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IS 7639:1975 is the Indian Standard (BIS) for methods of sampling of asbestos cement products. 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.
! 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.
ISO 390:1993International Organization for Standardization (ISO)
HighWithdrawn
Products in fibre-reinforced cement — Sampling and inspection
Provided a general methodology for sampling and inspection of fibre-cement products, very similar to IS 7639.
ISO 9933:2015International Organization for Standardization (ISO)
MediumCurrent
Fibre-cement flat sheets — Product specification and test methods
Contains specific sampling plans for fibre-cement flat sheets, a major product category covered by IS 7639.
ASTM C500-13(2018)ASTM International, USA
MediumCurrent
Standard Test Methods for Asbestos-Cement Pipe
Includes procedures for sampling asbestos-cement pipes for various tests, covering another key product type.
EN 12467:2012+A2:2018European Committee for Standardization (CEN), Europe
MediumCurrent
Fibre-cement flat sheets — Product specification and test methods
Specifies sampling rules for conformity assessment of fibre-cement flat sheets, largely harmonized with ISO 9933.
Key Differences
≠IS 7639 is a standalone, general sampling standard for all asbestos-cement products, whereas modern international standards typically integrate sampling procedures within specific product standards (e.g., for sheets, pipes, or corrugated roofing).
≠IS 7639 provides its own self-contained sampling tables. In contrast, modern standards like ISO 9933 and EN 12467 explicitly reference and require the use of the comprehensive statistical sampling schemes found in ISO 2859-1.
≠The Indian standard uses older terminology like 'consignment' and 'batch'. Modern standards are framed within a quality management context, using terms like 'Type Testing (TT)', 'Acceptance Testing (AT)', and 'Factory Production Control (FPC)' which are not present in IS 7639.
≠IS 7639 was written specifically for 'asbestos cement'. Most current international standards have transitioned to 'fibre-cement' to reflect the industry's move away from asbestos to alternative fibres like cellulose and PVA.
Key Similarities
≈Both IS 7639 and its international counterparts are fundamentally based on the principle of statistical sampling to assess the quality of a large 'lot' by testing a small, randomly selected sample.
≈The size of the sample to be tested is dependent on the size of the production lot or consignment in all mentioned standards, ensuring scalability of the inspection process.
≈All standards mandate that samples must be selected randomly from the lot to ensure they are representative of the lot's overall quality, a cornerstone of valid statistical sampling.
≈Both the Indian and international standards define clear acceptance and rejection criteria based on the number of non-conforming units found in the sample, often linked to an Acceptable Quality Level (AQL).
Parameter Comparison
Parameter
IS Value
International
Source
Referenced Sampling Scheme
Self-contained tables within IS 7639.
References ISO 2859-1 (Sampling procedures for inspection by attributes).
ISO 9933:2015
Specified Inspection Level for Acceptance
Not explicitly defined in ISO 2859-1 terms; a single sampling plan is provided.
Special Inspection Level S-3.
ISO 9933:2015
Sample Size for Lot Size 51-150
8
8 (for lot size 51-90, code E) or 13 (for lot size 91-150, code F)
ISO 2859-1 (as per ISO 9933)
Sample Size for Lot Size 501-1200
32 (for lot size 501-3200)
20 (code H)
ISO 2859-1 (as per ISO 9933)
Sample Size for Lot Size 3201-10000
50 (for lot size 3201-35000)
32 (code K)
ISO 2859-1 (as per ISO 9933)
Acceptance/Rejection Number (Sample=32, AQL=4.0%)
Accept: 3, Reject: 4
Accept: 3, Reject: 4
ISO 2859-1
⚠ Verify details from original standards before use
Key Values6
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
Tables & Referenced Sections
Key Tables
Table 1 - Scale of Sampling and Permissible Number of Defectives for Visual and Dimensional Requirements for Asbestos Cement Products Other than Pipes and Fittings
Table 2 - Scale of Sampling and Permissible Number of Defectives for Mechanical and Physical Tests for Asbestos Cement Products Other than Pipes and Fittings
Table 3 - Scale of Sampling and Permissible Number of Defectives for Visual and Dimensional Requirements for Asbestos Cement Pipes and Fittings
Table 4 - Scale of Sampling and Permissible Number of Defectives for Mechanical and Physical Tests for Asbestos Cement Pipes and Fittings
Key Clauses
Clause 3 - Lot
Clause 4 - Scale of Sampling
Clause 5 - Number of Tests and Criteria for Conformity
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).