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Molded PTFE Flange Gaskets from a Fluoroplastic Manufacturer
Gansu Juxiang Fluoroplastics Technology Co.,Ltd. molds PTFE flange gaskets in Yumen City, Gansu Province, within a fluoroplastic operation that also runs a production base in Zhejiang. Gaskets are compression molded from PTFE suspension resin and finished to the bore, outside diameter and thickness required by the mating flange, so the sealing face, bolt circle and gasket thickness arrive as one matched component instead of a trimmed sheet.
The published dimensional table runs from 10A to 650A with 3 mm as the standard thickness, and special specifications are produced to customer drawings. Around the molded PTFE gasket we supply modified PTFE, filled PTFE and expanded PTFE variants for joints where unfilled PTFE alone would creep, extrude or lose bolt load.
The Gasket Range and Where Each Type Fits
Each construction in the range answers a different bolted-joint problem. The table below sets out what we mold or machine, and the service condition each type is normally selected for.
| Gasket type | Construction | Typical joint fit | Supplied as |
|---|---|---|---|
| PTFE Flange Gasket | Compression molded from PTFE suspension resin, machined to final bore and outside diameter | Chemical transfer lines, tank nozzles, acid and caustic service, low-to-moderate bolt load | 10A–650A, 3 mm standard, special sizes to drawing |
| Modified PTFE Gasket | Modified PTFE resin with reduced cold flow under sustained compression | Thermal cycling, steam and hot process lines, joints that must hold torque between shutdowns | Thickness and diameter to drawing |
| Filled PTFE product | PTFE compounded with glass fiber, carbon, bronze or PHBA filler | Higher pressure classes, pump and valve flanges, wear-exposed sealing faces | Grade selected against the media and load |
| Expanded PTFE Reinforced Flange Gasket | Expanded PTFE with reinforcement layer | Irregular or lightly damaged flange faces, glass-lined and FRP equipment, low bolt load | Cut to size and bolt pattern |
| Large integrated molded PTFE sealing frame and gasket | Single molded sealing frame with integrated gasket geometry | Large vessel manways, rectangular and trough openings, non-circular sealing paths | Molded to drawing |
Where a project mixes flange sizes and duties, we supply the full set from one material batch so that installation crews are not matching gaskets from different lots on the same line.
Published Size Range and Dimensional Data
The standard table below is the reference we quote against for A-series nominal sizes. Representative entries are shown; the full table continues to 650A, and any size outside it is molded or machined to the flange drawing supplied with the enquiry.
| Nominal size | Outside diameter (mm) | Inside diameter (mm) | Thickness (mm) |
|---|---|---|---|
| 10A | 90 | 18 | 3 |
| 20A | 100 | 28 | 3 |
| 40A | 140 | 49 | 3 |
| 50A | 155 | 61 | 3 |
| 80A | 185 | 90 | 3 |
| 100A | 210 | 115 | 3 |
| 150A | 220 | 167 | 3 |
| 200A | 270 | 218 | 3 |
| 300A | 378 | 321 | 3 |
| 400A | 486 | 410 | 3 |
| 500A | 596 | 513 | 3 |
| 600A | 700 | 615 | 3 |
Bolt holes, tabs, reduced bore, groove profiles and non-standard thicknesses are added at the machining stage. When the flange standard on the drawing differs from the A-series table, the drawing governs and we confirm the resulting dimensions before molding.
Application Fit: Media, Flanges and Service Conditions
PTFE is specified for flange sealing because it resists acids, bases, solvents and oxidisers that attack elastomers, and because it holds its properties across a wide temperature band. That chemical breadth is why the material appears on chemical pipelines, storage tank nozzles, dosing skids, fume extraction ducting, electroplating lines and ultrapure water loops.
- Chemical and petrochemical piping: molded PTFE gaskets on acid, caustic and solvent lines, with filled grades where pressure class and bolt load rise.
- Tank and vessel connections: nozzle and manway gaskets, including large integrated molded frames for non-circular openings.
- Power and environmental systems: flue gas desulphurisation, wastewater and seawater lines where elastomer gaskets degrade.
- Semiconductor and electronics: high-purity PTFE gaskets on wet benches and chemical delivery lines where extractables and particle shedding matter.
