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- since 1996 -
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Technical Discussions
Oliver Deskovski
Other, NDT Engineer
TEAM Industrial Services Inspections , Netherlands, Joined Jan 2013, 4

Oliver Deskovski

Other, NDT Engineer
TEAM Industrial Services Inspections ,
Netherlands,
Joined Jan 2013
4
09:00 Sep-20-2015
PAUT setup and ghost echoes

Hi,
I am trying to implement inspection scan plan (weld inspection) containing multiple PA groups at the same scan run.
3 groups -90-probe (linear root, linear cap, sectorial)
3 groups 270-probe (linear root, linear cap, sectorial)
1 ToFD group

The problem is I receive ghost echoes on the PA channels which are related with the pulse repetition frequency(PRF).

If I lower the PRF they will disappear, but seriously affect the scanning speed ( approx 7mm/sec).

Is there a way to eliminate the ghost echoes and keep the optimum scanning speed without removing groups and making additional scans?

Thanks,

2
 
 Reply 
 
mark
mark
11:14 Sep-20-2015
Re: PAUT setup and ghost echoes
In Reply to Oliver Deskovski at 09:00 Sep-20-2015 (Opening).

Hi Oliver,

How much is PRF ? What is your instrument? Is it possible to upload some picture of scan?

2
 
 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
14:25 Sep-20-2015
Re: PAUT setup and ghost echoes
In Reply to Oliver Deskovski at 09:00 Sep-20-2015 (Opening).

Inspecting with 7 groups is always going to be slow, assuming you have analysed the physical set up , understand where the ghost echoes are coming from , (unusual in an angle beam scan) and can't change anything here there won't be much scope for increasing the PRF.

Some instruments may allow you to change the focal law order (e.g alternating between probes) and possibly reduce interference that way. (or if the probes are facing that may make it worse!)

Otherwise all you can do is look at the angular/ beam resolution [I.e. number of focal laws per group] and see if this can be reduced without losing detectability.

1
 
 Reply 
 
Ed Ginzel
R & D, -
Materials Research Institute, Canada, Joined Nov 1998, 1300

Ed Ginzel

R & D, -
Materials Research Institute,
Canada,
Joined Nov 1998
1300
16:32 Sep-20-2015
Re: PAUT setup and ghost echoes
In Reply to Joe Buckley at 14:25 Sep-20-2015 .

Agreed Joe. It sounds like there is a lot of demand being placed on the electronics.
In addition to your suggestion to perhaps reduce angular resolution perhaps it might be possible to reduce the digitisation rate (e.g. from 100MHz to 25HMz ), ensure that the averaging is as low as possible (e.g. none if possible) and the A-scan lengths being collected could be reviewed to make sure you are only collecting the time interval that is needed to analysis. And perhaps make sure that the linear scans are not being run the full length of the probe if not required to cover the root and cap regions.

1
 
 Reply 
 
Sumit Das
Sumit Das
09:26 Sep-21-2015
Re: PAUT setup and ghost echoes
Hi Oliver

Can u share the below details ;

1) Equipment (with number of channels)
2) Scanplan ( Number of focal laws, start and end element & angles for each group)
3) Job thickness
1
 
 Reply 
 
Oliver Deskovski
Other, NDT Engineer
TEAM Industrial Services Inspections , Netherlands, Joined Jan 2013, 4

Oliver Deskovski

Other, NDT Engineer
TEAM Industrial Services Inspections ,
Netherlands,
Joined Jan 2013
4
12:56 Sep-21-2015
Re: PAUT setup and ghost echoes
In Reply to Sumit Das at 09:26 Sep-21-2015 .

Download Scan plan

Hi,
Attached are details of equipment and inspection scan plan.

I removed the sectorial scans in a separate scan run and the maximum scanning speed without the efect of ghost echoes is 17mm/s. Still slow and painfull..


1
 
 Reply 
 
Nicholas Bublitz
Other,
VeriPhase, USA, Joined May 2010, 134

Nicholas Bublitz

Other,
VeriPhase,
USA,
Joined May 2010
134
13:27 Sep-21-2015
Re: PAUT setup and ghost echoes
In Reply to Oliver Deskovski at 12:56 Sep-21-2015 .

Olivier
Using OmniScan software 4.2 you can use Interleave (Interleave- the mixing of 2 or more digital signals by alternating between them or controlling the firing sequence) to help manage ghost echoes and maximize prf. It seems like maybe with your scan plan you could also limit the start range of the pa groups to the area of interest, i.e. if not using that group for first leg don't leave it in the inspection area, averaging with tofd may help as well. Turn off gates not being used or minimize them and make sure they are in the inspection range on each channel. If you would like to send me a setup to look at optimizing please do, i can note changes and effect. I am travelling and conducting training this week but will look at it as soon as possible.

1
 
 Reply 
 
Sumit Das
Sumit Das
08:07 Sep-22-2015
Re: PAUT setup and ghost echoes
In Reply to Oliver Deskovski at 12:56 Sep-21-2015 .

Hi,

Removing Sectorial in a separate setup wont affect that much. Make both linear in a separate setup. Hope it will work.

Take care of range. Keep it optimized.

If possible share a data.

1
 
 Reply 
 
mark
mark
08:29 Sep-22-2015
Re: PAUT setup and ghost echoes
In Reply to Nicholas Bublitz at 13:27 Sep-21-2015 .

Oliver ,
How much is the scan step? if you are following ASME code , scan step is only 1mm for thickness up to 75 mm. my suggestion is to use motorized scanner like weld rover if you couldn't solve the ghost echo problem and have to apply lower PRF and lower speed.
But according to BS EN ISO 13588:2012 : For thicknesses between 10 mm and 150 mm,
the scan increment shall be no more than 2 mm.That means if you are following ISO you can put scan step 2 mm and improve your scan speed.

First follow the equipment supplier advices . hope Nicholas solve your problem.


1
 
 Reply 
 
Massimo Carminati
Consultant, AUT specialist
IMG Ultrasuoni Srl, Italy, Joined Apr 2007, 691

Massimo Carminati

Consultant, AUT specialist
IMG Ultrasuoni Srl,
Italy,
Joined Apr 2007
691
19:58 Nov-07-2015
Re: PAUT setup and ghost echoes
In Reply to Oliver Deskovski at 09:00 Sep-20-2015 (Opening).

Oliver,
with such complex setup you have two choices: Reduce the overall "data" quality by decreasing sampling rate, reducing angle step in s-scan or, much better, use a motorized scanner with adjustable speed. If you wish, I can send you a data sheet of our simple price attractive and efficient motorized scanner for piping. Just drop me an e-mail.

 
 Reply 
 
Oliver Deskovski
Other, NDT Engineer
TEAM Industrial Services Inspections , Netherlands, Joined Jan 2013, 4

Oliver Deskovski

Other, NDT Engineer
TEAM Industrial Services Inspections ,
Netherlands,
Joined Jan 2013
4
10:56 Nov-08-2015
Re: PAUT setup and ghost echoes
In Reply to Massimo Carminati at 19:58 Nov-07-2015 .

Massimo,
Using motorized scanner will definitely solve my problem with maintaining constant scanning speed.
I order to achieve workable scanning speed with manual hand scanner I removed one of the linear scans.
The Client asked for additional scan runs (linear scans to hit the bevel line perpendicular) and used this ones to cover the cap zone.
Removing the linear scan and using the Interleave software option helped with the ghost echoes.

Many thanks to all for the support and useful hints ;)

 
 Reply 
 

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