Compression Sheets

Compression sheets, often referred to as sealing sheets or gasket sheets, are fundamental industrial components used to create a reliable, static seal between two mating surfaces. Their primary function is to prevent leakage of fluids or gases, isolate electrical currents, and dampen vibration and noise in a vast array of machinery, pipelines, and equipment. The effectiveness of a sealing solution hinges on selecting the correct compression sheet material for the specific application's pressure, temperature, and medium. At Kaxite Sealing, we engineer and manufacture premium-grade compression sheets designed to meet the rigorous demands of modern industry. Our commitment lies in providing durable, high-performance sealing solutions that enhance operational safety, reduce maintenance downtime, and improve overall system efficiency. ### Understanding Compression Sheet Materials and Properties The performance of a compression sheet is dictated by its base material and the compounding ingredients used in its manufacture. Each material offers a unique combination of properties suitable for different environments. **Common Base Materials:** * **Non-Asbestos Organic (NAO) / Aramid Fiber:** A modern, safe replacement for traditional asbestos sheets. Excellent for general-purpose sealing with water, steam, air, oils, and fuels. Known for good compressibility and recovery. * **Compressed Non-Asbestos (CNA):** Similar to NAO but undergoes a high-pressure calendering process, resulting in a denser, stronger sheet with superior blow-out resistance and dimensional stability for high-pressure flange applications. * **Expanded PTFE (ePTFE):** A soft, highly conformable material made from 100% PTFE. It is chemically inert, has an extremely wide temperature range, and is suitable for sealing irregular surfaces. It is also FDA compliant for certain applications. * **Graphite:** Offers exceptional thermal conductivity and stability at very high temperatures. It is highly compressible and creates an excellent seal in steam and hot oil services. Can be reinforced with stainless steel or other inserts for added strength. * **Rubber (NBR, EPDM, CR, Silicone, FKM/Viton):** Elastomeric sheets provide excellent flexibility and sealing force at lower pressures. Material choice depends on the fluid media: * **NBR (Nitrile):** Excellent resistance to oils, fuels, and hydrocarbons. * **EPDM:** Superior for hot water, steam, ozone, and weathering. * **FKM (Viton):** Outstanding chemical and high-temperature resistance. ### Key Product Parameters and Selection Criteria Selecting the right Kaxite Sealing compression sheet requires careful consideration of several technical parameters. The following table outlines critical factors to guide your selection process. **Compression Sheet Selection Guide Table** | Parameter | Description | Why It Matters | Common Values / Examples | | :--- | :--- | :--- | :--- | | **Material Type** | The primary composition of the sheet (e.g., CNA, ePTFE, Graphite, NBR). | Determines chemical compatibility, temperature limits, and fundamental sealing behavior. | CNA for high-pressure steam; ePTFE for aggressive chemicals. | | **Thickness** | The nominal thickness of the sheet, typically measured in inches or millimeters. | Affects compressibility and the ability to fill surface imperfections. Thicker sheets are used for more uneven surfaces. | 1/16" (1.5mm), 1/8" (3.0mm), 3/32" (2.4mm). | | **Density / Specific Gravity** | Mass per unit volume of the material. | Influences mechanical strength, creep resistance, and suitability for pressure. Higher density often indicates better blow-out resistance. | e.g., 1.8 g/cm³ for CNA; 0.6 g/cm³ for soft ePTFE. | | **Temperature Range** | The continuous operating temperature span the material can withstand. | Critical for preventing material degradation, hardening, or melting, which leads to seal failure. | -240°C to +315°C for ePTFE; -40°C to +120°C for NBR. | | **Pressure Rating** | The maximum static pressure the gasket can seal effectively. | Must exceed the system's maximum operating pressure with a safety margin. CNA sheets typically handle higher pressures than rubber. | Up to 3000 psi for reinforced graphite; 150-300 psi for standard NAO. | | **Compression Set** | The material's ability to return to its original thickness after compression is released. | A low compression set indicates good recovery and long-term sealing performance without constant bolt re-tightening. | Expressed as a percentage (lower is better). | | **Chemical Compatibility** | The resistance of the material to specific media (acids, alkalis, solvents, oils, etc.). | Prevents swelling, shrinking, or chemical attack that compromises the seal. Must be verified against the process fluid. | Consult a chemical resistance chart for the specific material. | | **Tensile Strength** | The maximum tensile stress the material can withstand while being stretched. | Indicates the sheet's mechanical robustness and handling strength during installation. | Measured in MPa or psi (lengthwise and crosswise). | ### Detailed Product Specifications for Kaxite Sealing Sheets To exemplify the professional grade of our products, here are detailed specifications for two of our flagship compression sheet lines. **1. Kaxite Sealing KX-CNA Series (Compressed Non-Asbestos)** * **Base Material:** High-quality aramid and cellulose fibers, bonded with nitrile rubber. * **Standard Thickness:** 0.4mm (0.016"), 0.8mm (1/32"), 1.5mm (1/16"), 3.0mm (1/8"). * **Density:** 1.75 - 1.95 g/cm³. * **Temperature Range:** -100°C to +400°C (-148°F to +752°F) short peak. * **Continuous Service:** -40°C to +290°C (-40°F to +554°F). * **Max Pressure:** Suitable for PN 40/Class 300 flanges and higher, depending on thickness. * **Applications:** Ideal for steam, hot oils, hydrocarbons, and chemical plant piping. Compliant with major international standards for non-asbestos materials. **2. Kaxite Sealing KX-ePTFE Series (Expanded PTFE)** * **Base Material:** 100% pure polytetrafluoroethylene, expanded into a microporous structure. * **Standard Thickness:** 0.5mm, 1.0mm, 1.5mm, 2.0mm, 3.0mm. * **Density:** 0.5 - 1.2 g/cm³ (variable grades: soft, medium, hard). * **Temperature Range:** -240°C to +315°C (-400°F to +600°F). * **Chemical Resistance:** Resistant to virtually all industrial chemicals and solvents. * **Applications:** Perfect for aggressive acids and alkalis, pharmaceutical and food processing (FDA grades available), and sealing corroded or imperfect flanges. ### Compression Sheets FAQ (Frequently Asked Questions) **Q: What is the main difference between a compression sheet and a pre-cut gasket?** A: A compression sheet is a bulk sheet material from which gaskets can be cut or punched on-site to any size or shape required. A pre-cut gasket is a ready-to-use component manufactured to the exact dimensions of a specific flange. Sheets offer flexibility and reduce inventory needs, while pre-cut gaskets ensure precision and save installation time. **Q: How do I determine the correct thickness for my application?** A: The optimal thickness depends on flange conditions and pressure. For standard, smooth flanges, thinner sheets (1/16" or 1.5mm) are typically sufficient and provide better stress distribution. For uneven, pitted, or warped flanges, a thicker sheet (1/8" or 3.0mm) may be necessary to compensate for surface irregularities and achieve a proper seal. Always refer to the flange manufacturer's specifications or engineering standards. **Q: Can I reuse a gasket made from a compression sheet?** A: It is generally not recommended to reuse any gasket, including those cut from compression sheets. During initial installation, the material compresses and conforms to the specific imperfections of the flange faces. Reusing it will likely result in an inadequate seal, as the material has already undergone compression set and may not recover fully or re-conform correctly. **Q: How should I store Kaxite Sealing compression sheets to ensure their longevity?** A: Store sheets in a cool, dry, and dark environment away from direct sunlight, ozone sources (like electric motors), and extreme temperatures. Keep them flat and supported to prevent bending or creasing. Sheets should be stored away from chemicals and solvents to prevent absorption of vapors that could degrade the material. **Q: What is the proper bolt tightening procedure when installing a gasket from a sheet?** A: Use a calibrated torque wrench and follow a cross-pattern tightening sequence (star pattern). Tighten bolts in several incremental steps (e.g., 30%, 60%, 100% of final torque) to ensure even compression across the entire gasket face and prevent distortion of the flange. Always refer to the specific torque values recommended for your flange class and gasket material. **Q: Are Kaxite Sealing compression sheets suitable for food and beverage applications?** A: Yes, we offer specific grades, particularly in our ePTFE and certain rubber series, that are compliant with FDA (U.S. Food and Drug Administration) and EU regulations for food contact. These materials are formulated without additives that could migrate into the product stream. It is crucial to specify this requirement when selecting your sheet material. **Q: How do I cut a gasket from a compression sheet accurately?** A: For simple shapes, a sharp utility knife and a metal template work well. For circular gaskets, use a compass-style gasket cutter for the most precise results. For high-volume or complex shapes, die-cutting is recommended. Always ensure the cutting tools are sharp to avoid tearing or fraying the sheet material, which can create leak paths. **Q: What does "blow-out resistance" mean in the context of compression sheets?** A: Blow-out resistance refers to the material's ability to withstand internal pressure without extruding or being forcibly expelled from the flange gap. Denser materials like CNA or reinforced graphite have high blow-out resistance, making them suitable for high-pressure applications. Softer materials require careful attention to flange design and bolt load to prevent blow-out. **Q: Can these sheets be used for electrical insulation purposes?** A: Many compression sheet materials, especially mica-based, some rubber compounds, and certain grades of ePTFE, possess excellent dielectric properties and are used as insulating gaskets. You must select a material specifically rated for the required dielectric strength and service voltage. Our technical team can assist with these specialized selections. **Q: My application involves rapid temperature cycling. Which material is best?** A: Materials with low thermal expansion and good recovery, such as flexible graphite or certain high-quality CNA sheets, often perform well in cyclic service. ePTFE also exhibits excellent stability across wide temperature swings. The key is a material that maintains its sealing force and does not become brittle or lose elasticity through the cycles.