Bulroc Bulring

Concentric Overburden Drilling System Bulroc Bulring System

Alternatively, and in certain ground conditions or particular pile requirements, the Bulring system may be more suitable. Thick bands of small size cobbles or extreme bands of inclined boulders are typical examples. Where holes are required to be fully cased into particularly deep sockets, the Bulring system would be more cost effective than the CDS. If the pile design requires that the casing is to form part of the pile, the Bulring system with a sacrificial ring bit can be a more suitable alternative.

The Bulring system is a "Full Face" concentric overburden system for continuous casing and comprises a ring bit and a one-piece pilot bit/driver.

The ring bit can be of a single use, sacrificial design or a heavy duty multi-use design. In either case the ring bit is attached to the casing shoe, that in turn is welded to the casing. When bedrock is reached and the socket has been drilled, the drill string can be rotated anti-clockwise, releasing the driver from the ring bit/casing. At this point the ring bit/casing can be either left in the hole if it is to form part of the pile or the ring bit/casing can be extracted as the pile is formed to be reused.

In addition to the developments in vertical Big Hole drilling, there is now an ever increasing market for Big Hole horizontal drilling, and as with the vertical systems Bulroc has developed equipment capable of drilling horizontal holes greater than 3.28 feet in diameter in a single pass. This is a cost-effective system of driving straight holes with high penetration rates through solid rock and rocky ground conditions where conventional augers cannot operate. In some instances being able to produce this diameter of horizontal hole through all ground conditions has resulted in project costs being reduced to a fraction of those costs incurred when producing multiple small diameter horizontal holes.

Bulroc Systems are capable of producing horizontal holes

Having the capability of drilling large diameter horizontal holes cost effectively has led to new designs in drainage systems and reduced the need for separate underground structures normally produced for electricity, cable, telephone services, etc. The set up is similar to that for drilling vertical holes using the Bulroc Bulring system, except that since the ring bit can now always be recovered and reused, a heavy duty multi-use ring bit is the standard design.

Once broken through, the ring bit can be salvaged and reused. The casing shoe can be ground/burnt off.

In most instances a cased hole will be necessary. A casing shoe will then be welded inside the front of the lead length of casing. This lead length will be passed over the sleeved DTH hammer and will locate against the shoulder of the driver. This will now leave the front face of the driver to accept the heavy duty ring bit, which is locked on to the pilot bit by a bayonet arrangement. The complete system is now ready to drill. Constant feed is required, and continuous clockwise rotation must be maintained to prevent loss of the ring bit. When the system breaks through the other end of the drive, the ring bit can be rotated and lifted off the driver ready for the next job. The hammer and driver can now be withdrawn back through the casing, leaving the protruding casing shoe, which can be cut or burnt off, leaving the casing supporting the drive.

The Bulroc Bulring range is ideally suited to horizontal drilling through all types of ground formations, from gravels and boulders to solid rock. A continuously cased hole is produced through to the open face and at this point.

The internal drill string, hammer, and pilot bit can be withdrawn to allow installation of cable, pipes, etc.

The Ring Bit can be removed with ease once the drill has broken through. Casing shoes can be retrieved by burning off.

The full face, comprising the ring bit and the pilot bit, provide for smoother rotation, with a minimum amount of torque required. The DTH hammer, positioned directly behind the driver and ring bit, provide the percussive energy and reduces the force necessary to advance the casing, which in turn reduces the incidence of hole deviation.

The Bulring range is also suitable for vertical drilling using a lower spec outer ring bit, which is sacrificial and is left in the hole along with the casing.

Once deep enough to avoid casing, a standard button bit can be sent through to continue to the required depth.