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 -

Sonatest Ltd
From our three distinct business centres in the UK, USA and CANADA, Sonatest design and produce a leading range of high performance ultrasonic NDT equipment and accessories.

732 views
Technical Discussions
LANRE ALAPINI
NDT Inspector,
NDT TRAINING AND TESTING CENTRE HOUSTON TEXAS USA, Nigeria, Joined Nov 2008, 3

LANRE ALAPINI

NDT Inspector,
NDT TRAINING AND TESTING CENTRE HOUSTON TEXAS USA,
Nigeria,
Joined Nov 2008
3
06:27 Dec-09-2008
flaw checking

can any body explain the term lack of back wall reflection


    
 
 
James Boaden
Sales,
Midas NDT Systems Ltd., United Kingdom, Joined Jun 2002, 6

James Boaden

Sales,
Midas NDT Systems Ltd.,
United Kingdom,
Joined Jun 2002
6
07:00 Dec-09-2008
Re: flaw checking
----------- Start Original Message -----------
: can any body explain the term lack of back wall reflection
------------ End Original Message ------------

Using ultrasonics, a signal is generated that reflects back from the back surface of a component (when generated outside the component some sound reflects off the front surface and some penetrates, this then reflects off the back surface).

You should always get reflections from the back surface unless something stops the sound reaching it. Lack of back wall reflection dictates that a defect has stopped the sound reaching the back surface and the area of lack of back surface will be the same as the planar area of the defect.


    
 
 
S.V.Swamy
Engineering, - Material Testing Inspection & Quality Control
Retired from Nuclear Fuel Complex , India, Joined Feb 2001, 787

S.V.Swamy

Engineering, - Material Testing Inspection & Quality Control
Retired from Nuclear Fuel Complex ,
India,
Joined Feb 2001
787
07:36 Dec-09-2008
Re: flaw checking
----------- Start Original Message -----------
: can any body explain the term lack of back wall reflection
------------ End Original Message ------------

Lack of back wall reflection or echo means that the transducer is not receiving the ultrasound signal reflected from the back surface (opposite side of the test object). This can happen due to one or more of the following reasons:

It is assumed that the instrument and the probe are working and that the range has been calibrated properly.

Very rough surface resulting in poor coupling

Highly curved surface resulting in sound not entering the test object

Lack of parallelism between the test surface and the back surface, for example a wedge

Sintered material with lot of porosity.

We had some interesting experiences while testing hot rolled austenitic stainless steel plates and tungsten-copper blocks. If any one is interested, I will share. Or I may submit a short case study like paper.

Swamy
NDT Guru





    
 
 

Product Spotlight

Research Center IDEKO develops an ultrasonic train wheel inspection system for CAF

The Basque Research centre IK4-IDEKO has developed a state-of-the-art ultrasonic inspection system f
...
or the train wheel. This system secures a sound condition of train wheels and is thus a significant contribution to rail transport safety. The device was delivered to CAF recently and its use allows the manufacturer to become an approved supplier of rolling stock in Italy, as it meets the demanding homologation standards of this country. \\\\r\\\\n
>

FAAST-PA! OEM Patented phased Array for high speed UT inspection

Multiangle, Multifocus, Multifrequency, Multibeam. Instead of stacking UT electronics and having m
...
any PA probes, FAAST-PA is able to transmit all delay laws within ONE single shot in Real time.
>

Semi-Automated Phased Array Immersion System for Small Composite Parts

Turn-key semi-automated system as an improved and affordable solution for inspection of small comp
...
osite parts. Includes support table, immersion tank, scanner, PA instrument, PC, Analysis software, database, wedge management and other options.
>

IntraPhase Athena Phased Array System

The Athena Phased Array system, manufactured by WesDyne NDE Products & Technology, consists of a pha
...
sed array acquisition system and PC running IntraSpect software. A PC is used to perform acquisition, analysis and storage of the data. System hardware is capable of operating up to four data sets with any combination of phased array or conventional UT probes. NOW AVAILABLE IN 64-64 CONFIGURATION.
>

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