UT Ultrasonic testing (UT)
Ultrasonic testing (UT) · Inspección y ensayos · ISO 1101 + ASME Y14.5
Example in plan
How to interpret it
On the drawing, “UT ISO 16810 on cast valve body” states a ultrasonic testing (ut) requirement.
What controls
Volumetric test that introduces ultrasonic waves into the material and analyzes the echoes to detect internal discontinuities and measure thickness. It provides depth information, which makes it possible to locate the defect within the part, and it does not require access from both sides. Its capability depends heavily on geometry, material grain structure and defect orientation: an unfavorably oriented planar discontinuity can go undetected.
How to verify
Probe and angle chosen according to the type and expected orientation of the defect, prior calibration on reference blocks, scanning per the procedure and evaluation of echoes against a reference curve or level. Indications are located by depth and position, sized and compared against the acceptance criterion. Qualified personnel, a written procedure and a record with the calibration parameters are all part of the test.
Common mistakes when interpreting it
- Declaring the part sound without checking that the setup was capable of detecting defects in that orientation.
- Using the equipment without calibrating on reference blocks of the same material and thickness.
- Applying it to coarse-grained materials and expecting the same sensitivity as on forged steel.
How to get it in the workshop / if it comes out of tolerance
It requires a reasonably smooth, clean surface to couple the probe and a suitable couplant. In coarse-grained castings and some austenitic steels, attenuation and background noise severely limit what can be seen. The equipment must be calibrated on reference blocks of the same material and thickness before each session; switching it on is not enough.
Loss of signal or erratic echoes: insufficient coupling, irregular surface or attenuation due to coarse material grain. Doubtful indications: change the beam angle to see whether the indication persists, which is the practical way to tell a real defect from a geometric effect. If the material does not allow a reliable test, the volumetric alternative is radiography, and that has to be decided before committing to a delivery date.
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