Traceable gasket and compression packing materials

Abstract

The material contains traceable particles that hold information about the manufacturing process of the material, which can be used to trace its origin, and provides gaskets that can be used to seal flanged fittings in the food and beverage industry, or to form compression packings used to seal around machinery such as valve shafts and pump shafts. [Solution] A gasket having filaments, comprising a polytetrafluoroethylene (PTFE) matrix and tracer particles 110 selected from fluorescent dye molecules and fluorescent dyes, wherein the tracer particles absorb light and emit light of a specific wavelength detectable by a microscope equipped with a filter set for the specific tracer particles, and the tracer particles are distributed throughout the matrix.

Description

Technical Field

[0001] This application claims the benefit of the filing date of U.S. Application No. 16 / 939,786, filed on July 27, 2020, and now issued as U.S. Patent No. 10,989,304, and its priority, the entire disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates to sealing materials such as gaskets for sealing flanged joints and compression packings for sealing around valve shafts, pump shafts, and similar mechanical elements.

Background Art

[0003] Sealing materials include static seals such as gaskets and dynamic seals such as compression packings. Generally, gaskets are installed between flat surfaces, and compression packings are arranged around mechanical elements such as valve shafts and pump shafts.

[0004] A gasket is a material widely used in various industrial fields as a sealing material for flanged joints. A gasket is designed to fill the space between two or more mating surfaces of mechanical parts and prevent leakage from and inflow into them. It can also withstand harsh conditions such as load, temperature, and pressure.

[0005] The most commonly used gasket material is polytetrafluoroethylene (hereinafter referred to as PTFE) polymer. PTFE is well known for its good chemical and mechanical properties. It has the advantages of excellent performance from low temperature to high temperature, low coefficient of friction, excellent electrical insulation, and resistance to chemical attack. Furthermore, it is easy to enhance some functions by combining with other substances such as fillers and additives.

[0006] However, the use of gasket materials in certain industries, such as the food and beverage industry, is not so straightforward. In such applications, these materials are exposed to varying temperatures and pressures, can undergo chemical attacks, and can degrade over time. Even worse, they can contaminate the process flow. Therefore, in these industries, a comprehensive safety strategy to avoid contamination is required, and the gasket materials must be carefully selected.

[0007] Therefore, the gasket material must meet the requirements of numerous standards and regulatory guidelines. For example, in the United States, the Food and Drug Administration (FDA) and the National Sanitation Foundation (NSF) play a vital role in managing the safety and quality of consumer products. Both organizations provide rigorous standards and tests to approve materials that come into contact with food and beverages during processing, packaging, or storage.

[0008] For example, two common standards used for testing PTFE gasket materials are FDA 21 CFR 177.1550 "Perfluorocarbon resins" and NSF / ANSI 51-2019 "Food equipment materials". Tests under these standards prove and guarantee that contaminants from the gasket material are below the maximum permissible limits.

[0009] In addition to compliance with guidelines, it is desirable to have means to indicate that the gasket material is contaminating the process flow if it deteriorates in any way and needs to be removed. Therefore, several tools such as metal detectors and visual inspections are provided to track the purity of the product along the process flow and to identify foreign matter from broken machine or processing equipment parts.

[0010] Traceability of foreign objects along the aforementioned process flow ensures the safety and quality of food and beverage products and prevents contamination. Foreign object contamination incidents typically lead to production line shutdowns, wasting enormous time and money, thus playing a crucial role. Therefore, machine parts and objects that can be detected if the process flow is contaminated in any way are of great value.

[0011] Therefore, conventional methods have involved changing the color of the gasket material or incorporating ferromagnetic additives. However, both methods have limitations in accurately tracking the source of contamination. First, the first method can only identify foreign matter if it is near the surface, and this identification may be performed after destroying a large number of products, resulting in wasted time and money. The second solution, conversely, has the limitation that the additive may be indistinguishable from its surroundings, making it difficult to truly determine whether the contamination is due to a failure in the gasket material or to other components in the process flow. Moreover, ferromagnetic additives may be associated with oxidation problems during the sintering process of the gasket material.

[0012] Compression packing is one of the most common leak-proof sealing materials used in industrial fields such as refining, chemical, pharmaceutical, shipbuilding, and the pulp and paper industry. Compression packing involves inserting a packing member made of a soft and flexible material into the space (so-called stuffing box) that seals the space between the rotating or reciprocating members of a pump or valve and the pump or valve body. When bolt stress is transmitted to the compression packing, the material is compressed axially and expands radially within the stuffing box, forming a seal.

[0013] Compression packing represents a compromise between leak suppression and packing friction. Compression packing with a high coefficient of friction on the sealing surface increases the power required to operate the equipment, and in extreme cases, can even cause the equipment to stop working. This problem exists in all types of equipment that use compression packing, but it is critical in control valves where rapid response is required.

[0014] Compression packings are used in a wide variety of devices under various conditions, and therefore come in a wide range of structures, configurations, materials, dimensions, shapes, and sizes. Here, we will describe the most common packing structures and their characteristics.

[0015] Square braiding is a process in which various materials, such as threads and ribbons, are woven together, either individually or in combination, overlapping with other threads running in the same direction. This process yields packaging materials with a square or rectangular cross-section. These square braided packings are typically soft and flexible and can carry a large proportion of lubricant, making them commonly used in services that rotate at high speeds under relatively low pressure. Furthermore, because square braided packings are soft, they can also be used in older or worn equipment.

[0016] The nominal dimensions of square braided packing are typically up to 6 mm (1 / 4 inch). Two-track square braiding, which uses 8 threads woven in two tracks on 4 corner strands, can form larger, coarser packing.

[0017] Intermediate braided packing, also known as cross braided or diagonally braided packing, is made by weaving threads, ribbons, or other materials individually or in combination, diagonally in a cross pattern from the surface through the body. Each strand is strongly fixed by the other strands, resulting in a one-piece structure that is resistant to unraveling. This braiding pattern ensures that the strands are uniformly distributed throughout the packing, resulting in a dense and flexible structure that improves the retention of lubricating oil.

[0018] For cross-braided packing, if a larger cross-section is required, 3-track or 4-track diagonal braiding can be used. 3-track braiding has a nominal size of 5–12mm and is typically performed using a braiding machine with 12–20 carriers. 4-track braiding is often 10–80mm (3 / 8–3 inch) and is performed using braiding machines with 24, 32, or more carriers.

[0019] Multi-layered braided packing consists of concentric or circular braids, including a thin tubular covering made of thread, ribbon, or other materials, woven around a core material. Cross-sectional shapes can be circular, square, or rectangular.

[0020] Similar to diagonally braided packing, the multi-layered braided packing structure also provides a fine and dense surface structure, but its abrasion resistance is not as high. The size and density of the packing can be increased by braiding several layers of the multi-layered braided structure onto a core. Depending on the size of the packing machine, 16, 48, or more carriers can be used. Furthermore, the core material can consist of parallel yarns or twisted yarns, both of which provide elasticity and flexibility. Cores made by extrusion molding of rubber or elastomer can also be used.

[0021] The aforementioned multi-layer braids can have a square, rectangular, or circular cross-section, depending on the shape of the packing. Large, endless concentric packing rings can be manufactured using a special braiding machine that can divide the upper part of the machine.

[0022] Another type of packing structure, called a braided overcore, involves weaving one or more coverings of various materials, such as threads, ribbons, or other forms, onto a core that can be twisted, braided, wound, or extruded. This type of structure can be used to create packings of various densities and cross-sections.

[0023] In addition to each packing structure, two or more packing structures can be used in combination, and these are called combination packing sets. Combination packing sets are generally used to prevent packing from being pushed out and consist of adding anti-extrusion rings to both ends of the packing set. These rings can withstand higher pressure than the packing, thus preventing the packing from being pushed out through the gap in the stuffing box. Typical combination packing sets that include anti-extrusion rings include carbon filament end rings and flexible graphite rings. End rings made of metal discs, machined plastic, or other similar materials can also be used.

