Rubber boards are widely utilized for sealing purposes in various rubber products. They typically include several types such as natural rubber boards, nitrile rubber boards, neoprene rubber boards, isobutadiene rubber boards, styrene rubber boards, ethylene propylene terpolymer rubber boards, silicone rubber boards, tetrafluoroethylene boards, and fluoroelastomer boards. Among these, the rubber sheets commonly used for creating gaskets fall into three primary categories: natural rubber, nitrile rubber, and neoprene. In recent years, special rubbers like fluoroelastomers have gained popularity and are increasingly being adopted.
Non-asbestos boards have emerged as an eco-friendly alternative in response to stricter environmental regulations. Sealpilot's non-asbestos boards are manufactured through a process involving the rolling and vulcanization of organic and inorganic fibers mixed with specific adhesive agents and minimal filler materials. This composition ensures they are free from harmful asbestos fibers, making them ideal substitutes for traditional asbestos gaskets. These non-asbestos gaskets boast impressive strength, excellent resilience, and exceptional resistance to permeation, making them a superior choice under high-temperature and high-pressure conditions.
Asbestos rubber plates, on the other hand, are produced by combining asbestos, rubber, and fillers under pressure. Depending on their formulation, processing method, performance, and application, these plates can be categorized into high-pressure, medium-low pressure, and oil-resistant types. The asbestos used in these sheets primarily consists of chrysotile (white asbestos) and crocidolite (blue asbestos). Chrysotile, a serpentine mineral, contains around 13% crystalline water and offers excellent heat resistance, alkali resistance, and tensile strength but lacks strong acid resistance. Crocidolite, belonging to the amphibole family, contains silicates with 2.5 to 3.5% crystalline water and has a higher iron oxide content compared to magnesium oxide. Its acid-resistant properties make it preferable for manufacturing acid-resistant asbestos rubber sheets.
The quality of asbestos fibers significantly impacts the performance of asbestos rubber sheets. Therefore, fibers used should exhibit high tensile strength, excellent heat resistance, and a certain length for optimal flexibility and elasticity. High-pressure asbestos rubber plates and certain oil-resistant types often employ grades 2 and 3 asbestos fibers. Given current restrictions on asbestos-based products, many manufacturers are transitioning towards asbestos-free alternatives like Bode’s non-asbestos rubber sheets.
Flexible graphite sheets and strips represent another innovative sealing material renowned for their elasticity, flexibility, media resistance, and temperature tolerance. This novel material has seen rapid adoption across chemical industries due to its versatility and reliability.
Polytetrafluoroethylene (PTFE) stands out as one of the most resilient synthetic resins, offering outstanding corrosion resistance. Its ability to function effectively in highly corrosive environments makes PTFE an ideal candidate for sealing gaskets, particularly in sectors like pharmaceuticals and food processing where contamination must be avoided. Although PTFE exhibits superior thermal stability compared to other plastics, it tends to undergo cold flow when compressed and creep upon heating, which can compromise sealing efficiency. To counteract these issues, additives such as glass fibers, graphite, or molybdenum disulfide are frequently incorporated to enhance creep resistance and thermal conductivity.
In addition to conventional options, Bode Seal has explored producing various non-asbestos gaskets tailored to address sealing challenges in chemical processes. For instance, asbestos resin plate gaskets are fabricated using a non-asbestos soft plate combined with polyvinyl chloride resin. These gaskets display robustness, pressure resistance, and affordability, with negligible weight loss after immersion in 65% nitric acid for an hour. Similarly, asbestos-impregnated gaskets involve punching acid-resistant blue asbestos boards and impregnating them with an acid-resistant coating, resulting in significantly reduced weight changes during acidic treatments compared to standard asbestos rubber sheets. Furthermore, asbestos braided gaskets involve weaving asbestos ropes into flat forms and securing the ends with additional asbestos strands. The type of asbestos used depends on the operating temperature, with blends containing up to 70% blue asbestos and first-grade temperature asbestos capable of withstanding temperatures up to 800°C.
These diverse sealing solutions cater to a wide range of industrial needs, ensuring efficient and reliable performance across different operational conditions.
The start of the shield machine refers to a series of work in which the shield machine is driven from the tunnel door to the undisturbed soil section by using the temporarily assembled pipe segments, Reaction Frame and other equipment of the working shaft. Reinforcement of the starting end, installation of shield machine, starting bracket, assembly of shield machine, installation of reaction frame, shield machine system debugging.
Starting Frame,Shield Launching Frame,Shield Starting Base Structure,Starting Base Frame
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