Abstract: High pressure ammonia pump is an important imported rotating equipment for urea production unit of one company. In order to save production cost, it was decided to have the mechanical seal of the pump domestically manufactured. During the process of domestication of the spare parts, leakage occurred soon after the operation of the mechanical seal of the pump. The leakage of the mechanical seal will not only bring hidden danger to the stable operation of the production unit, but also pollute the environment. In serious cases, it can even cause accidents with injuries and deaths. Therefore, during an overhaul, a detailed analysis on the disassembled mechanical seal and the site conditions was carried out to find out the causes of the leakage and the corresponding treatment measures were proposed. The above analysis and treatment measures can provide reference for the treatment of equipment with similar faults.

Key words: high pressure ammonia pump, mechanical seal, leakage, sealing water, O-ring