[0024] Mold-formed packings are pre-compressed ring-shaped. This type of structure compresses the packing material within a mold of a specified size. In this way, the packing material can be supplied at a specific density and size.

[0025] In addition to these packings, there are various other packing structures, including extruded packings, laminated packings, wrap, roll and fold packings, molded packings, machined packing rings, and flexible graphite tapes.

[0026] In the United States, the Environmental Protection Agency (EPA) regulates emissions and air quality. The EPA investigated the sources of fugitive emissions and determined that the largest source was process equipment used in refineries and chemical plants. According to Elliott MacKay, J. (2004) "Detection of Fugitive Emissions From Valve Stems-DC Resistance Response And Gas Adsorption Over Tin Dioxide Mixed With Alumina" by the University of British Columbia, valves are estimated to account for 60% to 85% of these fugitive emissions.

[0027] To confirm that such refineries and chemical plants are complying with the Clean Air Act (CAA) regulations, the EPA conducts plant audits. If it is found that a plant is exceeding its mandated emission limits, the EPA enters into a legally binding consent agreement with the violator. These consent agreements are generally made public by the EPA on its website. In a consent decree, the operation of the refinery or chemical plant is permitted, but the leak levels are closely monitored and expected to decline, and usually certified low-emission technology packings and valves are required. According to Paeffgen N. (2014), "EPA to Review Consent Decress to Ensure Compliance," by Alston & Bird LLP, as of 2011, 90% of the petroleum refining sector was subject to EPA consent decrees.

[0028] For a packing to be considered an "approved low-emission technology" as defined in the EPA's Enhanced Leak Detection and Repair (LDAR) Program Part G - Equipment and Improvement, the packing manufacturer must issue a certificate guaranteeing that no leaks of 100 ppm or more will occur over a total of five years when pressurized volatile organic compounds (VOCs) such as methane are sealed. Usually, the certificate is also accompanied by equivalent documentation showing that the packing has been tested in accordance with generally recognized proper technical practices and standards.

[0029] The most common standard used for testing low-emission packing is American Petroleum Institute (API) 622: Type Testing of Process Valve Pcking for Fugitive Emissions, Third Edition. Packings are certified under this standard, and the tests are performed on a standardized test apparatus, not on actual valves. During this test, the packing is subjected to 1,5101 mechanical cycles and 5 thermal cycles, which is considered to represent the lifecycle of an isolation valve well. The test apparatus is pressurized at 40 atmospheres with methane, a type of VOC. Leakage must never exceed 100 ppm at any moment, and retesting is not permitted, which is consistent with the LDAR performance requirements as mentioned above.

[0030] Another standard used in the industry is International Organization for Standardization (ISO) 15848-1 Industrial valves—Measurement, test and qualification procedures for fugitive emissions. This standard certifies valve designs and includes different procedures for isolation valves and control valves. Because this standard targets control valves, which are operated more frequently, it allows for a wider range of tests, with the most severe class consisting of 100,000 mechanical cycles and 4 thermal cycles. This standard does not specify standardized test equipment; instead, tests are performed on commercially available valves. The test results should be interpreted as an evaluation of the valve, not just as an evaluation of the packing.

[0031] Although some packing manufacturers offer low-emission gas technology guarantees, identifying the compression packing after it has been used in the field and verifying that it is a certified product compliant with leakage emissions services has remained an unsolved problem to date. Packing is usually subjected to high compression, friction and wear, and contact with process fluids during operation, and ultimately undergoes significant changes in structure, appearance, and composition. Tags and labels are the most commonly used methods in the industry for identifying compression packing. However, such external identification is subject to movement, forgetting, and accidental damage, during which information for identifying the compression packing in use may be lost.

[0032] Due to the low emission rates mandated by the EPA and the leakage emissions regulations described above, high packing installation stresses are usually required. This is to ensure low-emission services even after system relaxation during the equipment's life cycle. This high installation stress is typically the cause of standard packing being extruded between the valve shaft and the stuffing box. For soft packing, an anti-extrusion ring needs to be used to solve this problem, but this increases cost and complexity.

[0033] Flexible graphite packing is the most common solution for low emissions. However, flexible graphite tape is very brittle and cannot withstand the forces generated during the braiding process, so manufacturing can be difficult even with such excellent properties. Therefore, flexible graphite packing is manufactured using alternative processes such as graphite molding, but the performance required by leakage emissions regulations such as API622 cannot be obtained.

[0034] To withstand the braiding process of flexible graphite tape, reinforcing materials are used to enhance mechanical resistance. Commonly used reinforcing materials include cotton, acrylic, fiberglass, and metal. Cotton and acrylic reinforcing materials are unsuitable for low-emission technologies because they cannot withstand the temperatures required for this type of application. Fiberglass reinforcing materials can withstand high temperatures but cannot meet the performance requirements of leak emission standards. Metal reinforcing materials represent a significant improvement over previous alternatives and are currently used in state-of-the-art solutions for low-emission technologies. However, this reinforcing has two main drawbacks: it can increase friction due to contact with the packing and potentially damage the valve shaft surface, creating leak pathways.

[0035] Metal-reinforced flexible graphite packing is particularly suitable for ultra-high temperature applications, but it alone cannot achieve the performance required by leak emission regulations. To achieve such low emission levels, blocking agents are added to the packing as a coating. The most commonly used is polytetrafluoroethylene (PTFE), which not only helps reduce emissions but also acts as a lubricant, thereby reducing friction. However, the problem of the metal reinforcement scratching the surface of the valve shaft remains unresolved.

[0036] However, because the above-mentioned blocking agents lack fire resistance and high-temperature resistance, many standards and end-users strictly limit the amount of PTFE that can be added as a coating. For example, the American Society for Testing and Materials (ASTM) F2191 limits PTFE coatings to less than 5% by volume. For this reason, API 622 specifically requires the inclusion of weight loss and fluorine content tests in the final report. Controlling and minimizing the PTFE content is important because any mass lost due to temperature degradation becomes stress loss in the system, potentially leading to leaks.

[0037] In hydrocarbon processing at oil refineries and petrochemical plants, packings are required to be fire-resistant. The standard API 607: Fire Test for Quarter-turn Valves and Valves Equipped with Nonmetallic Seats, Seventh Edition, specifies fire test requirements and methods for verifying the pressure-holding ability of packing-sealed valves under pressure during and after fire testing. For use in oil refineries and petrochemical plants, this approval is necessary to guarantee the packing's ability to seal in the event of a fire. Generally, flexible graphite packings can obtain fire safety certification.

[0038] When using such graphite packing materials, particular attention must be paid to the possibility of electrolytic corrosion, which is an electrochemical reaction that occurs between the metal immersed in the electrolyte and carbon materials such as graphite, or between two different metals. Under these conditions, the material closer to the anode end of the potential train is likely to corrode. The potential difference between the materials determines the rate of corrosion, with a larger difference resulting in a faster corrosion rate.

