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Technical Discussions
PRADEEP SINGH
PRADEEP SINGH
08:24 Dec-22-2009
SDH

How to decide the diameter of SDH in ASME CALIBRATION BLOCK

 
 Reply 
 
Nigel Armstrong
Engineering, - Specialist services
United Kingdom, Joined Oct 2000, 1096

Nigel Armstrong

Engineering, - Specialist services
United Kingdom,
Joined Oct 2000
1096
08:41 Dec-22-2009
Re: SDH
In Reply to PRADEEP SINGH at 08:24 Dec-22-2009 (Opening).

Reading and understanding ASME V Article 4 (if for welds) para T.434 will tell you that SDH's are for non-piping only and the hole diameter should be according to the material thickness as per fig T-434.2.1

If for pipe material then the block should be furnished with notches as per fig T-434.3. Note that the block should be the same nominal size and schedule as the material to be tested.

Further, check your referencing code to make sure that there are no special requirements in it.

 
 Reply 
 
Phil Herman
Sales, - Manufacture of NDT Reference Standards/Test Blocks
PH Tool Reference Standards, USA, Joined Oct 1999, 79

Phil Herman

Sales, - Manufacture of NDT Reference Standards/Test Blocks
PH Tool Reference Standards,
USA,
Joined Oct 1999
79
14:24 Dec-22-2009
Re: SDH
In Reply to PRADEEP SINGH at 08:24 Dec-22-2009 (Opening).

Hello Pradeep,
You have not specified which block you are asking about, but since there are not normally side-drilled holes (SDHs) machined in the Calibration Block for Pipe (Fig. T-434.3), I will assume that you are asking about the Non-Piping Calibration Block (Fig. T-434.2.1). The hole diameters are:
up to 1" thickness - 3/32" (2.5mm) diameter SDH
over 1" to 2" thickness - 1/8" (3.0mm)
over 2" to 3" thickness - 3/16" (5.0mm)
Phil

 
 Reply 
 
Stan
NDT Inspector,
Canada, Joined Jan 2009, 31

Stan

NDT Inspector,
Canada,
Joined Jan 2009
31
15:57 Dec-22-2009
Re: SDH
In Reply to Phil Herman at 14:24 Dec-22-2009 .

Side Drilled Holes as per Fig T-434.2.1 are easy enough to understand, but how do you deal with the side drilled holes for nonpiping calibration blocks on material less than 20" in diameter, with the calibration block meeting the curvature requirements of Fig T-434.1.7.2. The SDH would have to be drilled in a circumferential direction to a minimum length of 1.5". How can this be accomplished?

Stan

 
 Reply 
 
Phil Herman
Sales, - Manufacture of NDT Reference Standards/Test Blocks
PH Tool Reference Standards, USA, Joined Oct 1999, 79

Phil Herman

Sales, - Manufacture of NDT Reference Standards/Test Blocks
PH Tool Reference Standards,
USA,
Joined Oct 1999
79
23:22 Dec-22-2009
Re: SDH
In Reply to Stan at 15:57 Dec-22-2009 .

Stan,
Great question. Circumferentially oriented holes in pipe are tricky. In a perfect world, we'd machine curved holes, along a radius matching the pipe diameter. Since this is virtually impossible to achieve affordably, the industry has long accepted straight holes. Rarely will these holes reach 1.5" minimum depth, except in those combinations of large diameter and heavy walls. Most simply enter the diameter by first carefully machining a spotface or perhaps a corner cutout, and exit by breaking out into the diameter a short distance away. The location of the hole through the wall thickness is accurate only at the midpoint of the hole depth. I'd be happy to assist further if required.

Phil Herman
PH Tool Reference Standards

 
 Reply 
 
Nigel Armstrong
Engineering, - Specialist services
United Kingdom, Joined Oct 2000, 1096

Nigel Armstrong

Engineering, - Specialist services
United Kingdom,
Joined Oct 2000
1096
10:32 Dec-23-2009
Re: SDH
In Reply to Stan at 15:57 Dec-22-2009 .

Most probably difficulty in accurate machining accounts for notches being required over SDH's for piping calibration blocks. After all UT of butt welds in small diameter pipework is not unusual, whereas non-piping (vessels) of 20 inches or less diameter for UT rather than RT must be a rare occurence.

Para. T-434.1.7.1. allows flat blocks for all non-piping diameters greater than 20 inches (500mm). For these, why incur extra cost when flat calibration blocks with non-curved SDH's are acceptable to Code.

I wonder about the relative sensitivities between notches, SDH's and FBH's - it is not comparing like-for-like on the dimensions of actual reflecting surfaces.

 
 Reply 
 
PRADEEP SINGH
PRADEEP SINGH
10:02 Dec-26-2009
Re: SDH
Sir,
As we know the diameter of SDH in non piping ASME CALIBRATION BLOCK in 38 mm block is 3mm.
But why, and How to decide the diameter of that SDH or also what is the general rule for the dia of other SDH or other reflectors.
 
