Expanded PTFE Gasket Sealing Performance
Expanded PTFE gaskets provide reliable sealing performance through good compressibility, resistance to creep and cold flow, and broad chemical compatibility.
Conformability to Sealing Surfaces: The flexible structure accommodates minor flange surface irregularities, helping establish effective sealing contact.
Resistance to Creep & Cold Flow: The multidirectional structure reduces creep and cold flow, helping maintain gasket stress under suitable operating conditions.
Excellent Chemical Compatibility : Expanded PTFE resists most industrial chemicals, including acids, alkalis, and solvents, subject to specific service conditions.
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A monthly production capacity of 1,000 pcs of expanded PTFE sheets ensures that we have a sufficient and reliable supply of gaskets.
| PROPERTY | STANDARD | VALUE |
| Color | – | White |
| Density | ASTM D792 | 0.70-0.9g/cm3 |
| Operating temperatures | – | -286 – 320°C |
| Compressibility | ASTM F36 | 45-50 % |
| Recovery | ASTM F36 | 10 -12% |
| Creep Relaxation | ASTM F38 | 35 – 36 % |
| Sealability (Nitrogen) | ASTM F 37B | 0.15 ml/hr |
| Sealability (Fuel A) | ASTM F 37B | 0.02 ml/hr |
| Service Pressure | – | Full Vacuum to 19 MPa |
| Tensile Strength Both directions | ASTM D638 | 19.6 MPa |
We produce expanded PTFE gasketing sheets by ourselves, allowing us to control both quality and cost from the source. We have advanced machinery and years of experience in expanded PTFE manufacturing, utilizing more efficient nesting and layout methods to produce gaskets. Our manufacturing process is highly efficient. All these distinctive characteristics ensure that we can maintain quality while controlling costs.
EPTFE GASKET FAQ
Expanded PTFE Gasket Selection & Custom Manufacturing Guide
Choosing the right expanded PTFE gasket involves more than selecting a chemically resistant sealing material. Gasket dimensions, flange configuration, operating conditions, and manufacturing accuracy all contribute to the performance and reliability of a finished sealing material.
Longseal manufactures standard and custom expanded PTFE gaskets for industrial equipment manufacturers, maintenance contractors, and sealing material distributors. The following guide outlines the key considerations for gasket selection, custom fabrication, quality evaluation, and ordering.
1.Expanded PTFE Gasket Types & Custom Dimensions
Expanded PTFE gaskets can be manufactured in various configurations to match different flange designs and equipment sealing requirements.
Ring Gaskets
Ring-type expanded PTFE gaskets are commonly used with raised-face flanges and other connections designed for ring gaskets. Key dimensions include the inner diameter (ID), outer diameter (OD), and gasket thickness.
Full-Face Gaskets
Full-face gaskets cover the flange face and include bolt holes corresponding to the flange configuration. In addition to ID, OD, and thickness, the bolt-hole diameter, number of holes, and pitch circle diameter (PCD) must be specified.
Custom-Shaped Gaskets
For non-standard equipment, expanded PTFE gaskets can be fabricated into rectangular, oval, irregular, and other specialized shapes. These may be required for equipment covers, process vessels, access openings, and customized sealing connections.
Dimensional Requirements
For standard pipe flanges, gasket dimensions can be specified according to applicable standards such as ASME B16.21 or EN 1514-1.
For non-standard equipment, manufacturing dimensions should be confirmed using approved drawings or samples
Longseal manufactures expanded PTFE gaskets using suitable sheet stock, with nominal material thicknesses ranging from 0.5 mm to 10 mm. Finished gasket dimensions and available thicknesses are available according to requirement
2. Expanded PTFE Gaskets for Different Flange Conditions
Expanded PTFE gaskets offer good compressibility and flexibility, making them suitable for various industrial flange applications when the material properties and joint design meet the service requirements.
However, gasket selection must consider the complete flange connection rather than the gasket material alone.
Steel Flanges
For steel flange connections, gasket selection should account for flange surface finish, available bolt load, sealing width, and operating conditions. Proper gasket compression is essential for establishing and maintaining sealing contact.
