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MIL-DTL-24688 Insulation, Thermal And Acoustic Absorptive, Cellular Polyimide FoamThis specification covers thermal and acoustic absorptive cellular polyimide foam insulation for use on bulkheads, overheads, and ventilation ducting. This specification also covers preformed thermal pipe insulation for use on piping operating at temperatures up to 600 degrees F in shipboard applications \(see 6.1\).

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MIL-DTL-24688A

3.4 Dimensions and tolerances.

3.4.1 Type I and type II. Unless otherwise specified (see 6.2), insulation panels shall be furnished in the

lengths, width, and tolerances as specified in table I. Dimensions and tolerances shall be determined in accordance

with 4.4.2.1.

TABLE I. Panel dimensions and tolerances.

Tolerances (inch)

Length

Width

Thickness

(inches)

Length

Width

Thickness

�, 1, or 2

��

-0

�, 1, or 2

��

-0

3.4.2 Type III. Unless otherwise specified (see 6.2), pipe insulation shall be furnished in the dimensions

specified in 3.4.2.1 through 3.4.2.3. Dimensions and tolerances shall be determined in accordance with 4.4.2.2.

3.4.2.1 Length. Pipe insulation shall be furnished in nominal lengths of 48 inches, with a tolerance of �3/16-inch

(see 4.4.2.2.1).

3.4.2.2 Size. Pipe insulation shall be furnished to fit Iron Pipe Sizes (IPS) of 1 inch to 5 inches (see 6.2). The

longitudinal seam shall close to within inch along the entire length of the section. The inside diameter of the

insulation shall not exceed the outside diameter of the pipe by � inch for nominal pipe sizes (nps) up to 4� inches

or by 5 percent on 5-inch nps (see 4.4.2.2.2).

3.4.2.3 Thickness. Pipe insulation shall be furnished in nominal thicknesses of � inch, � inch, 1 inch,

1� inches, 2 inches, and 3 inches (see 6.2) with a tolerance of �3/32-inch in thickness (see 4.4.2.2.3).

3.5 Weights and tolerances.

3.5.1 Type I and type II. Panel weight shall not exceed the maximum specified in table II. Weights and

tolerances shall be determined in accordance with 4.4.3.1.

TABLE II. Weight (areal density) (maximum).

Type and Class

Weight (lb/ft�)

� inch

1 inch

2 inches

Type I

0.02

0.04

0.08

Type II

Class 1

0.16

0.18

0.22

Class 2

0.14

0.16

0.20

Class 3

0.08

0.10

0.14

Class 4

0.18

0.20

0.24

Class 5

0.08

0.10

0.14

3.5.2 Type III. The base pipe insulation (unlagged) shall not exceed the maximum density specified in

table III. Density shall be determined in accordance with 4.4.3.2 and 4.4.3.3.