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- since 1996 -
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Technical Discussions
ASHWANI KUMAR
Engineering,
MIDHANI, Hyderabad, India, Joined Jun 2015, 96

ASHWANI KUMAR

Engineering,
MIDHANI, Hyderabad,
India,
Joined Jun 2015
96
08:06 Jun-02-2017
Recalibration of UT Reference Block

Dear Sirs,
Is recalibration of UT reference block required?
We have the Ti6Al4V UT reference block, which was dimensionally checked in 2000. Does it require the reclibration? In my opinion , it need not be reclibrated.

Regards
Ashwani Kumar

 
 Reply 
 
Anmol Birring
Consultant,
Birring NDE Center, Inc., USA, Joined Aug 2011, 747

Anmol Birring

Consultant,
Birring NDE Center, Inc.,
USA,
Joined Aug 2011
747
08:34 Jun-02-2017
Re: Recalibration of UT Reference Block
In Reply to ASHWANI KUMAR at 08:06 Jun-02-2017 (Opening).

No

 
 Reply 
 
R J CHAUDHARI
Director,
CALTECH ENGINEERING SERVICES, India, Joined Mar 2003, 13

R J CHAUDHARI

Director,
CALTECH ENGINEERING SERVICES,
India,
Joined Mar 2003
13
14:03 Jun-02-2017
Re: Recalibration of UT Reference Block
In Reply to ASHWANI KUMAR at 08:06 Jun-02-2017 (Opening).

As long as UT reference block is excellent in conditions, Calibration is not required.
Finally it is metal which has not any degradation or higher uses.
Purpose of calibration is not CERTIFICATE but to ensure quality and reliability of reference block.

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

Phil Herman

Sales, - Manufacture of NDT Reference Standards/Test Blocks
PH Tool Reference Standards,
USA,
Joined Oct 1999
79
14:46 Jun-02-2017
Re: Recalibration of UT Reference Block
In Reply to ASHWANI KUMAR at 08:06 Jun-02-2017 (Opening).

While I know of no code or specification that calls for periodic recalibration of UT blocks, this question is becoming a hot topic. More and more block owners send manufacturers such as PH Tool their blocks for this service. I agree that blocks maintained in perfect condition will not change dimensionally over time, however those subjected to excessive wear or abuse have been observed to be out of tolerance compared to new. In addition, blocks of unknown origin may be discovered to have been out all along, so giving them a look after some time may make sense. We see customers send us blocks anywhere from 2 to 5 years from original purchase.

Phil Herman
President/CEO
PH Tool Reference Standards
www.phtool.com

 
 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
15:09 Jun-02-2017
Re: Recalibration of UT Reference Block
In Reply to ASHWANI KUMAR at 08:06 Jun-02-2017 (Opening).

Dear Ashwani Kumar,

While there is probably no code that asks for periodic calibration of reference blocks, what is important is to know the conditions of its use. Are you really sure that there was no wear and tear at all for the block? In my view and experience, it is always prudent to check the dimensional stability of the reference standard every few years.

When all dimensional measuring instruments and secondary standards like slip gages need periodic calibration, why the reference standards have been exempted is subject to debate...cost of recalibration and the low probability of their going out of dimensional tolerance could be the main factor.

 
 Reply 
 
Rick Cahill
Engineering,
GE Inspection Technologies, USA, Joined Dec 2008, 40

Rick Cahill

Engineering,
GE Inspection Technologies,
USA,
Joined Dec 2008
40
13:08 Jun-12-2017
Re: Recalibration of UT Reference Block
In Reply to ASHWANI KUMAR at 08:06 Jun-02-2017 (Opening).

It depends on the requirements of your internal quality system. Our quality system, for example, requires that we verify the calibration of our reference standards annually. They are also required to be validated with measurement equipment that is traceable to NIST. For reference, our organization is ISO certified.

 
 Reply 
 
Justin Lehmann
Consultant,
Quality Testing Services, Inc, A Premium Inspection and Testing Group Affiliate, USA, Joined Sep 2007, 22

Justin Lehmann

Consultant,
Quality Testing Services, Inc, A Premium Inspection and Testing Group Affiliate,
USA,
Joined Sep 2007
22
18:27 Jun-12-2017
Re: Recalibration of UT Reference Block
In Reply to ASHWANI KUMAR at 08:06 Jun-02-2017 (Opening).

