UT minimun thickness

Question

UT minimun thickness

Joss10 (Mechanical)

(OP)

14 Mar 17 21:07

Dear all,
My contractor is telling me that conventional UT examination is not feasible on piping welds less than 9 mm. thickness.
Is that right?

Thanks for any input.

SectionIX (Petroleum) · Answer 1 · 2017-03-15 09:30:12

Probability of detection is dependent on several factors including but not limited to material type, thickness, outside diameter, welding process, expected imperfections, Code/specification acceptance criteria, ultrasonic shear wave/PA equipment, and technician experience.

I don't agree with the contractor, however, you didn't state the application. I would ask them for an explanation.

brimmer (Petroleum) · Answer 2 · 2017-03-15 16:08:54

WTF??? Your contractor is out to lunch.... Most of the pipelines I'm involved with have a wall thickness less than 9mm, but yet we do UT everyday on the welds... Get another contractor, one that is competent, without knowing all the details here...

DekDee (Petroleum) · Answer 3 · 2017-03-16 02:39:49

The contractor has said it is not "feasible" - they have not said it is not possible.
UT under 9 mm thickness is performed daily all over the world.
However, some codes require special procedures to be qualified for 8 mm and under and maybe the additional time or cost of developing these procedures leads the contractor to state it is not "feasible ?
Cheers,
Shane

Joss10 (Mechanical) · Answer 4 · 2017-03-16 09:15:36

Dear mates,
Allways keep in mind are talking about "conventional UT", neither phased array nor automatic or whatever more sofisticated.
Thanks for all input.

metengr (Materials) · Answer 5 · 2017-03-16 15:48:38

Keep in mind that Section I of ASME B&PV does not permit UT below 1/2" thickness. Also, keep in mid a code case was passed to allow the minimum thickness for UT to 1/4".

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UT minimun thickness