ISO 12101 ends assumptions in stem seal performance

The article shows how fugitive emissions are systematically underestimated because stem seals are often assessed using incomplete or non-representative test data. Despite existing standards such as ISO 15848-1, API 624 and TA Luft, leaks continue to occur because brochures and data sheets promise performance that cannot be achieved in practice without specific installation conditions or valve extensions. Zegers explains how seals regularly fail at relatively small temperature or pressure deviations – not due to material defects, but because of incorrect assumptions about application, assembly and load conditions. Stem seals thus become an underestimated failure source with direct consequences for safety, environmental damage, product loss and compliance with increasingly stringent VOC limits. This gap between promise and reality is made visible through targeted fugitive-emission tests on stem seals.

ISO 12101 positions itself as the missing cornerstone by providing a globally recognised method for testing, classifying and qualifying stem seals under realistic pressure, temperature and cycling loads. The standard complements ISO 15848-1 because it focuses not on the entire valve but on the sealing system, ensuring full transparency regarding test setups, installation parameters and performance limits. As initiator and team leader of ISO/TC 153 WG5, Colin Zegers shows how ISO 12101 enables manufacturers, end users and service companies to make proven choices, reduce emission risks and restore confidence in sealing performance. Anyone who wants to understand why ISO 12101 marks a turning point in emission control and valve integrity should read the full article.