Sandvik CDC system for DTH drilling


Roschen CDC system for DTH drilling    

Sandvik CDC system for DTH drilling    

Designed to enable fast, strong, accurate simple, effective and time-saving drilling, the Sandvik CDC is a concentric tool system for drilling-and-casing holes simultaneously. Strong and simple, yet advanced and effective, it can be used to install casings in many different types of overburdens, and in all types of natural formations. The CDC system drills straight holes and penetrates boulders easily as the system is designed for use with permanent casings, which are welded together progressively during drilling and left in the hole. It can be used to drill and-case comparatively deep holes, depending on the application, hole inclination and ground conditions.


Components and operating system

The Sandvik CDC system consists of a pilot bit and a concentric ring bit – casing shoe assembly. The ring bit and casing shoe are delivered as a single unit, connected to each other via a rotary joint. These two components, together with a DTH hammer, the drill pipes and the casings, make up the complete system. 


Simple, effective application

The pilot bit drills the pilot hole a few millimeters ahead of the ring bit; simultaneously the ring bit reams out the pilot hole to a diameter slightly larger than the OD of the casing. The casing shoe pulls the casing into the hole as drilling proceeds. The casing itself does not rotate, thanks to the rotary joint between the casing shoe and ring bit. When desired depth is reached the operator switches off the hammer and applies reverse rotation momentarily. This unlocks the pilot bit from the ring bit and casing shoe. The pilot bit, hammer and drill pipes are then withdrawn from the hole leaving the casings installed in the ground. 


Multi-purpose design for DTH hammers 

Sandvik CDC pilot bits are currently available with Sandvik M, DHD, QL and TD shank designs. Since some of these designs have become generic, and are used by a number of different manufacturers, it means that the system can be used with numerous different brands of hammer. Likewise, as the Sandvik CDC tool system does not rotate the casing during drilling, and is designed to install the casings permanently in the hole i.e. not to pull them up afterward, there are no significant extra demands on a standard DTH rig’s capacity with regards to pull-down, rotational torque, holdback or pullback. This means that a Sandvik CDC tool system of a given ring bit diameter can be used on most drill rigs that are equipped to drill the same diameter of hole using a normal DTH drill string. 


Light weight drilling units   

Additionally the Sandvik CDC system may be used with light weight drill rigs thanks to advanced bit design, precise concentricity and use of the percussive drilling method. This means the CDC system penetrates even hard rock easily, and in comparison with methods that rotate the casing, CDC needs little feed force and low rotational torque. The result of this is it can be used on comparatively lightweight drill rigs, which makes it suitable for use also in confined urban areas, and on weaker or more difficult terrain. 


Minimal noise and vibration  

Since all percussion takes place down the hole, the Sandvik CDC does not disturb the environment to the extent of other systems, and there is little risk of harmful vibrations being transmitted into nearby structures.  


As the flushing air and rock cuttings are extricated from the hole through the space between the drill pipes and the casings, hole wall degradation is minimal, and the surrounding ground is not disturbed to any great extent. This means that Sandvik CDC can be used in sensitive areas that contain underground structures which must not be disturbed.


The key applications for the Sandvik CDC system include:  


Drilled pile installation  

Pipe roof installation 

Water / energy well drilling 

Coffer construction

Anchoring and stabilization 

Ventilation holes 

Slope drainage 

Short horizontal holes

Ground investigation

Pre-drilling for grouting operations 

Roschen Inc. is constantly striving to improve its products and must therefore, reserve the right to change designs, materials, specifications and price without notice.

4" 4.5 4.03 114.21 102.28 22/10 8.6/3.9 IR3.5, COP34, COP32
5" 5.56 5.05 141.12 128.17 35/16 12.8/5.8 QL4, IR340, SD4
6" 6.63 6.07 168.27 154.06 59.5/27 16.5/7.5 QL5, IR350R, SD5
8" 8.63 7.98 219.04 202.54 118/53.5 27/12.3 QL6, IR360, SD6
10" 10.75 10.02 272.84 254.31 214/97 30/13.6 QL8, IR380, SD8
12" 12.75 11.94 323.6 303.05 275/125 48.5/22 QL8, IR380, SD8, SD10, N100
14" 14 13.13 355.33 333.25 485/220 57/26 SD10, N100, QL120, IR112, SD12, N120, N125
16" 16 15 406.09 380.71 573/260 57/26 QL120, IR112, SD12, N120, N125
18" 18 16.88 456.85 428.43 670/304 82/37 QL120, IR112, SD12, N120, N125
20" 20 18.81 507.61 477.41 Variable weights depending on shank QL120, IR112, SD12, N120, N125, SD15, IR112S, N180, SD18, QL200
24" 24 22.63 609.14 574.37 SD18, N180, QL200



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Casing Advancer

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HW/HWT Casing Advancer

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HQ Wireline Casing Advancer  

NQ Wireline Casing Advancer 

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BW Inner Assembly

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NW Inner Assembly

NW Wireline Casing Advancer

HW/HWT Inner Assembly

HWHWT Wireline Casing Advancer

PWT Inner Assembly

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SW Inner Assembly

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UW Inner Assembly

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ZW Inner Assembly

ZW Wireline Casing Advancer


casing advancer system

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