Stem seal leakage improvements can lead to smaller explosion proof areas

Valve stem seals have improved over the years and more and more low emission packings are applied. However several international documents still indicate that stem seals are major contributors to fugitive emissions. This raises the questions: is this leakage quantified in independent documents? What is the impact on the users Scope 1 GHG protocol?

Explosive atmosphere standards like the IEC60079 are considering leakages to evaluate which zone or area classification shall be applied. In IEC60079-10-1 in example 5, a release rate for control valve stem packing is indicated. The example is based on 5 bar pressure. However, in gas transmission systems usually pressures around 60 bar occur, which leads (according IEC60079) to a 12 times higher leak rate. Following the example 12 * 1,5 E–6 kg/s, is 568 kg per valve per year of Methane emission and therefore more than 45 ton CO2eq. per valve per year.

With the transitions for the necessary climate change in mind the reduction of these emissions reduces your Scope 1 GHG protocol strongly, but from an operational point of view it can result in smaller explosion proof areas with all its positive side effects too.

Contact Mokveld to see how we can help you to avoid stem seal leakage.