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 Phoenix Inspection Systems LimitedDesign and manufacture ultrasonic Transducers, Scanners and Custom Solutions for NDT inspections. Innovators in NDT technology
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Technical Discussions
Pedro Serruto
Director, Level II UT, PT
Red Code Quality, Peru, Joined Sep 2013, 87

Pedro Serruto

Director, Level II UT, PT
Red Code Quality,
Peru,
Joined Sep 2013
87
17:07 Dec-17-2014
How to calculate the AWS D Rating

Good Morning Friends, in internet, I found a way to calculate the Rating number using this formula:

A – B – C = D where

A = Discontinuity indication level in dB
B = Reference indication level in dB
C = Material attenuation factor, (2x [soundpath length in inches – 1 in.]) expressed in dB

I will appreciate if someone could give me examples of exercises to calculate Rating number because my equipment doesn't have the AWS software.

PHAN HOANG DIEP
NDT Inspector,
Vietnam, Joined Aug 2011, 15

PHAN HOANG DIEP

NDT Inspector,
Vietnam,
Joined Aug 2011
15
11:12 Dec-19-2014
Re: How to calculate the AWS D Rating
In Reply to Pedro Serruto at 17:07 Dec-17-2014 (Opening).

Dear Pedro!
I assume you inspection weld 30 mm in thickness for Statically loaded nontubular Connection Structure.
You only need use 70 Deg. probe (2 Mhz). Because AWS allowed: 2 upto 2.5 Mhz at 6.22.7.1 part F.
If your UT Set have not AWS software installed. I point out for you how to calculate Rating D in according with table 6.2 or 6.3 of code AWS D1.1 step by step as below:
Step 1. Calibration UT set to determine "0 point", True angle and "Index point" and selected range fit with thick. of weld will be tested.
Setting of reference sensitivity for UT system (UT set & probe, cable):
You Maximise pulse with side dirll hole (SDH) 1.5 mm in Diameter of V1 Block (it's 15 mm in Depth). Then You give to "50%" Full Screen Height (FSH) by gain control (AWS allowed 40% upto 60% FSH at Para.6.25.5.2 Part F). You noted this Gain (dB) (assume is 40 dB), this is Reference Sensitivity(b) determise in according AWS code required.
Step 2. when you carry out & detected Indication, you maximise to determine tip of pulse. Then you give 50% FSH by gain control, you noted this Gain (a), assume is 38 dB. And you noted sound path also, assume is 88.9 mm=3.5 in
Step 3. You apply fomula : D=a-b-c to calculate Rating "D"
Where: a=38 dB; b=40 dB and c=[Sound Path-1]x2=[3.5-1]x2=5 (dB).
Thus D=a-b-c=38-40-5=-7 (dB). You known "-7dB" is indication of Class A in according with 6.2 table statically loaded Nontubular Connection) with [20-38] in thick. Thus it's shall be reject.

Thanks & Best regard!
Phan Hoang Diep

Pedro Serruto
Director, Level II UT, PT
Red Code Quality, Peru, Joined Sep 2013, 87

Pedro Serruto

Director, Level II UT, PT
Red Code Quality,
Peru,
Joined Sep 2013
87
17:52 Dec-19-2014
Re: How to calculate the AWS D Rating
In Reply to PHAN HOANG DIEP at 11:12 Dec-19-2014 .

Thanks for the response dear Phan Hoang, I only ask you for more detailed explanation about the step 2, what you mean with "give 50% FSH by gain control" and why you asume 38 db, 38 db what? how you determine that. Thanks again

PHAN HOANG DIEP
NDT Inspector,
Vietnam, Joined Aug 2011, 15

PHAN HOANG DIEP

NDT Inspector,
Vietnam,
Joined Aug 2011
15
04:43 Dec-20-2014
Re: How to calculate the AWS D Rating
In Reply to Pedro Serruto at 17:52 Dec-19-2014 .

