Enhancement of Dry Gas Seal Reliability

Abstract Objective Shaft sealing prevent uncontrolled escape of process gas from the gas compressor casing. During shaft sealing failure, apart from loss of production, consequences due to loss of containment of hazardous and toxic process fluid may extend to multiple fatalities and major asset damage. Due to this high risk, the operation team is highly focused in improving reliability of compressor seals. Over the years, traditional oil film seals are replaced by dry running gas seals. Most of the process gas centrifugal compressors manufactured today are equipped with dry gas seals. Dry gas seals are available in a variety of configuration; the most common one for process gas application is tandem seals. This report describes a centrifugal compressor dry gas seal (tandem seal) failure investigation in an oil and gas field and the recommendations to enhance gas seal reliability. Dry gas seals in a medium pressure, hydrocarbon gas compressors had experienced frequent failures, to be precise, five dry gas seals failed in a span of seven months. These frequent failures become a serious challenge to sustain gas production. Analysis Data for analysis was gathered during site visit, in addition, discussion with operations & maintenance team was held to understand equipment performance and maintenance status. Real time operational data was obtained from data server for selected parameters. Defect elimination is the method used for analysis, this include identifying all possible causes of failure. The trends on key operating parameters that have the potential impact on seal failure and the variation of these parameters during the event are analyzed. The report describes the details of analysis performed. Results and conclusions An evidence based approach is used either to qualify or eliminate the cause of failure. The report indicates the most likely cause of seal failure based on the method of analysis. This report describes the modifications in the system and operating requirements to prevent future dry gas seal failures. Modification includes additional instrumentation for monitoring to increase safety of existing equipment and systems. Site utility conditions, compressor operating conditions, control and monitoring of key parameters can significantly influence dry gas seal reliability and requires special care in the design of seal auxiliary systems. By providing proper training to operators and maintenance team the seal reliability can be enhanced. Dry gas seals in critical rotating equipment are very common in the oil and gas industry. Seals can fail for a variety of reasons, hence improving reliability of gas seals is important for the operations to achieve hydrocarbon production targets.