Abstract: For low-temperature brine refrigeration systems, the double-end mechanical seals in brine transfer pumps were frequent failures due to incompatibility with operational conditions. This paper introduces the failure analysis of the seals and details modification measures. The double-end mechanical seal was replaced with the cartridge-type single-end seal, effectively isolating the corrosive 23% calcium chloride solution. The seal face materials were upgraded to the low-temperature and corrosion-resistant Cemented Carbide-Carbon Graphite. The diameter of the cooling system piping was increased from DN15 to DN20, and the flushing scheme was switched from PLAN 14 to self-flushing PLAN 11. The performance of the cartridge-type single-end mechanical seal was verified through field application. The improved mechanical seal operated with high stability, wherein the stationary and rotating rings formed the precise sealing interface. The spring assembly afforded enough face pressure, and the cooling system effectively dissipated frictional heat and removed impurities. Through optimal design and rigorous maintenance, the mechanical seal achieved long-term zero-leakage operation, significantly enhancing production reliability.