Double Jacketed Metal Clad Gasket are normally supplied with a non-asbestos, high temperature filler. The standard filler is normally sufficient for applications up to 900°F (482°C). Other soft fillers are available for higher temperatures or special applications. Standard metals used to make jacketed gaskets, regardless of the type, are aluminum, copper, the various brasses, soft steel, nickel, Monel, Inconel, and stainless steel types 304, 316, 321, 347, 410. The choice of metal used for the jacketed part of gasket would depend upon the service conditions being encountered.
Double Jacketed Metal Clad Gasket
Double jacketed gaskets are most commonly used in heat exchanger applications. They are available in virtually any material that is commercially found in 26 gauge sheet. They are also used in standard flanges where the service is not critical and at temperatures beyond which a soft gasket can be used. Since most double jacketed gaskets are custom made, there is virtually no limit to the size, shape or configuration in which these gaskets can be made. This particular type of gasket can be used in a myriad of applications. Since the size and shape are not a problem and since most materials can be obtained commercially, this particular gasket style is popular. It must be remembered that the primary seal against leakage, using a double jacketed gasket, is the metal inner lap where the gasket is thickest before being compressed and densest when compressed. This particular section flows, affecting the seal. As a consequence, the entire inner lap must be under compression. Frequently, the outer lap is not under compression and does not aid in the sealing of the gasket. On most heat exchanger applications the outer lap is also under compression, providing a secondary seal. The intermediate part of a double-jacketed gasket does very little to effect the sealing capability of the gasket. In some cases, nubbins are provided on heat exchanger designs to provide an intermediate seal. This nubbin is normally 1/64″ (0.4 mm) high by 1/8″ (3 mm) wide. Experience has indicated, however, that there is little advantage to this particular design. The primary seal is still dependent on the inner lap of the gasket doing the brute work and the secondary seal, when applicable, would be provided by the outer lap.
Double Jacketed Corrugated Gasket
The double jacketed corrugated gasket is an improvement on a plain jacketed gasket in that the corrugations on the gasket will provide an additional labyrinth seal. It also provides the advantage of reducing the contact area of the gasket, enhancing its compressive characteristics. A double jacketed corrugated gasket still relies on the primary seal on the inner lap. Double Jacketed Corrugated Gasket with a Corrugated Metal Filler At temperatures in excess of the range of 900°F (483°C) to 1000°F (538°C) where the standard soft filler is normally not recommended, a double jacketed corrugated metal gasket with a corrugated metal filler can be beneficial. This construction has the advantages of the double jacketed corrugated metal gasket and, in addition, since the filler is normally the same material as the gasket itself, the upper temperature limit would be determined by the metal being used. This type of gasket, depending upon metal selected, is designed to be a heat exchanger gasket for high pressure, high temperature applications.
Single Jacketed Gasket
The majority of applications for single jacketed gaskets are normally 1/4″ (6.35 mm) or less in radial width. This type of gasket is used in air tool applications and engine applications where space is limited, gasket seating surfaces are narrow and relatively low compressive forces are available for seating the gasket.
Single Jacketed Overlap
In the single-jacketed overlap construction the maximum flange width is approximately 1/4” (6.4 mm). This type of gasket is used when total enclosure of the soft filler material is required and when the flange width makes it impractical to use a double jacketed gasket. Double Jacketed Double Shell Gasket The double-jacketed, double-shelled gasket is similar to the double jacketed gasket except that instead of using a shell and a liner, two shells are used in the fabrication of the gasket. It has the advantage of a double lap at both the ID and the OD of the gasket, adding greater stability to the gasket. The construction will withstand higher compressive loads. Double-shell gaskets are normally restricted to use in high pressure applications.
Advantages
Application
Material
Standard jacket materials - soft iron, steel, SS316, SS304, SS321, SS410, brass, copper, monel. Standard filler materials - Non-asbestos, graphite, PTFE