 Reply 
 
Nigel Armstrong
Engineering, - Specialist services
United Kingdom, Joined Oct 2000, 1096

Nigel Armstrong

Engineering, - Specialist services
United Kingdom,
Joined Oct 2000
1096
11:06 Dec-26-2009
Re: SDH
In Reply to PRADEEP SINGH at 10:02 Dec-26-2009 .

Hi Pradeep

For the last part of your post:

ASME V Article 4 Fig T-434.2.1 For Non-piping calibration, "Note (1) For each increase in weld thickness of 2 in. (50 mm) or fraction thereof over 4 in. (100 mm), the hole diameter shall increase 1⁄16 in. (1.5 mm)."

I suppose the minimum 2,5mm diameter SDH geometric tolerances would be the easiest to achieve whilst simultaneously requiring sufficiently searching gain for weld inspection. My guess.

 
 Reply 
 
David Bunch
David Bunch
15:54 Dec-26-2009
Re: SDH
In Reply to PRADEEP SINGH at 08:24 Dec-22-2009 (Opening).

So can someone explain this a little better to me. If a pipe is under 20" in diameter, can the notches of the ASME basic block be used for calibrating sensitivity, or must an actual piece of pipe be used (with notches) to calibrate?

 
 Reply 
 
Ed Ginzel
R & D, -
Materials Research Institute, Canada, Joined Nov 1998, 1292

Ed Ginzel

R & D, -
Materials Research Institute,
Canada,
Joined Nov 1998
1292
17:04 Dec-26-2009
Re: SDH
In Reply to David Bunch at 15:54 Dec-26-2009 .

ASME Section V has become a bit of a hodge-podge and I think it might be time for a complete re-organisation. The "Basic" calibration blocks for non-piping and pipe welds are illustrated in T-434.2.1 and T-434.3. SDHs are to be used for non-pipe welds and notches for pipe weld. A range of thicknesses is given for the plate in which the diameters of SDH are indicated as Phil stated Dec 22. Pipe has traditionally used notches (10% T) as Nigel indicated....note that you are expected to use the exact same pipe (diameter and scheule) for the calibration block as is being tested...i.e. no range of diameters is allowed as is the case for non-piping!
Stan's concern for putting SDHs in curved plate is valid...particularly for the first 4 diameters noted in Figure T434.1.7.2 with the dimaters 26, 43, 72 and 120mm! Where practical" it has always been accepted that the SDH in this case would be made tangential such that it is at the appropriate depth at the tangent...clearly the length requirements cannot be met for these cases.
But there can be an alternative to all this strife if there are sensible AIs.
T-434.1.1 states that, "...An alternative reflector(s) may be used provided that the alternative reflector(s) produces a sensitivity equal to or greater than the specified reflector(s) (e.g. SDHs in lieu of notches, FBHs in lieu of SDHs).
Ermolov equations and CIVA modelling are useful tools to make such rationalisations.
But I would like to see the old "transfer-value" incorporated. I am surprised that ASME has not incorporated the "Transfer Value" technique using a pitch-catch shear wave pair of probes. The Appendix G takes up 3 pages of the Code and provides no practical assurance whereas the Transfer Value is a simple and practical technique that has been used around the world for decades and would be an ideal option to indicate a standarised method of compensation going from flat to durved surfaces.

 
 Reply 
 
Stuart Kenny
Stuart Kenny
16:01 Oct-08-2010
Re: SDH
In Reply to Ed Ginzel at 17:04 Dec-26-2009 .

Hi folks,

Appreciate this a late response to this thread, but I have a particular interest in this subject. I am wondering has anybody any advise for pipe weld ASME calibration blocks when using PA? In my opinion, it is imperative to use SDH's for sensitivity and TCG calibration when using phased array systems, but how do we get around the issue of machining SDH's into curved calibration blocks?

As ASME V states that the reflectors covered in article four are recommended practice and not mandatory, my thoughts are to use a flat calibration block with SDH's to calibrate (IOW or the basic ASME block) and then check adequate sensitivity by scanning the curved calibration block with notches (FIG. T-434.3)? Has anybody got any thoughts on getting around this?

 
 Reply 
 
Roger Duwe
NDT Inspector, API-510, 570, 653
MISTRAS, USA, Joined Jan 2009, 148

Roger Duwe

NDT Inspector, API-510, 570, 653
MISTRAS,
USA,
Joined Jan 2009
148
20:46 Oct-11-2010
Re: SDH
In Reply to Stuart Kenny at 16:01 Oct-08-2010 .

What works well for me is to establish my PA DAC curve using SDH's, typically using the PHTool PACS block, to cover a range greater that one full skip distance. Then I compare that cal with the ID and OD notches on a pipe of similar size. If a transfer coefficient is needed [usually isn't] I put it in by hand.

 
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