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WesDyne International (AMDATA Products)
WesDyne is an engineering and technical services firm dedicated to providing standard and custom nondestructive examinations (NDE) products and systems
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Technical Discussions
Tan, Nguyen Minh
NDT Inspector, - -
Vietnam, Joined May 2010, 5

Tan, Nguyen Minh

NDT Inspector, - -
Vietnam,
Joined May 2010
5
11:12 Oct-18-2012
Indication rating in AWS D1.1 (explain to me for clear the meaning)

6.26.6.5 Indication Rating. The “Indication Rating, d,” in the UT Report, Annex M, Form M-11, represents the algebraic difference in decibels between the indication level and the reference level with correction for attenuation as indicated in the following expressions:
Instruments with gain in dB:
a - b - c = d
Instruments with attenuation in dB:
b - a - c = d
I want to ask:
1) What is mean "Instruments with gain in dB" and "Instruments with attenuation in dB"?
2)What different "Instruments with gain in dB: a - b - c = d" and "Instruments with attenuation in dB: b - a - c = d"
After that when you calculation in report what formula do you use?

 
 Reply 
 
Adam
Adam
15:29 Oct-18-2012
Re: Indication rating in AWS D1.1 (explain to me for clear the meaning)
In Reply to Tan, Nguyen Minh at 11:12 Oct-18-2012 (Opening).

Here is the simplest way to put it.

1. After you calibrate on the IIW, peak up your signal to be 50% screen height on the .060 side drilled hole on the IIW block, and remember how many decibels it took to do this. Going forward, we will say it is 50 decibels.

2. When you find an indication in the material you are scanning, peak up on the indication, and manually drop your gain so that you are peaked up maximum on the indication and your signal is at 50% screen height. Look at how many decibels you are at to get the 50% screen height from the indication. Lets say for this discussion that you are at 60 dB.

3. Now, look at your soundpath as you are peaked up on the indication. It is the little arrow at the top pointing to about 4 o'clock. Lets say it is 3 inches for this discussion

4. So, take your reference number (50dB from #1 above) and subtract it from the dB you got to 50% screen height on the indication with (60dB in #2 above) and you get a 10. Then, take your soundpath number (3 from #3 above) and subtract 1 from it (which is 2) and multiply by 2 (which is 4). Thus, take the 10 from above and subtract the 4 and you get an "indication rating of 6."

This is how I always do it.

 
 Reply 
 
Michele Tonin
NDT Inspector,
UT ONE SL, Spain, Joined Jan 2012, 16

Michele Tonin

NDT Inspector,
UT ONE SL,
Spain,
Joined Jan 2012
16
22:19 Oct-18-2012
Re: Indication rating in AWS D1.1 (explain to me for clear the meaning)
In Reply to Tan, Nguyen Minh at 11:12 Oct-18-2012 (Opening).

Modern digital instruments are "with gain in db",some old instruments had a fixed output and attenuator device to adjust indications at determinated fsh. You have to think an attenuator as a reverse gain control,that´s whi in "gain db" you use the "a-b-c" formula and in "attenuation db" you use the other.
Best Regards.

 
 Reply 
 
Oliviero
NDT Inspector,
Quality Control srl, Italy, Joined Oct 2008, 414

Oliviero

NDT Inspector,
Quality Control srl,
Italy,
Joined Oct 2008
414
22:25 Oct-18-2012
Re: Indication rating in AWS D1.1 (explain to me for clear the meaning)
In Reply to Tan, Nguyen Minh at 11:12 Oct-18-2012 (Opening).

You can find another thread about this matter here
http://www.ndt.net/forum/thread.php?nc=1&rootID=18498

 
 Reply 
 
Carlos Correia
R & D, - -
UCV & EGROUP, Venezuela, Joined Oct 2008, 120

Carlos Correia

R & D, - -
UCV & EGROUP,
Venezuela,
Joined Oct 2008
120
23:43 Oct-18-2012
Re: Indication rating in AWS D1.1 (explain to me for clear the meaning)
In Reply to Oliviero at 22:25 Oct-18-2012 .

