(36c) Ethylene Product Pump Mechanical Seal Upgrade – Lessons Learned

LyondellBasell’s Corpus Christi Olefins unit experienced an increased number of seal failures during a plan 11/72/76 seal upgrade (originally an 11/52) on their ethylene product pump. These failures were originally attributed to contamination in the seal flush that built up inside the seal. Ultimately two sources of contamination were identified; 1) iron oxide that resulted from a lengthy outage with equipment open to atmosphere, and 2) internally generated polymer from local seal face hot spots exceeding the ethylene decomposition temperature.
Additionally, failures were also experience in the secondary seal associated with gradual loss of back pressure and ultimately process leakage. Several modifications were made on an expedited basis with the help of the seal vendor. The modifications that were made to solve the failures will be discussed such that the end results can be used as a template or shortcut for future applications of a similar nature.