Figure 1: Component contribution to fugitive emissions. π www. valve-world. net Valve World October 2026
FUGITIVE EMISSIONS
Beyond compliance: Why valve packing determines real fugitive emission performance
Fugitive emissions in industrial valve applications are often attributed to valve design. In practice, however, operational experience shows a different reality: many emission issues originate not from the valve itself, but from the longterm behaviour of the stem sealing system. Even well-designed valves can become emission sources if the packing system does not maintain stable performance under real service conditions.
By Holger Schröder, Director Strategic Markets,
Burgmann Packings
This raises a fundamental question for manufacturers, operators and sealing specialists alike: are sealing systems being developed primarily to pass qualification tests, or to remain stable throughout their operational life? The distinction is critical. A valve may meet all relevant emission standards and still show unstable sealing behaviour in service if the interaction between packing material, ring design, gland load, stem condition and operating profile has not been properly aligned. Fugitive emission performance is therefore not a property of a single component, but the outcome of a coordinated system.
Fugitive emissions are not a static phenomenon
In real operation, emissions rarely appear as an immediate failure. Instead, they develop progressively. Thermal cycling, pressure variation, stem movement and long-term relaxation continuously influence the sealing system. What initially performs well under controlled conditions can degrade if these effects are not properly managed. This is reflected in emission inventories from various plants, where valves and pressure relief valves typically account for the majority of fugitive emissions, as illustrated in Figure 1. For this reason, the decisive engineering criterion is not the initial leakage value, but the stability of leakage behaviour over time. Particularly in valves, where the sealing interface is subject to repeated mechanical and thermal loads, every cycle contributes to the long-term performance of the packing system. In many plants, recurring gland adjustment is still accepted as routine maintenance. From an
Others 5 % engineering perspective, however, it is not a necessity but an indicator of sealing instability – and often a hidden cost driver in maintenance and emission performance. A system that requires continuous correction is not operating within a stable sealing window.
Standards are essential – but not sufficient on their own
Standards such as ISO 15848, API 622, API 624, API 641 and TA-Luft have significantly improved the qualification of low-emission sealing systems. They provide a necessary framework for comparability and define minimum performance requirements under controlled conditions. This progress is indispensable. Without standardisation, meaningful evaluation would not be possible. At the same time, compliance with these standards should not be mistaken for proof of long-term operational reliability. Even advanced test procedures cannot fully replicate the variability of real service environments. Fluctuating temperatures, installation variability, non-ideal stem finishes, dynamic load changes and application-specific constraints all influence sealing behaviour in ways that are difficult to simulate completely. As a result, systems that perform well in qualification frequently show performance instability in operation if the sealing concept has not been developed with the actual load profile in mind.
Sealing performance depends on interaction
The discussion around valve packing is still often reduced to material selection. While
Valves( incl. Relief Valves) 75 %
Pumps & Tanks 20 %
Figure 1: Component contribution to fugitive emissions. π www. valve-world. net Valve World October 2026
41