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- since 1996 -
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langtuteng2
Armenia, Joined Nov 2014, 196

langtuteng2

Armenia,
Joined Nov 2014
196
06:32 Dec-12-2019
how to design the calibration block for piping when using PAUT
zoom image



hello!1.how length between the center of side drilled hole and the edge of the block when we use this block to calibration the TCG with PAUT equipment and there is no conner or edge reflection interference?
2. what the distance between side drilled hole will be reasonalbe when we use these side drilled hole to calibrate the TCG with PAUT equipment and no interference with adjacent side drilled holes, especially for piping inspection calibration? we have to avoid the edge, conner and adjacent side drill hole interferce when we calibrate the TCG. maybe it depends on the sector scan angle.
3. for PAUT TCG calibration, what the thickness of the block will be ok? is the same thickness of the inspected component, or twice thickness of the component? because, for mild steel, we normally will use the full skip scanning, and if the thickness of block is the same as the component, can we still use the echo reflected visa the back wall for PAUT? according to ASME Figure T-434.2.1, the block is used for conventional UT, could it be used for PAUT without the conner or edge interference?
thanks

 
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Paul Holloway
Consultant,
Holloway NDT & Engineering Inc , Canada, Joined Apr 2010, 217

Paul Holloway

Consultant,
Holloway NDT & Engineering Inc ,
Canada,
Joined Apr 2010
217
12:28 Dec-12-2019
Re: how to design the calibration block for piping when using PAUT
In Reply to langtuteng2 at 06:32 Dec-12-2019 (Opening).

zoom image

ERVW side-drilled hole block

Aaah, calibration blocks are my playground!

1) For phased array, as you know the termination echo from the end of the block is a real nuisance. It's not a concern for conventional mono-element UT. Many manufacturers taper (angle cut) the end of the block to redirect termination echoes. This is what I did for the ERVW piping calibration blocks that were designed in co-operation with PH Tool. The distance from the hole to the end of the block should be safely 2 x the thickness if you use a taper.

2) I think you are referring to the spacing between the stacked holes? This is only an issue when thickness is reduced, and remember that only the 1/2T hole is needed for thicknesses less than 3/4 inch (19 mm). I have found that the minimum ASME hole size of 3/32 inch (2.38 mm) is rather large and that thicknesses less than about 6 or 7 mm may result in competing echoes (i.e. the red banana from the 1st leg hole signal may smear and overlap with the outer bits of the red banana from the 2nd leg hole signal etc. etc.). This is less of an issue if you focus and/or use 32 elements.

3) The block thickness requirements are in the codes. In the ASME piping world, the same thickness and curvature requirements are used for both axial and circumferential scanning. However, the effects of curvature and thickness are much more significant when scanning circumferentially (e.g. inspecting long seams). I just did a paper and presentation on this at the 2019 ASNT conference in Las Vegas. In my opinion, if you're scanning in the circumferential direction you are much better served to use a block that closely matches the examination surface.
 
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langtuteng2
Armenia, Joined Nov 2014, 196

langtuteng2

Armenia,
Joined Nov 2014
196
11:37 Dec-13-2019
Re: how to design the calibration block for piping when using PAUT
In Reply to Paul Holloway at 12:28 Dec-12-2019 .

thanks, paul.
but there is another question: for thickness is less than 19mm, one side drilled hole located on depth T/2 is needed. this is only stipulated on the ASME standard. but using T/2 hole, how to calibration the TCG sensitivity? this we can just construct one point for TCG, not at least 3 points. how to solve this problem?

 
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langtuteng2
Armenia, Joined Nov 2014, 196

langtuteng2

Armenia,
Joined Nov 2014
196
11:45 Dec-13-2019
Re: how to design the calibration block for piping when using PAUT
In Reply to Paul Holloway at 12:28 Dec-12-2019 .

we can't construct DAC with 3 points, let alone to generate up to a 3T distance–amplitude correction (DAC) curve, where T is the thickness of the calibration block.

 
 Reply 
 
Paul Holloway
Consultant,
Holloway NDT & Engineering Inc , Canada, Joined Apr 2010, 217

Paul Holloway

Consultant,
Holloway NDT & Engineering Inc ,
Canada,
Joined Apr 2010
217
12:30 Dec-13-2019
Re: how to design the calibration block for piping when using PAUT
In Reply to langtuteng2 at 11:45 Dec-13-2019 .

Why can't you use 3 points for your low angles? Of course there's no need to drag the full beam (up to 70 deg) through all three points, but the low angles should be okay. In the image I posted you can see the actual response of a 5L16 on an Omniscan MX on one of the ERVW blocks. The holes are clean and distinct with no problems from the end of the block.

 
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Anmol Birring
Consultant,
Birring NDE Center, Inc., USA, Joined Aug 2011, 776

Anmol Birring

Consultant,
Birring NDE Center, Inc.,
USA,
Joined Aug 2011
776
04:35 Dec-15-2019
Re: how to design the calibration block for piping when using PAUT
In Reply to langtuteng2 at 06:32 Dec-12-2019 (Opening).

Are you doing inspection of longitudinal seam welds in pipes as shown by the diagram ?

 
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langtuteng2
Armenia, Joined Nov 2014, 196

langtuteng2

Armenia,
Joined Nov 2014
196
12:50 Dec-15-2019
Re: how to design the calibration block for piping when using PAUT
In Reply to Anmol Birring at 04:35 Dec-15-2019 .

yes. normally we construct the TCG including 2T thickness (where T is the thickness of the part to be inspected). for butt welding, we can use the side drilled hole located in different depth, until more than twice of thickness. but for the back wall which is concave or convex surface, I don't know how to deal with it. and I don't know how to choose which thickness sensitivity block is OK. for mono-element, we can make compensation for single angle beam, but for PA, there are so many beam angles, how to make correction or compensation?
thanks

 
 Reply 
 
Paul Holloway
Consultant,
Holloway NDT & Engineering Inc , Canada, Joined Apr 2010, 217

Paul Holloway

Consultant,
Holloway NDT & Engineering Inc ,
Canada,
Joined Apr 2010
217
13:40 Dec-15-2019
Re: how to design the calibration block for piping when using PAUT
In Reply to langtuteng2 at 12:50 Dec-15-2019 .

Which instrument are you using?

Also, for any longseam weld inspection from the OD you need to reduce your upper angle on the sectorial scan to ensure you actually can hit the ID surface.

See this article:
http://www.hollowayndt.com/news/2019/2/20/ultrasonic-inspection-angles-on-curved-surfaces

 
 Reply 
 
langtuteng2
Armenia, Joined Nov 2014, 196

langtuteng2

Armenia,
Joined Nov 2014
196
01:03 Dec-17-2019
Re: how to design the calibration block for piping when using PAUT
In Reply to Paul Holloway at 13:40 Dec-15-2019 .

hello, paul. the equipment is Omniscan SX 16:64 PR.

 
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