Evaluation of Mechanical Properties of High-Density Polyethylene Pipes Used in Water Distribution in Kano State

High-density polyethylene pipes are widely used in water distribution infrastructure across Nigerian states owing to their corrosion resistance, flexibility, and relatively low cost. This study evaluates the mechanical properties of HDPE pipes installed in water distribution networks across selected communities in Kano State, North West Nigeria, with emphasis on determining whether service conditions affect long-term material performance. Pipe samples of varying service ages, ranging from two to fifteen years, were retrieved from decommissioned segments and subjected to tensile testing, hardness measurement, and notched impact testing in accordance with relevant ASTM standards. Differential scanning calorimetry was also performed to assess crystallinity changes associated with thermal aging. Results indicate a progressive decline in elongation at break with increasing service age, from 620 percent in new pipes to 390 percent after fifteen years of service. Tensile strength showed modest reduction, while hardness increased marginally, suggesting embrittlement linked to photo-oxidative degradation under prolonged ultraviolet exposure during storage and installation. Crystallinity measurements confirmed increased crystalline fraction in aged samples. Despite measurable property changes, most aged pipes retained mechanical performance within acceptable operational thresholds for low-pressure distribution networks. The study concludes that HDPE pipes remain structurally viable for the service conditions prevalent in North West Nigeria but recommends improved storage practices and ultraviolet stabiliser specifications during procurement. Findings provide useful data for infrastructure planning agencies and water utility operators in Kano State. Keywords: HDPE pipes, mechanical properties, water distribution, thermal aging, Kano