In industrial production, sealing technology is a key link to ensure the normal operation of equipment and production safety. As a widely used sealing material, the PTFE gasket plays an important role in industries such as petroleum, chemical, pharmaceutical, electric power, and steel due to its excellent corrosion resistance, stable physical properties, and resistance to high and low temperatures. However, even such an excellent sealing material may fail for various reasons, leading to leakage and other problems. This article will explore in depth the causes of PTFE gasket failure and provide corresponding solutions to help maintain the sealing performance of equipment and ensure safe and efficient production.
The main manifestation of PTFE gasket failure is leakage. The occurrence of leakage mainly stems from two aspects: first, the existence of gaps on the sealing surface; second, the pressure difference on both sides of the sealing part. The pressure difference is the main driving force of leakage—the greater the pressure difference, the easier it is for the medium to overcome the resistance of the leakage channel, resulting in leakage. Therefore, to solve the leakage problem, the primary task is to eliminate or reduce the gap between sealing surfaces, including the gap between sealing surfaces and the internal gap of the sealing device.
The causes of PTFE gasket failure are various, involving working condition factors, problems in assembly and operation, material and design issues, auxiliary parts and design defects, and problems in raw materials and the production process. These factors interact with each other, jointly leading to the decline or even failure of the sealing performance of PTFE gaskets.
The sealing performance of PTFE gaskets is affected by many working condition factors, among which the pressure and temperature of the medium are the most important. Under different pressures and temperatures, the leakage rate varies. Temperature has a significant influence on the sealing performance of the connecting structure. Studies have shown that as the temperature rises, the elasticity and plastic deformation of the PTFE gasket increase, while the resilience decreases, and the creep amount increases. These changes lead to increasingly serious aging, weight loss, creep, and relaxation of the PTFE gasket, thus reducing its sealing performance. In addition, temperature has a great influence on the viscosity of the medium. As the temperature increases, the viscosity of liquids decreases, while the viscosity of gases increases. This change makes leakage easier to occur.
During assembly, if the required compressive force of the PTFE gasket cannot be achieved, or during long-term operation, the loosening of bolts caused by mechanical vibration of the equipment will lead to gasket failure and leakage. In addition, the aging deformation of PTFE gasket material will also cause it to lose its original elasticity, resulting in failure. If the compressive stress of the PTFE gasket is too large, it may be crushed and lose its rebound ability, making it unable to compensate for the separation of the flange surface caused by temperature and pressure, thus causing a sharp increase in leakage rate. Therefore, to maintain good sealing performance, the compressive stress of the PTFE gasket must be kept within a certain range.
If the internal structure or thickness of the PTFE gasket material is uneven, or materials with cracks or creases are used, gaps will form inside the gasket itself. When the force acting on the gasket is insufficient to completely fill these gaps, leakage becomes inevitable. In addition, the incompatibility between the PTFE gasket material and the conveyed medium is also one of the common causes of failure. Due to the diversity of chemical properties of chemical products and various additives added to fuels, it is not easy to select a PTFE gasket material compatible with the medium being transported. Therefore, corrosion of the gasket due to incompatibility often leads to leakage.
During the sealing process, many auxiliary parts may cause the failure and leakage of the entire sealing gasket if problems occur. For example, using incorrect bolts, damaged threads on bolts, uneven bolt loads, and misalignment of flange surfaces are all fatal mistakes. If the PTFE gasket and auxiliary parts themselves have no problems, the issue is likely due to design defects. Excessive load or insufficient bolt load are both causes of design defects, while the incorrect selection of flanges and bolts is a serious design error.
Improper selection of raw materials for producing PTFE gaskets, such as using old gaskets that have been used before, will cause their sealing performance to be reduced from the beginning under the influence of media and working environments. In addition, if the PTFE gasket is not properly selected, for example, under the same compressive load and medium pressure, the thicker the PTFE gasket, the lower the leakage rate. This is because thick PTFE gaskets have a greater compression and rebound amount. If the gasket material is not compatible with the conveyed medium, its sealing performance will also be affected.
After fully understanding the causes of PTFE gasket failure, we can take a series of targeted measures to solve these problems, thereby ensuring the sealing performance of PTFE gaskets and extending their service life.
To ensure the sealing performance of PTFE gaskets, it is necessary to select suitable sealing gasket materials according to the actual temperature, pressure, pH value, acidity, and alkalinity of the medium. For example, the sealing material BD 7701 PTFE gas sealing material is designed based on specific working conditions. At the same time, drastic temperature changes should be avoided, as they directly affect the sealing performance of the gasket and lead to leakage. In addition, the vibration of the pipeline system, deformation of connection components, and deviation of installation position should be reduced, as these factors adversely affect the sealing performance. Especially during vibration, the clamping force between the raised surfaces will change periodically, causing the connecting bolts to loosen and leading to sealing failure.
During assembly, it is necessary to ensure that the required compressive force of the PTFE gasket is achieved. Tools such as torque wrenches can be used to ensure that the bolt tightening force is uniform and meets design requirements. At the same time, the vibration condition of mechanical equipment should be checked regularly, and loosened bolts should be tightened in time. In addition, excessive compressive stress on the PTFE gasket should be avoided to prevent it from being crushed. Proper assembly and maintenance are the keys to ensuring the sealing performance of PTFE gaskets.
Choosing a PTFE gasket material compatible with the conveyed medium is an important link to ensure sealing performance. According to the chemical properties, temperature, and pressure of the medium, materials with appropriate elasticity and corrosion resistance should be selected. At the same time, the internal structure of the PTFE gasket material should be uniform, and the thickness should be consistent, avoiding materials with cracks or folds. In the design stage, design defects such as excessive load or insufficient bolt load should be avoided, and correct selection of flanges and bolts should be ensured.
When producing PTFE gaskets, high-quality raw materials must be selected, and old or unqualified materials should be avoided. Quality control during the production process must be ensured. For example, the accuracy of dimensions during cutting should be maintained to avoid unevenness or damage. At the same time, the appropriate thickness of PTFE gaskets should be selected according to actual application requirements to ensure sufficient compression and rebound, thereby improving sealing performance.
Due to their excellent performance, PTFE gaskets are widely used in industrial production. They can not only be used for crack repair in industrial facilities but also for the installation and connection of brittle materials. In addition, PTFE gaskets are widely used in some related facilities in the food or pharmaceutical fields because they do not cause any contamination to the substances in the repaired facilities, making them an ideal product with excellent sealing and cleanliness.
The main advantages of PTFE gaskets lie in their high corrosion resistance, stable physical properties, and tolerance to both high and low temperatures. These characteristics allow them to maintain good sealing performance under various harsh working conditions. In addition, PTFE gaskets are soft and easy to cut, allowing both mechanical and manual cutting for convenient installation. After special processing, PTFE gaskets have good creep resistance and cold flow resistance, enabling them to be used safely over a wide temperature range for long periods.
As an important sealing material, PTFE gaskets play an indispensable role in industrial production. However, due to various reasons, PTFE gaskets may fail, leading to leakage and other problems. By deeply analyzing the causes of PTFE gasket failure, corresponding solutions can be adopted, optimizing working conditions, ensuring correct assembly and maintenance, selecting appropriate materials and designs, and improving raw material and production quality, to ensure the sealing performance of PTFE gaskets. Only in this way can we achieve safe and efficient operation of equipment in industrial production, reduce losses caused by leakage, and protect the environment and personnel safety.