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DEVELOPMENT OF LOW-POWER EMAT INSTRUMENTATION FOR IN-SERVICE CORROSION INSPECTION AND MONITORING IN HIGH TEMPERATURE ASSETS

Periodic Reporting for period 1 - LOPEMAT (DEVELOPMENT OF LOW-POWER EMAT INSTRUMENTATION FOR IN-SERVICE CORROSION INSPECTION AND MONITORING IN HIGH TEMPERATURE ASSETS)

Reporting period: 2020-09-07 to 2021-09-06

EMAT is an advanced couplant-free ultrasonic technology that overcomes the achilles heel of conventional ultrasonic testing (UT), transferring energy from the probe into the material inspected. Unlike UT, EMAT does not require couplant nor direct contact with the target surface, making the technology ideal for field-use and automation. Unlike UT, EMAT does not require couplant nor direct contact with the target surface, making the technology ideal for field-use and automation. EMATs do not suffer from curie temperature limitations as in conventional PZT ultrasonic elements. Furthermore, as EMAT transducers can work while remaining slightly separate from the surface under inspection, these are able to withstand high temperatures allowing for in-service inspection and monitoring of assets in working conditions.
The biggest drawback of this technology is its high-power consumption, which in turn leads to bulky instrumentation and higher pricing when compared to conventional ultrasonic devices. LOPEMAT project tackles this challenge, paving the way to a new generation of ultrasonic EMAT technology through the development of the first line of Low-Power EMAT systems.
The main goal of the LOPEMAT project is to develop and validate a first working prototype of low-power EMAT system for normal beam and guided wave generation. In line with the trend to make technology cheaper, lighter and more efficient, recent publications have shown it feasible to generate EMAT bursts with a far lower excitation, both in terms of power and voltage, using a combination of advanced signal processing techniques such as binary quantization and coded excitation. Such a change in power consumption could constitute a total gamechanger in the field, allowing for cheaper and lighter EMAT instruments, no bigger than a smartphone, that could be powered trough a power-bank or USB port, and could compete with conventional ultrasonic devices across the whole range of NDT applications.
The project work plan is divided in three main blocks, a first one dedicated to training the new associate, a second one in which the associate use all his knowledge and skills to assist in the development the new low power EMAT solution, and a third one dealing with project management tasks.
The training tasks have all been successfully completed with some minor deviations mainly due to the effects of the COVID19 pandemic.

Once the training activities were successfully completed, the associate tackled the development tasks starting with a review of the state of the art, which was followed by hands-on experimentation.
The associate lead the definition of requirements and selection of a new equipment which improved lab capabilities. Once all lab equipment was in order, the associate concentrated in assisting the design of the hardware boards for the new prototype together with the new algorithms required to operate at such low voltage.
The combined development gave birth to a coarse prototype of the final system that could be used to stimulate ultrasounds in a metal plate and get the first readings.
The initial trials returned signals which contained quite a lot of noise, although showing some structure which indicated that the system was capturing information.
Further developments resulted in a drastic improvement in the quality of the signal, reducing the signal to noise ratio, and enabling the successful inspection of metallic plates.
All objectives have been successfully achieved.
The state of the art claims good results at voltages below 5V, therefore, the project did not manage to improve on the theoretical state of the art, although the results succeed to provide the basis for a future low power EMAT solution.
The company will continue the efforts to complete and improve the prototype so that it becomes Innerspec´s low power EMAT commercial solution in the near future.
LOPEMAT pulser prototype