[0039] When using carbon or graphite-based sealants in equipment such as valves with metal shafts or shafts, electrolytic corrosion is associated with the use of compression packing. Because iron has a higher anodic polarity than graphite, when valves are exposed to electrolyte during hydrostatic pressure tests, the shaft can undergo electrolytic corrosion, making it easier for leaks to form. The following are prior art documents related to the invention of this application (including documents cited in the international phase after the international filing date and documents cited when the application entered the national phase in other countries): (Prior art document) (Patent Document) (Patent Document 1) Specification of Chinese Patent Application Publication No. 106009432 (Patent Document 2) U.S. Patent No. 5,492,336 (Patent Document 3) International Publication No. 2008 / 125539 (Patent Document 4) U.S. Patent No. 10,989,304 (Patent Document 5) U.S. Patent Application Publication No. 2013 / 0307229 Specification (Patent Document 6) U.S. Patent No. 5,472,031 (Patent Document 7) U.S. Patent No. 6,531,217 (Patent Document 8) U.S. Patent No. 9,701,058 (Patent Document 9) U.S. Patent Application Publication No. 2015 / 0082757 Specification (Non-patent literature) (Non-patent document 1) Diaz et al. "Fluorescent labeling and tracking of nanoclay" Nanoscale. Vol 5(08 November 2012):Pages 164-168;entire document, but especially: abstract,page 165 col 1 para 2 (Non-Patent Document 2) Elliott MacKay, J. (2004), in "Detection Of Fugitive Emissions From Valve Stems - DC Resistance Response And Gas Adsorption Over Tin Dioxide Mixed With Alumina", University of British Columbia. (225 pages) (Non-patent document 3) Paeffgen N. (2014), Elise, in "EPA To Review Consent Decrees To Ensure Compliance", Alston & Bird LLP, as of 2011. (2 pages) (Non-patent Document 4) International Search Report and Written Opinion of the International Search Authority issued by the USPatent and Trademark Office for International Application No.PCT / US2021 / 071021 dated December 28,2021.(15 pages) [Overview of the project]

[0040] This disclosure relates to a composite gasket material, a method for manufacturing the composite gasket material, and a gasket formed using the composite gasket material. The disclosed composite gasket material is particularly useful in the food and beverage industry for monitoring any foreign matter contamination in food and / or beverage products. In this industry, it is common to use metal detectors, optical scanners, or X-rays to detect foreign matter contamination during the food / beverage manufacturing process. This invention relates to a sintered polytetrafluoroethylene (PTFE) gasket material having metal powder and traceable particles, and a method for manufacturing the same. Using gaskets having metal powder, traceable particles, or both metal powder and traceable particles is beneficial in any manufacturing process requiring rigorous foreign matter detection. The metal powder allows contamination from the composite gasket to be easily detected by standard metal detectors used in the industry. The traceable particles retain manufacturing information of the gasket material, allowing the contamination to be traced back to the exact origin of the detected material. These particles (e.g., traceable particles) withstand harsh application conditions such as chemically invasive fluids, abrasion, high pressure, and even high temperatures. Thus, the addition of these traceable particles provides a permanent identification method embedded in the gasket, which cannot be misplaced, switched off, or lost. Adding traceable particles to the gasket offers benefits not found in conventional gaskets, such as improved reliability in identifying the source of contamination. These benefits include not only identifying composite gaskets that may be contaminating the manufacturing process, but also determining that the contamination is unrelated to the composite gasket (e.g., if the contamination does not involve tracer particles). This tracking method is more reliable than currently used written identification methods and other currently available forms. This tracking method is particularly useful for users who need to ensure they are using uncontaminated products or who need to identify the exact origin if contamination occurs.

[0041] This disclosure also relates to compression packing. The compression packing of this disclosure carries particles that retain information about its manufacture and can be used to track the packing. The tracer particles withstand harsh application conditions involving chemically aggressive fluids, abrasion, high pressure, and even high temperatures. The tracer particles, embedded in the compression packing, provide a permanent identification method that cannot be misplaced, switched off, or lost. The tracer particles are far more reliable than written or other currently available identification methods and are particularly useful for end users who must ensure they are using guaranteed compression packing. Companies that have received EPA consent rulings for violations of the Air Pollution Control Act are required to use low-emission valve technology (including compression packing assemblies) and issue warranties that the product will not emit leak emissions above a certain level and that the product will be replaced if leak emissions occur within five years of initial use. This disclosure enables the identification of guaranteed packing itself and avoids the complexity of claims arising from incorrect product identification. Furthermore, the compression packing of this disclosure can be adapted to extrusion resistance and leak emission service without the use of metal reinforcements common in the industry. [Brief explanation of the drawing]

[0042] [Figure 1] Figure 1 is a perspective view of a traceable composite sheet according to an exemplary embodiment of the present disclosure. [Figure 2] Figure 2 is a flowchart illustrating a method for manufacturing the traceable composite sheet shown in Figure 1, according to an exemplary embodiment. [Figure 3] Figure 3 is a perspective view showing a circular traceable composite gasket cut from the traceable composite sheet of Figure 1, according to an exemplary embodiment. [Figure 4] Figure 4 is a perspective view of another embodiment of a composite gasket having traceable particles, according to an exemplary embodiment. [Figure 5] Figure 5 is a flowchart illustrating a method for manufacturing a composite gasket having traceable particles as shown in Figure 4, according to an exemplary embodiment. [Figure 6] Figure 6 shows the results of a sealing test using an embodiment of the present disclosure. [Figure 7] Figure 7 shows the results of a comparative sealing performance test between gaskets according to embodiments of the present disclosure and other types of PTFE gasket materials. [Figure 8] Figure 8 shows the results of a comparative test of gaskets according to embodiments of this disclosure and other types of PTFE gasket materials. [Figure 9] Figure 9 shows a partially exploded view of one embodiment of the compression packing according to the present disclosure. [Figure 10] Figure 10 shows a core made from a flexible graphite tape reinforced with PTFE filaments containing tracer particles. [Figure 11] Figure 11 is a perspective view showing one embodiment of the flexible graphite tape reinforced with PTFE filaments having the tracer particles in a braided configuration, and shows the distribution of the tracer particles. [Figure 12] Figure 12 is a schematic diagram showing the types of braiding (square braiding, inter-braiding with 3 tracks, inter-braiding with 4 tracks, and circular braiding). [Figure 13] Figure 13 shows one embodiment of the compression packing according to this disclosure for a larger cross-sectional packing compared to the smaller cross-sectional packing shown in Figure 9. [Figure 14] Figure 14 is a schematic diagram of an electrolytic cell used to evaluate the efficiency of corrosion inhibitors. [Figure 15] Figure 15 shows a comparison of the efficiency of corrosion inhibitors when used in combination with the tracer particles. [Figure 16] Figure 16 shows the results of a control valve friction test comparing an embodiment of the present disclosure with current state-of-the-art technology, both without PTFE coating. [Figure 17] Figure 17 shows the results of a control valve friction test comparing an embodiment of the present disclosure with current state-of-the-art technology, both having a PTFE coating. [Figure 18] Figure 18 shows the results of an API622 leak discharge test comparing embodiments of the present disclosure with current state-of-the-art technology, both without PTFE coating. [Figure 19] Figure 19 shows the results of a leak discharge test of API622 comparing an embodiment of the present disclosure with current state-of-the-art technology, both with PTFE coating. [Figure 20] Figure 20 shows the test results for the ISO 14848-1 leak discharge test according to an embodiment of the present disclosure. [Figure 21] Figure 21 shows the results of a pump test according to the standard EN 16752 according to an embodiment of the present disclosure. [Figure 22] Figure 22 is a flowchart of a method for identifying fragments from a seal according to an exemplary embodiment. [Modes for carrying out the invention]

[0043] Herein, we refer to drawings illustrating specific embodiments of the present disclosure. It should be understood that the present disclosure is not limited to the embodiments shown in the drawings.

[0044] According to exemplary embodiments of the present disclosure, Figure 1 shows a perspective view of a traceable composite sheet, commonly referred to as reference numeral 100. In some embodiments, the sheet is a PTFE sheet 100. In some embodiments, the sheet 100 comprises a sintered PTFE matrix 102, metal powder 105, and traceable particles 110. Since both the metal powder 105 and the traceable particles 110 are not visible without using a specific identification method, dotted circles indicate areas of the traceable composite sheet 100 showing the distribution of the powder 105 and the particles 110 within the matrix 102. The sheet 100 is a traceable composite gasket material.

[0045] Figure 2 shows a method for manufacturing the traceable composite sheet 100, which is generally referred to by reference numeral 200. The sheet 100 can be manufactured using a process similar to or identical to conventional processes known in the art, such as the DuPont "HS-10" or "HS 10" process. Referring to Figure 2, the method 200 for manufacturing the traceable composite sheet 100 includes the steps of deaggregating fine PTFE powder in step 205, adding metal powder and traceable particles to the mixture in step 210, filtering the mixture to form a cake in step 215, calendering the cake to form a sheet in step 220, drying the sheet in step 225, and sintering the sheet in step 230.

