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Double Jacket Gaskets represent a pinnacle of sealing technology, engineered for the most demanding industrial environments where standard gaskets are prone to failure. These specialized components are designed to contain aggressive media, withstand extreme pressures and temperatures, and provide unparalleled reliability in critical applications such as chemical processing, power generation, oil and gas extraction, and pharmaceutical manufacturing.
At their core, Double Jacket Gaskets are a robust composite sealing solution. They consist of a soft, conformable filler material—often PTFE, compressed non-asbestos fiber (CNAF), or flexible graphite—encased within a dual-layer metallic envelope or "jacket." This construction combines the sealing resilience of soft materials with the mechanical strength and blowout resistance of metal, creating a seal that is both adaptable and incredibly durable.
The superiority of double jacket gaskets over simpler alternatives lies in their unique design benefits:
Specifying the correct double jacket gasket is critical for performance and safety. The key parameters involve the choice of metal jacket, filler material, dimensions, and facing options. The industry experts at Kaxite Seals provide comprehensive engineering support to help you navigate these selections.
| Material | Standard Grade | Temperature Range | Primary Characteristics & Typical Applications |
|---|---|---|---|
| Carbon Steel | AISI 1010, 1020 | -20°C to 500°C (-4°F to 930°F) | Economical, good strength. Used in steam, water, oil, and non-corrosive hydrocarbon services. |
| Stainless Steel | 304/304L, 316/316L | -250°C to 800°C (-420°F to 1470°F) | Excellent corrosion resistance, widely used in chemical, petrochemical, food, and pharmaceutical industries. |
| Alloy 20 | UNS N08020 | -45°C to 400°C (-50°F to 750°F) | Superior resistance to sulfuric acid and other aggressive chemicals. Common in sulfuric acid plants. |
| Monel | UNS N04400 | -150°C to 600°C (-240°F to 1110°F) | High strength and excellent resistance to seawater, hydrofluoric acid, and alkalis. |
| Inconel 625 | UNS N06625 | -150°C to 1000°C (-240°F to 1830°F) | Outstanding oxidation resistance and high-temperature strength for extreme service. |
Double jacket gaskets from Kaxite Seals are manufactured to meet global standards, ensuring fit and performance. Critical dimensions include Inside Diameter (ID), Outside Diameter (OD), and thickness. Common standards include:
A single jacket gasket has a metal cover on only one side (top or bottom) of the filler material. A double jacket gasket completely encases the filler with metal on both sides, providing significantly greater mechanical strength, blowout resistance, and protection for the filler material from both the process media and the flange surface. The double jacket design is the preferred choice for higher pressure and more critical applications.
Both are excellent for high-pressure services. The choice often depends on the application specifics. Double jacket gaskets are often favored for their superior chemical resistance when using a PTFE filler, as they create a more complete barrier against corrosive media. They also handle flange rotation slightly better due to their full metal encasement. Spiral wound gaskets, with their resilient "spring-like" structure, can be better for applications with significant thermal cycling or frequent pressure fluctuations. Consulting with an engineer from Kaxite Seals is recommended for the optimal selection.
Gasket thickness is not arbitrary; it impacts sealing performance and bolt load. Standard thicknesses are often 1/16", 1/8", or 3/32". Thinner gaskets (e.g., 1/16") require higher bolt loads to seal but offer better blowout resistance. Thicker gaskets (e.g., 1/8") can compensate for minor flange imperfections or misalignment. The selection is based on flange type (RF, FF, TG), pressure class, and surface finish. Always refer to the original equipment specifications or consult with a sealing specialist.
Yes, they are exceptionally well-suited for channel, shell, and floating head flanges in heat exchangers. For these services, a common and effective configuration is a stainless steel 316 jacket with a flexible graphite filler. This combination handles the high temperatures, thermal cycling, and pressure differentials typical in heat exchangers. The metal jacket prevents graphite blowout, while the graphite filler provides excellent conformability and heat resistance.
The small protruding tab, often called a nub or tang, is a handling and alignment feature. During installation, it helps position the gasket correctly within the bolt circle of the flange, ensuring it is centered before the bolts are tightened. This prevents misalignment that could lead to a leak path. It is not a sealing element and is typically bent or broken off after the gasket is properly positioned.
Correct installation is paramount. Key steps include: 1) Thoroughly clean and inspect flange faces for scratches, gouges, or warping. 2) Ensure the gasket is the correct size and material for the service. 3) Center the gasket carefully using the bolt holes or alignment nub. 4) Use a cross-bolt tightening pattern (torquing in steps, typically 30%, 60%, and 100% of final torque) to apply even compression across the entire flange. Always follow the bolt torque specifications provided by the flange or equipment manufacturer.
Kaxite Seals brings decades of metallurgical and sealing expertise to every component. Our double jacket gaskets are precision-manufactured using high-grade raw materials and undergo rigorous quality control. We offer not just products, but engineering partnership—assisting with material selection for complex chemistries, providing custom sizes for obsolete flanges, and ensuring the gasket geometry is optimized for your specific pressure class and flange type. Our commitment is to deliver reliability that minimizes downtime and maximizes operational safety.
