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Technical Discussions
Kalaiselvan
India, Joined Feb 2016, 6

Kalaiselvan

India,
Joined Feb 2016
6
00:37 Mar-23-2018
Comparison of Back Wall Reflection technique vs flat bottom hole defect

Hello Everyone,
Could anybody please confirm and explain whether NDE procedure using a Back Wall Reflection technique with a defect indication rejection limit of greater than 5% of the calibration back reflection is approximately equivalent to a 4mm flat bottom hole defect indication or not.

Appreciate your help.
Thanks in advance.

 
 Reply 
 
Joe Buckley
Consultant, ASNT L-III, Honorary Secretary of BINDT
Level X NDT, BINDT, United Kingdom, Joined Oct 1999, 528

Joe Buckley

Consultant, ASNT L-III, Honorary Secretary of BINDT
Level X NDT, BINDT,
United Kingdom,
Joined Oct 1999
528
11:59 Mar-23-2018
Re: Comparison of Back Wall Reflection technique vs flat bottom hole defect
In Reply to Kalaiselvan at 00:37 Mar-23-2018 (Opening).

It might be ( but almost certainly isn't..)

Comparing energy lost from the back wall reflection with energy reflected from an intermediate defect is likely to be valid only in a very specific situation of defect type, location, probe, and material.

Generally you monitor back wall echo amplitude to find the effect of defects that do NOT give a clear reflection.

Not clear what you are trying to do, but it looks like you will need to get someone involved with the necessary expertise. Probably not something that can be done on line.

Good luck
Joe

 
 Reply 
 
Anmol Birring
Consultant,
Birring NDE Center, Inc., USA, Joined Aug 2011, 805

Anmol Birring

Consultant,
Birring NDE Center, Inc.,
USA,
Joined Aug 2011
805
13:45 Mar-23-2018
Re: Comparison of Back Wall Reflection technique vs flat bottom hole defect
In Reply to Kalaiselvan at 00:37 Mar-23-2018 (Opening).

No, backwall signal monitoring is used only for gross defects typically when the lamination will block the entire beam

 
 Reply 
 
kalaiselvan
India, Joined Feb 2016, 6

kalaiselvan

India,
Joined Feb 2016
6
15:35 Mar-23-2018
Re: Comparison of Back Wall Reflection technique vs flat bottom hole defect
In Reply to Joe Buckley at 11:59 Mar-23-2018 .

Sir, Cloud you help me out?
We have purchased Raw Material as per our customer requirement and NDE should be performed as customer procedure. Our Customer specification refers to ASTM E114 (Direct Contact Method) for establishing examination techniques and the specification further defines a satisfactory NDE procedure using a Back Wall Reflection technique with a defect indication rejection limit of greater than 5% of the calibration back reflection. But, while review the Raw Material Test Certificate it was found that the NDE inspection was carried out as per the Supplier NDE Procedure. Upon clarification with the supplier, the supplier informed us that they have applied 2mm FBH sensitivity/recording level which is a more stringent test than that achieved using 5% of the calibrated back reflection as the reject level. No indications greater than 2mm FBH were reported in the material supplied and also they further explained that the Back Wall Reflection technique with a defect indication rejection limit of greater than 5% of the calibration back reflection (This is approximately equivalent to a 4mm flat bottom hole defect indication).
Kindly assist me to figure it out.
Appreciate your response and thanks for your valuable comments.

 
 Reply 
 
kalaiselvan
India, Joined Feb 2016, 6

kalaiselvan

India,
Joined Feb 2016
6
15:39 Mar-23-2018
Re: Comparison of Back Wall Reflection technique vs flat bottom hole defect
In Reply to Anmol Birring at 13:45 Mar-23-2018 .

Sir,
Thanks for your valuable comments. Could you please help me out for the above question?
Appreciate your response.

 
 Reply 
 
Joe Buckley
Consultant, ASNT L-III, Honorary Secretary of BINDT
Level X NDT, BINDT, United Kingdom, Joined Oct 1999, 528

Joe Buckley

Consultant, ASNT L-III, Honorary Secretary of BINDT
Level X NDT, BINDT,
United Kingdom,
Joined Oct 1999
528
16:21 Mar-23-2018
Re: Comparison of Back Wall Reflection technique vs flat bottom hole defect
In Reply to kalaiselvan at 15:35 Mar-23-2018 .

Could you clarify if the inspection technique is monitoring the back wall reflection, or if the back-wall reflection height is just used as a reference level for a 'standard gate'.

Your expanded explanation suggests the latter, in which case, assuming the comparison with a 4mm FBH has been done, it may be acceptable.

Again, though, it sounds like you may need an independent level III to review the procedures.

 
 Reply 
 
Anmol Birring
Consultant,
Birring NDE Center, Inc., USA, Joined Aug 2011, 805

Anmol Birring

Consultant,
Birring NDE Center, Inc.,
USA,
Joined Aug 2011
805
20:26 Mar-23-2018
Re: Comparison of Back Wall Reflection technique vs flat bottom hole defect
In Reply to kalaiselvan at 15:35 Mar-23-2018 .

2 mm FBH sensitivity is better than BW>5%

 
 Reply 
 
Anmol Birring
Consultant,
Birring NDE Center, Inc., USA, Joined Aug 2011, 805

Anmol Birring

Consultant,
Birring NDE Center, Inc.,
USA,
Joined Aug 2011
805
13:52 Mar-24-2018
Re: Comparison of Back Wall Reflection technique vs flat bottom hole defect
should be
2 mm FBH sensitivity is better than BW>5%
 
 Reply 
 
Harsha
kalva, India, Joined Dec 2019, 3

Harsha

kalva,
India,
Joined Dec 2019
3
12:44 Jan-23-2020
Re: Comparison of Back Wall Reflection technique vs flat bottom hole defect
In Reply to Joe Buckley at 16:21 Mar-23-2018 .

Sir I'm very honoured having a chat with you sir.. Please clarify my query sir.. Please explain me when to use back wall reflection and reference block technique in SA 388 And how to evaluate sir?? I will be very lucky to get clarity sir..

 
 Reply 
 
THEO MICOTTIS
Italy, Joined May 2013, 82

THEO MICOTTIS

Italy,
Joined May 2013
82
18:15 Jan-23-2020
Re: Comparison of Back Wall Reflection technique vs flat bottom hole defect
In Reply to Harsha at 12:44 Jan-23-2020 .

5.Ordering Information-, 9.2.2 BW Method.
Regards

1
 
 Reply 
 
harsha
kalva, India, Joined Dec 2019, 3

harsha

kalva,
India,
Joined Dec 2019
3
02:44 Jan-24-2020
Re: Comparison of Back Wall Reflection technique vs flat bottom hole defect
In Reply to THEO MICOTTIS at 18:15 Jan-23-2020 .

good morning
thanks for answering my query.It is really helpful information. I treat myself amateur in this field but i hope someday this amateur turns into a giant one day by the grace of god and guidance from personnel like you sir.
thanks a lot

sir please make some time and kindly let me know the procedure for performing ultrasonic testing using back wall echo method.
please enlighten me the procedure in the scanning process after calibration for performing this test.

 
 Reply 
 

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