[0046] In some embodiments and during step 205, the fine PTFE powder is deaggregated in a hydrocarbon liquid, such as Exxon ISOPARTM L, an isoparaffinic hydrocarbon from Exxon Chemical, Irvine, Texas, in any suitable mixing apparatus, such as an industrial mixer. In some embodiments, the fine PTFE powder is PTFE powder having a particle size of less than 600 μm. Specific parameters such as mixing rate and amount of hydrocarbon liquid are adjusted based on the apparatus used. Generally, a PTFE mixture is created during step 205.

[0047] In some embodiments, during step 210, the metal powder 105 and the traceable particles 110 are added to the PTFE mixture. In some embodiments, the amount of metal powder added to or present in the gasket material is about 1% to about 70% of the total weight of the gasket material. In some embodiments, the amount of traceable particles is less than 5% of the total weight of the gasket material. The metal powder 105 and the traceable particles 110 are generally dispersed within the PTFE mixture. In some embodiments, the metal powder 105 and the traceable particles 110 are homogeneously dispersed within the PTFE mixture, but in other embodiments, some variation in the location of the metal powder 105 and the traceable particles 110 within the PTFE mixture is expected. The mixing step in step 210 may be carried out in the same apparatus as in step 205 (e.g., a mixing apparatus) over a period of time such as about 5 to 15 minutes. However, step 210 may also be completed using a different apparatus than that used in step 205. Even if described as batch processing, continuous amounts of the metal powder 105 and the traceable 110 should be added to the PTFE mixture at a rate sufficient to allow for complete mixing.

[0048] As described above, the metal powder 105 is added during step 210 and dispersed within the PTFE mixture or PTFE polymer matrix. The metal powder 105 can be found in different compositions, particle size distributions, and particle morphologies. A suitable metal powder 105 may consist of stainless steel powder, which will react to magnetic fields and light with detectable behavior and be readily detectable by metal detectors or X-ray inspection equipment commonly employed in process streams of the food and beverage industry.

[0049] As described above, the traceable particles 110 are added during step 210 and dispersed within the PTFE mixture or PTFE polymer matrix. The traceable particles 110 can be found in different forms and compositions. Suitable traceable particles 110 may include phosphors, fluorescent dyes, phosphors, porous silicon, and microdots. These are suitable for identifying the gasket formed by the sheet 100 after the gasket has been placed in use, although there may be some differences in the mechanism used for identification.

[0050] According to one embodiment, the traceable particles 110 are formed of a fluorophore or a fluorescent dye. According to such an embodiment, suitable fluorophores include chalcogenides such as selenides, sulfides, and tellurides of metals such as cadmium, lead, and zinc. Suitable fluorophores also include chemical compounds such as C62H87N13O16. Fluorophores are widely available commercially and are fluorescent chemical compounds that absorb light and re-emit light at specific wavelengths. The wavelength of the re-emitted light is typically measured using a microscope equipped with a filter set for the specific phosphor or fluorescent dye of interest.

[0051] In other embodiments, the traceable particles 110 take the form of a phosphor. A phosphor is a material that absorbs light in wavelengths invisible to the naked eye and emits light in the visible range. Some phosphors absorb light in both the ultraviolet and infrared ranges and emit light of multiple colors, including red, green, and yellow. Specifically, upconversion type hexagonal yttrium sodium fluoride (β-NaYF4), which emits visible light in response to infrared excitation, is a suitable phosphor. Depending on the selection of the phosphor, it can be excited with a portable laser pen or an ultraviolet flashlight.

[0052] According to another embodiment, the traceable particles 110 take the form of porous silicon (PS), which is silicon containing synthetic nanopores added to its microstructure. The porous silicon can be produced by methods well known to those skilled in the art, such as anodizing or stain etching of silicon wafers. According to such embodiments, the nanopores reflect visible white light. The wavelength of this light is characteristic of the size and topology of the nanopores in the silicon and can be measured with a standard spectrometer.

[0053] In yet another embodiment, the traceable particles 110 take the form of microdots, which are small discs typically made of ceramic, polymer, and metal. The discs are usually engraved with a pattern of very small dots by a laser. The dot pattern can later be extracted for identification by examining one of the discs with a microscope or similar magnification technique.

[0054] In additional embodiments, any number of fillers are also added during step 210. The fillers may be any one or more of barite, silica, natural hollow glass microspheres, and synthetic hollow glass microspheres.

[0055] In another additional embodiment, an inorganic pigment is also added during step 210. Due to the high sintering temperature of PTFE, any inorganic pigment can be used.

[0056] In some embodiments, during step 215, the mixture from step 210 is filtered to remove most of the hydrocarbon liquid, forming a cake which has sufficient lubricity to pass through the calendering process.

[0057] In some embodiments and during step 220, the cake from step 215 passes through a transverse calender roll to orient the PTFE matrix, the metal powder 105, and the traceable particles 110 within the material. This calendering process yields a biaxially oriented sheet. The shape and size of the sheet are not limited and can be adjusted.

[0058] In some embodiments, during step 225, the sheet from step 220 is dried to remove the lubricant. In one embodiment, step 225 includes a conventional method of drying the PTFE in an oven.

[0059] In some embodiments and during step 230, the sheet is sintered at a temperature of 300°C to 400°C to produce the traceable composite sheet 100.

[0060] Using method 200, the traceable composite sheet 100 having the metal powder 105 and the traceable particles 110 is formed. As described above, this sheet 100 results in improved traceability and contamination identification in the manufacturing process. In one embodiment, the amount of the metal powder 105 is about 1% to about 70% of the total weight of the composite sheet 100. In another embodiment, the amount of the traceable particles 110 is less than about 5% of the total weight of the traceable composite sheet 100.

[0061] Different discrete gaskets can be cut from the traceable composite gasket sheet 100. Figure 3 shows a perspective view of a circular traceable composite gasket, commonly referred to as reference numeral 300. The gasket 300 was cut from the traceable composite gasket sheet 100 according to an exemplary embodiment of the present disclosure.

[0062] The traceable composite gasket material may also be manufactured using the manufacturing method disclosed in U.S. Patent No. 9,701,058, the entire disclosure of which is incorporated herein by reference. According to another exemplary embodiment of the present disclosure, Figure 4 shows a perspective view of the helically wound traceable composite gasket, generally referred to by reference numeral 400. The gasket 400 comprises a sintered PTFE matrix, the metal powder 105, and the traceable particles 110. Referring further to Figure 4, the gasket 400 defines a gasket thickness 400a, a gasket inner diameter 400b, and a gasket outer diameter 400c.

[0063] Figure 5 shows a method for manufacturing a helical-wound traceable composite gasket 400, which is generally referred to by reference numeral 500. Referring to Figure 5, the method 500 for manufacturing the helical-wound traceable composite gasket 400 includes: de-aggregating fine PTFE powder with a hydrocarbon liquid in step 505; adding the metal powder 105 and the traceable particles 110 to a mixture in step 510; forming a traceable composite material rod in step 515; laminating the traceable composite material rod to a traceable composite tape in step 520; helically winding the traceable composite tape onto a traceable composite cylinder in step 525; compressing the traceable composite cylinder in step 530; drying the traceable composite cylinder in step 535; sintering the traceable composite cylinder in step 540; and cutting the traceable composite cylinder radially in step 545. In some embodiments, the term “laminate” in step 520 means forming the material into multiple layers. Thus, in some embodiments, the traceable composite tape formed in step 520 is formed from multiple layers of the traceable composite rod.

