Chapter 5
Technical Risks of Offshore Structures
Job Klijnstra, Xiaolong Zhang, Sjoerd van der Putten
and Christine Röckmann
Abstract Offshore areas are rough and high energy areas. Therefore, offshore
constructions are prone to high technical risks. This chapter elaborates on the
technical risks of corrosion and biofouling and technical risks through mechanical
force. The expected lifetime of an offshore structure is to a great extent determined
by the risk of failures through such risks. Corrosion and biofouling threaten the
robustness of offshore structures. Detailed and standardized rules for protection
against corrosion of offshore structures are currently lacking. There is a need for an
accepted uniform specification. A major technical risk of a combined wind-mussel
farm is that of a drifting aquaculture construction that strikes a wind turbine
foundation. We investigate two scenarios related to this risk: (1) Can a striking
aquaculture construction cause a significant damage to the foundation? (2) If a
drifting aquaculture construction gets stuck around a turbine foundation and thus
increases its surface area, can the foundation handle the extra (drag) forces
involved? A preliminary qualitative assessment of these scenarios leads to the
conclusion that a drifting mussel or seaweed farm does not pose a serious technical
threat to the foundation of a wind farm. Damage to the (anticorrosive) paint of the
turbine foundation is possible, but this will not lead to short term structural damage.
Long term corrosion and damage risks can be prevented by taking appropriate
maintenance and repair actions. Contrarily to mussel or seaweed farms, the
impact/threat of a drifting fish farm on structural damage to a wind foundation
depends on type, size and the way of construction of the fish cages. The risk of
extra drag force due to a stuck aquaculture construction relates particularly to jacket
constructions because any stuck construction may lead to (strong) increase of the
J. Klijnstra (&) Á X. Zhang
Endures BV, Bevesierweg 1 DC002, 1781 AT Den Helder, The Netherlands
e-mail: job.klijnstra@endures.nl
S. van der Putten
TNO Structural Dynamics, Van Mourik Broekmanweg 6,
2628 XE Delft, The Netherlands
C. Röckmann
Wageningen University and Research—Wageningen Marine Research,
P. O. Box 57, 1780 AB Den Helder, The Netherlands
© The Author(s) 2017
B.H. Buck and R. Langan (eds.), Aquaculture Perspective of Multi-Use Sites
in the Open Ocean, DOI 10.1007/978-3-319-51159-7_5
115
Technical Risks of Offshore Structures
Job Klijnstra, Xiaolong Zhang, Sjoerd van der Putten
and Christine Röckmann
Abstract Offshore areas are rough and high energy areas. Therefore, offshore
constructions are prone to high technical risks. This chapter elaborates on the
technical risks of corrosion and biofouling and technical risks through mechanical
force. The expected lifetime of an offshore structure is to a great extent determined
by the risk of failures through such risks. Corrosion and biofouling threaten the
robustness of offshore structures. Detailed and standardized rules for protection
against corrosion of offshore structures are currently lacking. There is a need for an
accepted uniform specification. A major technical risk of a combined wind-mussel
farm is that of a drifting aquaculture construction that strikes a wind turbine
foundation. We investigate two scenarios related to this risk: (1) Can a striking
aquaculture construction cause a significant damage to the foundation? (2) If a
drifting aquaculture construction gets stuck around a turbine foundation and thus
increases its surface area, can the foundation handle the extra (drag) forces
involved? A preliminary qualitative assessment of these scenarios leads to the
conclusion that a drifting mussel or seaweed farm does not pose a serious technical
threat to the foundation of a wind farm. Damage to the (anticorrosive) paint of the
turbine foundation is possible, but this will not lead to short term structural damage.
Long term corrosion and damage risks can be prevented by taking appropriate
maintenance and repair actions. Contrarily to mussel or seaweed farms, the
impact/threat of a drifting fish farm on structural damage to a wind foundation
depends on type, size and the way of construction of the fish cages. The risk of
extra drag force due to a stuck aquaculture construction relates particularly to jacket
constructions because any stuck construction may lead to (strong) increase of the
J. Klijnstra (&) Á X. Zhang
Endures BV, Bevesierweg 1 DC002, 1781 AT Den Helder, The Netherlands
e-mail: job.klijnstra@endures.nl
S. van der Putten
TNO Structural Dynamics, Van Mourik Broekmanweg 6,
2628 XE Delft, The Netherlands
C. Röckmann
Wageningen University and Research—Wageningen Marine Research,
P. O. Box 57, 1780 AB Den Helder, The Netherlands
© The Author(s) 2017
B.H. Buck and R. Langan (eds.), Aquaculture Perspective of Multi-Use Sites
in the Open Ocean, DOI 10.1007/978-3-319-51159-7_5
115