The function of metal wound gaskets

Metal wound gaskets offer high safety performance. For example, when asbestos gaskets are used in circulating water systems, over the years they thin out due to exposure to water flow, which eventually leads to leaks. Once an asbestos gasket leaks, it can only be fixed by using clamps or by replacing it; when replacing the gasket, the sealing surface must be cleaned thoroughly. Asbestos stuck to the sealing surface is difficult to remove, especially in areas where the pipes cannot be moved. Metal wound gaskets do not have the above problems; they are easy to replace, and leaks can usually be reduced or eliminated by increasing the tightening force. Metal wound gaskets are recommended for flammable, explosive, and high-pressure environments.

Soft gaskets are used in pipelines with relatively low pressure; high-pressure rubber gaskets can withstand pressures of up to 5.0 MPa. Spiral gaskets are suitable for various pipe flanges. If a gasket with a thickness of 4.5 mm leaks, one with a thickness of 6.5 mm can be used instead.

From a process manufacturing perspective, wound gaskets can be used below 6.0 MPa, graphite gaskets can be used below 2.5 MPa, asbestos gaskets can be used below 0.6 MPa, and octagonal steel ring gaskets should be considered for pressures above 4.0 MPa.

　Metal wound gaskets are made by using high-quality alloy strips or stainless steel strips as the base material, with graphite, asbestos, and tetrafluoroethylene as filling materials, which are then spirally wound in a alternating \"V\" or \"W\" pattern. 　　　It is used for static sealing at flange connections in industries such as petroleum, chemicals, machinery, metallurgy, power generation, shipbuilding, as well as in pipelines, valves, pumps, pressure vessels, condensers, towers, manholes, and handholes. Due to its high mechanical strength, ease of use, and good compressive resilience, it is more suitable for use in environments with severe temperature fluctuations. 　　　Materials for inner and outer rings: OCr18N19, SS304, 316, 316L, Monel; pure titanium for the outer ring; available with an inner ring as well; in basic design. 　　　The operating temperature range for graphite metal wound gaskets is -200 to 850°C, with a working pressure of 0-20 MPa. The operating temperature range for asbestos metal wound gaskets is -200 to 500°C, with a working pressure of 0-25 MPa. The operating temperature range for PTFE metal wound gaskets is -200 to 260°C, with a working pressure of 0-10 MPa. You can choose the materials for the metal strips, soft fillers, and inner and outer positioning reinforcement rings that make up these wound sealants based on different media and operating conditions, by selecting from the options listed in this table as appropriate. Name: Metal strip, soft filler; outer positioning reinforcement ring, inner positioning reinforcement ring
Material: SUS-316, SUS-316L, SUS-321, pure titanium, SUS-304, SUS-310S (selected by the user), special asbestos, flexible graphite, polytetrafluoroethylene (PTFE), A3, SUS-316, SUS-316L, pure titanium, SUS-321, SUS-304, SUS-310S, A3, SUS-316, SUS-316L, pure titanium, SUS-321, SUS-304, SUS-310S
Properties: Test conditions and criteria for gasket compression and rebound performance
Specifications of the gasket core sample: Compression stress in MPa (bar); loading/unloading speed in MPa/s (bar/s); compression rate, %; rebound rate, %
Metal strip + special asbestos strip: DN80mm, with inner and outer rings; 70.0±1.0 (700±10), 0.5 (5.0), 18–30, ≥19
Metal strip + flexible asbestos strip: ≥17; Metal strip + PTFE strip: ≥15
Wrapped gaskets (steel vessel gaskets): These are made by wrapping sealing materials such as flexible graphite, asbestos, and PTFE around metal materials like stainless steel, copper, and carbon steel. 　　　Primary uses: Suitable for sealing pumps, valves, heat exchangers, and other equipment in various media, as well as for sealing various types of flanges. 　　　Performance: Operating temperature: -200～650°C, operating pressure: 3.5 MPa. Metal toothed gaskets, octagonal gaskets, elliptical gaskets, and copper gaskets. Materials: carbon steel, stainless steel 304, 316, etc. Shapes: toothed, octagonal, elliptical. Application range: Temperature: -200-800°C; Pressure: 0-40 MPa. Suitable for sealing pipeline flanges under high temperature and high pressure conditions. 　　　Toothed gaskets are used as graphite toothed gaskets applied over the sealing gaskets of pressure vessels, towers, tanks, valve covers, pipe flanges, etc., for sealing in heat exchangers, towers, tanks, and similar devices. Elliptical or octagonal gaskets used for flanges, pressure vessels, valve covers, etc. 　Graphite-reinforced composite gaskets are made by cutting or stamping various graphite-reinforced composite sheets, and are primarily used for sealing flanges, observation ports, cover plates, water level gauges, and other components in environments with corrosive substances or extreme temperatures. 　　　Specifications: Ф10-Ф3000mm 　　　Operating temperature: -200-650℃ 　　　Operating pressure: ≤6.3MPa Last edited by hw197358 on 2009-4-4 21:46]

Metal wound gaskets use thin cold-rolled steel strips that are stamped into V, U, SU, or W shapes as the metal strips of the wound gasket, in order to achieve a certain degree of elasticity and resilience. W-shaped steel strips have better resilience than V-shaped ones, but they are more difficult to process, more expensive, and thus less commonly used. The machinery uses patented SU-type steel strips, which offer improved elasticity and resilience, and as a result are widely used. The metal forming strip also serves to hold the non-metallic filler in place, thereby ensuring that the gasket maintains sufficient tension on the flange’s sealing surface. The thickness of the metal strip is 0.006～0.009 in (0.15～0.23) mm. Common materials for metal strips include low-carbon steel, 304 stainless steel, 316 stainless steel, and special alloys.

It seems no one has mentioned the wave-shaped padding?

Metal wound gaskets are made by using high-quality alloy strips or stainless steel strips as the base material, with graphite, asbestos, or tetrafluoroethylene as filling materials, and are then wound in a alternating \"V\" or \"W\" pattern. It is used for static sealing at flange connections in industries such as petroleum, chemicals, machinery, metallurgy, power generation, shipbuilding, as well as in pipelines, valves, pumps, pressure vessels, condensers, towers, manholes, and access holes. Due to its high mechanical strength, ease of use, and good compressive resilience, it is more suitable for applications in environments with severe temperature fluctuations.

There is no need to use this type of gasket in low-pressure environments, and it cannot be used in environments with corrosive media either~ These are all conditions that must be taken into account

Even with low-pressure steam, metal wound gaskets prove to be very effective; they are just a bit more expensive. Metal wound gaskets are available not only in carbon steel but also in stainless steel, and can be used in situations where the level of corrosion is not too high.

The maximum operating temperature for metal wound gaskets is 650 degrees; for temperatures above 1000 degrees, ceramic fiber gaskets are used.

The selection of metal wound gaskets should be matched to the type of flange: Type A basic metal wound gaskets are used for tongue-and-groove flanges, while Type B gaskets with an inner ring are suitable for male and female flanges. Type C gaskets with an outer ring, and Type D gaskets with both inner and outer rings, are used for fully flat and raised face flanges.

Metal wound gaskets are available with and without centering rings; what is the difference?

The inner ring, outer ring, and ringless type use different forms of sealing surfaces

Could you explain in detail? We’ve always thought it’s related to stress

Use an inner ring gasket for concave-convex surfaces, no ring for tenon-mortise surfaces, and an inner or outer ring for convex surfaces.