process involving many functions within the company, each
contributing a perspective to the assessment, financial,
management of changes to the system, inspection and
associated personnel and equipment requirements,
environmental and social implications. The important thing
is: you need data to assess the condition of pipelines – so
inspections are obviously central to integrity management.
What is Nord Stream doing in terms
inspections and what has Nord Stream done
so far?
For identified risk scenarios, an Integrity Management Plan
is designed: which surveys and inspections are needed to
gather what data; how to properly assess the results and
what remedial measures and repairs are needed in each
case, including what preparation is needed to ensure repair
readiness.
Inspections are undertaken regularly to gather data on
the condition of the pipeline and its components, and the
subsequent data is analysed by us and our contractors in
order to assess whether any remedial work is required.
We conducted the baseline surveys, both external
by ROV and internal with an intelligent pig, in 2013. Both
confirmed that the pipeline is in ‘factory new’ condition.
Last year, we conducted the first follow-up external
inspection by ROV, both visual and geophysical. We
compared the results to the baseline to see how the pipeline
is behaving under continuous operation conditions. As
expected, the pipeline is settling into the seabed. We also
checked for foreign objects in the vicinity of the pipelines
and found nothing unusual.
As expected, we are seeing that the pipeline is
overgrown with small mussels in certain depths, forming an
artificial reef for the species.
We will conduct further external surveys in summer 2015,
to continually monitor the geophysical stability and position.
How is Nord Stream setting up its repair
readiness and capabilities?
Thanks to a comprehensively engineered design; a high
standard of material used for pipeline construction; carefully
planned routing; and regular inspection and maintenance
activities, a significant pipeline repair event is not expected
during the pipeline system’s design life of 50 years.
For repair and remedial works, we are putting a lot of
efforts into readiness.
We introduced a repair preparedness strategy designed
to guarantee a level of preparedness and response capability
in the event of an incident, to ensure that the asset can be
recovered safely back to its normal operational performance
in an efficient and reliable manner.
We started with upfront development of procedures
for a spectrum of possible repair cases and set up an
organisational structure including internal functions for
repair and qualified and trained personnel with the expertise
to implement repairs in accordance to best industry practice.
An important part is also ensuring the availability of
necessary spares and upfront investment in long lead items
of repair equipment to be stored and maintained for the
pipeline operational life. We are storing a variety of spare
parts and 450 (equivalent to approximately 5.5 km) spare
pipes near the landfalls for repair cases.
Agreements with appropriate industry specialist
contractors are also a key element.
Who is Nord Stream partnering with to
ensure repair capabilities?
Nord Stream has secured the services of specialised offshore
construction company Saipem as Main Repair Contractor
(MRC).
The MRC, together with Nord Stream’s own in-house
technical specialist support, has conducted significant
levels of detailed engineering to develop the necessary
operational procedures and definition of equipment needs
to ensure that, in the event of an incident, MRC is ‘ready to
act’ to return the pipeline system back to full operational
capacity. Saipem has the inherent advantage that it was the
main contractor involved in the construction of the offshore
pipeline system and therefore has the familiarity. It can also
potentially provide the necessary types of marine vessel
spread to undertake recovery and repair of the damaged
section of the pipeline.
Another significant element of the Nord Stream Repair
Strategy is its membership to the Pipeline Repair and Subsea
Intervention (PRSI) Pool,
which is administered
by Statoil. Through the
membership, Nord Stream
has access to a range of
specialised services and
equipment technically
suited for performing
large diameter subsea
repairs, including a
remotely operable habitat,
pipeline support frames
and auxiliary support
systems which were
already deployed for
Table 1. Different repair service types defined in the repair strategy, for which procedures were developed
and specialised partners and equipment are contracted
Type of service
Reference description
Type 1
FIRST REACTION + DAMAGE ASSESSMENT
External inspection
Type 2
MAINTENANCE/REMEDIAL WORKS
e.g. rock placement for stabilisation; free span correction;
pipeline protection; anode replacement; other
Type 3
LOCAL DAMAGE REPAIR
Externally fitted 48 in. dia. repair clamp
Type 4
SHORT DAMAGE REPAIR
Section replacement up to 2 pipe joints ~24 m
Type 5
LONG DAMAGE REPAIR
20
World Pipelines
/
AUGUST 2015