- Food, pharmaceutical and medical equipment: inert, non-toxic sealing faces on process and purification lines.
The limiting behaviour of unfilled PTFE is cold flow under sustained bolt load, not chemical attack. Where a joint sees thermal cycling, high bolt torque or a thin flange, the specification usually moves to a modified or filled grade, or to a thinner gasket that reaches seating stress at lower torque.
Configuration Options and Machining
Gaskets are configured against the joint, not against a catalogue number alone. The variables we confirm before production are:
- Nominal size, flange standard and pressure rating, with the mating face type and finish.
- Inside diameter, outside diameter and thickness, including non-standard bores and reduced sealing widths.
- Bolt hole count, hole diameter and pitch circle where a full-face pattern is required.
- Tab, ring, tongue-and-groove or custom profile geometry for specific equipment.
- Material grade: unfilled molded PTFE, modified PTFE, filled compound or expanded PTFE with reinforcement.
- Marking, edge finish and orientation detail for installation on site.
Because the gasket is molded and then machined in-house, a change of bore or bolt pattern does not require a new compound batch. That keeps mixed-size orders on a single material reference, which simplifies acceptance at the receiving inspection stage.
Quality Control, Documentation and Acceptance
Molding parameters are monitored through the cycle, and finished gaskets are checked dimensionally against the approved drawing before packing. Material is tracked by batch so that a delivered gasket can be traced back to the resin lot used to mold it.
- Dimensional inspection record against the approved drawing, covering bore, outside diameter, thickness and bolt pattern.
- Material batch reference issued with the shipment documentation.
- Handling and storage guidance supplied with the order so that gaskets reach the flange without deformation or contamination.
- Technical review of the joint conditions before production where the duty is unusual, including media, temperature and assembly torque.
Documentation and usage guidance are issued with each order, and technical questions raised during installation or commissioning are handled by the same team that configured the gasket.
Information We Use to Configure Your Solution
A workable quotation needs the joint defined rather than the part described loosely. The inputs below are what we work from when preparing a configuration and price.
- Flange drawing or standard designation, size and pressure class, with face type and surface finish.
- Gasket dimensions if already fixed: inside diameter, outside diameter, thickness and bolt pattern.
- Media, concentration and phase, plus operating and design temperature including cycling.
- Assembly method and available bolt torque, and whether the joint is opened frequently.
- Quantity per size, whether a single batch is required, and the delivery schedule.
- Documentation, marking and packaging requirements, and the destination for freight planning.
Where a drawing is not yet available, a sketch of the flange with measured bore and bolt circle is enough for us to propose dimensions for confirmation.
Installation, Repeat Supply and Spares
PTFE gaskets are single-use components: once compressed and removed, the sealing face is not reinstalled. We supply installation guidance covering alignment, clean and undamaged flange faces, and a cross-pattern torque sequence so that the gasket seats evenly without over-compressing one side.
Repeat orders are produced against the original drawing number and material grade, which keeps replacement gaskets interchangeable with what is already on the line. Spare sets for planned shutdowns can be packed and labelled by line or tag number to match the maintenance schedule.
Frequently Asked Questions
What sizes of PTFE flange gasket do you manufacture?
The standard table covers 10A to 650A at 3 mm thickness, with outside and inside diameters listed per size. Sizes outside that table, non-standard thicknesses and bolt patterns are molded or machined to the customer drawing.
Should a joint use unfilled, modified or filled PTFE?
Unfilled molded PTFE suits chemically aggressive service at moderate bolt load. Modified PTFE is chosen where thermal cycling or sustained compression causes cold flow, and filled grades are used where pressure class and mechanical load are higher. We confirm the grade against the media, temperature and assembly torque before production.
Can you supply gaskets with bolt holes and non-circular profiles?
Yes. Full-face patterns with drilled bolt holes, tabs, ring profiles and large integrated molded sealing frames for rectangular or trough openings are produced to drawing, including single-piece frames for vessel manways.
What do you need to quote a PTFE flange gasket order?
Flange standard or drawing, size and pressure class, gasket dimensions, media and operating temperature, required quantity per size, and any documentation or marking requirements. With those details we return a dimensioned configuration and price for confirmation.
