【Equipment Reliability Improvement】Replacing the sliding bearings in the mixing tank from nylon to polytetrafluoroethylene to extend their service life

Thread Content

During operation, due to the operating conditions and the properties of the materials used, some components tend to get damaged frequently, which prevents them from meeting the required performance standards or necessitates frequent repairs and replacements. All of this **reduces the reliability of the equipment’s operation. Through targeted modifications, it is possible to ensure the normal functioning of the equipment.** Case study: On December 7th, the Equipment Operation and Management Center of Baling Petrochemical’s Synthetic Rubber Division conducted thorough tests and found that after the modification of the sliding shaft in the SEBS production unit, its operation became stable; the longest continuous operation period achieved was 10 months, resulting in improved quality, increased production, and reduced costs – achieving three benefits at once. This division has a total of 33 polymerization kettles for thermoplastic rubber production, and the sliding bearings of the stirring shafts in these kettles are all made of nylon. Due to its poor heat resistance, the sliding bearing melts and loses its structural integrity under high operating temperatures, resulting in an average service life of only 4 months, which severely affects the long-term operation of the condensation unit. At the same time, the damaged black nylon particles will also enter the post-treatment process along with the glue particles and water, blocking subsequent equipment and mixing into the products, thereby affecting product quality. Frequent maintenance of the agitator tank not only affects the plant’s production capacity but also increases the labor, resources, and maintenance costs involved. At the beginning of this year, the Equipment Operation and Management Center of this division established a task force to address the issues related to the sliding bearings of the condensation tanks. By leveraging its expertise in equipment management and using continuous improvement techniques, the team compiled, analyzed, and integrated the problems that had occurred in previous condensation tanks, thereby determining the directions for improvement. They focused on the key factor related to the bearing material and attempted to make modifications by replacing nylon with polytetrafluoroethylene composite materials that possess excellent heat resistance and lubricity. They also developed a project action plan and conducted pilot tests in the mixing tank of the SEBS workshop first. Through continuous efforts and repeated optimizations, the pilot project for modifying sliding bearings achieved good results, after which it was subsequently rolled out in 3 more workshops. Based on the current operating conditions, it is estimated that the service life can be extended to over 1 year, and the number of times bearings need to be replaced per year can be reduced from 3 to 1. This not only helps to increase the output and quality of the equipment but also saves more than 800,000 yuan in maintenance costs each year.