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Charles Bassey
NDT Inspector,
Nigeria, Joined Oct 2015, 8

Charles Bassey

NDT Inspector,
Nigeria,
Joined Oct 2015
8
15:13 Jan-25-2017
AWS D1.1 Table 6.2 and 6.3 class A, B, C and D.
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AWS D1.1, Table 6.2 and 6.3 class A B C and D acceptance standard.
Regarding: Indication level, reference level, attenuation factor and indication rating. a-b-c=d respectively.
a = indication level from a discontinuity, b=reference level from 1.6mmDia hole on V1 block, c=attenuation faction, the beam path travel in inches while the d is indication rating which determined acceptance nor rejection.
My concern is the dB for reference level (b), Dose the dB for reference level b = to the dB use to set 1.6mmDia hole on V1 block to 80% + the transfer correction? what is the actual dB for b( reference level).

 
 Reply 
 
James Scalf
NDT Inspector,
Global Integrity, Canada, Joined Oct 2012, 276

James Scalf

NDT Inspector,
Global Integrity,
Canada,
Joined Oct 2012
276
20:54 Jan-25-2017
Re: AWS D1.1 Table 6.2 and 6.3 class A, B, C and D.
In Reply to Charles Bassey at 15:13 Jan-25-2017 (Opening).

Charles,

The reference level dB for "b" in the acceptance formula for the D1.1 is the total gain setting established as your scanning level for the component being assessed. This would be the dB required to bring your reference reflector to the established required level plus any transfer correction dB. For your example you are using a 1.6mm hole set to 80% FSH and then you have a transfer value dB to apply for the material differences between the reference block material and the examination material the combination of both is your value for "b" in the a-b-c=d formula.

Hope this helps. Cheers...

 
 Reply 
 
David Hermanutz
David Hermanutz
17:03 Jan-30-2017
Re: AWS D1.1 Table 6.2 and 6.3 class A, B, C and D.
In Reply to James Scalf at 20:54 Jan-25-2017 .

Hi,

It is my understanding that AWS D1.1 and other similar fixed attenuation codes such as CSA W59 do not have a transfer correction involved in the "b" reference value. The carbon steel material group of structural steel is understood not to be a factor. Although in practice this may have a significant affect on the dB level between the calibration block and the material it is not used in AWS D1.1 or CSA W59 .

AWS D1.1/D1.1M:2015
"6.24.5.2 Zero Reference Level. The zero reference
level sensitivity used for discontinuity evaluation (“b” on
the ultrasonic test report, Annex L, Form L-11) shall be
attained by adjusting the calibrated gain control (attenuator)
of the discontinuity detector, meeting the requirements
of 6.21, so that a maximized horizontal trace
deflection (adjusted to horizontal reference line height
with calibrated gain control [attenuator]) results on the
display between 40%..."

 
 Reply 
 
John Brunk
Engineering, NDT Level III
Self employed, part-time, USA, Joined Oct 1999, 162

John Brunk

Engineering, NDT Level III
Self employed, part-time,
USA,
Joined Oct 1999
162
19:09 Jan-30-2017
Re: AWS D1.1 Table 6.2 and 6.3 class A, B, C and D.
In Reply to David Hermanutz at 17:03 Jan-30-2017 .

It is correct that no transfer correction is used with AWS D1.1. This document applies to a very limited range of structural steel and all the approved AWS D1.1 reference blocks are made of similar material. There are even very specific straight beam and angle beam probes required for these inspections. Even the beam angles and scanning surfaces are prescribed for various weld configurations. This takes most of the fun out of it until something has to be done different from the approved drawings and the Level III has to get approval from the Owner and the Engineer to do something that will actually work.

 
 Reply 
 
Charles Bassey
NDT Inspector,
Nigeria, Joined Oct 2015, 8

Charles Bassey

NDT Inspector,
Nigeria,
Joined Oct 2015
8
10:14 Feb-01-2017
Re: AWS D1.1 Table 6.2 and 6.3 class A, B, C and D.
In Reply to David Hermanutz at 17:03 Jan-30-2017 .

