Laying of HDPE protective pipes with - TERRA-JET DJ 20
Laying of HDPE protective pipes for gas pipes
A few kilometers northwest of Klett near Trondheim, Norway, HDPE protective pipes had to be laid for gas pipes to be pulled in later. The special civil engineering company from Trondheim chose its new HDD dril rig TERRA-JET DJ 20 to cross below a quite busy road.
The two bores started in flat terrain approximately at right angles to the roadside in starting pits only a few meters away with an entry angle of 30 and 45 % (incl. rear blade). The drilling lengths of 22 and 34 m resulted also because of the slightly rising terrain on the other side of the road. For the drill rods (Ø 60/54 mm), which have a minimum bending radius of 35 m, it was no problem to steer in the ground.
The almost clay-rich and easily drillable lake and fjord deposits were drilled through after 1 to 1.5 hours. Despite the predominantly low material resistance - apart from a few stones occurring in the lowest 10 cm range - the required direction changes could be carried out with the 3-finger directional head.
The pulling of the 110 mm HDPE pipe was carried out with a reamer ROCK 135 R. Already during the pilot drilling, but especially here, the ADBS (Automatic Drilling and Backreaming System) proved its worth by preventing the reamer from getting stuck in the few stony passages by automatically regulating the torque and pull-in force and thus optimizing the pull-in speed over the entire distance.
The semi-automatic rod changer, as well as the heatable, rotatable cabin and the LED headlights permitted comfortable and efficient working despite the sometimes changeable, cold weather conditions and short days.
Pic 1: TERRA-JET DJ 20 lays gas pipelines.
Pic 2: Aligning the TERRA-JET DJ 20 before using the anchoring system; LED-headlights in action.
Pic 3: Pilot drilling with an entry angle of about 24° resp. 45% applying the rear blade.
Pic 4: TERRA-JET DJ 20 in action.
Pic 5: Reaming and pipe pulling at drilling location 2 (length 34 m); Disassembly of the expander chuck.
Pic 6: Evacuation of the HDD bore rig TERRA-JET DJ 20.
