ADVANCED ANALYSES OF LET-DOWN VALVES TO IMPROVE LDPE PLANT PERFORMANCE

High pressure plants for LDPE production are characterized by machinery and equipment undergoing severe fatigue, pulsation, vibration and erosion problems. The collection of data relevant to the performance of compressors and plants has to be properly carried out to help the maintenance engineering team to identify the possible ways of improvement. The use of advanced laboratory analyses gives a valid contribution to the investigations and the determination of the root causes of the existing problems. While on the compressors the wear and fatigue are generally the reasons for a shut-down, on the plant there are other critical components like the letdown valves, needing careful consideration. Their periodical actuation implies fatigue and erosion appreciably influencing the MTBF and the availability of the plant. These valves are real critical components on tubular reactor plants. The analyses carried out at different times have allowed to change material so improving the resistance to wear and the mechanical properties resulting in a higher reliability.