Causes of Aging Cracking of Rubber Expansion Joint Used for Nuclear Power Plants

The penetrating cracking of rubber expansion joint used in the water system of emergency diesel engine in a nuclear power plant led to leakage. Using ultra-depth of field three-dimensional microscope and electronic universal material testing machine, the causes of aging and cracking of rubber expansion joint were analyzed from the aspects of mechanical properties, morphological characteristics and environmental factors. The results showed that rubber expansion joint materials had the problem of mixed use. Under the combined action of hot air, water and external forces, the deterioration of mechanical properties of the rubber led to serious aging. Under the periodic action of external forces, the rubber eventually underwent penetration cracking.