[0064] The traceable composite gasket material 100 disclosed herein has several features and advantages. One feature and advantage is the ability to identify a seal that may be contaminating a product or to confirm that a seal is not contaminating a product, particularly for industries such as the food and beverage industry, which monitor, identify, and track any contamination. Another feature and advantage of the traceable composite gasket material 100 is that, by containing the metal powder 105, fragments of the traceable composite gasket material 100 are readily detectable with a standard metal detector. A feature and advantage of a further embodiment of the disclosed traceable composite gasket material 100 is the ability of the composite gasket material 100 to resist harsh application conditions, such as chemically aggressive fluids, abrasion, high pressure, and even high temperatures. An additional feature and advantage of the disclosed traceable composite gasket material 100 is that the composite gasket material 100 has traceable particles that retain information about its manufacture and can be used to track the exact origin of the detected material. Another feature and advantage of the disclosed traceable composite gasket material 100 is that the composite gasket material 100 has a permanent identification method embedded in the product made of the composite gasket material 100 that cannot be misplaced, switched off, or lost. Another feature and advantage of the disclosed traceable composite gasket material 100 is that it has a much more reliable tracking method than currently available forms, which is particularly useful for users who need to identify the exact origin in case of contamination.

[0065] Figure 6 is a graph showing the sealing performance test results of a gasket according to an exemplary embodiment of the traceable composite gasket 300. The sealing performance test in Figure 6 was performed at ambient temperature in accordance with the DIN EN 1355:2014 standard (title: Flanges and Their Joints - Gasket Parameters and Test Procedures Rlevant to the Design Rules for Gasketed Circular Flange Connections). The tested embodiment of the traceable composite gasket 300 meets the requirements of the standard.

[0066] Figure 7 is a graph illustrating the results of comparative sealing tests between a gasket according to an exemplary embodiment of the traceable composite gasket 300 and a conventional PTFE gasket. The test results related to the conventional PTFE gasket are shown by line 702, and the test results related to the exemplary embodiment of the traceable composite gasket 300 are shown by line 704. The conventional PTFE gasket was cut from a PTFEE sheet filled with hollow glass microspheres and manufactured using a process similar to the HS-10 method. The sealing tests in Figure 7 were performed at ambient temperature in accordance with the DIN EN 1355:2014 standard (title: Flanges and Their Joints - Gasket Parameters and Test Procedures Relevant to the Design Rules for Gasketed Circular Flange Connections). The tested embodiments were subjected to a minimum gasket surface pressure to ensure initial sealing, and helium was used as the test medium. As shown in Figure 7, the addition of the metal powder 105 and the traceable particles 110 does not interfere with the sealing properties of the tested embodiment of the traceable composite gasket 300.

[0067] Figure 8 is another graph showing the test results of a gasket according to an exemplary embodiment of the traceable composite gasket 300 and a conventional PTFE gasket. The conventional PTFE gasket is filled with hollow glass microspheres and cut from a PTFE sheet manufactured using a process similar to the HS-10 method. The tests in Figure 8 were conducted according to the DIN EN 1355:2014 standard (title: Flanges and Their Joints - Gasket Parameters and Test Procedures Relevant to the Design Rules for Gasketed Circular Flange Connections), and the creep relaxation coefficient was determined from relaxation tests in a dedicated test apparatus, considering an initial load of 30 MPa and a temperature of 150°C. As shown in Figure 8, the addition of the metal powder 105 and the traceable particles 110 does not impair the mechanical properties of the traceable composite gasket 300 in the tested embodiment.

[0068] To evaluate the magnetic force of several embodiments of the traceable composite gasket 300, a laboratory test was developed. The test consisted of fixing an embodiment of the traceable composite gasket 300 to a permanent magnet and then applying a vertical load until the gasket 300 peeled off. This test highlighted that the traceable composite gasket material is magnetic, and that its magnetic force increases with the weight percentage of the metal powder 105.

[0069] To evaluate the interaction of several embodiments of the traceable composite gasket 300 with a magnetic field, laboratory tests were developed. These tests consisted of tracing exemplary embodiments using a commercially available metal detector, model MetroTokyo MTK-3000. The tests highlighted that the traceable composite gasket material is readily detectable by industrial metal detectors commonly used by the food and beverage industry.

[0070] Figure 9 is a partially exploded view of one embodiment of the compression packing of the present disclosure. As shown in Figure 9, the illustrated embodiment is a compression packing having anti-extrusion properties 810, comprising a re-braided core 812 made of composite yarn including a flexible graphite tape reinforced with PTFE filaments 816 having tracer particles, and an outer layer 814 of the PTFE filaments 816. The flexible graphite tape is commercially available from many suppliers, including Zhejiang Cathay Packing & Sealing Co Ltd in Xiaoshan District, Puyang Industrial Zone, Hangzhou, China. The PTFE filaments can be manufactured by techniques well known to those skilled in the art, such as extruding PTFE resin through a die to obtain PTFE filaments having a linear density of about 30 to about 1100 denier. The flexible graphite tape can be reinforced with the PTFE filaments by techniques well known to those skilled in the art, such as braiding, twisting, or arranging the flexible graphite tape and the PTFE filaments in symmetrical orientations. The tracer particles are not visible without a specific identification method, but for illustrative purposes only, a dotted circle defines the extent of the outer layer 814 showing the distribution of the tracer particles 819. A more detailed description of available identification methods is provided below. To suppress electrolytic corrosion, zinc wire 818 can be added to the interwoven core 812. Those skilled in the art will recognize that other corrosion inhibitors, including passive corrosion inhibitors such as phosphates, barium molybdate, and sodium molybdate, can also be used. According to another embodiment, the PTFE filament comprises a PTFE matrix and traceable particles, the traceable particles distributed throughout the filament, resisting friction, temperature, pressure, and abrasion without loss of information.

[0071] Throughout this disclosure, the terms “traceable particle” and “tracer particle” are used interchangeably.

[0072] Figure 10 shows further details of the interwoven core 812. Specifically, the composite yarn 816 is shown to include a flexible graphite tape 820 reinforced with PTFE filaments 822 containing tracer particles.

[0073] Figure 11 shows an embodiment of the composite yarn 816 in which the PTFE filament having tracer particles 822 is knitted as a coating and used as a reinforcing material for the flexible graphite tape 820. Focus on the tracer particles 819. Since the flexible graphite tape 820 is very fragile, the PTFE filament having tracer particles 822 acts as a reinforcing material, increasing the mechanical resistance of the composite yarn 816 so that it can withstand the knitting process without degradation. Those skilled in the art will recognize that the PTFE filament having tracer particles 822 can be added to the flexible graphite tape 820 as a reinforcing material in many other suitable ways.

[0074] The tracer particles 819 are added during the manufacturing of the PTFE filament 822 and distributed within its polymer matrix. As described above, the tracer particles are invisible unless a specific method of identification is used, so Figure 9 includes a dotted circle defining the extent of the outer layer 814 showing the distribution of the tracer particles 819. The distribution of the tracer particles 819 in the PTFE filament having the tracer particles 822 is not shown in Figure 10, but those skilled in the art will recognize that such a distribution of tracer particles is similar to that shown in Figure 9. The tracer particles 819 are resistant and will not be damaged as long as the compression packing 810 is used within its operating limits. If degradation occurs, it indicates that the operating limits have been exceeded.

[0075] The tracer particles 819 can be found in different forms and compositions. Suitable tracer particles 819 may include fluorescent dye molecules, fluorescent dyes, phosphors, porous silicon, and microdots. They are suitable for identifying the compression packing after use, although they may differ slightly in the mechanism used for identification.

[0076] According to one embodiment, the tracer particles 819 are formed of a fluorescent dye molecule or a fluorescent dye. According to such an embodiment, suitable fluorescent dye molecules include chalcogenides such as selenides, sulfides, and tellurides of metals such as cadmium, lead, and zinc. Suitable fluorescent dye molecules also include chemical compounds such as C62H87N13O16. Fluorescent dye molecules are widely available commercially and are fluorescent chemical compounds that absorb light and re-emit light at a specific wavelength. The wavelength of the re-emitted light is usually measured with a microscope equipped with a filter set for the specific phosphor or fluorescent dye of interest.

