The standard delineates specifications for asbestos cement pipes and fittings tailored for sewerage and drainage systems functioning under gravity flow at atmospheric pressure. It details classifications, dimensions, mechanical characteristics, jointing techniques, and optional assessments such as hydraulic pressure and acid resistance testing. This code is vital for manufacturers, engineers, and contractors engaged in the design, fabrication, inspection, and installation of asbestos cement sewerage pipelines in India.
Overview
The standard delineates specifications for asbestos cement pipes and fittings tailored for sewerage and drainage systems functioning under gravity flow at atmospheric pressure. It details classifications, dimensions, mechanical characteristics, jointing techniques, and optional assessments such as hydraulic pressure and acid resistance testing. This code is vital for manufacturers, engineers, and contractors engaged in the design, fabrication, inspection, and installation of asbestos cement sewerage pipelines in India.
Audience
Contents
Structure
This section outlines the scope of the standard, focusing on the required dimensions and permissible tolerances for asbestos cement pipes and fittings. It specifies that main dimensions should align with the manufacturer’s catalogue and provides detailed tolerance limits for wall thickness, external diameter, and nominal length.
Lists the key referenced specifications related to dimensional tolerances, thickness, diameter, and length permissible deviations that pipes and fittings must conform to, ensuring manufacturing precision and uniformity.
Describes the classification system of asbestos cement pipes according to their ultimate crushing loads per meter length, defining the mechanical strength classes and providing minimum load requirements to ensure safety and durability.
Details the dimensional and geometrical characteristics of pipes and fittings, including the main dimensions, tolerances, and how these dimensions should be verified against manufacturer catalogues.
Explains the types of jointing systems recommended for asbestos cement pipes, including asbestos cement couplings with rubber seals and cast iron detachable joints, along with their material requirements and performance under hydrostatic pressure testing.
Describes the methodology for sampling pipes and fittings either before or after delivery, outlines the tests required to verify physical, mechanical, and chemical properties, and states the acceptance criteria based on test outcomes.
Defines the conditions for acceptance of asbestos cement pipes and fittings, including dimensional tolerances, mechanical and chemical property compliance, and the necessity for independent testing when requested.
States the obligation of manufacturers to certify that pipes and fittings meet the standard’s requirements, specifying pipe class, dimensional deviations, compliance with catalogue dimensions, and results of representative sample testing.
Outlines the inspection process based on sampling according to the IS 7639:1975 standard, defining inspection lot sizes by pipe diameter, sampling methods, and acceptance or rejection criteria.
Specifies the mandatory marking details on pipes and fittings including manufacturer identification, production date, nominal diameter, pipe class, and safety warning symbols, ensuring traceability and safety adherence.
Mandates the inclusion of a Safety Rules Sheet with all deliveries, as per IS 11769 (Part 1):1987, detailing safety measures for handling, transport, storage, installation, and disposal of asbestos cement pipes and fittings.
Lists the members of the Technical Committee responsible for the development of this standard, including representatives from academia, industry, government, research institutes, and standardization bodies.
Frequently Asked
IS 6908 classifies asbestos cement pipes primarily based on their intended use and mechanical strength, particularly for sewerage and drainage systems operating under gravity at atmospheric pressure. The pipes are composed of asbestos fibers combined with Portland cement types and possibly siliceous fillers. Classification considers minimum ultimate crushing loads, straightness, transverse crushing strength, bending strength, and optional hydraulic pressure testing, while also adhering to specified dimensional tolerances and acceptance criteria.
The standard defines pipe sizes by nominal internal diameter and prescribes dimensional tolerances for wall thickness, external diameter, and nominal length. Thickness tolerances vary depending on the wall thickness range, with values ranging from -1.57 mm to -4.0 mm. Diameter tolerances range from ±1.0 mm to ±1.5 mm depending on nominal diameter. Length tolerances typically range between +50 mm to -40 mm based on size. Fittings manufactured from pipes follow the same tolerance guidelines. Verification can be by full inspection or sampling as per purchaser’s instructions.
IS 6908 recommends two main types of joints: asbestos cement couplings using rubber sealing rings, and cast iron detachable joints incorporating rubber rings along with bolts and nuts. The asbestos cement couplings must conform to the pipe composition requirements, while cast iron joints comply with IS 8794:1988. Both types of joints are required to withstand a hydrostatic pressure of 0.25 MPa as per IS 5913:1989, maintaining integrity even at maximum angular deviations.
Under IS 6908, hydraulic pressure and acid resistance tests are classified as optional. Pipes and fittings may undergo hydraulic pressure testing at 0.25 MPa to ensure no leakage or fissures, and acid resistance testing limits acetic acid neutralization to 0.100 g/cm². These tests are conducted based on project requirements or quality assurance needs but are not compulsory.
Pipes and fittings must bear clear and permanent markings including the manufacturer’s name or trademark, manufacturing date, nominal diameter, pipe or fitting class, and a pictorial warning symbol as specified in IS 12081 (Part 2):1987. Optionally, the Standard Mark may also be included. These markings ensure traceability, facilitate quality control, and provide safety information on-site.
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