Technical Information

FEATURES AND BENEFITS OF HELICAST

MULTI TURN CAST STEEL SCREW PILES

Multi - Fin High Strength Helix

  • Greater Geotechnical contact area for founding due to bulb effect, than single turn plate helix
  • Uplift capacity (tension load) of conical shape Multi turn Helix is equal to compression (down load) capacity for lighter load shafts in dense soils, subject to minimum depths.
  • Ideal for cyclone and earth quake rated construction.
  • A perfect solution when correctly deployed for foundations in aggressive expansive soils affected by dry/wet ground cycle conditions.
  • Helix tip able to penetrate rocky and shaly grounds much better than plate helix
  • Helix attached to shaft end by Mig welding allows full structural capacity to be to be used without collapsing shaft wall.
  • Cast steel Helix cannot bend or fold up against a shaft as plate helix does. Very high ultimate tensile strength of cast steel (typical 600 Mpa) protects against catastrophic Pile failure if design loads exceeded.

Single Fin High strength Cast Helix

  • Lower cost pile manufacture than traditional Plate Helix Pile- simple butt-weld attachment.
  • Single fin casting Design consists of centred attack type screws tip with shaft end completely blocked off and water tight.
  • Casting is versatile and takes multiple pipe shaft diameters.
  • Very high ultimate tensile strength of cast steel minimize against catastrophic helix failure if design load exceeded, unlike plate helix with lower ultimate tensile strength.
  • Casting allows metal to be thickened at critical load points thereby improving performance with no weight / cost increase.
  • Pitch of casting is the same as traditional plate helix with similar installation time as for same diameter Helix.
  • Cast single turn Helix ideal for soft and poor grounds where a large footprint desired to carry load.

Cast steel Couplings – Female

  • Female drive coupling allows easy disconnect from drive tool once pile is installed.
  • Should pile installation torque not be achieved then the female coupling allows quick wind connection of pile extension to facilitate deeper pile placement
  • Coupling allows full reversal wind of pile to remove and reinstall.
  • Female coupling allows quick attachment of multiple extension pieces for installation of deep piles – No welding on site required.
  • For low head height work areas, multiple short piles/ extensions can be quickly connected using female drive coupling.
  • Female couplings can be colour code branded for easy identification of piles on site if required.
  • Banded female couplings increase coupling stiffness and joint integrity.
  • Female coupling has aligned bolt holes to pin coupling to drive tool for safety whilst lifting pipe and securing to male to avoid disconnection of deep piles whilst uncoupling planetary drive unit.

Cast steel Couplings – Male

  • Used on extension pieces for quick connection to female coupling on pilot piles. They are pre welded in house to nominated extension lengths removing need for any site welding and improved quality assurance.
  • Forms the basis for any “quick hitch” connection accessories or attachments to Pilot Piles, e.g. pile caps, tension load tests etc.
  • Allows for short length components to be installed in areas with serious height restrictions e.g. internal foundation repair.
  • Interlocking bayonet design will allow joint to withstand installation torques equal to that of the design capacity of the pile shaft.
  • Heavy duty coupling system will allow Helicast™ piles to be installed to 40metres if required, deeper piles subject to Geotech reports and Engineering approval.
  • Helicast™ system design using a butt-welded end connection from pipe shaft to casting, allows full structural design use of pile shaft diameter and wall thickness. Pilots and Extensions typically up to 6m length with multiple pieces used for deeper piles.

SHAFT SIZE RANGE CHART

All Helicast™ couplings are manufactured in weldable cast steel equivalent to ASTM WCB 216B grade and are connected direct to the end of the pipe shaft using a butt-welded joint. As such Engineers are able to use the full structural design capacity for the pile Shaft diameter and wall thickness.

The following Pipe diameters and wall thickness can be welded directly to the helix diameters nominated.

HELICAST tm MULTI TURN CAST HELIX

Helix Series Helix Diameter Pipe Shaft Diameter Wall Thickness Load Range
150 150mm 33.4 (Rod) 3.4-4.5 55-70Kn SWL
60.3 3.6-5.5 110-170 Kn SWL
76.1 3.6-5.2 140-200 Kn SWL
88.9 4.0-5.5 185-260 Kn SWL
280 280mm 76.1 3.6-5.2 140-200 Kn SWL
88.9 4.0-5.5 185-260 Kn SWL
88.9 4.0-5.5 185-260 Kn SWL
350 350mm 88.9 4.0-5.5 185-260 Kn SWL
101.6 4.0-5.0 210-270 Kn SWL
114.3 4.0-7.1 240-440 Kn SWL
139.7/141.3 4.8-6.0 370-455 Kn SWL
165.1/168.3 4.8-7.1 365-670 Kn SWL
450 450mm 168.3 4.0-8.0 365-755 Kn SWL
177.8 6.0-8.2 600-825 Kn SWL
219.1 6.4-12.7 795-1590 Kn SWL
273.1 with adaptor ring 6.4-12.7 1000-2000 Kn SWL
600 600mm 219.1 6.4-12.7 795-1590 Kn SWL
273.1 6.4-12.7 1000-2000 Kn SWL
323.9 6.4-12.7 1190-2400 Kn SWL

NOTE: The above loads are the safe working loads for shaft capacity when installed in dense sands and clays or when shaft is taken down to Rock, using the Helicast™ system.

HELICAST tm SINGLE TURN CAST HELIX

Designed for Poorer soil conditions where the Multi Turn “Bulb effect” does not occur and hence a wide footprint is required to carry the desired load.

Helix Series Helix Diameter Pipe Shaft Diameter Wall Thickness Load Range
750 750mm 219.1 6.4-12.7 795-1590 Kn SWL
273.1 6.4-12.7 1000-2000 Kn SWL
323.9 with adaptor ring 6.4-12.7 1190-2400 Kn SWL
900 900mm 219.1 8.2-12.7 1025-1590 Kn SWL
(Under development) 273.1 9.3-12.7 1470-2000 Kn SWL
323.9 9.5-12.7 1790-2400 Kn SWL

NOTE: The above loads are the safe working loads for shaft capacity when installed in dense sands and clays or when shaft is taken down to Rock, using the Helicast™ system. These load capacities DO NOT APPLY with plate Helix welded circumferentially to the pile shaft.  Other Diameters available subject to inquiry.

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