Design and development of water-immersible two-channel high-voltage spike pulser for under-water inspection and gauging of pipes.

Abstract

A water-immersible two-channel high-voltage (HV) spike pulser has been designed, developed, and mounted inside the IP 67 (Ingress Protection 67) grade enclosure, and it is suitable for the ultrasonic Pipe Inspection and Gauging (PIG) system utilized in the petrochemical industry. Such a critical and strategic application requires a portable, miniaturized, and water-immersible water-tight pulser module, which resides inside the pipe carrying water or liquid petrochemicals. The developed spike pulser printed circuit board (PCB) generates a HV negative spike pulse up to -300V and 100ns half-amplitude pulse width, required for the energization of ultrasonic immersion transducers of 5-10MHz frequency. The water-immersible pulser is mounted inside the water-tight IP 67 grade enclosure, and it is operated through an external DC power supply/lithium batteries. The evaluation of the module was carried out using a two-channel water-immersible HV spike pulser, in-house developed preamplifier, and inspection head supported by four sets of spring-loaded Teflon balls for centering, and the inspection head carries two ultrasonic immersion transducers placed 180° apart and a sample SS pipe with a length of 400mm, Inner Diameter of 200mm, and Wall Thickness of 9mm. The two-channel pulser module was evaluated in water to measure the dimensions of the sample SS pipe. This two-channel water-immersible novel spike pulser has dedicated circuitry, and each channel is a standalone PCB and it operates through external LV and HV DC supplies. The module can be scaled up to 256 channels for dimension measurement and flaw detection of long length pipes. In the absence of any literature available on the water-immersible pulser for PIG systems, the present two-channel pulser module has been designed and developed, and the module was evaluated by gauging of the SS pipe from inside. This paper provides the details of the water-immersible HV spike pulser module suitable for the gauging of metallic pipes.