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Gansu Juxiang Fluoroplastics Technology Co.,Ltd. manufactures fluoroplastic and high-performance sealing products from production bases in Zhejiang and Gansu, supplying semi-finished shapes, machined seals and finished gaskets to chemical, refining, power and equipment-building projects. As a Wrapped Gasket manufacturer, we interwind a profiled metal strip with a non-metallic sealing strip to produce semi-metallic flange gaskets for high and medium pressure service, built to the flange standard, pressure class and medium that the line actually runs.
The wrapped gasket range sits inside a wider sealing programme that also covers PTFE sheet, rod, machined seals and moulded sealing frames, so a single package can be supplied with consistent material identification across gasket types.
Construction Styles We Build
The winding is the functional core of the gasket. A V-profiled metal strip and a soft filler strip are interleaved under controlled tension, so the metal carries the bolt load while the filler flows into the flange surface and seals the leakage path. Ring configuration follows the flange facing and the bolt-up conditions rather than habit.
| Style | Construction | Where it fits |
|---|---|---|
| Type A | Winding only, no reinforcing rings | Confined joints such as tongue-and-groove or male-and-female facings, where the groove locates and contains the gasket |
| Type B | Winding with inner ring | Graphite-filled gaskets in hot service and joints where the bore must be protected from turbulence and inward buckling |
| Type C | Winding with outer ring | Raised-face and flat-face flanges; the ring centres the gasket on the bolts and acts as a compression stop |
| Type D | Winding with inner and outer rings | High-pressure, vacuum and cyclic duty where bore support and centring are both required |
- The outer ring is normally specified in a material matched to the flange or bolt grade, and carries the ASME B16.20 colour marking on its outside diameter.
- The inner ring is a corrosion-resistant alloy in most specifications; it also limits filler intrusion into the bore.
- Ring width, thickness and fit are checked against the facing dimensions before winding, not after.
Winding Metal and Filler Selection
Winding metal is chosen against medium corrosivity, operating temperature and the expansion difference between flange and gasket. The grades below are our standard winding and ring stock; special materials can be proposed and agreed case by case.
| Metal | Abbreviation | Colour code |
|---|---|---|
| Carbon steel | CRS | Silver |
| 304 stainless steel | 304 SS | Yellow |
| 304L stainless steel | 304L SS | Colourless |
| 316L stainless steel | 316L SS | Green |
| Monel 400 | MCN 400 | Orange |
| Titanium | TI | Purple |
| Nickel 200 | NI 200 | Red |
| Hastelloy C | HAST C | Gold |
| Inconel 600 | INC 600 | Beige |
Filler strips are stocked in flexible graphite, PTFE, mica graphite, ceramic, vermiculite and asbestos-free grades, each identified by a stripe colour on the winding edge. Graphite covers steam, hydrocarbon and high-temperature duty; PTFE is used where chemical resistance matters more than temperature headroom; mica graphite and ceramic serve oxidising and high-temperature applications where graphite is not suitable. We confirm the filler against medium, concentration and design temperature before the winding schedule is released.
Dimensional Scope and Standard Coverage
Wrapped gaskets are wound to the ordered flange size rather than cut from stock, which keeps ring fit and winding density consistent across a batch.
- Outer diameter from 20 mm to 4000 mm, covering small instrument joints through large exchanger and vessel flanges.
- Gasket thickness from 2.5 mm to 6.5 mm, with 4.5 mm as the recommended working thickness for most raised-face joints.
- Narrowest single-side ring width 5 mm, which sets the lower limit for small-bore and narrow-facing configurations.
- Dimensional and marking practice aligned with ASME B16.20, including material colour coding on the outer ring.
- Gaskets can be supplied to ASME B16.20, JPI-7S-41, JIS B2404, DIN 2699, BS 3381, EN 1514.2, EN 12560.2, GB/T 4622.1 and 4622.2, HG/T 20610 and 20631, JB/T 90 and SH/T 3407.
Application Fit
The construction suits bolted flange joints that see pressure and thermal movement together: the metal winding recovers with the joint while the filler maintains contact. Typical service includes refinery and chemical process piping, heat exchangers, column and vessel nozzles, valve bonnets, steam headers and utility lines.