All,

We have seen may quality systems require the calibration/verification of UT Reference Blocks for several years. Some of these instances were for good reason, some have little justification. In several cases, the blocks were made incorrectly, even though the paperwork from the manufacturer stated it met the requirements. We have found blocks worn beyond dimensional limits. Another situation occurs where reference defects corrode, especially if the standard is used for immersion, changing the response from the reflector. We have even seen this happen in blocks that were plugged such as distance-amplitude blocks.

 
 Reply 
 
James Scalf
NDT Inspector,
Global Integrity, Canada, Joined Oct 2012, 273

James Scalf

NDT Inspector,
Global Integrity,
Canada,
Joined Oct 2012
273
13:36 Jun-13-2017
Re: Recalibration of UT Reference Block
In Reply to Justin Lehmann at 18:27 Jun-12-2017 .

To All,

I would like to pose a question regarding "Recalibration" of Ultrasonic Test Blocks, regardless of form or function. When performing this "Recalibration" what exactly are they calibrating?

Ultrasonic Blocks are manufactured normally to strict guidelines out of sonically sound material. Most of the blocks are manufactured by machining solid stock into set shapes and designs.

To calibrate something means that there is something within the component that can, over time, move out of tolerance and when you calibrate it you bring it back into tolerance. Most Ultrasonic Reference Blocks I know of do not have the ability to be adjusted therefore you cannot calibrate them. What you can do is verify them.

In my industry it is very common to perform regular verification checks of our reference standards to ensure they still meet the minimum specification that they were machined to. This is inclusive of our eddy current standards but we do not "Recalibrate" them.

I too have seen Quality Control Processes calling for Ultrasonic Blocks to be "Recalibrated" at a specific frequency. When I come across this I always laugh a little and if I know the author I try to correct them.

Ironically I have a similar issue with some of the newer instrumentation, which is solid state such as Olympus' new EPOCH 650 Ultrasonic Units, GE's USM-GO, Etc. The manufacturers, by the sticker on the new instrument, recommends recalibration of the instrument annually. As it is solid state what exactly are they "Recalibrating"? Personally I think they are simply performing the routine performance verifications and charging a pretty penny to do so. I have asked them directly what it is they are calibrating and have never gotten a satisfactory response.

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

Phil Herman

Sales, - Manufacture of NDT Reference Standards/Test Blocks
PH Tool Reference Standards,
USA,
Joined Oct 1999
79
14:01 Jun-13-2017
Re: Recalibration of UT Reference Block
In Reply to James Scalf at 13:36 Jun-13-2017 .

James makes an excellent point in raising his question about "what is really be calibrated in a recalibration?" A better word, and one that I should have used in my earlier post is "Recertification" since no altering/adjusting/tweaking of the test block is performed. Rather, a re-measurement of the physical features of the block is performed.

 
 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
15:28 Jun-13-2017
Re: Recalibration of UT Reference Block
In Reply to Phil Herman at 14:01 Jun-13-2017 .

Calibration has the meaning of test, measure also and thus recalibration means re-test or remeasure to ensure that the reference block continues to meet the specification. In that sense, it is synonymous with re-certification or verification.

The beauty of English language (and for that matter many other languages) is that the same word can be used to convey different meanings and as long as the intended meaning is conveyed through the context, it is OK.

 
 Reply 
 
Ed Ginzel
R & D, -
Materials Research Institute, Canada, Joined Nov 1998, 1274

Ed Ginzel

R & D, -
Materials Research Institute,
Canada,
Joined Nov 1998
1274
19:14 Jun-13-2017
Re: Recalibration of UT Reference Block
In Reply to Phil Herman at 14:01 Jun-13-2017 .

