Papers # 2016 Berlin
Inspection of non-metallic materials is becoming more important as more and more non-metallic materials are used in various applications. One method for inspecting this non-metallic material is by electromagnetic radiation in the 1GHz to 100 GHz range, or microwave energy. Microwaves interact with material in a fundamentally different way than other energies and thus, represent a unique inspection opportunity
As the use of HDPE pipe continues to grow, the piping is being applied to more and more diverse situations and applications. In some of these applications, the failure of a fusion joint may have severe consequences. As a result, the use of various nondestructive examination techniques to determine the quality of the fusion joint and piping has recently attracted more interest throughout the industry. Among these methods is the use of electromagnetic radiation in the 3 to 50 GHz region, or microwave energy, to inspect the pipe and fusion joints and create images of both. This method is currently in use in several countries to inspect HDPE butt and electro-fusion as well as the pipe material itself. As the use of this inspection method expands, continuing research on the exact microwave energy interaction with the HDPE material continues to further the interpretation of the results.
This paper reviews several fundamental aspects of microwave interaction with HDPE and how changing external conditions and HDPE processing changes might impact complex permittivity of the HDPE. These changes in complex permittivity are applied to the microwave imaging system and their effect is investigated and discussed. The microwave inspection images and analysis are compared directly to mechanical waisted tensile tests of the samples.