FRP & Glass-Lined Flanges
FRP and glass-lined flanges may have restrictions on allowable assembly loads. The compressibility of expanded PTFE can be advantageous in suitable applications; gasket selection needs to avoid excessive flange stress.
Flanges with Minor Surface Irregularities
The flexible structure of expanded PTFE helps accommodate certain minor surface irregularities. However, significant flange damage, misalignment, or surface defects should be corrected rather than compensated for by increasing gasket thickness.
Operating Conditions & Material Selection
The following factors should also be evaluated:
Chemical Media: Compatibility depends on the process fluid, concentration, temperature, and specific material grade.
Temperature & Pressure: Permissible operating limits depend on the gasket material, dimensions, flange design, and applied gasket stress.
Operation Cycles: Repeated temperature or pressure changes may influence gasket compression and stress retention.
Gasket Thickness: Thickness should be selected according to flange geometry, surface condition, and available assembly load. A thicker gasket does not necessarily provide better sealing.
For critical sealing service, gasket suitability shall be evaluated against validated material data and applicable equipment specifications
3. Custom Expanded PTFE Gasket Manufacturing
Longseal combines in-house expanded PTFE sheet production with gasket cutting and fabrication, supporting the manufacturing of finished sealing components according to customer requirements.
Our custom manufacturing process focuses on accurate specifications, strict material selection, efficient fabrication, and consistent finished dimensions.
Drawing & Specification Review
Production begins with reviewing customer drawings, approved samples, or dimensional requirements. Gasket geometry, thickness, tolerances, material specifications, and order quantities are confirmed before manufacturing.
Material Selection & Preparation
Expanded PTFE sheet stock is selected according to the approved gasket specifications. In-house sheet manufacturing allows us to coordinate material availability, production scheduling, and relevant quality requirements.
Cutting Layout & Fabrication
Cutting layouts are arranged according to gasket dimensions, geometry, and production quantities. Suitable cutting methods are used to manufacture ring gaskets, full-face gaskets, and custom sealing components.
For batch production, efficient sheet utilization helps reduce material waste and control manufacturing costs.
Finished Gasket Inspection
After fabrication, finished gaskets are checked against the specified dimensional requirements before packaging.
4. Quality Control for Finished Expanded PTFE Gaskets
For industrial customers, the quality of a finished gasket depends on both the properties of the expanded PTFE material and the accuracy of the fabrication process.
Longseal emphasizes material consistency, dimensional verification, and finished product inspection for the gasket manufacturing.
Dimensional Accuracy
Gasket dimensions should conform to the approved drawing or applicable specification. Inspection points may include inner and outer diameters, thickness, specified tolerances, etc.
Cutting & Edge Quality
Finished gasket edges and openings are checked for unacceptable cutting defects that could affect handling, installation, or sealing contact.
Material Consistency
Expanded PTFE sheet stock is evaluated according to relevant material specifications. Properties such as density, tensile strength, compressibility, and recovery may be considered when reviewing material quality and consistency.
Visual Inspection
Finished gaskets are inspected for visible damage, contamination, and other defects before packaging and shipment.
Technical & Inspection Documentation
Available material technical data and inspection documentation can be provided according to the product specification and agreed order requirements.
For repeat orders, maintaining consistent material specifications, approved drawings, and inspection requirements helps reduce variation between production batches.
5.Custom Gasket Ordering & Quotation Requirements
For custom expanded PTFE gasket inquiries, we recommend providing the following information:
Gasket Type: Ring, full-face, rectangular, or custom-shaped gasket.
Dimensions: ID, OD, thickness, bolt-hole arrangement, or a detailed manufacturing drawing.
Material Requirements: Expanded PTFE grade and any specific technical requirements.
Order Quantity: Required quantities and expected purchasing frequency.
Operating Conditions: Temperature, pressure, chemical media, and flange information when application review is required.
Quality Requirements:Dimensional tolerances, inspection reports, or relevant documentation.
Delivery Requirements: Destination, packaging preferences, and requested delivery schedule.
Longseal supports custom gasket manufacturing, bulk supply, and regular purchasing arrangements for industrial distributors, OEM customers, and equipment maintenance suppliers.
If you require uncut expanded PTFE material for your own gasket fabrication, please also explore our Expanded PTFE Sheet products.
