Double-ice-plug freezing using liquid nitrogen for water pipe repairs

Accidentally a new method of water pipe repairs using liquid nitrogen freezing was discovered in 2008. Freezing water creates an ice plug to stop water flow. The new method uses double-ice-plug freezing instead of the world widely used single-ice-plug freezing. We have investigated the static sliding (shear) friction between the water pipe and the frozen ice-plug(s). The proposed method significantly increases water pressure in order to stop water flow. The experimented result shows that the ice adhesive strength of double-ice-plug freezing is roughly four times higher than that of single-ice-plug freezing. The unfrozen part of the water pipe plays a key role for achieving the high ice adhesive strength by taking advantage of water expansion upon freezing. The brief results were published in Science Advances. Further results are detailed in this note.