IS 14695:1999 delineates the specifications for glass fibre-based coal tar pitch outerwraps primarily utilized to safeguard buried mild steel pipelines against corrosion. This standard elaborates on the material composition, physical characteristics, testing protocols, and quality benchmarks for glass fibre mats coated with plasticized coal tar enamel and finished with mineral powder surfacing. It is vital for producers, inspectors, and engineers engaged in pipeline protection to adhere to these criteria to assure robustness and field durability.
Overview
IS 14695:1999 delineates the specifications for glass fibre-based coal tar pitch outerwraps primarily utilized to safeguard buried mild steel pipelines against corrosion. This standard elaborates on the material composition, physical characteristics, testing protocols, and quality benchmarks for glass fibre mats coated with plasticized coal tar enamel and finished with mineral powder surfacing. It is vital for producers, inspectors, and engineers engaged in pipeline protection to adhere to these criteria to assure robustness and field durability.
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IS 14695 establishes the requirements for glass fibre base outerwraps incorporated within insulation systems. It specifies weight parameters for 10 square meters of product, detailing untreated and treated base weights alongside total dry weight inclusive of surfacing. Values must comply with rounding rules as per IS 2:1960. Compliance ensures product suitability for insulation applications.
This section enumerates the standards referenced within IS 14695, emphasizing the necessity to consult the latest editions to maintain compliance. It also mandates numerical rounding following IS 2:1960, retaining the prescribed number of significant digits.
Details the makeup of the glass fibre tissue, consisting of borosilicate staple glass fibres bonded with phenolic resin. Specifies physical parameters such as minimum weight per unit area, nominal thickness, tensile strength, porosity, and resistance to high-temperature bitumen exposure. Defines coal tar pitch properties including softening point, penetration, and ash content.
Outlines the minimum tensile strength in wrap and weft directions and pliability criteria after low-temperature conditioning. Sampling methods for testing and conformity assessment are explained, including calculations involving average strength and range to determine acceptance.
Specifies weight requirements for untreated and treated bases per 10 m², including surfacing materials such as sand. Describes composition and surface finishing of the outerwrap, with procedures for weight determination and mechanical property verification.
Reiterates weight, tensile strength, and pliability requirements. Describes random sampling per IS 4905 for quality control and evaluation criteria for batch acceptance.
Provides detailed sampling plans based on lot sizes, permissible defect limits, and sub-sample requirements. Acceptance of lots hinges on defect counts and test results meeting specified thresholds.
Specifies mandatory markings including manufacturer details, dimensions, batch number, and production date. Packaging must preserve roll integrity using protective materials and ensure the product is free from damage and deformation.
Summarizes testing methodologies for weight, thickness, tensile strength, pliability, air permeability, and temperature resistance. Includes apparatus setup, specimen conditioning, and evaluation criteria for quality assurance.
Frequently Asked
The glass fibre tissue must be a thin, flexible mat composed of chemically resistant borosilicate staple glass fibres bonded with phenolic resin. Key physical properties include a minimum weight of 40 g/m², nominal thickness of 0.50 mm ± 0.1 mm, breaking strength of at least 45 kgf per 150 mm in the longitudinal direction, and porosity ranging from 0.6 mm to 1.9 mm. It must also withstand exposure to hot bitumen at 280°C for 1 minute without degradation. These are tested according to specified IS methods such as IS 13826 (Parts 1 and 2).
Thickness measurement involves placing a sample on a glass plate and applying pressure using a metallic cylinder with a foot and anvil area of 6.45 cm². A pressure of 35 g/cm² is exerted, and deflection is measured with a dial gauge having a least count of 0.01 mm. This procedure ensures precise thickness determination as described in Clause 6.45 and illustrated in the standard's figures.
Sampling requires random selection of rolls from the lot as per IS 4905. The sample size and allowable defective rolls depend on lot size, for example, up to 100 rolls require 5 samples with zero defects permitted. Acceptance depends on the number of defective rolls not exceeding permissible limits and meeting mechanical property criteria, including the formula X - 0.6R ≥ specified minimum breaking strength, where X is average strength and R is the range. All samples must pass pliability tests to be accepted.
The outerwrap must be exposed to hot bitumen at 280°C for one minute under load to verify temperature resistance. It must retain its physical integrity without damage or deformation post-exposure. This test, detailed in Clause 1.9, is mandatory to confirm the outerwrap’s suitability for pipeline insulation applications.
The standard specifies inert mineral fillers that are insoluble in water and fine enough to pass through a 75-micron IS sieve, used as fillers. The surfacing powder comprises finely powdered minerals such as talc or mica passing through a 600-micron IS sieve, or alternatively, sand passing through a 250-micron sieve. Approximately 2.3 kg of sand per 10 m² is applied for dusting to prevent sticking and ensure a smooth, defect-free surface finish.
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