Apparatus, systems, and methods for non-invasive measurement of flow in a high temperature pipe

An apparatus, comprising:

• first and second waveguides adapted to be connected to a pipe;
• and
• first and second transducers adapted to be connected to the first and second waveguides, respectively, and to exchange ultrasonic wave signals through the first and second waveguides, the pipe, and a fluid flowing in the pipe;
• wherein a temperature of the fluid flowing in the pipe exceeds about 600° C.;
• and
• wherein the first and second waveguides are configured so that, when the first and second transducers are connected to the first and second waveguides, respectively, and
• the first and second waveguides are connected to the pipe:
• the first and second waveguides insulate the first and second transducers from the pipe thereby causing a working temperature of the first and second transducers to be maintained below a first threshold despite the temperature of the fluid flowing in the pipe exceeding about 600+ C., above which first threshold the working temperature would cause the first and second transducers to fail;
• and
• the first and second waveguides maintain an acoustic attenuation of the ultrasonic wave signals below a second threshold thereby permitting propagation of the ultrasonic wave signals between the pipe and the first and second transducers, respectively, in a manner that does not adversely affect the ability of the first and second transducers to exchange the ultrasonic wave signals despite the temperature of the fluid flowing in the pipe exceeding about 600° C., above which second threshold the acoustic attenuation would prevent propagation of the ultrasonic wave signals in said manner.