What is the purpose of this standard?

To provide a uniform procedure for selecting a representative sample from a lot of asbestos cement products to determine its conformity to a specification.

How many sheets should be taken for visual inspection from a lot of 1000?

For a lot size of 501 to 1000, the sample size for visual inspection is 32 sheets (Table 1).

If I take a sample of 32 sheets for visual inspection, how many can be defective for the lot to be accepted?

For a sample size of 32, the lot is accepted if the number of defective sheets is 2 or less (Table 1).

Does this code tell you how to perform the tests?

No, this code is only for sampling. The actual test procedures are described in the respective product specification codes (e.g., IS 459 for pipes, IS 2096 for flat sheets).

IS 7639

: 1975

Methods of sampling of asbestos cement products

CurrentSpecializedTesting MethodMaterials Science · Cement Matrix Products

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This standard specifies the methods for sampling asbestos cement products like sheets, pipes, and boards. It provides statistical sampling plans, defining the lot size, sample size, and the permissible number of defective items for acceptance for visual, dimensional, and physical/mechanical tests.

Methods of sampling of asbestos cement products

Quick Reference Values

Lot Size (Sheets, Visual)Up to 500

Sample Size for Lot up to 500 (Sheets, Visual)20

Permissible Defectives for Sample of 20 (Sheets, Visual)1

Lot Size (Pipes, Mechanical)Up to 100

Sample Size for Lot up to 100 (Pipes, Mechanical)5

Permissible Defectives for Sample of 5 (Pipes, Mechanical)0

Practical Notes

The use of asbestos products is now heavily regulated or banned in India due to severe health risks. This code is mainly relevant for quality assessment of existing materials or for rare, specific applications where permitted.

The standard is based on statistical quality control. It is critical to correctly identify and segregate the 'lot' before drawing any samples.

Note the different sampling scales for visual/dimensional checks versus destructive mechanical/physical tests; the latter uses a much smaller sample size.