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l Encourage development of an

Free span analysis ‘umbilicals network’ that involves the entire supply chain from an

On a separate but related theme, the Umbilical early stage of a project.

Manufacturer’s Federation has recently l Develop a global ‘lessons learned’ published a guidance note on the subject of database.

free span analysis. l Develop training modules to The term ‘free span’ is used to refer to the

Subsea – UmbilicalsSubsea – Umbilicals educate design and installation scenario whereby a section of installed static personnel.

umbilical is unsupported along its length on l Survey/review current the seabed for a distance, typically greater than installation spreads to identify 3m. any shortcomings with a view If the lay route includes free spans longer to developing a specifcation for than the critical length then the umbilical may spreads for umbilical installation be subject to vortex induced vibration purposes.

possibly leading to one or more of the following: fatigue, wear, curvature and courtesyduco

Results infringement of local structural capacity at

The workshop closed with strong span shoulder.

installation companies, equipment feedback from attendees that The reasons for the umbilical being designers and manufacturers. the issues highlighted should be eg unsupported can be various, local seabed

Morning presentations highlighted followed up. As a result, the UMF topology, scouring of the soil from underneath a number of signifcant issues in undertook to raise the output from the umbilical, the physical confguration of the relation to umbilical installation. the seminar with a number of subsea terminations, spans between I-tube and

In the afternoon, the audience was major installation companies. A seabed, and at pipeline crossings. organized into groups, each to meeting took place with installation The guidance note describes the typical discuss a topic arising out of the contractors in early 2010. The process employed when conducting free span morning session. The major themes various themes raised at the analysis on umbilicals, and describes the were : previous workshop were tabled and primary and secondary parameters utilised in l Reducing the size of subsea discussed.

the analysis. The document is intended as a terminations. A considerable amount of free reference source for all engineers involved l Matching vessel spreads to time was spent on the subject in umbilical system specifcation, design and umbilical needs. of umbilical terminations, this installation, and can be downloaded from l Better understanding of umbilical being one of the major concerns of www.umf.as/downloads internal behavior. installation companies.

Case A l Standards and specifcations. The general view was that

L (critical) l Lessons learned. terminations were too large and l Training and awareness. heavy, quite often not cylindrical, Various suggestions to improve and lacked suffcient handling installation activities arose from points. The size and weight the different discussion groups caused problems when loading including: onto a vessel, and even more so l Address the issue of termination when over-boarding during the size and weight by designing installation process. This often led smaller units, relocate distribution to increased installation time and

L 1

OK onto subsea structures, change handling/deployment

Case B methodologies, or combinations of

L (critical) such actions.

l Develop best and recommended practice documents.

l Assess and revise the current

Span shoulder

Umbilical/soil standards and specifcations.

interaction boundary l Standardize terminology condition throughout the industry.

l Standardize information

L2 presentation throughout the parties

Further investigation required involved.

courtesynexans

OE | February 2013 OE | February 2013 oedigital.com 5858 oe_umbilicals2.indd 58 31/01/2013 17:04