PTFE Envelope Gasket
Model:KXT 1320
PTFE Envelope Gasket flexible materials insert. Wide working temperature range. Excellent weathering and aging characteristics
PTFE Envelope Gasket – KXT 1320 for Glass-Lined & Chemical Processing Equipment
Kaxite Sealing, a leading China PTFE envelope gasket manufacturer, presents the KXT 1320 PTFE Envelope Gasket – a high-performance sealing solution designed for critical applications where chemical resistance, purity, and reliability are paramount. This gasket consists of a flexible filler material completely encased in a protective PTFE (Teflon®) jacket, providing an impervious barrier against aggressive chemicals while maintaining the mechanical strength and compressibility of the filler. It is the preferred choice for glass-lined equipment, pharmaceutical reactors, food processing vessels, and chemical piping systems where media purity and corrosion resistance are non-negotiable.
Why KXT 1320? The PTFE envelope acts as a chemical shield, preventing the filler material from contacting the process media, while the filler provides the necessary resilience and sealing force. This design offers the best of both worlds: the universal chemical resistance of PTFE (pH 0–14, except molten alkali metals and strong oxidizers) and the mechanical robustness of the chosen filler. Available in three configurations – S-type (machined), V-type (slit cut), and U-type (folded) – our envelope gaskets accommodate various flange designs and installation preferences. They are widely used in glass-lined vessels, heat exchangers, pumps, valves, and pipe flanges across the chemical, pharmaceutical, and food industries.
As a trusted PTFE gasket supplier in China, Kaxite offers the KXT 1320 in standard ANSI/ASME and DIN sizes, with custom dimensions available on request. We support a variety of filler materials – including graphite, non-asbestos, asbestos (where permitted), rubber, and more – to meet specific service conditions. Whether you require bulk gaskets for plant maintenance or custom envelope gaskets for unique flanges, we ensure consistent quality and full material traceability. Request a free sample or get a wholesale quote today.
Temp. Range (PTFE)-100°C to +260°C
Pressure RangeUp to 40 bar (depends on filler)
pH Range0 – 14 (except strong oxidizers)
TypesS / V / U (machined, slit, folded)
Filler OptionsGraphite, Rubber, Non-asbestos
ComplianceFDA, REACH, RoHS
Why KXT 1320 PTFE Envelope Gasket?
- ✅ Superior Chemical Resistance – PTFE jacket protects against virtually all aggressive chemicals (pH 0-14)
- ✅ Ideal for Glass-Lined Equipment – Prevents media contact with filler, eliminating contamination risks
- ✅ Three Configurations – S-type (machined), V-type (slit), U-type (folded) for different flange requirements
- ✅ Flexible Filler Selection – Choose from graphite, rubber, non-asbestos, or asbestos to match your service
- ✅ Excellent Temperature Resistance – -100°C to +260°C, suitable for cryogenic and high-heat applications
- ✅ Custom Sizes Available – Any dimension, any standard (ANSI, DIN, JIS, custom)
Available Configurations – S-Type, V-Type, U-Type
Kaxite offers three distinct designs of PTFE envelope gaskets to suit different installation preferences and flange face conditions. Each type is manufactured with the same high-quality PTFE jacket and compatible filler materials.
Style KXT 1320 S-Type (Mechanical Processing)
The S-type (machined) envelope gasket is produced by precision milling the PTFE jacket and filler to a unified, smooth profile. This design offers a uniform cross-section and is ideal for applications requiring high dimensional accuracy and a flush fit. It is commonly used in standard flange connections where the gasket is compressed evenly across its entire face.
Style KXT 1330 V-Type (Slit Cut)
The V-type (slit cut) envelope gasket is manufactured by cutting a slit into the PTFE envelope, allowing the filler to be inserted and the jacket to be sealed. This design is particularly suitable for larger flange sizes and applications where a folded construction may be more prone to stress. The slit enables easy assembly and provides a reliable, leak‑tight seal.
Style KXT 1340 U-Type (Folded)
The U-type (folded) envelope gasket is formed by folding the PTFE jacket around the filler core. This economical design is ideal for low to moderate pressure applications where quick installation and cost-effectiveness are priorities. The folded construction provides good conformability to flange surfaces and is widely used in glass-lined and plastic flanges.
* All three types can be supplied with any filler material and to any flange dimension. Contact us for specific application recommendations.
