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Technical Discussions
General
General
03:58 Nov-10-2004
Perspex insert in IIW Block

What is the purpose of this plastic insert in the IIW Block? What type of check is this used for?


    
 
 Reply 
 
Hmmmm
Hmmmm
04:43 Nov-10-2004
Re: Perspex insert in IIW Block

And why is it slightly thinner than the IIW block itself (23mm) when the block is 25mm?



    
 
 Reply 
 
Ed T.
Ed T.
04:43 Nov-10-2004
Re: Perspex insert in IIW Block
----------- Start Original Message -----------
: What is the purpose of this plastic insert in the IIW Block? What type of check is this used for?
------------ End Original Message ------------
I believe it is supposed to have a velocity that represents 2" of steel. I could be wrong.



    
 
 Reply 
 
Phil Herman Jr.
Sales, - Manufacture of NDT Reference Standards/Test Blocks
PH Tool Reference Standards, USA, Joined Oct 1999, 79

Phil Herman Jr.

Sales, - Manufacture of NDT Reference Standards/Test Blocks
PH Tool Reference Standards,
USA,
Joined Oct 1999
79
00:41 Nov-11-2004
Re: Perspex insert in IIW Block
Ed is correct. The plug in an ASTM E164 IIW-Type 1 Block (Inch version) measures 0.923" thick. Since the velocity of acrylic is 46% of steel, this is the same as 2.000" in steel. The metric version (or V1 block) plug measures 23.0mm, and is matched to 50.0mm in steel. Not sure how useful this plug really is, but there you have it. By the way, some specs consider it optional, which explains why some manufacturers opt to exclude it. The unplugged 2" (or 50mm) diameter hole makes a nice lifting feature for carting this heavy block around.

Phil Herman Jr.
PH Tool Reference Standards

----------- Start Original Message -----------
: : What is the purpose of this plastic insert in the IIW Block? What type of check is this used for?
: I believe it is supposed to have a velocity that represents 2" of steel. I could be wrong.
------------ End Original Message ------------




    
 
 Reply 
 
Hermann Wüstenberg
R & D
BAM Berlin, Germany, Joined Nov 1998, 26

Hermann Wüstenberg

R & D
BAM Berlin,
Germany,
Joined Nov 1998
26
06:07 Nov-11-2004
Re: Perspex insert in IIW Block
----------- Start Original Message -----------
: Ed is correct. The plug in an ASTM E164 IIW-Type 1 Block (Inch version) measures 0.923" thick. Since the velocity of acrylic is 46% of steel, this is the same as 2.000" in steel. The metric version (or V1 block) plug measures 23.0mm, and is matched to 50.0mm in steel. Not sure how useful this plug really is, but there you have it. By the way, some specs consider it optional, which explains why some manufacturers opt to exclude it. The unplugged 2" (or 50mm) diameter hole makes a nice lifting feature for carting this heavy block around.
: Phil Herman Jr.
: PH Tool Reference Standards
: : : What is the purpose of this plastic insert in the IIW Block? What type of check is this used for?
: : I believe it is supposed to have a velocity that represents 2" of steel. I could be wrong.
------------ End Original Message ------------
Perspex insert of the IIW block Nr. 1 (ISO 2400)

May be that there are today some other uses of the perspex insert, but the original raison d´être for it are twofold:
-The early ultrasonic pulse echo apparatuses haven´t been equipped with logarithmic amplification control calibrated in dB.
- At that time many probes used quartz as a piezoelectric transducer, which had not been provided with an electrically conducting layer at it´s front end. Therefore coupling had only been possible at conducting surfaces.
In order to indicate a quantitative figure for the relatively poor sensitivity of quartz equipped probes linked to an UT equipment without dB-controller one had to put the probe at the perspex insert and count the number of just readible echos within the sequence of echos with a mutual distance of 2`` or 50 mm. This number has been used to characterize the sensitivity reserve of the given probe/equipment combination. The quartz has electrically been coupled to the thin silver layer at one side of the perspex insert by a spring.
This special use of the perspex insert seems nowadays obsolete. One should replace it or find another reason for it.




    
 
 Reply 
 
General
General
01:05 Nov-12-2004
Re: Perspex insert in IIW Block
Thanks for the reply. I had always wondered about this. I guess its 2" of steel when using a 0 deg. probe (long. waves). Is that correct?


