Emissions from seal elements - localization, origins and decrease by accurate inspections

It has been demonstrated that leakage rates across almost all seals are about on-tenth or less than one-tenth of the values taken from the literature. Outliers, which raise the figure for the average leakage, occur most frequently in seals for shut-off valves, gate valves and control valves. Hence, those types to present most problems. However, the studies have demonstrated that the average leakage rate also for these types of seals can be kept below one-tenth of the value cited in the literature by paying more attention to maintenance. (orig.)