RT vs UT

Date 10-28-2008 19:12

Sammi,
Though they are both volumetric NDE methods, it is almost like comparing apples to oranges. The relative "accuracy" depends on many, many factors. In order to get a better answer you should provide more detailed information on what exactly is your examination need.
Mankenberg

By SammyShine (**)

Date 10-28-2008 21:26

If there are imperfections, will UT testing results be the same as RT results? Are both test equally as a thorough?

If we know a weld will not pass RT...

Could it pass UT?

By Noel Tan (**)

Date 10-29-2008 01:12

SammyShine,

UT and RT results in some cases cannot be the same, that is why we perform sometimes both UT and RT together for the same joint.
Just because two of them having different limitation.
for example:
porosity in UT might not cause rejection but RT may.
crack/lamination orientated perpendicular to the RT source radiation direction will not show any indication but UT does.
UT could tell the defect depth but RT does not.
blah...blah...blah...

Regards,
Noel

By SammyShine (**)

Date 10-29-2008 02:10

Thank you...actually, your answer helps a lot.

By BamaDave (**)

Date 11-06-2008 18:00

Using a truly qualified and certified "Shear Wave" UT technician can detect flaws equal to RT results in many cases. The beauty to UT is it's much faster and not limiter to thickness and/or configuration.

David

By hogan

Date 11-06-2008 19:58

And in many cases the tech can not

By SammyShine (**)

Date 11-07-2008 03:45

So Hogan...are you saying that UT is not as exact?

Ot that there aren't many good tech's?

By RonG

Date 11-07-2008 15:20

Yes UT can be very exact, even straight beam. We have an acceptance critera of 1/32" flat botom hole with in 1" sq.
When you get to Shear wave and Phase array you leave RT pretty much in the dust dealing with heavy mass's.

By hogan

Date 11-07-2008 16:09

SammyShine,
One example, when dealing with shear wave, is porosity that will fail on RT can pass with UT. Due to the ability of RT to see round indications and the difficulty, regardless of the tech's ability, to get a reflection to return with shear wave. But as RonG has stated, phased array will typically provide a more accurate examination.

By Metarinka (****)

Date 11-07-2008 19:56

they both have there pros and cons. Accuracy is defined in different terms under each process, and is further impacted by the material configuration to be inspected. It is impossible to say that one process is more accurate than others across the board. In order to pick the correct process one must consider all variables as well as anticipate the types of defects that would be present in the specimen.

It would also help if you defined what type of accuracy you are looking for. resolving power (minimum size defect that can be found), positioning accuracy. Repetability etc.