ISO 9001:2015 FDA 21 CFR 177.1550 REACH & RoHS Compliant Glass-Lined Equipment Certified Custom Sizes & Fillers
Key Advantages of KXT 1320 PTFE Envelope Gasket
Universal Chemical Resistance – The PTFE jacket protects against virtually all chemicals (pH 0–14), including acids, alkalis, solvents, and hydrocarbons, ensuring long-term reliability in aggressive environments.
Designed for Glass-Lined Vessels – Envelope gaskets are the standard sealing solution for glass-lined reactors and storage tanks, preventing media contact with the filler and avoiding contamination of sensitive products.
Flexible Filler Selection – Choose from graphite (high temperature), rubber (low stress), non-asbestos (general purpose), or other materials to balance sealing performance with cost and service life.
Three Installation Types – S-type (machined), V-type (slit), and U-type (folded) cover all flange designs and pressure requirements, giving you the flexibility to choose the most suitable option.
Excellent Temperature Range – PTFE remains stable from -100°C to +260°C, making it suitable for both cryogenic and high-temperature processes, with short-term excursions possible.
FDA & Food-Grade Compliance – The PTFE jacket meets FDA 21 CFR 177.1550 requirements, making it safe for use in food and pharmaceutical processing applications.
Filler Materials & Technical Data
The performance of a PTFE envelope gasket is highly dependent on the filler material. Kaxite offers a range of fillers to match your specific service conditions – temperature, pressure, media, and flange type. The table below outlines the most common options and their typical applications.
| Filler Material | Max Temperature | Pressure Range | Typical Applications |
|---|---|---|---|
| Graphite | +450°C | Up to 40 bar | High-temperature, steam, and aggressive chemical services |
| Non-Asbestos | +250°C | Up to 30 bar | General chemical and industrial flanges |
| Rubber (EPDM / Nitrile) | +120°C | Up to 16 bar | Low-pressure, water, and mild chemicals |
| Asbestos* | +500°C | Up to 50 bar | High-temperature, high-pressure (restricted regions) |
* Asbestos fillers are only available in regions where permitted by local regulations. Non-asbestos alternatives are recommended for most modern applications. Contact our technical team for filler selection guidance.
PTFE Envelope Gasket vs Standard PTFE Sheet Gasket – Comparison
| Feature | PTFE Envelope (KXT 1320) | Standard PTFE Sheet Gasket |
|---|---|---|
| Chemical Resistance | Excellent (PTFE jacket) | Excellent |
| Mechanical Strength | High (filler dependent) | Low (cold flow) |
| Glass-Lined Equipment Use | Ideal (prevents contamination) | Not recommended |
| Compressibility | Controlled by filler | High (but prone to creep) |
| Maximum Temperature | Up to 500°C (with graphite filler) | +260°C (PTFE limit) |
| Cost | Moderate to high | Low |
* The envelope gasket is the superior choice for critical applications where media purity, high temperature, or mechanical strength are required.
Typical Applications & Industries
Glass-Lined Vessels Sealing of reactors, storage tanks, and distillation columns with glass or enamel linings – the PTFE envelope prevents media contact with the filler, protecting the glass surface.
Pharmaceutical & Biotech FDA-compliant gaskets for fermenters, mixers, and clean-in-place (CIP) systems – non-contaminating and easy to clean.
Chemical Processing Flange seals for reactors, heat exchangers, and piping systems handling aggressive acids, alkalis, solvents, and hydrocarbons.
Also explore our full PTFE gasket range for other sealing solutions.
Food & Beverage Gaskets for pasteurizers, homogenizers, and filling lines – meets FDA regulations for direct food contact.
Pumps & Valves Sealing of pump casings, valve bonnets, and flange connections in corrosive service environments.
General Industrial Maintenance Replacement gaskets for flanges, manholes, and equipment where chemical compatibility is critical.
Why Choose Kaxite for PTFE Envelope Gaskets?
PTFE Processing Expertise – With decades of experience in PTFE fabrication, Kaxite ensures consistent wall thickness, accurate dimensions, and defect-free envelope bonding for every gasket.
ISO 9001:2015 Certified – Our manufacturing processes are fully certified, with strict quality controls from raw material to finished product, including dimensional inspection and leak testing.
Custom Engineering Capability – We manufacture envelope gaskets to any flange standard (ANSI, ASME, DIN, JIS, BS) and can accommodate non-standard bore sizes and bolt hole patterns.