Hello Tan.

I think Adan is right but the SCANNING LEVEL shall be considered (Table 6.2 and 6.3 ADW D1.1 2008 edition).

After the REFERENCE LEVEL has been stablisehed as Adam said, some decibel shall be added before to perform the examination. This is the SCANNING LEVEL. And is a function of the SOUND PATH. You shall check bellow the Table 6.2 at right another small table.

So after you add the scanning level, you can proceed with step No2 of Adam´s Procedure.

I am not an expert in D1.1 but it seems to be in this way... Sorry if I am in mistake...

 
 Reply 
 
Carlos Correia
R & D, - -
UCV & EGROUP, Venezuela, Joined Oct 2008, 120

Carlos Correia

R & D, - -
UCV & EGROUP,
Venezuela,
Joined Oct 2008
120
23:56 Oct-18-2012
Re: Indication rating in AWS D1.1 (explain to me for clear the meaning)
In Reply to Carlos Correia at 23:43 Oct-18-2012 .

Hello again Tan...

Oliviero had made and excellent job... please follow the link...

http://www.ndt.net/forum/files/utawsd1.1.pdf

 
 Reply 
 
John
John
00:31 Oct-19-2012
Re: Indication rating in AWS D1.1 (explain to me for clear the meaning)
In Reply to Carlos Correia at 23:56 Oct-18-2012 .

Just one more point to add to this discussion : per AWS D1.1 - under qualification requirements, qualification of the UT operator SHALL include a specific & practical examination based on the requirements of this code. You must apply the rules of the code with accurate detection and disposition of defects. If you have not done this, you are not qualified to do the AWS work. Simply stated, if you are actually following the code, this question should not be asked and is moot. On the other hand, if this question is just for self training purposes or refreshing knowledge, the other answers are spot on, but also remember that the length is also very important depending the defect classification.

Regards

 
 Reply 
 
Manuel Haces
Director, - Wire rope inspection
Haces Inspección del Noreste and Wire Rope Inspection, Mexico, Joined Jun 2002, 124

Manuel Haces

Director, - Wire rope inspection
Haces Inspección del Noreste and Wire Rope Inspection,
Mexico,
Joined Jun 2002
124
18:35 Oct-20-2012
Re: Indication rating in AWS D1.1 (explain to me for clear the meaning)
In Reply to John at 00:31 Oct-19-2012 .

In order to decide if the discontinuity is rejected, you should consider the length, also there is a table in AWS D 1.1, regarding this matter. Also there is an explanation when you have variations in dB within the length of discontinuity. I hope this helps.

 
 Reply 
 
John
John
22:20 Oct-20-2012
Re: Indication rating in AWS D1.1 (explain to me for clear the meaning)
In Reply to Manuel Haces at 18:35 Oct-20-2012 .

" Also there is an explanation when you have variations in dB within the length of discontinuity. I hope this helps."

Could you cite where you find this? Are you referring to planar reflectors under 6.13.2.1?

According to 6.25.6.3, the max indication is what is used for the indication level.

 
 Reply 
 
Tan, Nguyen Minh
NDT Inspector, - -
Vietnam, Joined May 2010, 5

Tan, Nguyen Minh

NDT Inspector, - -
Vietnam,
Joined May 2010
5
02:24 Oct-22-2012
Re: Indication rating in AWS D1.1 (explain to me for clear the meaning)
In Reply to John at 22:20 Oct-20-2012 .

"According to 6.25.6.3, the max indication is what is used for the indication level".
This is: According to 6.26.6.3, the max indication is what is used for the indication level.
Thanks

 
 Reply 
 
John
John
17:06 Oct-22-2012
Re: Indication rating in AWS D1.1 (explain to me for clear the meaning)
In Reply to Tan, Nguyen Minh at 02:24 Oct-22-2012 .

Tan, you are correct. Fat fingers - small phone

Manuel, i don't know where the explanation in the code is that you are talking about that deal with variations in dB in the length of an indication. Could you enlighten me please?

 
 Reply 
 

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