A-A-1187
September 29, 1981
COMMERCIAL ITEM DESCRIPTION
GASKET
(ASBESTOS)
The General Services Administration has authorized the use of this
Commercial Item Description in preference to Federal Specification
HH-G-76C, type II
This description covers metallic cloth gaskets for use with flamed joints, boiler manholes and handholes and in applications using steam, gases, air and aqueous solutions other than strong mineral acids up to 300 psi and 600oF.
Salient characteristics:
Gaskets shall be jointed type. The cloth shall be cut on the bias folded into required shapes and thicknesses after the ends have been securely jointed together.
Gaskets shall contain not less than 3 plies of asbestos wire inserted cloth.
Plies of asbestos cloth shall be uniformly impregnated with friction compound. The friction compound shall be not more than 50 percent, by weight of the finished gasket and shall not contain more than 30 percent, by weight, of rubber hydrocarbon.
Shall be of the following sizes, as specified:
3 x 4 inches I.D. (Size 1)
3-1/2 x 4-1/2 inches I.D. (Size 2)
11 x 15 inches I.D. (Size 3)
Dimensions and tolerances shall be as follows in Table I.
TABLE I. Dimensions and Tolerances
|
Inside Dimensions |
Flange Width |
Thickness |
Tolerances 1/ |
||
|
Minor Axis Inches |
Major Axis Inches |
Inches |
Inches |
Inches |
Perimeter |
|
11 |
15 |
1-1/4 |
1/4 |
1/22 |
1/32 on I.P 2/ 20 inches or less. |
|
3 |
4 |
5/8 |
1/4 |
1/32 |
|
|
3-1/2 |
4-1/2 |
5/8 |
1/4 |
1/32 |
1/16 on I.P. more than 20 inches. |
1/ No minus tolerances permissible
2/ I.P.- Inside perimeter
Each strand of the warp and filler on the cloth used in construction of the gaskets shall consist of 3 plies of asbestos yard for thicknesses, and 1 copper zinc alloy wire twisted together.
Each strand of yard contain not less than 18 strands per inch in the warp and not less than 9 strands per inch in the filler.
The copper zinc alloy wire used in the construction of the strands shall be 0.007 inch in diameter with a tolerance of -.001 inch + .002 inch.
The weight of the asbestos wire-inserted cloth before insertion shall be not less than 2.75 pounds per square yard.
Workmanship. Gaskets shall be free from cracks, hardening, flowing in the friction compound and any other defects that will affect their function or serviceability.
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
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