Across the global valve industry, low-emission packing solutions are generally categorized into three main structural types: composite designs (where a graphite ring is sandwiched between upper and lower braided rings), fully braided structures, and special profiles such as V-type or X-type configurations. To further enhance sealing performance and reduce emissions, many manufacturers also apply surface impregnation treatments to the packing.
Limitations of Conventional Approaches
While these solutions represent significant manufacturing progress, they are largely developed from the packing manufacturer’s perspective—often without fully addressing the real operating demands of valve systems in diverse industrial environments.
In practical applications, such as in Northern Europe, operating conditions can be extremely harsh. Pipeline media may reach 300°C during operation, then drop to -40°C after shutdown overnight. Under such severe thermal fluctuations, packing materials experience substantial tensile stress, providing the most realistic test of their sealing principles and structural integrity.
Challenges Under Extreme Temperature Cycles
It has been observed that while some packing products can successfully pass ISO 15848-1 type tests from ambient temperature up to 400°C and back, they frequently fail during low-temperature cycles (e.g., from ambient down to -50°C).
The underlying reason lies in the excessive use of impregnating emulsions—additives intended to improve sealing performance by reducing leakage. Although effective in laboratory settings, these treatments often cause undesirable effects in real-world environments:
Thermal shrinkage at low temperatures
Softening and deformation at high temperatures
These behaviors significantly increase emission risks under operating conditions characterized by repeated thermal cycling, such as in regions where the media fluctuates between +300°C and -40°C.
Testing Limitations and the Need for Realistic Evaluation
Another challenge arises from the segmented testing procedures commonly used in ISO 15848-1 compliance testing. Many laboratories conduct high-temperature and low-temperature cycles independently, rather than as a continuous, integrated process. This approach fails to replicate the dynamic nature of real operation, leaving critical gaps in verifying the true low-emission performance of packing materials.
A Redefined Approach to Low-Emission Graphite Packing
Through long-term research and field testing, we have redefined the performance standards and manufacturing criteria for low-emission graphite packing, aligning them with actual operating conditions rather than laboratory assumptions.
In temperature ranges from +300°C to -40°C, our focus is on achieving a precise balance between:
Sealing effectiveness, to ensure low leakage under high pressure, and
Thermal adaptability, to maintain resilience and dimensional stability through extreme temperature fluctuations.
This balance is achieved through materials and structures designed according to the principle of “pressure-responsive adaptability.” This concept ensures that the packing remains flexible and responsive to variations in both pressure and temperature—maintaining its sealing integrity rather than becoming brittle or permanently deformed after repeated thermal cycling.
Defining a Truly Reliable Graphite Packing
We define a truly reliable graphite packing not simply as a well-made sealing product, but as an engineered system component—one that is responsive, adaptive, and capable of delivering consistent, low-emission performance across a full spectrum of real-world valve operating conditions.
This philosophy shifts the focus from “how the packing is made” to “how the packing performs,” ensuring safer, more stable, and more sustainable sealing solutions for modern industrial valve applications.
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