The 1983 edition of IS 10753 outlines the recommended procedures for preserving wooden railway sleepers through pressure treatment. It covers essential aspects such as timber preparation, preservative selection, treatment techniques, and quality assurance to guarantee the longevity and functional integrity of sleepers used in railway tracks.
Overview
The 1983 edition of IS 10753 outlines the recommended procedures for preserving wooden railway sleepers through pressure treatment. It covers essential aspects such as timber preparation, preservative selection, treatment techniques, and quality assurance to guarantee the longevity and functional integrity of sleepers used in railway tracks.
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Contents
Structure
This section defines the standard's coverage for wooden sleepers in railway tracks, emphasizing durability requirements, treatment procedures, and quality verification. It also includes rounding rules for test results according to IS 2:1960 and outlines methods to control end checking using antichecking clamps and coatings detailed in Appendix A. Preservative specifications referenced include creosote, anthracene oil, fuel oils, and water-soluble preservatives like ACC and CCA.
Describes the kinds of preservatives applicable — oil-based such as creosote and anthracene oil, and water-soluble types like CCA and ACC. It explains the pressure treatment process conducted at 80-90°C, detailing full-cell (Bethell) and empty-cell methods. End checking prevention measures like the use of iron clamps and end coatings are reiterated.
Outlines mechanical preparation steps including cleaning and removal of bark, with incisions recommended for refractory timber species to depths of 12–19 mm for improved preservative penetration. Specifies penetration requirements: 35–40 mm through sapwood and non-durable heartwood, and at least a 12 mm penetrated shell for partially treatable heartwood. Discusses post-treatment asphalt coating to prevent splitting.
Details the required depths of preservative penetration, emphasizing through-and-through penetration in sapwood and non-durable heartwood (35–40 mm) and incisions for refractory species to enable a minimum 12 mm penetrated shell. Provides incision pattern dimensions and spacing, together with retention requirements noting gross absorption rates necessary in empty-cell processes.
Focuses on the pressure treatment processes, highlighting temperature control (80-90°C) during pressure periods for oil-type preservatives and the use of full-cell or empty-cell methods. It emphasizes treatment variations based on timber type and reiterates the importance of post-treatment coating with asphalt solution for water-borne preservatives.
Discusses after-treatment practices including required gross absorption rates (2 to 3 times net retention) in empty cell processes, and the application of a 10% asphalt solution in crude oil to protect against splitting and checking. Reaffirms treatment conditions and methods for both oil-based and water-soluble preservatives.
Specifies inspection rights for purchasers or their agents at treatment plants, and mandates testing according to IS 401:1982. It includes control strategies for end checking such as antichecking clamps and end coatings, as well as rounding off test results per IS 2:1960. The section ensures uniform adherence to quality requirements.
Explains the use of antichecking iron clamps ('C' and 'S' clamps per IS 10394-1982) applied immediately after cutting to prevent cracking caused by rapid drying. Also covers suitable end coatings—coal tar and crude earth oil mixtures for treatable sleepers and white lead, aluminium paint, pitch resin, or hardened glass oil for refractory types—ensuring these do not block preservative penetration or plant equipment.
Lists species that need surface incisions to improve preservative penetration, specifying incision depth (20 mm), spacing (rows 57–60 mm apart, incisions 22–25 mm apart with 5–7 mm staggering), and orientation parallel to grain on all faces except ends. Includes details on durability class and treatability for various species such as Fir, Mundani, Kokko, Axlewood, Sal, and Teak.
Frequently Asked
IS 10753 recommends several preservatives for pressure treatment of wooden sleepers, typically including creosote oil known for its water repellency and resistance to fungi and insects, copper-chrome-arsenic (CCA) for long-lasting protection, copper naphthenate as a less toxic alternative, and pentachlorophenol (PCP) used in oil-borne preservatives for effective penetration. Specific preservative grades and concentrations should be confirmed from the latest edition or railway directives.
Before treatment, sleepers must have moisture content at or below 25%, measured to a 20 mm depth approximately 30 cm from the ends. This can be assessed using moisture meters or oven drying with increment boring samples. The timber surface should be clean and free from bark, dirt, or moisture. All mechanical preparation, such as adzing, boring, and incising, should be completed before treatment to avoid exposing untreated wood. Post-treatment, freshly cut or bored areas must be protected with preservative coatings or retreatment as specified.
IS 10753 requires through-and-through penetration for sapwood and non-durable heartwood, with a minimum penetration depth of 35 to 40 mm for species that do not require incision. For refractory species (listed in Appendix B-1), surface incisions of 12 to 19 mm depth on all faces except ends are necessary to achieve a penetrated shell of at least 12 mm thickness, ensuring effective treatment of difficult heartwood.
Two main pressure treatment processes are outlined: the empty cell process, suitable for timbers containing mixed species or both sapwood and heartwood, which achieves penetration primarily in the sapwood; and the full cell process, used for refractory species, involving treatment until preservative absorption is complete. Both processes utilize pressure and temperature controls to ensure effective preservation.
To minimize end checking and splitting, IS 10753 mandates the application of antichecking iron clamps or wire straps immediately after cutting, before cracks appear. End coatings such as coal tar mixtures or paints are recommended to slow moisture loss. Moisture content should be maintained at or below 25% during seasoning. Following water-borne preservative treatment, a 10% asphalt solution in crude oil should be applied to prevent splitting during service.
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