N ational and regional pipelines for
natural gas transport offer an ideal
pathway for telecommunications
backbones. Because a cable route often
runs parallel to a gas pipeline, minimal
additional civil works are necessary.
Standard cable laying methods, like
direct burial or duct installation can be
Alcatel 6851
Gas Lines
used. Gas distribution networks within
cities offer another promising pathway
for metro and access optical networks.
Here, optical cable is installed inside
the gas line, requiring a unique and
innovative solution provided by
Metro Access - the Challenge of Installation Inside Gas Lines
L ow gas-pressure, together with numer-
ous valves which offer "natural" fiber
access points, makes distribution network
an ideal pathway for optical metro
backbone and access networks. Cables
in gas pipelines are well-protected from
external hazards since gas pipelines
are located deep underground, and are
usually handled with extraordinary care.
Alcatel has developed a complete solution for fiber installation inside medium
pressure natural gas pipes, including
a specially designed cable as well as all
required installation hardware and tools.
Using this solution, cable installation
lengths up to 4 km are possible.
A cable entry point consists of a steel
dome welded to the pipe, with a sealed
cable inlet. The gas flow is stopped for
the cable laying process. The cable being
pulled by a specially designed parachute
system which is propelled by controlled
gas flow or compressed air. Pulling speeds
of up to 250 m/min have been demonstrated. The solution is designed to be fully
compatible with the gas environment and
does not affect the operation and maintenance of the gas system.
As a special benefit for the gas operator,
the system can be equipped with a
fiber-based leakage monitoring system.
© Copyright 2002 ALL RIGHTS RESERVED
The optical cable is laid in sections
between valves, which it has to bypass,
thus establishing a potential access point.
Closure and spare
cable length
branching point
Weld-on flange
with cable entry port
Shut-off valve or
rubber bubble seal
By-pass and
customer access point
The diagram shows the principle of cable installation in gas pipes.
Rev 1, June 02
Alcatel 6851
Gas Lines
Environmentally Adapted Components for Highest Safety
C able and sealing elements are specially
designed for installation in natural gas
networks at pressure levels up to 20 bars.
The sealing package consists of a set of
ethylene-propylene-diene rubber (EPDM)
rings which are proven to be chemically
resistant and stable under thermal and
mechanical loads. The cable sealing
system has been tested for tightness of
up to 100 bars.
Monitoring Options
Optical fibers inside gas pipes offer
supplementary benefits for gas operators which can greatly enhance
efficiency. The cables can be used to
remotely control pumping stations and
to provide a backbone for network
management. The fibers can be used to
continuously monitor for leakage along
the pipeline. This is based on the fact
that wherever the gas pressure sinks,
the temperature also sinks. The latter
can be precisely measured via Raman
Scattering together with the JouleThomson effect, with a high time and
spatial resolution.
Easy Interconnection
The jointing and branching of cables
is carried out in manholes. Alcatel
connectivity elements form a modular
fiber management system.
With distribution frame systems, closures
and subscriber boxes, Alcatel's product
range meets the diverse connectivity
needs throughout optical networks.
Gas Solution Benefits
Fast installation with immediate high returns on investment
Gas pipes in urban areas virtually pass every telecommunications customer
Easy-to-install with minimum civil works
Cables and materials fully compatible with the gas environment
Easy access for splices and repairs
Shut-off valves in city networks provide convenient fiber access points
© Copyright 2002 ALL RIGHTS RESERVED
For additional information visit Alcatel online or call
your nearest Optical Fiber Sales Representative
Value added option for gas operator by monitoring and managing the gas network
Brazil.................................+55 11 3068 9993
France (HQ) .................+33 1 39 77 15 28
Germany.....................+49 2166 134 1100
India .....................................+91 11 335 9650
Spain.....................................+34 942 247 111
UK .......................................+44 1633 413 600
North America ..............+1 828 459 9787
800 879 9862
Rev 1, June 02