FIGURE 2 (FOR SIMULATED STEP 2)

Dear Pedro!
+My meaning " Gain Control" = " Gain Rotary Knob " to give tip of pulse to 50% FSH.

+ 38 dB is "random" assume value. Assume that when you maximise tip of pulse from side drill hole 1.5 mm (V1 Block) and then you use "Gain Rotary Knob" to give tip of pulse to 50% FSH. (At the moment Gain display on Screen is 38 dB). But really, when you calibration, maybe is other value (is not 38 dB). You understood!

thanhtrinh
NDT Inspector,
Vietnam, Joined Aug 2014, 4

thanhtrinh

NDT Inspector,
Vietnam,
Joined Aug 2014
4
05:18 Dec-22-2014
Re: How to calculate the AWS D Rating
In Reply to PHAN HOANG DIEP at 11:12 Dec-19-2014 .

dear Pedro !
In explanation from PhanHoang . I think in his opinion (40%-60% FSH) is the height value of indication in CRT when you setting sensitivity,which it confirmed in AWS D1.1-2010 Para 6.25.5.2 part F using 1,5mm dia SDH in IIW V1 block. 40%, 50% or 60% FSH also can,it depen you . 50%FSH , i think its his way used to setting sensitivity .
- 38dB is a concrete assumptions example, which at this value , peak of indication reaching 50%FSH in CRT while setting sensitivity .
- for object tested, 40dB is a gain value concrete example so that the peak of indication discontinuiti reaching 50%FSH in CRT.

Jorge Perdigon
NDT Inspector, Teacher at Universidad Central de Venezuela - Factultad de Ingenieria
IEMAT, ca, Venezuela, Joined Jul 2009, 10

Jorge Perdigon

NDT Inspector, Teacher at Universidad Central de Venezuela - Factultad de Ingenieria
IEMAT, ca,
Venezuela,
Joined Jul 2009
10
22:49 Dec-29-2014
Re: How to calculate the AWS D Rating
In Reply to Pedro Serruto at 17:07 Dec-17-2014 (Opening).

Dear Pedro

About the explanation from PhanHoang . If you see 6.22.7.1 Frequency. The transducer frequency shall be between 2 and 2.5 MHz, inclusive and by Table 6.2 or Table 6.3 the Search Unit Angle = 70o

If you send me your email at jperdigon@gmail I send to you a AWS calibration (in powerpoint format)

See you

NDT Inspector,
Nusantara Technologies Sdn bhd, Malaysia, Joined Oct 2014, 3

NDT Inspector,
Nusantara Technologies Sdn bhd,
Malaysia,
Joined Oct 2014
3
05:05 Dec-30-2014
Re: How to calculate the AWS D Rating
In Reply to Jorge Perdigon at 22:49 Dec-29-2014 .

hye jorge Perdigon,

Can i get the AWS calibration ( in power point) from you.

achavezsr2
USA, Joined May 2017, 1

achavezsr2

USA,
Joined May 2017
1
05:38 Aug-07-2019
Re: How to calculate the AWS D Rating
In Reply to Jorge Perdigon at 22:49 Dec-29-2014 .

Hello,

Can you send me the power point on dB rating per AWS

langtuteng
Armenia, Joined Nov 2014, 196

langtuteng

Armenia,
Joined Nov 2014
196
16:24 Aug-14-2019
Re: How to calculate the AWS D Rating
In Reply to PHAN HOANG DIEP at 04:43 Dec-20-2014 .

dear friend, after I finished reading the AWS d1.1, I cann't find the evaluating level (for EN17640, we can find the recording level, evluating level and sizing level). I just find : the indications exceed level D shall be evaluated. Is it right?
thanks

CHASHI
CHASHI
07:10 Jan-19-2020
Re: How to calculate the AWS D Rating
In Reply to Pedro Serruto at 17:07 Dec-17-2014 (Opening).

for 80mm thickness plate ,how can i measure the reference dB

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