Cfa Kelly Extension Rod Pipe Od470mm Length 6m with Cfa Octagonal Connector Sw25
详细信息
CFA kelly extension rod od419mm with cfa octagonal connector sw200 match liebherr-lb28 cfa rigCfa kelly extenson sleeve od419mm,length 6m match liebherr-lb24 cfa rig with cfa octagonal connector sw190
cfa kelly extension rod od419mm length 8m with cfa coupling match liebherr- LB35.1 rig for cfa pile
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These extended concreting kellys ,cfa kelly extension rod increase the maximum achievable drilling depth for continuous flight auger drilling ith cfa rig
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Other brand cfa rig kelly extension rod , size and length can design too
In Continuous Flight Auger (CFA) piling, a Kelly extension sleeve (or extended concreting Kelly setup) is used to extend the drilling depth beyond the standard mast stroke length without needing to add extra auger sections.
It passes directly through the rotary drive unit, acting as both a structural drive extension and a conduit for concrete/grout pumping during auger extraction
Core Functions & Mechanism
1.
Depth Extension: Adds 6 to 12 meters of depth capacity to the standard auger string without increasing overall transport dimensions.
2.
Torque & Crowd Transfer: The rotary head's internal drive sleeve (or drive box) engages the outer keyways or polygonal profile of the extended Kelly tube, transferring rotation and downward crowd force.
3.
Pumping Conduit: Features a concrete swivel connection at the top, allowing uninterrupted high-pressure concrete or grout injection through the central stem as the auger is extracted.
Key Structural Components
Extended Kelly Tube: Heavy-walled alloy steel tube with welded outer drive ribs or keyway grooves.
Rotary Drive Box / Inner Sleeve: The replaceable drive collar/sleeve mounted inside the rig's rotary head that meshes with the Kelly tube's drive profile.
Quick Couplings (Pin & Sleeve): Octagonal or hexagonal male-female couplings with hardened safety pins. These transfer extreme torque and tensile forces when pulling the auger string out of dense ground.
Concrete Top Swivel: A heavy-duty,
rotating head connected to the concrete delivery hose at the top of the Kelly extension.
Technical Selection & Specification Criteria
Feature
Key Selection Parameters
Drive Profile & Rig Match
Ensure keyway alignment, outer diameter (OD), and torque capacity match your rig's rotary head drive sleeve (e.g., Soilmec, Casagrande).
Concrete Passage (ID)
Standard inner diameters range from 125 mm (5 in) to 150 mm (6 in). Match the ID to your concrete pump discharge lines to prevent pressure buildup or plugging.
Torque & Tensile Ratings
Rated torque () and maximum extraction pull force () must exceed the rig's maximum output to prevent fatigue failure under suction pull.
Coupling Type
Verify compatibility with your existing auger top connection (octagonal pin/sleeve, hexagonal, or flanged joints).
Maintenance & Operational Checklist
Sleeve Key Inspection: Inspect the internal keyways of the rotary drive sleeve and the drive ribs on the Kelly extension for uneven wear, mushrooming, or cracking.
Safety Lock Pins: Always verify that quick-coupling safety pins are present, fully seated, and locked with linchpins before lowering into the hole.
Concrete Washout: Flush the internal stem of the extension immediately after every concreting cycle to prevent concrete buildup and internal restriction.
Swivel Seal Maintenance: Lubricate top swivel bearings and check internal seals daily to prevent concrete slurry from invading the rotating assembly.
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