[0077] In other embodiments, the tracer particles 819 take the form of a phosphor. A phosphor is a material that absorbs light in wavelength ranges invisible to the naked eye and emits light in the visible range. Some phosphors absorb light in both the ultraviolet and infrared regions and emit light of multiple colors, including red, green, and yellow. Specifically, upconversion type hexagonal yttrium sodium fluoride (β-NaYF4), which emits visible light in response to infrared excitation, is a suitable phosphor. Depending on the selection of the phosphor, it can be excited with a portable laser pen or an ultraviolet flashlight.

[0078] According to another embodiment, the tracer particles 819 take the form of porous silicon (PS), which is silicon containing synthetic nanopores added to its microstructure. The porous silicon can be produced by methods well known to those skilled in the art, such as anodizing or stain etching of a silicon wafer. According to such an embodiment, the nanopores reflect visible white light. The wavelength of this light is characteristic of the size and topology of the nanopores in the silicon and can be measured with a standard spectrometer.

[0079] In yet another embodiment, the tracer particles 819 take the form of microdots, which are small discs typically made of ceramic, polymer, and metal. The discs are usually engraved with a pattern of very small dots by a laser. The dot pattern can later be extracted for identification by examining one of the discs with a microscope or similar magnification technique.

[0080] A test was developed to evaluate the temperature resistance of the tracer particles 819 after the compression packing 810 has been exposed to extreme temperatures. In this test, the compression packing 810 having the tracer particles 819 was exposed to a temperature of 650°C, which is the maximum temperature that the compression packing 810 is expected to be subjected to, for 4 hours. After the test, the tracer particles 819 could still be identified.

[0081] A test was developed to evaluate the chemical resistance of the tracer particles 819 after the compression packing 810 had been subjected to extreme conditions. The test involved exposing the compression packing 810 to two different environments for three months each. The first test involved a 98% sulfuric acid (H2SO4) solution, and the second test involved a 50% sodium hydroxide (NaOH) solution. After exposure to both environments, the compression packing 810 maintained its structure, and the tracer particles 819 could still be identified.

[0082] To evaluate the resistance of the tracer particles 819, a test was developed in high-frequency valve operation, which is a polishing operation. The test was performed in accordance with standard ISO 15848-1, and the compression packing 810 was subjected to 60,000 mechanical cycles and three thermal cycles up to 260°C. After the test, the compression packing 810 maintained its structure, and the tracer particles 819 were still identifiable. The sealing aspect of this test is described below.

[0083] According to the embodiments, the PTFE filament 822 may be filled with materials such as carbon black, graphite, barite, talc, and other mineral fillers, but is not limited thereto. The fillers may be selected to achieve specific goals, such as increasing the resistance of the PTFE filament 822 and thus improving braiding performance, reducing the overall PTFE content, or reducing surface friction with, for example, a valve shaft. These fillers may be included simultaneously with, and do not diminish or interfere with, the use of the tracer particles 819. The PTFE filament 822 can also be made thinner or thicker against the flexible graphite tape 820 for applications where the PTFE content must be precisely controlled. Exemplary embodiments have successfully manufactured and braided using yarns with PTFE content of 4, 10, 16, and 21% by varying the weight of the PTFE filament 822 in the knitted covering configuration.

[0084] According to certain embodiments, the interlocked, circular, or square braided core 812 and the interlocked, circular, or square braided outer layer 814 are achieved by weaving the flexible graphite tape, reinforced with PTFE filaments having tracer particles 819, diagonally in a cross shape through the body from the surface of the core 812 or outer layer 814. For such interlocked braids, the various strands of the composite yarn 816 are locked together, providing an overall strong, integrated structure that is generally less prone to fraying. The weaving pattern of such interlocked, circular, or square braids distributes the various strands of the composite yarn 816 uniformly throughout the core 812 and the outer layer 814, respectively, resulting in an overall dense and flexible structure. The interlock braids in the illustrated embodiments of Figures 9 and 10 include the composite yarn 816, but ordinary technicians in the art of compression packing will understand that other materials other than the composite yarn, including tapes, ribbons, etc., and other forms of these materials may be used to make the interlock braid core 812 and the interlock braid outer layer 814. Figure 12 is a schematic diagram showing the types of braids (square braid 830, three-track interlock braid 832, four-track interlock braid 832, circular braid 833).

[0085] According to one embodiment for creating a density-controlled core 812 to have a desired density to ensure the anti-extrusion properties of the final packing for a relatively small cross-sectional packing mold as shown in Figures 9 and 13, the core includes a single interlocking braid or square braid core 812.

[0086] As shown in Figure 13, according to another embodiment for making the density-controlled core to have the desired density to ensure the extrusion-resistant properties of the final packing, in the case of a packing with a relatively large cross-section, the packing 834 includes a core 812, an outer layer 814 consisting of a re-braided, circular braided or square braided layer 836 arranged on the re-braided, circular braided or square braided core 812, and a composite yarn 816 made of re-braided flexible graphite tape of PTFE-reinforced filaments with tracer particles.

[0087] In certain embodiments of this disclosure, corrosion inhibitors may be added to suppress electrolytic corrosion. As shown in Figures 9 and 13, zinc wire 818 may be added to the core 812 to suppress electrolytic corrosion. Those skilled in the art will recognize that other corrosion inhibitors, such as passive corrosion inhibitors containing phosphates, barium molybdate, and sodium molybdate, are also used.

[0088] To evaluate the efficiency of the electrolytic corrosion inhibitor, a laboratory test was developed to determine whether the tracer particles retain their intended function. For this test, an embodiment of the present disclosure having zinc wire as the corrosion inhibitor was compared with another embodiment without the zinc wire or other types of corrosion inhibitor. As schematically shown in Figure 14, the test was carried out using a galvanic cell 840 in which a compression packing 842 and a stainless steel rod 844 act as electrodes. Both were immersed in an electrolyte solution 846 and connected to a voltmeter 848 that recorded the potential difference between the packing 842 and the stainless steel rod 844. The expected behavior of the corrosion inhibitor in operation, i.e., protecting the valve shaft from corrosion, is indicated by electrons moving from the packing 842 toward the stainless steel rod 844. The direction of the electron flow can be determined by the sign of the voltage. As shown in Figure 15, this test showed that the zinc wire could provide the expected protection 850. Eventually, the zinc was consumed, determining the point at which corrosion of the valve shaft began, which can be seen in the change in the direction of the electron flow. This result is in contrast to Embodiment 852 without a corrosion inhibitor, where the voltage sign indicates corrosion from the start of the test. This indicates that the tracer particles 819 do not interfere with the functionality of the corrosion inhibitor, and that the zinc wire functions as a suitable corrosion inhibitor in the embodiment of the compression packing according to this disclosure. Those skilled in the art will recognize that other corrosion inhibitors, such as passive corrosion inhibitors containing phosphates, barium molybdate, and sodium molybdate, may also be used.

[0089] According to certain embodiments of the present disclosure, the packing may include a coating of lubricant, blocking agent, or both. Such blocking agents and lubricants may include any number of agents well known to those skilled in the art, such as animal fats, vegetable oils, PTFE, petroleum or mineral lubricants, synthetic lubricants, silicones, chlorofluorocarbons, graphite, paraffin, mica, tungsten disulfide, molybdenum disulfide, or grease. For example, the compression packing according to the present disclosure is impregnated with PTFE, which accounts for less than 5% of the total packing weight. This coating is not required but may be added to further reduce friction in the packing.

[0090] Laboratory tests were conducted to evaluate the packing friction of commercially available control valves. These tests measured packing friction under different assembly stresses, considering various applications. The tests aimed to compare a compression packing with the structure shown in Figure 10—namely, a knitted flexible graphite tape reinforced with tracer particles—with a prior art compression packing made of a knitted flexible graphite tape reinforced with nickel-chromium threads, for two different applications. The first application involved both packings without PTFE coating, while the second application involved both packings containing the same type of PTFE coating.

