used for pipeline installations under rivers or crossings underneath
roads and railway embankments etc, i.e. wherever a pipeline has to
k.
iver Borrida near
the city of Mombaldone in the province of Asti, Italy. The pipeline
ran above ground mounted to a railway bridge. In order to protect
it from flooding and flushing, it was relocated underground using
an HDD rig type PD 80/50 RP.
The special challenge here was the varying ground conditions
along the bore path. The 8 in. pipe was successfully installed
under the Bormida river within only six days. Covering a drilling
length of 328.17 m and a height difference between entry and exit
point of 11.5 m, the project was realised quickly and without any
complications, though the varying geology on site represented a
major challenge for the equipment.
Key facts:
)
Technique: horizontal directional drilling.
)
Type of bore: crossing underneath the river Borrida/Italy.
)
Equipment: HDD rig PD 80/50 RP.
)
Pipe: oil pipe PE 8 in. (204 mm).
)
Soil type: sand and silt, marly rock (over 75% of the total bore
length).
)
Bore length: 328.17 m.
)
Entry angle: 12°.
)
Exit angle: 12°.
)
Straight entry length: 4263 m.
)
Height difference: 11.5 m.
)
Contractor: LMR Drilling GmbH.
)
Remarks: installation speed of 20 - 25 min. per drill rod at 9.5 m.
Gas pipeline through the Uzbek sand
In the Central Asian state of Uzbekistan, near the industrial city
of Nukus, the crossing of the country’s longest river has been
successfully realised. Thanks to the horizontal directional drilling
rig type PD 250/90 RP designed as trailer version and the team of
experts onsite, the installation works were completed quickly and
easily. Over a length of 1000 m the steel product pipe of diameter
1.042 mm was pulled in under the Armudaja river. The drilling rig
had to withstand the most difficult conditions prevailing in the
Uzbek steppe region, such as frequent desert storms and extreme
temperatures. In the fine, sandy, demanding soil the drilling rig
impressively proved its exceptional performance. After only three
weeks from the start of the project, the successful completion of
the gas pipe installation was reported to the highly pleased client
company, Neftegazmontajz.
Key facts:
)
Technique: horizontal directional drilling.
)
Type of bore: crossing underneath the river Armudaja/
Uzbekistan.
)
Equipment: trailer-based PD drill rig with 250 t pullback
force and mixing and recycling unit with a flow capacity of
2.500 l/min.
)
New pipe: gas pipe, steel Ø 1042 mm.
)
Soil type: fine sand.
)
Bore length: 1000 m.
)
Client: Neftegazmontajz.
)
Contractor: PRIME Drilling GmbH.
)
Remarks: subsequently a parallel bore of the same dimensions
was executed within 2.5 weeks.
Hard rock HDD
Modern HDD rigs can be equipped with special rock drilling tools
to be used for pipeline installations in mountaineous regions. Even
under very rough and rigid topographic and geologic conditions
and circumstances, successful and even excellent HDD bores are
possible.
In some critical hillsides that often require a renewal of pipes
with flexible plastic pipelines, due to an amount of swellable
clay minerals in the soil, trenchless construction offers additional
advantages that can have moderating and stabilising effects on the
slopes.
Gas pipeline through a ravine
In June 2012 a rockslide with a volume of 1000 m
3
occured in the
Gastein ravine near Salzburg in Austria, which hit a roadway and
ripped off the downhill support wall to the Gastein mountain
Figure 3.
The steel pipe Ø 1042 mm which was installed over
more than 1000 m length.
Figure 2.
The red line indicates the bore path underneath the
Borrida river.
108
World Pipelines
/
JUNE 2015
