Workers on an offshore rig are exposed not
only to harsh elements, but also to harsh
working conditions. There is constant noise
from drilling motors, pumps and other
heavy-duty machinery, which must be contained
in special noise enclosures for the
comfort and safety of the employees.
The design of these enclosures is determined
not only by acoustic requirements,
but also by other factors. Weight, for example,
is a natural concern on an isolated platform
in heaving seas. At a typical weight of
over 9 tonnes, traditional enclosures of insulated
steel have serious drawbacks.
For this reason, Diab AS in Norway has led
a team to develop an alternative, lightweight
noise enclosure using sandwich composites.
Comprising specialist offshore suppliers
Mundal Subsea AS, Maritime Enginering
AS and Frank Mohn Flatoy AS, the team
has arrived at a unique sandwich construction
that meets the structural, environmental
and fire-safety requirements of offshore
The new enclosure is based on Divinycell P
core from Diab, produced in a thickness
that yields ample panel strength and insulating
properties. The panels are given fiberglass
laminate skins created with a fire-retardant
resin, then bolted together and attached to
the floor by means of a steel frame. Although
they cut the enclosure weight by half – to
just 4.5 tonnes – the panels reduce noise from
114 dB inside to well below 65 dB outside.
The solution was first implemented on
the Gullfaks oil platform in the North Sea,
where an enclosure was installed in May
2011. Following successful tests, the enclosure
concept was presented officially during
the OTD (Offshore Technology Days) in
Stavanger, Norway on October 18-20, 2011.
At present, the team is developing a further
four enclosures for Statoil, who will use
them on the new Goliat FPSO platform in
the Barents Sea. Designed to withstand a
seawater or explosion wave with an impact
of 0.6 bar, the new enclosures will be larger,
with dimensions of 5.7 x 2.9 x 3.7 m. In total,
they will offer an extraordinary weight savings
of 18 tonnes over their traditional counterparts.