DESCRIPTION
A Jacketed Gasket is comprised of a soft pliable core inside a metallic jacket. The following outlines several styles and applications.
METALLIC JACKET
Almost any metal or alloy found in sheet form can be used as a jacket; its choice must take into consideration the fluid to be sealed. The metallic jacket is 0.016 in (0.4 mm) to 0.020 in (0.5 mm) thick.
FILLER
The standard filler material is Flexible Graphite. Other fillers like ceramic, mica-graphite, PTFE or another metal can be used.
DESIGN
The following recommendations are based on successful practical applications: Gaskets confined by the inside and outside diameters:
Gasket inside diameter = groove inside diameter plus 1/16 in (1.6 mm).
Gasket outside diameter = groove outside diameter less 1/16 in (1.6 mm).
Gaskets confined by outside diameter:
Gasket inside diameter = flange inside diameter plus a minimum of 1/8 in (3.2 mm).
Gasket outside diameter = groove outside diameter less 1/16 in (1.6 mm).
Non confined gaskets:
Gasket inside diameter = flange inside diameter pIus 1/8 in (3.2 mm).
Gasket outside diameter = bolt circle diameter less bolt diameter.
STYLES AND APPLICATIONS
STYLE 920 The style 920 is a round single jacket gasket. Used in applications where the seating stress and width are limited. It can be manufactured in circular or oval shape. The maximum gasket width is 1/4 (6.4 mm) and the standard thickness is 3/32 in (2.4 mm).
STYLE 923 The style 923 is a flat double jacket gasket. Its most typical applications are as pipe flange gaskets and in Heat Exchangers. ASME B 16.20 shows the gasket dimensions for ANSI B 16.5 flanges. The standard thickness is 1/8 in (3.2 mm). This style is also used in large size reactors in chemical plants. Another important use is for flanges in the large, low pressure ducting in Steel Mill Blast Furnaces. To compensate for distortions and irregularities of these flanges gaskets have the thickness from 5/32 in (4 mm) to 1/4 in (6 mm).
STYLE 926 Similar to style 923 but the metallic jacket is corrugated. The corrugations act as a labyrinth increasing the sealability. For ASME B 16.5 flanges, the gasket dimensions are also covered by the ASME B 16.20 standard.
STYLE 929 Similar to style 926 with a grooved metallic filler. Used in applications where it is necessary to have a gasket without non-metallic materials, temperature limits and chemical resistance depend upon of the metal only.