----------- Start Original Message -----------
: Ed is correct. The plug in an ASTM E164 IIW-Type 1 Block (Inch version) measures 0.923" thick. Since the velocity of acrylic is 46% of steel, this is the same as 2.000" in steel. The metric version (or V1 block) plug measures 23.0mm, and is matched to 50.0mm in steel. Not sure how useful this plug really is, but there you have it. By the way, some specs consider it optional, which explains why some manufacturers opt to exclude it. The unplugged 2" (or 50mm) diameter hole makes a nice lifting feature for carting this heavy block around.
: Phil Herman Jr.
: PH Tool Reference Standards
: : : What is the purpose of this plastic insert in the IIW Block? What type of check is this used for?
: : I believe it is supposed to have a velocity that represents 2" of steel. I could be wrong.
------------ End Original Message ------------




    
 
 Reply 
 
Gordon E. Smith
Gordon E. Smith
04:07 Nov-12-2004
Re: Perspex insert in IIW Block
----------- Start Original Message -----------
: : What is the purpose of this plastic insert in the IIW Block? What type of check is this used for?
: I believe it is supposed to have a velocity that represents 2" of steel. I could be wrong.
------------ End Original Message ------------

This plastic insert is the correct thickness and velocity material to represent
2" of steel when a 2.25mhz longitutional transducer is applied to either face
with the instrument set up for shear wave velocities.

This allows setting up the screen for longitutional ( Base Metal ) testing without
adjusting the velocity controls. This dates from the 1950's when instrument setups
were much more difficult than today.



    
 
 Reply 
 
Udo Schlengermann
Consultant, -
Standards Consulting, Germany, Joined Nov 1998, 177

Udo Schlengermann

Consultant, -
Standards Consulting,
Germany,
Joined Nov 1998
177
09:24 Nov-12-2004
Re: Perspex insert in IIW Block
reply:
In addition to the prevailing comments I want to give some further information:
The calibration block type 1(with acrylic insert)was internationally standardized as ISO 2400 in 1972:
Welds in steel - Reference block for the calibration of equipment for ultrasonic examination.
The acrylic insert (PMMA) could be used for distance calibrations. As the longitudinal wave velocity for PMMA is 2730 m/s and for steel is 5920 m/s, the thickness 23.0 mm was chosen to represent 50 mm of steel.
But the acrylic insert could also be used to generate a reference echo amplitude, if the echo out of the 25 mm steel path was saturating the amplifier or if the dead zone of the probe was larger than 25 mm.

Since these old times of UT the equipment has been improved very much. Quartz transducers which need a conductive test object as a counter-electrode are no longer used.
But this standard ISO 2400 never has been revised.

On the other hand today there is a European standard for this block, EN 12223(1999), which is much younger:
Nondestructive testing - Ultrasonic examination - Specification for calibration block no 1.
This EN 12223 block does not include any requirement for a plastics insert (because there is no longer a need for it). The hole of 50 mm diameter is only used as a reflector to determine beam angles.

Kind regards
Udo Schlengermann
GE Inspection Technologies Systems GmbH
Chairman DIN standards committee on UT

----------- Start Original Message -----------
: What is the purpose of this plastic insert in the IIW Block? What type of check is this used for?
------------ End Original Message ------------




    
 
 Reply 
 
Dave
Dave
04:09 Nov-13-2004
Re: Perspex insert in IIW Block
----------- Start Original Message -----------
: What is the purpose of this plastic insert in the IIW Block? What type of check is this used for?
------------ End Original Message ------------

I believe another purpose of the insert was as a measure of crystal ageing. One of the regular checks we had to do with the old Barium Titanate? crystals was take regular sensitivity readings against a fixed reflector. The high attenuation of perspex allowed us to monitor probe loss of sensitivity on low frequency probes e.g. third back wall echo to 50% FSH. Sometimes we would struggle to see the side drilled holes and the insert saved having to keep a flat bottomed hole. Also the presence of a 50mm signal could help when setting up high ranges to ensure that you counted the first echo from the 25mm thickness, (this could be done without turning the block). Long dead zones on early equipment meant it was sometimes not easy to see the first echo, yes equipment was that bad.
You shouldn't calibrate from it because of the temperature variance of the velocity in perspex and steel but it was useful as a quick check.

Obsolete now but useful 30+ years ago. Glad I don't have to carry that block around anymore, useful as it was.



    
 
 Reply 
 
Ed T.
Ed T.
03:20 Nov-13-2004
Re: Perspex insert in IIW Block
----------- Start Original Message -----------
: : What is the purpose of this plastic insert in the IIW Block? What type of check is this used for?
: I believe another purpose of the insert was as a measure of crystal ageing. One of the regular checks we had to do with the old Barium Titanate? crystals was take regular sensitivity readings against a fixed reflector. The high attenuation of perspex allowed us to monitor probe loss of sensitivity on low frequency probes e.g. third back wall echo to 50% FSH. Sometimes we would struggle to see the side drilled holes and the insert saved having to keep a flat bottomed hole. Also the presence of a 50mm signal could help when setting up high ranges to ensure that you counted the first echo from the 25mm thickness, (this could be done without turning the block). Long dead zones on early equipment meant it was sometimes not easy to see the first echo, yes equipment was that bad.
: You shouldn't calibrate from it because of the temperature variance of the velocity in perspex and steel but it was useful as a quick check.
: Obsolete now but useful 30+ years ago. Glad I don't have to carry that block around anymore, useful as it was.
------------ End Original Message ------------

Well that would cetainly explain the inaccuracy in the measurements I have observed as far as representing 2” of steel.


