no matter which tools you are using - namely, traceability, accuracy and repeatability. Before commencing calibration ensure you are familiar with all your equipment's characterisitics (read manufacturer's literature/operating manuals/technical references) and that it is undamaged and in good working order. Both the thickness meter or flaw detector, depending on which you are using) and the calibration block should bear valid calibration certificates and have passed the most recent proceduralised in-house checks as evidenced by a log record. The calibration block MUST be respresentative (very similar sound velocity) of the material which you wish to inspect/measure. You can accept equivalence within but not across material groups, e.g. low alloy steels, austenitics, aluminium, copper. Find yourself a comprehensive table of sound velocities in various materials and get to know the percentage variations.
: Now the same applies whether you are calibrating single or twin crystal probes with the keywords in either case being:
: TRACEABILITY, ACCURACY, REPEATABILITY.
: As always watch out for careless and lazy assumptions creeping in, the major cause of disastrous measurement error.
: Cheers
: Nigel
: : this kind of question could be could there be any diferent between the calibration of a single element transducer and dual element transducer
------------ End Original Message ------------




    
 
 
Nigel Armstrong
Engineering, - Specialist services
United Kingdom, Joined Oct 2000, 1094

Nigel Armstrong

Engineering, - Specialist services
United Kingdom,
Joined Oct 2000
1094
06:23 Nov-20-2008
Re: calibration
Lanre, if your equipment is fitted with a single or twin option ensure that you are in the correct mode. With BOTH single and twin I would position the 1st backwall echo at zero on the timebase and the second and 3rd at 5 and 10 and then delay off so that the 1st BWE is on 5 and the 2nd on 10 (illustrative figures for compression wave only). That takes care of any delay line/perspex wedge sound path.

Tom Nelligan wrote some technical differences, i wrote that the concept of calibration is identical for both single and twin - traceability, accuracy, repeatability.

Enlighten me please Lanre, what has happened or been said that makes you concerned there may be a difference?

----------- Start Original Message -----------
: nigel, if i get you right, all things being equal theres no different between calibrating with dual element transducer and single element transducer
: : Lanre
: : Aside form the technical differences which Tom has outlined, the philosophy of calibration must be the same nomatter which tools you are using - namely, traceability, accuracy and repeatability. Before commencing calibration ensure you are familiar with all your equipment's characterisitics (read manufacturer's literature/operating manuals/technical references) and that it is undamaged and in good working order. Both the thickness meter or flaw detector, depending on which you are using) and the calibration block should bear valid calibration certificates and have passed the most recent proceduralised in-house checks as evidenced by a log record. The calibration block MUST be respresentative (very similar sound velocity) of the material which you wish to inspect/measure. You can accept equivalence within but not across material groups, e.g. low alloy steels, austenitics, aluminium, copper. Find yourself a comprehensive table of sound velocities in various materials and get to know the percentage variations.
: : Now the same applies whether you are calibrating single or twin crystal probes with the keywords in either case being:
: : TRACEABILITY, ACCURACY, REPEATABILITY.
: : As always watch out for careless and lazy assumptions creeping in, the major cause of disastrous measurement error.
: : Cheers
: : Nigel
: : : this kind of question could be could there be any diferent between the calibration of a single element transducer and dual element transducer
------------ End Original Message ------------




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

Tom Nelligan

Engineering,
retired,
USA,
Joined Nov 1998
390
06:24 Nov-20-2008
Re: calibration
I believe that Mr. Armstrong and I have interpreted your original question in different ways.

Is there a difference in the "philosophy" of calibration to insure accurate depth or thickness measurements? No.

Is there a difference in specific instrument setup? Yes, due to the much greater zero offset required when using dual element versus single element transducers.

----------- Start Original Message -----------
: nigel, if i get you right, all things being equal theres no different between calibrating with dual element transducer and single element transducer
: : Lanre
: : Aside form the technical differences which Tom has outlined, the philosophy of calibration must be the same no matter which tools you are using - namely, traceability, accuracy and repeatability. Before commencing calibration ensure you are familiar with all your equipment's characterisitics (read manufacturer's literature/operating manuals/technical references) and that it is undamaged and in good working order. Both thethickness meter or flaw detector, depending on which you are using) and the calibration block should bear valid calibration certificates and have passed the most recent proceduralised in-house checks as evidenced by a log record. The calibration block MUST be respresentative (very similar sound velocity) of the material which you wish to inspect/measure. You can accept equivalence within but not across material groups, e.g. low alloy steels, austenitics, aluminium, copper. Find yourself a comprehensive table of sound velocities in various materials and get to know the percentage variations.
: : Now the same applies whether you are calibrating single or twin crystal probes with the keywords in either case being:
: : TRACEABILITY, ACCURACY, REPEATABILITY.
: : As always watch out for careless and lazy assumptions creeping in, the major cause of disastrous measurement error.
: : Cheers
: : Nigel
: : : this kind of question could be could there be any diferent between the calibration of a single element transducer and dual element transducer
------------ End Original Message ------------




    
 
 

Product Spotlight

MUSE Mobile Ultrasonic Equipment

The MUSE, a portable ultrasonic imaging system, was developed for in-field inspections of light-weig
...
ht structures. The MUSE consists of a motor-driven manipulator, a water circulation system for the acoustic coupling and a portable ultrasonic flaw detector (USPC 3010). The MUSE provides images of internal defects (A-, B-,C- and D-scan).
>

Exertus Dual 120

The Exertus Dual 120 Projector has the ability to accept Iridium 192 sources or Selenium 75 source
...
s. This projector incorporates design and safety features that make it flexible, compact and lightweight. The Projector is lighter than most of its competitors. It incorporates an improved source channel, based on a new helicoidal design, which makes maintenance easier. The helicoidal design also allows smoother movement of the source assembly inside the device, making it easier for the operator and improving safety. The Projector also has a unique safety feature not found in competitive products. The source assembly locking mechanism is triggered by the source holder capsule at the front of the source assembly, thereby always assuring the operator that the source has returned to the safe position. The Exertus Dual 120 is ISO3999:2004 compliant.
>

NEW! The PragmaPro Instrument Platform

The PragmaPro is based on a modular cartridge technology and supports various NDT instrument modal
...
ities such as UT, PAUT, ECT and many more. This new platform is based on a machined, powder-coated aluminum frame for shock-proofness, best sealing qualities and maximum heat dissipation. This is practical to extend the outdoor temperature range and/or to extend the power injected in the transducers. The PragmaPro is aiming at a very wide range of applications, such as weld scanning, corrosion mapping and composite testing.
>

ISONIC 3510

Very Powerful Superior Performance Extremely Portable Smart Phased Array Ultrasonic Flaw Detector an
...
d Recorder with 2 Conventional UT and TOFD Channels uniquely combines PA, single- and multi-channel conventional UT, and TOFD modalities providing 100% raw data recording and imaging. Suitable for all kinds of every-day ultrasonic inspections
>

Share...
We use technical and analytics cookies to ensure that we will give you the best experience of our website - More Info
Accept
top
this is debug window
s