This specification outlines the criteria for timber poles, known as ballies, used in applications like scaffolding, fencing, pile foundations, and flood defense. It details the timber species permitted, dimensional standards, acceptable defects, and preparation methods to ensure the poles meet strength and durability requirements for construction and temporary structures.
Overview
This specification outlines the criteria for timber poles, known as ballies, used in applications like scaffolding, fencing, pile foundations, and flood defense. It details the timber species permitted, dimensional standards, acceptable defects, and preparation methods to ensure the poles meet strength and durability requirements for construction and temporary structures.
Audience
Contents
Structure
Frequently Asked
IS 3337:1978 Appendix A provides a list of timber species suitable for ballies employed in scaffolding, fencing, shuttering supports, and flood protection. Some key species include Arjun (Terminalia arjuna - ARJ), Axlewood (Anogeissus latifolia - AXL), Ballagi (Poeciloneuron indicum - BAL), Teak (Tectona grandis - TEA), Sissoo (Dalbergia sissoo - SIS), and Sal (Shorea robusta - SAL). These species are selected based on their strength, durability, and availability, and the timber should be sound, well-seasoned, and free from defects to ensure structural reliability.
The standard defines three classes of ballies based on diameter and length: Class 1 with a top diameter over 8.5 cm up to 12.5 cm and butt diameter over 15 cm up to 20 cm, Class 2 with top diameter over 6.5 cm up to 8.5 cm and butt diameter over 11.5 cm up to 15 cm, and Class 3 with top diameter over 5 cm up to 6.5 cm and butt diameter over 7.5 cm up to 11.5 cm. All classes have lengths ranging from 3 to 9 meters. Length tolerances allow for pieces up to 7.5 cm shorter or 15 cm longer than the ordered length. These dimensions ensure the ballies meet the structural requirements for various applications.
Permissible defects as per IS 3337 include surface cracks, dead knots, and scattered pin holes caused by dead insect infestation. For surface cracks, Class I ballies can have cracks up to 20 mm deep and 3 mm wide, while Classes II and III allow cracks up to 12 mm deep and 3 mm wide; these cracks must not be numerous or impair usability. Dead knots must not exceed 5 cm in diameter. Pin holes are acceptable only if scattered, not concentrated, and must not be caused by powder post beetles. Defects such as cuts across the grain, live insect attacks, rot, pronounced spiral grain, and hollow heart are not permitted as they compromise strength and durability.
Ballies should be air-dried to reduce moisture content to a maximum of 20% within a 12 mm depth from the surface, measured at one-third of their length from the butt end. The drying process must be conducted in open air but shielded from direct sunlight and rain. Diameters at the top and butt ends are to be measured at the extreme ends to verify compliance with size requirements. After drying, ballies should undergo preservation treatment using appropriate preservatives to enhance their durability against decay and insect attack, ensuring their suitability for structural and temporary uses.
While ISI certification is not compulsory for ballies, it can be applied optionally to indicate conformity with IS 3337. The ISI mark reflects adherence to the standard through rigorous inspection, testing, and quality assurance under the supervision of the Indian Standards Institution. It assures users of the product's quality, safety, and reliability. Manufacturers must secure a license from ISI to use the certification mark legally, and continuous surveillance by ISI ensures ongoing compliance with the specifications.
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