Foundation Drilling Machine
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This page explains how Kelly Bar is classified within Machinery and Equipment Manufacturing. Technical values and manufacturer relationships are research references; confirm the current specification and supplier evidence for each order.
A hollow, square or hexagonal steel bar that transmits torque and vertical force from the drilling rig's rotary table to the drill string in foundation drilling operations.
Technical details and manufacturing context for Kelly Bar
| Parameter | Typical range | Notes & selection driver |
|---|---|---|
| Cross-section Shape | Square/Hex | Square for standard, hex for higher torque |
| Cross-section Width | 100–400 mm | Common sizes for foundation drillingGB/T 3428 |
| Length | 3000–12000 mm | Custom lengths available |
| Wall Thickness | 20–60 mm | Affects torsional strength |
| Tensile Strength | 700–900 MPa | High strength alloy steelGB/T 3077 |
| Yield Strength | 500–700 MPa | Minimum yield for plastic deformationGB/T 3077 |
| Hardness | 280–340 HBW | Brinell hardness for wear resistanceGB/T 231.1 |
| Straightness Tolerance | ≤1.5 mm/m | Critical for drill string alignmentGB/T 19863 |
| Surface Finish | Ra 3.2–6.3 μm | Smooth finish reduces frictionGB/T 1031 |
| Operating Temperature | -20–80 °C | Above 80°C reduces strength |
| Weight | 500–3000 kg | Depends on size and length |
Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.
| pressure: | Up to 500 bar (dependent on wall thickness and material grade) |
| temperature: | -20°C to 150°C (operational range for standard steel grades) |
| vertical load: | Up to 3000 kN (axial compression/tension capacity) |
| torque capacity: | 50 kNm to 1000 kNm (varies by cross-section and size) |
| slurry concentration: | Up to 40% solids by weight (for standard abrasion-resistant grades) |
Indicative industry ranges for design and RFQ preparation. Confirm the exact figures and applicable standard with the manufacturer before specifying.
Quoted from the published standard.
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The Kelly Bar transmits torque and vertical force from the rotary table to the drill string, allowing continuous drilling without disconnecting the string. Its hollow center also enables drilling fluid to be pumped to the bit.
Kelly Bars typically have a square or hexagonal cross-section. Square is standard, while hexagonal is used for higher torque applications. The shape affects engagement with the kelly bushing.
Typical cross-section widths range from 100 to 400 mm, lengths from 3000 to 12000 mm, and wall thicknesses from 20 to 60 mm. Tensile strength is 700–900 MPa, yield strength 500–700 MPa, and hardness 280–340 HBW. These are reference ranges; confirm with the manufacturer.
Check compliance with relevant standards such as GB/T 3428, GB/T 3077, GB/T 231.1, GB/T 19863, and GB/T 1031. Verify straightness tolerance (≤1.5 mm/m) and surface finish (Ra 3.2–6.3 μm). Always request material certificates and test reports from the supplier.
This component is essential for the following industrial systems and equipment:
Commonly used trade names and technical identifiers for Kelly Bar.
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