DMTA-10040-01EN, Rev. E, February 2018
Using the Instrument
215
Figure 5
‑
134 The list of all parameters
5.3.3
Inspecting Heat Exchanger Tubing Using Dual Frequency —
NORTEC 600D Model
The procedure in this section uses the dual frequency function to remove the heat
exchanger’s tube-support signal in order to obtain cleaner readings of possible flaws
at support locations. You can use this procedure on any type of heat exchanger tubing
as long as it is non-ferromagnetic. Although this procedure has been prepared using a
differential bobbin probe, other types of tube probe coils can also easily be used; for
example, differential pancake coils for air conditioner tubing. Several tips for absolute
measurements have been provided at the end of this section.
The frequency calculation for the prime frequency should follow the ASME standard
or be based on obtaining at least a 90° phase lag between the thru-wall hole and the
20 % outside flat-bottom holes. The following formula is also recommended:
Prime frequency = 5 × resistivity / (wall thickness)
2
where
•
Resistivity is in micro-ohm centimeters (µ
Ω
-cm);
•
Wall thickness is in millimeters (mm); and
•
Frequency is in kilohertz (kHz).
Summary of Contents for nortec 600
Page 8: ...DMTA 10040 01EN Rev E February 2018 Table of Contents viii...
Page 16: ...DMTA 10040 01EN Rev E February 2018 Labels and Symbols 6...
Page 30: ...DMTA 10040 01EN Rev E February 2018 Introduction 20...
Page 58: ...DMTA 10040 01EN Rev E February 2018 Chapter 1 48...
Page 71: ...DMTA 10040 01EN Rev E February 2018 Software User Interface 61 Press the Return key to exit...
Page 72: ...DMTA 10040 01EN Rev E February 2018 Chapter 2 62...
Page 342: ...DMTA 10040 01EN Rev E February 2018 Chapter 7 332...
Page 356: ...DMTA 10040 01EN Rev E February 2018 Appendix B 346...
Page 366: ...DMTA 10040 01EN Rev E February 2018 List of Figures 356...
Page 368: ...DMTA 10040 01EN Rev E February 2018 List of Tables 358...