    
 
 Reply 
 
ED T.
ED T.
03:34 Nov-13-2004
Re: Perspex insert in IIW Block
----------- Start Original Message -----------
: : : What is the purpose of this plastic insert in the IIW Block? What type of check is this used for?
: : I believe another purpose of the insert was as a measure of crystal ageing. One of the regular checks we had to do with the old Barium Titanate? crystals was take regular sensitivity readings against a fixed reflector. The high attenuation of perspex allowed us to monitor probe loss of sensitivity on low frequency probes e.g. third back wall echo to 50% FSH. Sometimes we would struggle to see the side drilled holes and the insert saved having to keep a flat bottomed hole. Also the presence of a 50mm signal could help when setting up high ranges to ensure that you counted the first echo from the 25mm thickness, (this could be done without turning the block). Long dead zones on early equipment meant it was sometimes not easy to see the first echo, yes equipment was that bad.
: : You shouldn't calibrate from it because of the temperature variance of the velocity in perspex and steel but it was useful as a quick check.
: : Obsolete now but useful 30+ years ago. Glad I don't have to carry that block around anymore, useful as it was.
: Well that would cetainly explain the inaccuracy in the measurements I have observed as far as representing 2” of steel.
------------ End Original Message ------------

You know, I was thinking. What if someone from the International Institute of Welding (IIW) was to provide us with some insight as to this perspexing question.



    
 
 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
06:15 Nov-13-2004
Re: Perspex insert in IIW Block
----------- Start Original Message -----------
: Thanks for the reply. I had always wondered about this. I guess its 2" of steel when using a 0 deg. probe (long. waves). Is that correct?
:
: : Ed is correct. The plug in an ASTM E164 IIW-Type 1 Block (Inch version) measures 0.923" thick. Since the velocity of acrylic is 46% of steel, this is the same as 2.000" in steel. The metric version (or V1 block) plug measures 23.0mm, and is matched to 50.0mm in steel. Not sure how useful this plug really is, but there you have it. By the way, some specs consider it optional, which explains why some manufacturers opt to exclude it. The unplugged 2" (or 50mm) diameter hole makes a nice lifting feature for carting this heavy block around.
: : Phil Herman Jr.
: : PH Tool Reference Standards
: : : : What is the purpose of this plastic insert in the IIW Block? What type of check is this used for?
: : : I believe it is supposed to have a velocity that represents 2" of steel. I could be wrong.
------------ End Original Message ------------

Yes. That is correct. The thickness is for longitudinal waves.




    
 
 Reply 
 
gopi mech
gopi mech
07:51 Mar-13-2013
Re: Perspex insert in IIW Block
In Reply to Hmmmm at 04:43 Nov-10-2004 .

why the reason for v1 - block perspex thickness 23 mm?

    
 
 Reply 
 
Ed Ginzel
R & D, -
Materials Research Institute, Canada, Joined Nov 1998, 1268

Ed Ginzel

R & D, -
Materials Research Institute,
Canada,
Joined Nov 1998
1268
12:30 Mar-13-2013
Re: Perspex insert in IIW Block
In Reply to gopi mech at 07:51 Mar-13-2013 .

Gopi, I think your answer is given in the discussions of this same thread. A similar topic was discussed in January of this year http://www.ndt.net/forum/thread.php?admin=&forenID=0&msgID=46698&rootID=46695#46698
Doing a search on NDT.net for "IIW" and "insert" you find this old thread (2004) where you have repeated the question 9 years later

    
 
 Reply 
 
andrew cunningham
NDT Inspector
Canada, Joined Jun 2008, 238

andrew cunningham

NDT Inspector
Canada,
Joined Jun 2008
238
17:43 Mar-16-2013
Re: Perspex insert in IIW Block
In Reply to General at 03:58 Nov-10-2004 (Opening).

The plastic in the IIW v1 is a calibration check and it is a tool to demonstrate acoustic impedance.

    
 
 Reply 
 
Mike Shakinovsky
Mike Shakinovsky
16:29 Jun-12-2013
Re: Perspex insert in IIW Block
In Reply to General at 03:58 Nov-10-2004 (Opening).

The Plexi insert will simulate a 2" thickness in steel. This is because there is no 2" dimension on the IIW Block.

    
 
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