where expertise comes together - since 1996 -

The Largest Open Access Portal of Nondestructive Testing (NDT)

Conference Proceedings, Articles, News, Exhibition, Forum, Network and more

where expertise comes together
- since 1996 -

Modsonic Instruments Mfg Co Pvt Ltd
We are leading Indian manufacturer and exporter of portable “Ultrasonic Testing Equipment” offering comprehensive range of Ultrasonic Fla ...
596 views
Technical Discussions
Doug Mendes
NDT Inspector, R & D
Imetrix Inc., USA, Joined Oct 1999, 7

Doug Mendes

NDT Inspector, R & D
Imetrix Inc.,
USA,
Joined Oct 1999
7
09:18 Dec-08-1999
Double hulled structures

I'm interested in using ultrasonics to inspect a structure that has two steel plates which have a water path between the two plates. I need to inspect one of the plates for corrosion and pitting through the water column and the other plate. I only have access to one side of this structure which complicated matters. The plates are less than 1/2'' (12.7mm) thick but the water path is unknown. My question is could this inspection be performed and what if any special equipment would be needed? The water path would be known before the inspection. Any help would be grreatly appreciated.


 
 Reply 
 
M. William Moyer
M. William Moyer
02:17 Dec-08-1999
Re: Double hulled structures
Another approach is to use a pitch catch setup, particularly if you are inspecting in immersion. Set up the transducers for 45 deg
shear in the steel. The spacing should be such that you can geometrically focus the transducer array at about 3-4 inches (for 0.5 inch steel).
Move the transducer pair toward the part until they are geometrically focused on the back surface of the first hull. This signal will peak up. Then
continue to move in until you are focused on the surface of interest. Because of the angles, the multiple reflections will be very small and only the
signal of interest will be seen. This technique works well on many multilayer inspections.
The technique is described in "Ultrasonic Inspection Using the Pitch-Catch Technique," M. W. Moyer,Materials Evaluation, Vol 37, Number 5, April, 1979,
pg. 51.

M. William Moyer
ult@y12.doe.gov.

:
: : I'm interested in using ultrasonics to inspect a structure that has two steel plates which have a water path between the two plates. I need to inspect one of the plates for corrosion and pitting through the water column and the other plate. I only have access to one side of this structure which complicated matters. The plates are less than 1/2'' (12.7mm) thick but the water path is unknown. My question is could this inspection be performed and what if any special equipment would be needed? The water path would be known before the inspection. Any help would be grreatly appreciated.

: This is an application that we've run into on several previous occasions, with mixed results. The biggest complication is that multiple echoes from the outer plate and the water gap will be superimposed over the echoes from the near and far wall of the inner plate. Whether this will be a major problem or just an annoyance will depend on the exact thickness of the outer plate and the exact length of the water path and thus the spacing of the echoes. If you're lucky, the echoes from the inner plate will occur between, rather than on top of, other signals. (But Murphy's Law usually insures that everything will be superimposed!)

: In that case, you might investigate the possibility of using digital signal processing to subtract the outer plate and water path echoes from the wave train. Unfortunately, that too gets complicated if the outer plate thickness and water gap length are varying from point to point, since that will change the wave pattern that you need to subtract.

: --Tom Nelligan




 
 Reply 
 

Product Spotlight

YXLON Cougar EVO

Scalable small footprint X-ray inspection systems for assembly and laboratory applications. The
...
YXLON Cougar EVO series was designed to provide the "best-in- class" inspection solutions for SMT, semiconductor, and laboratory assembly applications, while maintaining a small system footprint for maximum convenience. With optimized software and hardware, these systems produce higher quality and more consistent results than other electronics inspection systems currently on the market.
>

32:128PR PAUT & 2-ch TOFD Flaw Detector: SyncScan 2

●32:128PR PAUT with optional 2-ch TOFD to maximize your efficiency ●Support PR mode for corrosi
...
on inspection ●Multiple solutions for welds & corrosion ●Faster scan speed (Approximately 3 meters/minute) ●Light weight: 4kg only including battery
>

Compact NDT inspection-heads for measurements with active thermography

The compact inspection head is suitable for thermographic ndt tasks. The uncooled infrared camera
...
is specially developed for NDI-tasks and offers a thermal sensitivity until now known only from thermal imagers with cooled detector. All required components and functions are integrated into the inspection-head. You will only need an ethernet cable to connect the sensor with the evaluation system.
>

CIVA 2020 UT Module

CIVA NDE Simulation Software is the world leader of NDT Simulation. The UT simulation Module incl
...
udes: - "Beam computation": Beam propagation simulation - "Inspection Simulation": Beam interaction with flaws or specimens The user can simulate a whole inspection process (pulse echo, tandem or TOFD) with a wide range of probes (conventional, Phased- arrays or EMAT), components, and flaws.
>

Share...
We use technical and analytics cookies to ensure that we will give you the best experience of our website - More Info
Accept
top
this is debug window