What is the main preservative specified for wooden sleepers?

A 50:50 mixture of Creosote (conforming to IS 218) and fuel oil (Clause 3.1).

What is the purpose of pressure treatment?

To force the preservative deep into the wood under pressure, ensuring thorough penetration that cannot be achieved by simple dipping or brushing (Clause 4).

How is the quality of treatment checked?

By measuring the net retention of preservative in kilograms per cubic meter (kg/m^3) and checking the penetration depth, which must meet the minimum values specified in Table 1.

Why is pre-treatment conditioning necessary?

To reduce the moisture content of the wood (seasoning) so that it can absorb the preservative effectively. Unseasoned wood will not allow proper penetration (Clause 5).

IS 10753

: 1983

Code of practice for preservation of wooden sleepers for railway track by pressure treatment

CurrentSpecializedCode of PracticeTransportation · Timber and Timber Stores

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This standard provides the code of practice for preserving wooden sleepers for railway tracks using pressure treatment. It covers the types of preservatives (like creosote-fuel oil mixture), conditioning of timber before treatment, the treatment process itself, and the required net retention of preservatives to ensure durability against decay.

Code of practice for preservation of wooden sleepers for railway track by pressure treatment

Quick Reference Values

Creosote to Fuel Oil ratio50:50 by volume

Min net retention for Creosote-Fuel Oil mixture112 to 160 kg/m^3 (depending on wood species)

Max treatment pressure14 kgf/cm^2

Max treatment temperature105 °C

Min seasoning period for sleepers6 to 12 months, depending on species

Practical Notes

Effective preservation is highly dependent on the initial seasoning of the timber; moisture content must be sufficiently low for the preservative to penetrate.

Pre-boring of holes for spikes and adzing of the rail seat area before treatment is crucial for protecting the most vulnerable parts of the sleeper.

While this IS code exists, Indian Railways primarily follows its own updated standards (IRS specifications) issued by RDSO for sleepers.