Double Jacketed Gaskets

Description

A Jacketed Gasket is comprised of a soft pliable core inside a metallic jacket.

Nowadays many double jacketed gaskets are already substituted by higher end kammprofile gaskets.

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 (0.4mm) to 0.020 in (0.5mm) thick.

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.

Filler

The standard filler material is Flexible Graphite. Other fillers like ceramic, PTFE or another metal (corrugated, flat, or serrated) can be used.

STYLES AND APPLICATIONS

Style 923 and 927

Style 923 (Figure 1) is a flat double jacket gasket. Its most typical applications are 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 a thickness from 5/32 in (4 mm) to 1/4 in (6 mm).

Style 927 (Figure 2) is similar to style 923 with the addition of flexible graphite facing.