- Low-temperature duty down to -196 °C is supported through the winding and filler combination selected for the joint.
- Low preload stress versions are wound for flanges where bolt load is limited, such as light-duty or non-metallic-faced equipment.
- Fugitive-emission service is addressed with constructions meeting VDI 2440 low-leakage requirements.
- Fire-safe duty is covered by constructions that have passed the API 6FB fire test.
- Cycling, thermal shock and vacuum service are handled through style D construction and adjusted winding density.
Quality Control and Acceptance
Winding tension, filler overlap, ring fit and final thickness are controlled at each stage, and finished gaskets are checked dimensionally against the ordered flange data before packing. Annual capacity of 10 million pieces supports both repeat line-item supply and project quantities released in phases.
- Material identification is verified on incoming strip and ring stock and carried through to the finished gasket marking.
- Fire and leakage performance evidence is referenced to the ordered construction: API 6FB fire test and VDI 2440 low-leakage testing.
- The acceptance package is agreed at order stage and can include dimensional records, material identification and the test documentation applicable to the construction supplied.
- Gaskets are packed flat, protected against edge damage and labelled to the marking scheme agreed for the project.
Information We Use to Configure Your Solution
A workable proposal needs the joint defined, not just the size. The following inputs let us fix style, winding metal, filler, thickness and marking in one pass.
- Flange standard, nominal size and pressure class, plus facing type: raised face, flat face, tongue-and-groove or male-and-female.
- Medium, concentration and phase, together with design temperature and design pressure.
- Operating conditions that affect the joint: cycling, thermal shock, vacuum, vibration or frequent dismantling.
- Bolt load limits or preload restrictions where the flange is light-duty or non-metallic.
- Required product standard, marking and colour-code convention, and any project specification that overrides them.
- Quantities per size, release schedule, spare allowance and packaging or labelling requirements.
Sealing Products Supplied Alongside
Where a flange needs a softer seating material or a larger sealing face, the wrapped gasket is combined with other products from our range. The Expanded PTFE Reinforced Flange Gasket covers aggressive chemical duty at lower bolt loads, the Modified PTFE Gasket serves high-purity and pharmaceutical joints, and the large integrated molded PTFE sealing frame and gasket handles oversized and non-circular sealing faces. Supplying these from one production organisation keeps material records and dimensional conventions consistent across a project.
Frequently Asked Questions
Which wrapped gasket style should be used on a raised-face flange?
Type C, the winding with an outer ring, is the standard answer for raised-face and flat-face flanges: the outer ring centres the gasket on the bolt circle and stops over-compression. Where the bore also needs protection from turbulence or where the joint is cycled or under vacuum, Type D with both rings is the better fit. Type A is reserved for confined tongue-and-groove and male-and-female joints.
How do you choose between graphite, PTFE and mica fillers?
Flexible graphite is the default for steam, hydrocarbon and general high-temperature service. PTFE is selected where chemical resistance to acids, solvents or high-purity media matters more than temperature headroom. Mica graphite and ceramic fillers are used in oxidising or very high temperature duty where graphite would not survive. We confirm the filler against the medium, concentration and design temperature supplied with the enquiry.
What sizes and standards can you supply?
Outer diameters run from 20 mm to 4000 mm, with thickness from 2.5 mm to 6.5 mm and 4.5 mm recommended for most joints; the narrowest ring width is 5 mm. Gaskets can be produced to ASME B16.20, JPI-7S-41, JIS B2404, DIN 2699, BS 3381, EN 1514.2, EN 12560.2, GB/T 4622, HG/T 20610 and 20631, JB/T 90 and SH/T 3407, with material colour marking to ASME B16.20.
What do you need from us to prepare a quotation?
Send the flange standard, size and pressure class, facing type, medium and concentration, design temperature and pressure, the product standard to be met, quantities per size and the required marking. Drawings or existing gasket samples help where the joint is non-standard. With those details we return a configuration with style, winding metal, filler, thickness and documentation scope defined.
