As part of an extensive programme on the development of a novel pigging technique using crushed ice, work has been undertaken to investigate the propensity of fluids to mix in ducts when pumped. Experimental work suggests that the ice pig will tend to hold together, be self-healing, and maintain its identity under most flow conditions. The crushed ice making up the pig will tend to form a sharp interface between itself and the fluid following it. Any water resulting from melting ice will tend to be transported to the front of the pig, thus ensuring that the back of the pig will maintain its sharp interface. A simple theoretical model is proposed that is in qualitative agreement with the experimental results. Both experimental data and the proposed model are consistent with the literature. The importance of the self-healing properties of the ice pig is briefly explored.

Experimental work has been carried out to investigate the use of ultrasound in the detection of slurry ice flows within pipes. The work sets out the basis for a novel device that is both portable and adaptable to retrofitting onto existing pipelines. This method of noninvasive pipeline interrogation has applications within many parts of the chemical and process industries. The work described here relates particularly to the use of ultrasound to detect the presence of an ice pig within product pipelines in the food industry. Research has shown that the products tested and the ice slurry have very different ‘sound signatures’. The signals obtained from ultrasonic tests proved to be reproducible, even under dynamic flow conditions. Contamination of products with slush ice was detectable down to the levels of a few per cent of slush ice. The technique was verified for detection of the interface between the product and the ice pig under flow conditions.

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