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 -

Technical Discussions
NDT Inspector,
QTech Instutitu of Nondistractive Testing, India, Joined Sep 2009, 1


NDT Inspector,
QTech Instutitu of Nondistractive Testing,
Joined Sep 2009
19:21 Sep-29-2009
what is mean by tandam echo

dear sir
i am work in forging company
some doutful question in UT what is mean by tandam echo

Peter Bruckner
NDT Inspector, NDT Manager
United Kingdom, Joined Jul 2008, 19

Peter Bruckner

NDT Inspector, NDT Manager
United Kingdom,
Joined Jul 2008
23:08 Sep-29-2009
Re: what is mean by tandam echo
In Reply to Ramalingam at 19:21 Sep-29-2009 (Opening).

Hi Ramalingam,
Usually tandem testing involves 2 identical shear wave probes facing the same direction on the surface of the bar a fixed distance apart. The distance between the probes is 1/2 skip, for 45 degree probe that is the thickness or diameter of the bar under test.
The only type of defect this will find is a planar one transverse to the beam at 1/2 thickness/diameter. The test standard usually consists of a flat bottomed hole drilled in the end of the bar.

I hope this is of some assistance.

Uli Mletzko
R & D, Retired
Germany, Joined Nov 1998, 89

Uli Mletzko

R & D, Retired
Joined Nov 1998
11:44 Sep-30-2009
Re: what is mean by tandam echo
In Reply to Peter Bruckner at 23:08 Sep-29-2009 .

Hi Peter and Ramalingam,

the expression 'tandem' originates from a bicycle type for two persons, where the second person is sitting behind the first, both looking into the forward direction, and both pedaling.

In UT the distance between the two probes is not limited to 1/2 skip, but usually ist smaller than full skip. In testing of medium and heavy wall nuclear components, tandem is a standard system at least in Germany. We have arrangements of e.g. 3, 4 or 5 or more probes, each behind the other. Usually one probe acts as transmitter, the other ones as receivers. All sound pathes are reflecting on the surface opposite to the probe system, so in general you can inspect only components with parallel or coaxial surfaces. Using more than two probes will split the cross section to be inspected into several layers.

The presumed defects at tandem UT are not transverse to the sound beam, but perpendicular to the surface.

As far as I can remember, tandem UT was invented about 1970 by the German institutes and companies BAm and/or AEG, MAN and Siemens.

Uli Mletzko (retired, from MPA/University of Stuttgart/Germany)


Product Spotlight

Research and Applications Development For NDT

The Research and Applications Development (RAD) group is a newly formed team within Acuren dedicat
ed to tackling challenging inspection problems. Our focus is the development of novel, field deployable, advanced inspection techniques for use in cases where standard NDT methods are ineffective. We don't wait for new innovations, we engineer them. From concept to commissioning.

Ultrasonic tomograph for imaging of concrete structures А1040 MIRA

Applicable for concrete inspection allowing imaging of the internal structure of objects from conc
rete, reinforced concrete, different stones. The operation applies pulse-echo technique at one-side access to the object. The instrument is feasible for concrete inspection for searching conduct ducts, conduits, detection of foreign inclusions, holes, honeycombing, cracks and other concrete defects.

IRIS 9000Plus - Introducing the next generation of heat exchanger inspection.

Representing the seventh generation of the IRIS system, the IRIS 9000 Plus has nearly 200 years of c
ombined field inspection experience incorporated in its design. This experience combined with a strong commitment to quality and a history of innovation has made Iris Inspection Services® the undisputed leader in IRIS technology.

X-ray CT aids research into defect formation in AM parts

X-ray CT is used to research how additive manufacturing process parameters influence defect format
ion in AM parts.

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