[0091] Figure 16 shows a comparison of the first application type between the compression packing according to Embodiment 880, which has the structure shown in Figure 10, i.e., both without PTFE coating, and in which the compression packing is made of a knitted structure of flexible graphite tape reinforced with PTFE filaments having tracer particles, and the prior art compression packing 882, which has a structure of a knitted structure of flexible graphite tape reinforced with nickel-chromium yarn. As a result, it was found that the compression packing according to Embodiment 880 has an average friction value that is 17% lower than the prior art compression packing 882.

[0092] Figure 17 shows the results for the second application type, i.e., comparing the two packings described above, but with the same PTFE coating applied to both packings. These results show that the compression packing according to embodiment 890 having the structure shown in Figure 11, i.e., the compression packing made of flexible graphite tape reinforced with PTFE filaments having tracer particles in a knitted coating configuration, has an average friction value 19% lower than the prior art compression packing 892 having a structure reinforced with nickel-chromium threads in a knitted coating configuration.

[0093] Laboratory tests were conducted according to the procedures described in the leak discharge standard API 622. Figure 18 shows a comparison of the results of a compression packing according to Embodiment 860 of the present disclosure, which has the structure shown in Figure 11, i.e., neither of which includes a PTFE coating, and which has a structure including a flexible graphite tape reinforced with PTFE filaments having tracer particles in a knitted coating configuration, with the results of a prior art compression packing 862, which has a structure including a flexible graphite tape reinforced with nickel-chromium yarn in a knitted coating configuration. The compression packing according to Embodiment 860 of the present disclosure met the approval criteria of the standard and had lower leakage than the prior art compression packing 862. Furthermore, the prior art compression packing 862 failed the test when the measured leakage exceeded the permissible limit of 100 ppm after 950 mechanical cycles.

[0094] As shown in Figure 19, further leak discharge tests in accordance with API 622 were performed comparing the compression packing according to Embodiment 870 of the present disclosure having the structure shown in Figure 11, namely, the compression packing having a knitted coating structure of flexible graphite tape reinforced with PTFE filaments having the tracer particles, and the prior art compression packing 872 having a structure including flexible graphite tape reinforced with nickel-chromium yarn in a knitted coating structure, and the case in which both compression packings have a PTFE coating. Both packings met the approval criteria and had similar performance in maintaining leaks well below the 100 ppm threshold. Note that the PTFE coating is required for the prior art compression packing 872 to maintain a leak below the 100 ppm threshold, whereas the PTFE coating is not required for the compression packing according to Embodiment 870 of the present disclosure to reduce leaks.

[0095] Laboratory testing was conducted in accordance with the leak discharge standard ISO 15848-1. For this test, an ASME B16.34 size 2-inch class 300 control valve was selected. The procedure followed the endurance class CC2, equivalent to 60,000 mechanical cycles and 3 thermal cycles, at the same temperature, pressure, and test medium as described in API 622. The results are shown in Figure 20, and the compression packing according to embodiment 900 having the structure shown in Figure 11, i.e., the compression packing being made of flexible graphite tape reinforced with PTFE filaments having tracer particles in a knitted coating configuration, showed leakage well below the 50 ppm required for the most restrictive airtightness class of the standard, thus meeting the approval criteria.

[0096] A laboratory fire test simulating a standard API 607 ​​Fire Safee was conducted. The test was performed using a device simulating a stuffing box for a 4-inch 300# valve. The test device was placed in a 1000°C oven, the temperature was monitored, and heating was stopped when the temperature reached 650°C. The test device was then removed from the oven, cooled to room temperature, and pressurized with 40 bar of water. Leakage was collected for 5 minutes at this stage, and the maximum allowable leak rate for a valve of this size was 600 ml / min. A compression packing according to the embodiment having the structure shown in Figure 11, i.e., the compression packing consisting of a knitted coating of flexible graphite tape reinforced with tracer particle-filled PTFE filaments, was tested and showed leakage below the allowable leak rate, meeting the approval criteria.

[0097] The compression packing according to the embodiments of this disclosure was also tested in pump applications, which are fundamentally different from valve applications due to the low installation stress and significantly high shaft speed. For this purpose, a test apparatus based on EN 16752:2014 was used with a packing cross-sectional size of 3 / 8 inch. The compression packing was exposed to water pressurized at 6 bar for a total of 100 hours at a shaft speed of 1750 rpm (6.4 m / s). The test results are shown in Figure 21, and fluid leakage was collected and measured separately for the shaft side 1110 and the stuffing box side 1112. The embodiment of the compression packing tested in this disclosure had the structure shown in Figure 11, namely, the compression packing was made of flexible graphite tape reinforced with PTFE filaments having tracer particles in a knitted coating configuration without PTFE coating. The compression packing leaked an average of 37 ml / min during the test. This test, combined with the fact that the pump shaft is typically softer than the valve shaft, immediately damages the equipment and thus creates a leakage path, making it unsuitable as a replacement for metal-reinforced packing for valves, which is currently the most advanced type of leak discharge. This test result is unexpected, and it shows that the packing is a flexible sealing solution applicable not only to valves but also to pumps.

[0098] The above-described embodiments of the compression packing of this disclosure are developed to enable leak discharge services that do not require extrusion and do not require metal reinforcement, which is common in the industry, and to resist high installation stresses. Because there is no metal reinforcement, sealing performance is not impaired, operating friction is reduced as shown in Figures 16 and 17, and the possibility of damage or chipping of the shaft or axis can be eliminated. The above-described embodiments of the compression packing of this disclosure carry tracer particles that enable the compression packing to retain information about its manufacture and can be used to trace the origin of the compression packing. The tracer particles are added directly when manufacturing the PTFE filament. This PTFE filament can then be added to the compression packing in various forms and configurations. For example, the PTFE filament containing the tracer particles can be added as a single filament to the core portion of the compression packing, utilizing only its tracking properties, while the rest of the compression packing can be made of leak discharge-compatible material. The tracer particle-containing PTFE filament can be wrapped around a conventional flexible graphite tape, providing the packing with traceable properties, as well as mechanical resistance to the flexible graphite tape, enabling it to withstand the destructive forces generated during the braiding process. The tracer particle-containing PTFE filament can be used in the form of a knitted mesh around a conventional flexible graphite tape, providing the compression packing with traceable properties, extrusion resistance, and mechanical resistance to the flexible graphite tape, enabling braiding. The PTFE filament containing the tracer particles can be used in the same way as a conventional PTFE packing without the use of the flexible graphite tape, but with the added property of traceable properties. For example, the packing can be fully braided using the tracer particle-containing PTFE filament, and the particle-containing PTFE can be directly extruded to the size of the stuffing box. The tracer particles are resistant to typical applications such as abrasion, mechanical deformation, chemical attack, and high temperatures, as demonstrated in the various tests described above.Therefore, the tracer particles constitute a permanent identification method and are thus far more reliable than currently available identification forms, as the tracer particles will not be lost or misplaced. This is particularly useful for end users who need to ensure they are using guaranteed compression packing that can meet leak emission requirements, such as users who have received a consent judgment with the EPA for Clean Air Act violations, and furthermore, the embodiments of the prevention disclosure meet the approval criteria for laboratory testing conducted in accordance with the procedures of the API 622 and ISO 15848-1 leak emission standards. As an additional application, the compression packing of the foregoing disclosure, having no shaft damage and a soft outer sheath, can be successfully used to control leaks in pump and dynamic applications, as demonstrated in laboratory testing under EN16752.

[0099] In some embodiments, the contamination described above includes fragments of the sealing material. The fragments of the sealing material are any part of the sealing material that has peeled off from the seal.

[0100] Figure 22 illustrates a method for classifying or identifying fragments from a sealing material, commonly referred to as reference number 2100. Referring to Figure 22, method 2100 includes steps 2105 (placing a portion of the fragment under a microscope), 2110 (using the microscope to determine whether the portion of the fragment contains traceable particles), 2115 (if the portion of the fragment does not contain the traceable particles) (if the portion of the fragment does not contain the traceable particles, 2115 (classifying the fragment as fragment from a seal that does not contain the traceable particles), and 2120 (if the portion of the fragment does contain the traceable particles, using the traceable particles to identify the seal from which the fragment originated).

