Project Deliverable D50 Report on Best Practices ... - ESONET NoE

springs for release has shown its performances for two years deployments in the deep sea (EC
funded Mast - Alipor project). On offshore oil production templates, more and more
equipments include glass-epoxy elements. Carbon fibres Lighter structures may be designed
using carbon fibres. Under tensile or flexural strength design criteria, the additional cost finds
good arguments. It is more limited for structures dimensioned by the compressive strength.
The feasibility of carbon epoxy pressure hulls has been demonstrated by the EC project
Composite Housing. Syntactic foam A composite material made up with very small hollow
glass spheres inside a plastic matrix is able to provide buoyant material. It has been qualified
for full water depth floats as well as pipe insulation material. PAGE 231
Use of brittle materials Brittle materials such as glass or ceramics have exceptional
compressive strength. But any tensile or shear stress may lead to rupture. They are used for
electric insulation in connectors with a very stringent manufacturing process. Glass spheres
are often used for the buoyancy necessary during deployment phases of subsea observatories.
They are a major component of landers and used as instrument containers (on seismometers
of GEOSTAR, neutrino detectors of ANTARES…). The rules for deep-sea manned
submersibles from the international committee PVHO (Pressure Vessels for Human
Occupancy vehicles) have banned the glass spheres in the vicinity of a submersible. It is still
the rule for submersible Nautile, Alvin and Shinkai and a few ROV such as ROPOS in
Canada. Brittle materials may be used provided a reliability study based on their probability
of failure. The Weibull coefficient must be determined for this purpose. The complete
interoperability of deep-sea intervention underwater vehicles will have to address the
acceptance or not of glass spheres.
Biofouling Any material immersed in seawater will be covered by a first biofilm layer. From
this layer and thanks to its bonding characteristics, a microscopic fauna will initiate
colonization by all kind of living species. This phenomenon is site dependent and must be
analyzed case by case for long-term deployment of subsea observatories. The EC project
Mispec has proposed a method of evaluation of biofilm on optical components: the Biopam.
EC projects BRIE and BRIMON have developped and tested protections for oceanographic
instruments. The main idea is to release biocide from a coating or by active production. The
limitation is to avoid the use of forbiden substances such as TBT. When biofouling is a main
issue for the instruments on a subsea observatory, a specific study with in-situ tests is
necessary: it has been done for neutrino observatories sites such as Antares and is underway
in EC FP6 project Exocet/D.
4.4.3.3 Panel sessions
Panel P3.3 – Underwater intervention” led by Volker Ratmeyer (KDM-UNIHB-MARUM),
Marck Smit (NIOZ), Dominique Choqueuse (IFREMER) and Jean-François Drogou
(IFREMER).
Infrastructure visit: Qualification facilities and tour of IFREMER.
Participants list:
Names Surnames Institutions Emails
Friedrich Abegg KDM-IFM-GEOMAR fabegg@ifm-geomar.de
Dominique Choqueuse IFREMER dominique.choqueuse@ifremer.fr
Jean-François Drogou IFREMER jfdrogou@ifremer.fr
Nadine Lanteri IFREMER nadine.lanteri@ifremer.fr
<strong>Deliverable</strong> #50 - update October 2010 39