World Pipelines - June 2015 - page 114

In the early morning hours, the gas main was interrupted and
the service connections were disconnected. After the necessary
preparations and subsequent machine set-up within 30 minutes,
the pushing in of the QuickLock bursting rods began. After
20 minutes, this operation was finished. It took only a few simple
movements to link together the laid out pipe string, the expander
and the bursting head with the rods. Shortly before noon, the
pulling in process was started using a GRUNDOBURST 400G
rig in the pedestrian zone of Harkort Street. Residents were not
disturbed by open trenches, noisy breaking up and other related
excavating works thus allowing for the business shops in the direct
vicinity to carry on as usual. After only 30 minutes, the new pipe
string was pulled in. The bursting rig was already removed from
site at 12:15 p.m. and the crew proceeded with the pressure test
and integration of the service connections. At 4 p.m., all of the
households were re-connected to the gas network.
Key facts:
)
)
Technique: static pipe bursting.
)
)
Equipment: GRUNDOBURST 400G.
)
)
Host pipe: Gas main, cast iron ND 100 (4 in.).
)
)
New pipe: PE with protection coating ND 100 (4 in.).
)
)
Pipe bursting length: 60 m (197 ft).
)
)
Client: Dortmunder Energie- und Wasserversorgung GmbH.
)
)
Pipe bursting contractor comapany: PAUL SPEECK GmbH,
Dortmund, Germany.
)
)
Location of job site: Dortmund-Hombruch, Germany.
)
)
Duration: one day.
)
)
Remarks: performing the job in January without the need of
temporary supply.
Close-fit lining of a gas mains using the reduction
method in the UK
National Grid is one of the world’s largest utility companies
and the biggest gas and power supplier in the UK. The so-called
reduction method has successfully been used to refurbish large
diameter medium pressure gas mains. The existing 458 mm (18 in.)
dia. cast iron main has been relined with a 469 mm SDR21 - PE80
pipe.
The usual cumbersome 40 t capacity hydraulic capstan was
replaced with a specially adapted GRUNDOBURST 800G pipe
replacement rig, fitted with the unique QuickLock ladder type
rods for fast, reliable and safe handling. Due to some of the offset
bends of the existing main, the QuickLock rod’s flexible joints easily
overcame the associated pushing and pulling side load forces.
Installation speeds were as high as 180 m in just 1 hr 35 min., but
what was equally impressive was the ease of docking the new pipe
in the specially constructed reduction dye which together with the
GRUNDOBURST’s push pull brake and fingers, ensured minimum
pipe contraction both during the installation and reversion process.
Key facts:
)
)
Technique: reduction method.
)
)
Equipment: GRUNDOBURST 800G.
)
)
Old pipe: gas main, cast iron ND 458 (18 in.).
)
)
New pipe: PE 80 SDR21, ND 469 (18.5 in.).
)
)
Pipe bursting length: 60 m (197 ft).
)
)
Client: National Grid/PMC, UK.
)
)
Pipe bursting contractor: Morrison Utility Services, UK.
)
)
Remarks: installation speed of 180 m in 1 hr 35 min.
Conclusion
The applications described show that trenchless technologies
are becoming more and more important in pipeline installation
and rehabilitation due to the sustainability of the methods. Their
share compared to open trenching is ever increasing because
the underground installation and renewal of supply pipes bears
major technical and economical advantages as excavation and
re-instatement work are almost omitted and construction times
are short and the environment is hardly impaired.
Figure 8.
The new pipe srtring is pulled through the reduction
dye being slightly reduced to fit tightly into the old pipe
afterwards.
Figure 7.
View of a pit within the area of a service connection
showing the new pipe installed without any damage.
112
World Pipelines
/
JUNE 2015
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