[0101] In some embodiments and in step 2105, the fragment is placed under a microscope. The fragment may be a fragment from a seal. In some embodiments and in step 2110, the microscope is used to determine whether traceable particles are contained within the fragment. In some embodiments, in step 2110, the microscope is equipped with a filter set for a particular phosphor or fluorescent dye of interest. Determining whether the fragment contains traceable particles using the microscope includes viewing the fragment using the filter set to determine whether traceable particles are visible. However, in some embodiments, step 2105 includes using a portable laser pen or ultraviolet flashlight that brings excitation by traceable particles that are or contain a phosphor.

[0102] In some embodiments and in step 2115, if traceable particles are not present in any portion of the fragment, the fragment is classified as a fragment from a seal that does not contain traceable particles. The absence of traceable particles indicates that the fragment is not a fragment from a seal that contains traceable particles. This is useful in narrowing down the type of seal from which the fragment originated.

[0103] In some embodiments and in step 2120, if traceable particles are present in a portion of the fragment, the seal from which the fragment originated is identified. In some embodiments, the traceable particles include a pattern of microdots, which is identified in step 2120. The identified pattern is then used to identify the source of the seal that produced the fragment or other identifying data.

[0104] The method 2100 can identify the composite gasket 300, the composite gasket 400, the compression packing 810, or the PTFE filament having the tracer particles 822 as the source of the debris, but it can also confirm that the composite gasket 300, the composite gasket 400, the compression packing 810, and the PTFE filament having the tracer particles 822 are not the source of the debris.

[0105] It is understood that modifications may be made to the foregoing without departing from the scope of this disclosure.

[0106] This disclosure discloses a traceable composite gasket material comprising a sintered polytetrafluoroethylene (PTFE) matrix, a metal powder, and traceable particles, wherein the metal powder and the traceable particles are dispersed within the PTFE matrix. In some embodiments, the metal powder reacts to a magnetic field and light with detectable behavior. In some embodiments, the traceable particles are selected from phosphors and fluorescent dyes. In some embodiments, the traceable particles absorb light and emit light at specific wavelengths that are visible under a microscope equipped with a filter set for the traceable particles. In some embodiments, the traceable particles are phosphor particles. In some embodiments, the phosphor particles absorb light in the invisible wavelength range and emit light in the visible range. In some embodiments, the traceable particles include porous silicon particles. In some embodiments, the porous silicon traceable particles have nanopores that are visible under white light. In some embodiments, the traceable particles include microdot particles. In some embodiments, the microdot particles are visible under a microscope. In some embodiments, the material also comprises any number of fillers. In some embodiments, the fillers comprise any one or more of barite, silica, natural hollow glass microspheres, and synthetic hollow glass microspheres. In some embodiments, the PTFE matrix comprises finely powdered PTFE. In some embodiments, the gasket material has a total weight, and the amount of PTFE is greater than 30% of the total weight of the gasket material. In some embodiments, the gasket material has a total weight, and the amount of metal powder is about 1% to about 70% of the total weight of the gasket material. In some embodiments, the gasket material has a total weight, and the amount of traceable particles is less than 5% of the total weight of the gasket material.

[0107] The disclosure also discloses a method for identifying a fragment, comprising the steps of: placing the fragment under a microscope; using the microscope, determining whether the fragment contains traceable particles; if the fragment does not contain traceable particles, classifying the fragment as a fragment that does not contain traceable particles; and, if the fragment contains tracer particles, using the tracer particles to identify the seal from which the fragment originated. In some embodiments, the seal is a gasket. In some embodiments, the seal is a compression packing.

[0108] In some exemplary embodiments, elements and teachings of various exemplary embodiments may be combined in whole or in part in some or all of the exemplary embodiments. Furthermore, one or more elements and teachings of various exemplary embodiments may be omitted at least partially and / or combined at least partially with one or more other elements and teachings of various exemplary embodiments.

[0109] For example, arbitrary spatial references such as "up," "down," "above," "downward," "between," "below," "vertical," "horizontal," "corner," "upward," "downward," "side to side," "left to right," "left," "right," "right to left," "upper part to lower part," "lower part to upper part," "upper part," "lower part to upper part," and "upper part to lower part" are for illustrative purposes only and do not limit the specific orientation or position of the structures described above.

[0110] In some exemplary embodiments, different steps, processes, and procedures are described as appearing as separate acts, but one or more steps, one or more processes, and / or one or more procedures may be performed in different orders, simultaneously, and / or sequentially. In some exemplary embodiments, steps, processes, and / or procedures may be integrated into one or more steps, processes, and / or procedures. In some exemplary embodiments, one or more operating steps in each embodiment may be omitted. Furthermore, in some exemplary embodiments, some features of the present disclosure may be adopted without corresponding use of other features. Furthermore, one or more of the embodiments and / or modifications described above may be combined in whole or in part with any one or more of the other embodiments and / or modifications described above.

[0111] While several exemplary embodiments have been described in detail above, the embodiments described are illustrative and not limiting, and those skilled in the art will readily understand that many other modifications, changes, and / or substitutions are possible in the exemplary embodiments without substantially departing from the novel teachings and merits of the present disclosure. Accordingly, all such modifications, changes, and / or substitutions are intended to be within the scope of the present disclosure as defined in the following claims. In the claims, any means plus function clause is intended to cover not only the structures and structural equivalents described herein as performing the cited function, but also equivalent structures.

Claims

1. It is a filament, Polytetrafluoroethylene (PTFE) matrix and Tracer particles selected from fluorescent dye molecules and fluorescent dyes It has, The tracer particles absorb light and emit light of a specific wavelength detectable by a microscope equipped with a filter set for the particular tracer particles, and the tracer particles are distributed throughout the matrix, forming filaments.

2. In the filament according to claim 1, further, A filament having a mineral or synthetic filler selected from barite, graphite, and carbon black.

3. It is a composite yarn, Flexible graphite tape and PTFE filament having a PTFE matrix and tracer particles It has, The flexible graphite tape is reinforced with PTFE filaments by a method selected from the steps of weaving the flexible graphite tape and the PTFE filaments in symmetrical directions, twisting them, or arranging them, thereby forming a composite yarn.

4. A compression packing for sealing a valve shaft and a pump shaft, comprising a PTFE matrix and filaments containing tracer particles.

5. A compression packing according to claim 4, comprising a core and an outer layer, wherein the core and the outer layer each have one or both of the following: a filament comprising a PTFE matrix and tracer particles, and a flexible graphite tape reinforced filament comprising a PTFE matrix and tracer particles.

6. In the compression packing according to claim 4, further, A compression packing having at least one of a lubricant and a blocking agent.

7. A compression packing according to claim 6, wherein the lubricant is one or more of graphite, paraffin, silicone, mineral oil, grease, animal fat, vegetable oil, petroleum-based or mineral-based lubricant, synthetic lubricant, chlorofluorocarbon, mica, tungsten disulfide, and molybdenum disulfide.

8. A compression packing according to claim 6, wherein the lubricant and blocking agent are added in a form impregnated with PTFE.

9. In the compression packing according to claim 4, further, A compression packing having an activated corrosion inhibitor selected from zinc and zinc wire.

10. In the compression packing according to claim 4, further, Compression packing having a passive corrosion inhibitor selected from phosphates, barium molybdate, and sodium molybdate.

11. It is a filament, Polytetrafluoroethylene (PTFE) matrix and Phosphorescent tracer particles, wherein the tracer particles are distributed throughout the matrix, absorb light in the invisible wavelength range, and emit light in the visible range, and / or Porous silicon tracer particles distributed throughout the matrix, wherein the porous silicon tracer particles have synthetic nanopores, and the nanopores reflect visible white light, and / or Microdot tracer particles distributed throughout the matrix, wherein the microdot tracer particles are identifiable by microscopic examination, and A filament having

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