Competitive Factory-Direct Pricing – As a China PTFE gasket manufacturer, we supply directly to end-users and distributors, offering significant cost advantages.
Rapid Quote & Technical Support – Our engineering team provides fast turnarounds on custom designs, material recommendations, and installation guidance – with a response time of under 2 business hours.
Global Supply Chain – We ship to over 40 countries, with flexible packaging and shipping options to meet your project deadlines.
Proven Reliability: Kaxite PTFE envelope gaskets are specified by leading chemical and pharmaceutical companies worldwide for their exceptional performance in corrosive and high-purity environments.
Quality Assurance & Regulatory Compliance
Kaxite Sealing is an ISO 9001:2015 certified manufacturer. Our PTFE envelope gaskets are produced under strict process controls – from PTFE sheet preparation, filler selection, and envelope fabrication to final cutting and inspection. Each gasket is inspected for dimensional accuracy, envelope integrity, and finish quality. We provide material test certificates (MTCs) and can supply FDA compliance documentation upon request, ensuring full traceability from raw material to finished product.
- ISO 9001:2015
- FDA 21 CFR 177.1550
- REACH & RoHS Compliant
- 100% Dimensional Inspection
- Full Material Traceability
Quality you can depend on – our envelope gaskets are trusted by maintenance engineers and plant managers in critical service applications worldwide.
Custom Manufacturing & OEM Services – Free Sample Available
As a professional PTFE envelope gasket manufacturer in China, we offer complete customisation to meet your exact specifications. Request a free sample or get a bulk quote today:
- Custom sizes for any flange standard (ANSI, ASME, DIN, JIS, BS)
- All three types: S (machined), V (slit), U (folded)
- Filler selection: graphite, rubber, non-asbestos, asbestos*
- FDA-compliant PTFE materials on request
- Private label packaging for distributors
- Just-in-time delivery and inventory management
Get a free sample or request a tailored bulk quote – our team responds within 24 hours with competitive factory pricing and lead‑time estimates.
Frequently Asked Questions About PTFE Envelope Gaskets
- Q: What is a PTFE envelope gasket and when should it be used?
- A: A PTFE envelope gasket consists of a flexible filler material completely encased in a PTFE jacket. It is primarily used in glass-lined, enameled, or plastic flanges where the filler must not contact the process media. The PTFE jacket provides universal chemical resistance, while the filler supplies mechanical strength. It is the standard sealing solution for glass-lined reactors, storage tanks, and piping systems in the chemical and pharmaceutical industries.
- Q: What are the differences between S-type, V-type, and U-type envelope gaskets?
- A: S-type (machined) is milled from a solid block, offering the highest precision and a uniform cross-section. V-type (slit cut) is made by cutting a slit into the PTFE jacket and inserting the filler, suitable for larger sizes. U-type (folded) is formed by folding the jacket around the filler, which is the most economical option for low to moderate pressures. All three types are available with any filler material.
- Q: What filler materials are available and how do I choose?
- A: We offer graphite, non-asbestos, rubber (EPDM/Nitrile), and asbestos* fillers. Graphite is best for high-temperature and high-pressure applications; rubber is suitable for low-pressure, moderate temperatures; non-asbestos is a general-purpose choice; asbestos offers excellent heat resistance but is restricted in many regions. Contact our technical team for a recommendation based on your service conditions.
- Q: Is the PTFE envelope gasket FDA compliant?
- A: Yes. The PTFE jacket is manufactured from FDA-compliant PTFE (21 CFR 177.1550), making it suitable for direct food contact and pharmaceutical applications. We can provide a Certificate of Compliance upon request.
- Q: What sizes and thicknesses can you manufacture?
- A: We can manufacture envelope gaskets to any flange standard (ANSI, ASME, DIN, JIS, BS) and any custom dimension. Typical thicknesses range from 1.5 mm to 6.0 mm, but we can accommodate special requirements. Contact us with your flange drawing for a custom quote.
Partner with Kaxite Sealing – your trusted PTFE envelope gasket manufacturer and supplier in China. With decades of PTFE processing expertise, advanced fabrication capabilities, and a steadfast commitment to quality, we deliver sealing solutions that perform reliably in the most demanding chemical, pharmaceutical, and food processing applications. Request a free sample or get a tailored bulk quote today – our engineers respond within 24 hours.
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