David,

"Based on your respond that no transfer correction is require" I have a concern here, I have some weld to inspect as per AWS D1.1, Table 6.2 and 6.3 class A B C and D acceptance standard. and I have on V1-block for my calibration, I use 1.6mmDia SDH on V1-block to set the reference level and it was 34dB. but if I scan the material with 34dB I observed no reflection which mean attenuation factor between V1-block and test coupon is very high. so how do I correct this?

 
 Reply 
 
Paul Holloway
Consultant,
Holloway NDT & Engineering Inc , Canada, Joined Apr 2010, 255

Paul Holloway

Consultant,
Holloway NDT & Engineering Inc ,
Canada,
Joined Apr 2010
255
13:22 Feb-01-2017
Re: AWS D1.1 Table 6.2 and 6.3 class A, B, C and D.
In Reply to Charles Bassey at 10:14 Feb-01-2017 .

You need to add scanning gain as per the levels defined in the sub-tables below Tables 6.2 and 6.3.

 
 Reply 
 
St. Neel
NDT Inspector,
Bureau Veritas Industrial Services, United Arab Emirates (UAE), Joined Jun 2015, 27

St. Neel

NDT Inspector,
Bureau Veritas Industrial Services,
United Arab Emirates (UAE),
Joined Jun 2015
27
18:26 Mar-01-2017
Re: AWS D1.1 Table 6.2 and 6.3 class A, B, C and D.
In Reply to Charles Bassey at 15:13 Jan-25-2017 (Opening).

yes you can set your echo 80% of FSH . also you have to increase up your indication's echo dB. upto level of refrence , 80% of FSH.

 
 Reply 
 
Charles Bassey
NDT Inspector,
Nigeria, Joined Oct 2015, 8

Charles Bassey

NDT Inspector,
Nigeria,
Joined Oct 2015
8
09:58 Mar-02-2017
Re: AWS D1.1 Table 6.2 and 6.3 class A, B, C and D.
In Reply to Paul Holloway at 13:22 Feb-01-2017 .

Regarding setting the reference amplitude to 80%, which calibration block is suitable? are we using IIW-V1 Block or are we to make a reference block for the same weld material.

 
 Reply 
 
Mario Talarico
NDT Inspector,
Italy, Joined May 2010, 423

Mario Talarico

NDT Inspector,
Italy,
Joined May 2010
423
22:23 Mar-03-2017
Re: AWS D1.1 Table 6.2 and 6.3 class A, B, C and D.
In Reply to Charles Bassey at 09:58 Mar-02-2017 .

Charles,
the code requires reference level calibration with SDH 1.6 of V1 between 40% and 60% of the display. Additional dB for scanning level shall be as prescribed in tables 6.2 and 6.3. As regards the attenuation, code considering 2 dB for every inch of the indication path under examination, excluding the first inch of path (Par.6.26.6.4.ed. 2010): to be consider when calculating the rating. Everything else is out of the code.

Otherwise the annex 'S' contains alternative techniques (dac, signal characterization, tranfer correction, and so on, apply as described).
greetings
mario

 
 Reply 
 
RAHUL
RAHUL
16:41 Dec-24-2019
Re: AWS D1.1 Table 6.2 and 6.3 class A, B, C and D.
In Reply to Charles Bassey at 15:13 Jan-25-2017 (Opening).

for value of B we are used iiw block, but what will use for value of A

 
 Reply 
 
Michel Couture
NDT Inspector,
consultant, Canada, Joined Sep 2006, 897

Michel Couture

NDT Inspector,
consultant,
Canada,
Joined Sep 2006
897
19:09 Dec-24-2019
Re: AWS D1.1 Table 6.2 and 6.3 class A, B, C and D.
In Reply to RAHUL at 16:41 Dec-24-2019 .

Your value "A" is taken from your indication once it is brought back to the amplitude of the signal obtained during calibration ("B" Reference dB with amplitude of 0.060" SDH between 50-75% FSH).

 
 Reply 
 

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