Clad Pipe - Metallurgically Bonded
How accurate can you measure the wall thickness using a zero degree probe on Clad pipe? Would you adopt a 2Mhz or 5Mhz zero degree probe? Is there an alterantive?
|Tom Nelligan |
retired, USA, Joined Nov 1998, 390
Re: Clad Pipe - Metallurgically Bonded First, I assume that your total pipe thickness is under an inch or so with the cladding representing 25% or less of the total thickness.
With a properly set up precision thickness gage like a Panametrics-NDT Model 35 and an appropriate contact transducer, we can normally measure metal pipe wall thickness to an accuracy of +/- 0.001" or better. However in this sort of case the measurement accuracy is potentially affected by the small difference in sound velocity between the cladding and the base metal. The effective sound velocity of a two-metal sandwich is the weighted average of the velocities of the two metals. As the thickness of one or the other varies, changing the ratio between them, the composite velocity varies too. Because the accuracy of any ultrasonic thickness measurement is only as good as the velocity calibration, this introduces some uncertainty.
If you know the sound velocity of the cladding and the substrate, and the range of thickness for each, then you can easily calculate the worst-case uncertainty. Calculate the weighted average velocity of the sandwich, and then calculate the error that would result from measuring either of the two metals alone over the appropriate thickness range. That's your absolute worst case, which you're unlikely to ever see. As a practical matter, velocities of typical claddings like inconel and substrates like carbon steel alloys are within 5% of each other, and the substrate metal will always be the majority of your sound path, so in practice the potential uncertainly seldom exceeds a couple percent.
I'd have to know the specific thickness range involved to recommend an optimum transducer, but assuming a maximum thickness around an inch, a 5 MHz, 0.5" diameter contact transducer would be my first choice.
Corrosion gages and flaw detectors will be slightly less accurate than precision gages, but only on the order of +/- 0.002" with proper setup, so the potential velocity variation is still the limiting factor for accuracy.
|Neil Burleigh |
Krautkramer Australia Pty Ltd, Australia, Joined Dec 2002, 152
Re: Clad Pipe - Metallurgically Bonded The 1st series questions we would ask would relate to the material type of the cladding. Is it ferrous or non ferrous? Is the clad material coarse grained? Is there much difference acoustically between the clad material and the base material?
Next we would be asking do you want to measure the total thickness, just the clad thickness or the thickness of the base pipe?
We would need to look at all these factors before even considering your questions.
----------- Start Original Message -----------
: How accurate can you measure the wall thickness using a zero degree probe on Clad pipe? Would you adopt a 2Mhz or 5Mhz zero degree probe? Is there an alterantive?
------------ End Original Message ------------
Teletest Focus+ electronics have superior capabilities than rivals on
the market. Beyond the usual
test features, Focus+ has 24 transmit
channels and 24 receive channels, with an additional on-board
switching capabilities. The instrument's frequency range is 10–300
GEKKO, Standard and Advanced phased-array for Easier inspection
With a 64-channel parallel architecture, GEKKO is a flaw detector
offering at the same time conven
tional UT, standard PAUT, TOFD and
real-time Total Focusing Method (TFM). GEKKO improves the
detection, with better defects characterization
and sizing as well as for misoriented defects.
Some procedures require standard UT, others TOFD or PA. GEKKO
includes all these techniques to offer a versatile and field-ready
- 64:64 parallel channels
- + 4 additional TOFD
- Conventional UT channels
- International code compliance: ASME, AWS, API, ASTM, ISO-EN
Watch the video: https://youtu.be/kuEY_RwWS3Q
Next generation for Phased Array UT is here now with FMC/TFM! Have higher
resolution imaging, impr
oved signal to noise ratio, characterize, size and analyze
defects better with access to several wave mode views and save raw FMC data for
higher quality analysis. Some of the benefits are:
- Beautiful Image! Easier to understand what you're looking at
- Completely focused in entire image or volume
- Much easier to define setups before inspection
- Easier to decipher geometry echoes from real defects
- Oriented defects (e.g. cracks) are imaged better
- See image from different wave modes from one FMC inspection
- FMC data can be reprocessed/analyzed without going back to the field
HD-CR 35 NDT Computed Radiography System
Portable high-resolution CR scanner for all radiography applications - weld testing, profile images
and aerospace. No matter what type of radiographic testing you are performing, the unique TreFoc Technology of the HD-CR 35 NDT imaging plate scanner always guarantees the highest image quality.