An experimental investigation into the pressure - leakage relationship of some failed water pipes

This paper reports on an experimental study that was conducted to measure the leakage exponents of different types of leak openings (holes, corrosion holes, and longitudinal and circumferential cracks) and pipe materials (asbestos cement, mild steel and uPVC). A number of failed pipes taken from the Johannesburg water distribution system were tested, as well as a number of pipes with artificially induced leaks. The results of the study confirmed that leakage exponents can be significantly higher than the theoretical value of 0.5. While leakage exponents for round holes were close to 0.5, the values for corrosion holes varied between 0.67 and 2.30, for longitudinal cracks between 0.79 and 1.85, and for circumferential cracks between 0.41 and 0.52. Conclusions include that the highest leakage exponents were found in corroded steel pipes and that under certain circumstances, leakage exponents can be less than 0.5.