Phil, we do not normally expect calibration blocks (that have not seen rough use) to exhibit any changes.
One of the cal blocks that is not possible to measure directly with metrology equipment is the ALCOA-style block (Area amplitude and Distance amplitude series). These are the cylinders with the encased (plugged) FBHs. Most recently I heard of a situation where the users check the responses daily and use them to set up sensitivity for immersion scanning. I found it odd, but perhaps it is a matter of convenience, that the blocks were left in the water day after day. Annual checks with a "reference probe" are done and they occasionally detect changes in the hole responses. Perhaps the plugging is not always perfect and a minor corrosion can occur. Having a good baseline would be needed in such cases. It is far more difficult to make acoustic comparisons than to check physical dimensions.

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

Phil

Sales, - Manufacture of NDT Reference Standards/Test Blocks
PH Tool Reference Standards,
USA,
Joined Oct 1999
79
19:29 Jun-13-2017
Re: Recalibration of UT Reference Block
In Reply to Ed Ginzel at 19:14 Jun-13-2017 .

Hi Ed,
This has been an interesting thread (to me at least!) and hits on some important points regarding re-certification of NDT test blocks and the question as to the need for this step. I knew it was only a matter of time until someone mentioned the ASTM E127 and E428 FBH sets (Alcoa-type). These are the tricky ones due to the plugged holes as you mentioned. I have long argued that there is no need to open up the plugs to peek inside the holes and inspect diameter, depth, angularity, finish and flatness if they have been sealed properly. For that reason, this is the one block type that we offer only an ultrasonic inspection and response plotting vs a true dimensional inspection. We too have seen situations where clients leave the sets immersed long-term, and depending on the water in the tank, corrosion is likely. Switching to a hardcoat anodic process (vs sulfuric anodize) ensures protection on aluminum alloys. I agree that a daily or other periodic check vs the baseline is a far better approach than a dimensional check of the exterior features. This tells you very little.

 
 Reply 
 
J.B.
J.B.
12:01 Jun-20-2017
Re: Recalibration of UT Reference Block
In Reply to Phil at 19:29 Jun-13-2017 .

I think, the reverfication/recalibration is an important part of any quality system in a company.
Yes, in the past, especiall some 20 years ago, we all did not take this too serious. Especially in aerospace the MROs had been companies with good reputatiions, e.g. the maintenance centers of large airline systems, and they took care of their NDT equipment as part of their own quality startegy to be reputated as a safe airline - that time you paid it with your air fares.
Now in time of budget airfares and cost efficiecy the maintenance had been subcontracted to MROs with low cost offers. Andthey even have more problems to maintain a low cost base: they are no direct customers of the large airframes so they do not get cheap access to the databases and customer support of Airbus, Boeing, Bombardier, Embraer.... so they have to ss how they reduce costs.
Periodical/yearly checks of all NDT equipment is expensive. So could you argue, a reference block with only a drill hole and a plug does not need any recalibration? Of course you can't recalibrate it. But it needs to be verified, dimensionally and in its use for NDT - with all necessary parameters.

in a good quality system you define porcesses for all these task. This should be part of the written practice. You can do geometrical checks by your own, if the measuring tools for this verification can be traced down in their own calibration/recalibration/reverification to a national standard institution.
So you could maybe save some money. If you subcontract those verification, you can influnece this process, as you have a written process describing the recalibration/verification technically and you subcontract just this. Of course your process description should follow the national/international standards valid for your business. In this case you can avoid unnecessary tasks which you would be charged if you just send your tools to any agancy offering general purpose recalibration.

Even if you establish your own process descriptions to perorm the recalibration/verification, and you do it proppperly, you increase the quality of your QC system. Things become better tracable.
There is even one advantage of authoring your own processes in detall: you can even better decide, what to do when.
I have long checked this problem for a major air framer, and I found out, that in the standards no demand of a fixed defined period was set for such rechecks like e.g. 1 year period. Finally it is up to the deciders of your company to define this period for each task in the written practice for QC. But it has to be defined and the definition must be plausible.
I think this way is better than having a strikt rule in standards saying, you have to do things yearly.
Nevertheless in big companies such periods are often defined with a fixed period of e.g. 1 year except something else is stated for a specific task. So if you are subcontracted by a big company, you have to work according to their process descriptions regarding NDT equipment rechecks.

 
 Reply 
 

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