Advanced Materials International Forum, Bari 18-19 settembre, conferenza internazionale dedicata ai materiali avanzati e alle loro possibili applicazioni nei settori industriali, con un focus particolare sui trasporti (aerospazio, automotive, navale e cantieristico).

1. CHALLENGES
OF USING
COMPOSITES OFFSHORE
Andreas T. Echtermeyer
Department of Engineering Design and Materials,
Norwegian University of Science and Technology (NTNU),
Trondheim, Norway

2. Composites Offshore

3. Corroded Structures
A. Echtermeyer!
Piping ! !ISO 14692!
Low pressure, water!

4. Why should we use composites?
Typically stated:
Light : High specific strength & high specific modulus
Easy to form complicated shapes
Good long term properties
– Very good fatigue resistance
– No corrosion (in certain environments)
No maintenance
Material is expensive (prices are falling), but system cost
are lower
Why is not everybody using them?

5. Composites are being used more and more
Boeing Dreamliner
50% (Vol) Composite
BMW Composite Car It has taken a long time

6. Perceived Disadvantages of Composites
• Limited Fire Resistance
• Higher Component Cost (maybe)
• Difficult to inspect (need new approaches)
• Lack of supplies?
• Difficult to qualify?
• Less experience / psychological barrier
• Let´s see if this is true...

7. MATERIAL A5
- after 6 minutes
MATERIAL A4
- after 19-20 minutes
(no flashover)
Fire Performance
ROOM CORNER FIRE TESTS for PANELS
Fire resistance is still a big challenge topside, its no problem subsea.

8. Higher component cost
Typically material costs of composites are
more expensive than steel, especially for
carbon fibers.
Composite prices have been falling.
They are easier to form. Large pressure
vessels are cheaper.
Important cost is the Metal Composite
Interface MCI – need more clever
solutions
- less critical for long spoolable tubes
with just 2 endfittings
M. Salama, A.T. Echtermeyer, O. Lindefjeld, Composite Risers for Deepwater
Applications, Deepwater Offshore Technology (DOT), Stavanger, 1999

9. Lower system cost
Less weight gives many advantages
– No buoyancy
– Smaller cranes
– Smaller platform
– Easier to handle
The advantages are only achieved if the entire
system is designed for the composite solution.
If composites just replace steel parts, they are
often less interesting.
Exception: rescue an overloaded platform

10. Lack of Supplies
Early 2000s
– Composite riser and tether for Magnolia (3000 m water depth)
– Composite CNG transport in ships (large tanker)
– Each of these projects alone would have used 1 years world supply of
carbon fibers at that time.
Capacity has increased very much.
Airbus, Boeing and military are still the main carbon fiber customers.
BMW have bought part of a carbon fiber producer to guarantee
supplies.
Glass fibers are no problem, wind turbine blades are the biggest
consumer.
Production capacity for tubes is limited.
Factories for flow lines exist.

11. Difficult to inspect?
Many standard NDT methods do not work
Most subsea components are designed
for “no inspection”
Use integrated sensors instead!
Optical fibers can be a good solution:
Foto: NTNU
Foto: NTNU
• N = 3000, damage = 113 mm
• N = 8000, damage = 132 mm
4000
3500
3000
2500
2000
1500
1000
500
0
← →Damage
-150 -100 -50 0 50
Patch length [mm] (Center = 0 mm)
Microstrain
N = 3000
N = 8000
Raman
Back-scattering
Andreas T. Echtermeyer and Jon Harald L. Grave, “Composite Metal Adhesive Joints
– Long-term performance and condition monitoring”, Proceedings: AVT –211
Workshop on Understanding Failure Mechanisms Of Composites For Sustaining &
Enhancing Military System Structures, 2013

12. Difficult to qualify?
To some extend this is a myth
Composites are still new products and need more attention
Standards exist
Relatively high test requirements
High cost? Still small compared to project costs, but high
in the development phase
Long time – 10000 hour testing
Main challenge: resistance to long tem degradation

13. Relevant Documents for Composites
Offshore Standard
DNV-OS-C501
COMPOSITE COMPONENTS
2013
DET NORSKE VERITAS
Recommended Practise
DNV-RP-F202
COMPOSITE RISERS
2003
DET NORSKE VERITAS
JIP started in summer 1999,
completed end of 2001,
official DNV document since 2003.
JIP started in summer 2000,
completed end of 2001,
now official DNV document
Give the same level of safety
as standards for metals

14. API Standards – Flexible Risers
Refers to DNV-OS-C501
for composites
New - Currently
JIP document

15. 15#
Anisotropic*Composites*–*Many*Material*Data*
9#Elas)c#proper)es#(12#if#tensile#/#compressive#different)#
9#Strength#values#
Cri)cal#energy#release#rates#
Thermal#expansion#coefficients#
Swelling#coefficients#
+++#
Even%more%if%long%term%proper/es%are%considered%
#
#

16. Material*Parameters*
16#

17. Long Term Testing: Carbon Rods for Umbilicals
e↑
f↑
AKER

18. Too much testing?
Would you like to sit on
a plane where the
design was based on
materials data taken
from a text book?

19. Simplify Long Term Testing
Data interpretation
Data collection
Global Micro Molecular
New JIP Initiative

20. Most critical component – Endfitting
Difficult to analyze (stress concentrations etc.)
Uncertainty of interface properties.
Proprietary technology

21. Experience with qualifying composites
(risers and others)
Loads are needed more accurately than for metals
Material input data are initially not available. Obtaining them
takes time and is costly.
FE analysis a bit more complicated than for metals.
Showing chemical compatibility is not straight forward.
High temperature (80, 100, 120 oC) plus fluid tends to reduce
long term properties, especially through thickness strength.
Most projects struggle here.
These properties should be obtained first!!!
What has been qualified, has worked well.

22. Less experience / psychological barrier
Maybe the biggest challenge
Many people think composites are exotic
Planes 50%, cars more and more ... Its changing
No standard materials prevent that a good basis of
experience and easily available data is built up

23. Examples of Applications

24. Pressure Vessels - CNG Transport
A couple
of different
concepts
are being
discussed

25. Patch Repair of corroded plate with composite
Repair without hot-work! JIP project at DNV & EU project

26. Free falling lifeboats

27. Impact...

28. Most Composites are used Subsea

29. Tethers in
each corner
CompTetherTM
PVC
Spacers
Strands
made up of
carbon fiber
rods
Tether Cross Section
Outer
Jacket
DEEPWATER COMPOSITES!
Spoolable, low weight tether with excellent fatigue properties. Enabling
technology for deepwater TLPs!

30. Subsea Protection Structures

31. Impact on panels – Numerical model
0o
90o
0o

32. Composite Air Pressure Vessels

33. Thermoplastic Composite Pipe
• Fully bonded flexible pipe, one solid wall, melt-fused
Document long term properties, much testing!
JIP guideline has been written
DNV RP is being planned

35. Buoyancy Materials / Elements
CompBuoy can deliver material to all this applications
DEEPWATER
MODULAR BUOYS DRILLING RISER
BUOYANCY
ADCP BUOYS

37. Conclusions*
• Many exciting applications
• The trend going to deep water will increase the use
of composites
• Documentation and understanding of long term
properties under extreme conditions (hot-wet) is a
challenge
• Good design of the composite-metal joint is critical
• Impact resistance is becoming more important

38. 38#
Composites*Offshore*