The kelly-method is used to produce uncased, partially or fully cased or slurry-supported bored piles. The soil is excavated by a drilling tool mounted at the tip of a telescopic
kelly bar. When the fully cased pile technique is used, the insection of the full depth casing is simultaneous to the excavation, until the final depth is reached.
Kelly bars are key components in the execution of boreholes with hydraulic rotary drilling rigs. They transfer the torque of the rotary drive and the crowd pressure of the crowd system concurrently to the drilling tool. A Kelly bar consists of some telescopic tubular sections with a system of drive keys and lock recesses, welded onto their outer surfaces. High strength steel tube material is procured and duly heat-treated before production, which enables the Kelly bars to work well under maximum torque. Kelly lock and guides inside Kelly joints are made in highly wear-resistant material for a prolonged life. Special tooling is set up to ensure the straightness of tubes during welding process.
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FES frictional kelly bar consists of 3-6 fold telescopic sections for the drilling depth range from 49m-110m.
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FES interlocking kelly bar consists of 3-5 fold telescopic sections for the drilling depth range from 36m-63m.
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torque transfer capacity 120 - 400 kNm
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cams and large wear-resistant guides
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spring-type shock absorbers
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standardised square kelly drive stub for connecting all types of drilling tools
