Relative Attenuation Measurement - Olympus EPOCH 650 User Manual

To adjust the registration level
 Choose DGS/AVG > Reg Level to adjust the current registration-level value.
11.3.6

Relative Attenuation Measurement

There are several methods for measuring the ultrasonic attenuation within a material.
Often the procedure measures absolute attenuation in a material. This usually
requires an immersion test setup and a time-consuming set of measurements. For the
purpose of flaw sizing with the DGS/AVG method, it might be suitable in many
conditions to measure relative attenuation in the test piece or calibration block as
needed. This section outlines one simple method of relative attenuation measurement
that is generally effective. Perhaps there are more suitable methods available. You
must decide the most appropriate method to arrive at the values for ACV Specimen
and ACV Cal Block based on the application and local requirements.
Measurements:
∆ Vg = Gain difference between two successive back-wall echoes (d and 2d)
∆ Ve = From DGS/AVG diagram. Gain difference on back wall curve from d to 2d
Calculations:
Sound attenuation coefficient:
11.4 AWS D1.1/D1.5 Weld Rating Software
The AWS D1.1 software feature for the EPOCH 650 ultrasonic flaw detector has been
created to assist you in performing inspections covered under the American Welding
Society D1.1 (or D1.5) Structural Welding code for steel. This code provides inspectors
with a method to classify discontinuities found in welds using ultrasonic inspection.
This code uses the following formula to develop an indication rating for a reflector
found during an inspection:
∆ Vs = ∆ Vg − ∆ Ve [mm]
α = ∆ Vs / 2d * 1000 [dB/m]
A − B − C = D
Software Features and Options
DMTA-10055-01EN, Rev. A, February 2015
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