DEVELOPMENT OF ON-LINE, HIGH TEMPERATURE, NON-DESTRUCTIVE MEASUREMENT/SENSING TECHNIQUES DURING MANUFACTURING OF POWER PLANT COMPONENTS

The Centre for Nondestructive Evaluation (CNDE) at Indian Institute of Technology Madras (IITM) in collaboration with the Centre for Industrial Ultrasonics (CIU) at the Department of Physics and School of Engineering at the University of Warwick (UW), will develop new next generation sensing and measurement technologies that will bring a paradigm change in the ability to control the manufacturing processes of power plant components. Bharat Heavy Electricals Limited (BHEL), is the largest manufacturer of power plant boilers in Asia, and will be the key industry partner. A key priority and requirement for BHEL is the online, in-process, high-temperature measurement of weld quality of steel tubes. The ability to perform NDT on welds during manufacture will improve production efficiency and the manufacturing process, but more importantly will lead to the production of higher quality and safer plant. BHEL has evaluated currently available technologies and has found that they are not capable of performing pipe weld inspection in process, at high temperatures. This project will establishing a new scientific approach to the inspection of pipe welds using ultrasonic guided waves over a "medium range" in a tomographic type approach[1], where the ultrasonic transducers are tens of centimetres away from the weld. The nature of the project combines the complementary expertise of CNDE, CIU and BHEL, to provide a measurement solution for an industrial manufacturing process that has applications in a diverse range of manufacturing industries. The work effort is defined in the form of work packages which will involve the three partners in collaboration, exchange of scientists and engineers, utilizing the expertise of each group and transferring knowledge between the three organisations. A complete suite of new ultrasonic transducer technologies will be developed using electromagnetic acoustic transducers (EMATs)[2], piezo-electric transducer rings[3], and laser-ultrasonic methods, to cover a wide range of application conditions. When the transducers must operate at high temperatures, or when the manufacturing process makes it difficult to reliably and accurately deploy contact transducers to the pipe, EMATs will be used. Where it is possible to deploy piezoelectric transducer rings, then these shall be used as they are significantly more efficient and sensitive than EMATs. Laser Ultrasonic methods permit a remote method for generation and detection of ultrasonic wave modes, particularly at high temperatures. Because a wide range of pipe materials, sizes and manufacturing process are used, we will need to create new transducers and inspection processes using both types of transducers. The NDE technologies for high temperature measurements proposed here also potentially benefit other manufacturing processes at BHEL and elsewhere. It is also envisaged that the collaborative effort will contribute to improving scientific skills in the area of sensing technologies for manufacturing in both countries. The proposed collaborative research duration under this program is for a period of 36 months.

With increasing energy requirements under constraints of depleting natural resources and environmental concerns, power plant industries worldwide are faced with unprecedented demands for improving the efficiency and volumes of manufacturing at both component and unit levels. Coupled with the critical need to ensure quality and safety of manufactured pipe components whose failure in-service failure could lead to catastrophic consequences, reliable online inspection methods for manufacturing process are crucial for improved efficiencies. This project will address one key aspect of this need, namely the improved inspection of pipe welds during manufacture.