bulk carrier 0905
TRANSCRIPT
8/3/2019 Bulk Carrier 0905
http://slidepdf.com/reader/full/bulk-carrier-0905 1/128 SHIPREPAIR AND CONVERSION TECHNOLOGY 3RD QUARTER 2005
STEEL repairs, carried out earlier this year on
two Torvald Klaveness-owned bulk carriers,
Ballangen and Bauta, at Malta Shipyards,
demonstrated how Intelligent Engineering's (IE)
SPS Overlay technology can be used to speedup repairs to this type of vessel.
Until recently, re-instating tanktops was an
expensive and time-consuming process
involving the cropping out of steel and replacing
it with new plating and longitudinals. However,
in this situation, using SPS Overlay, the existing
thinned tank tops of the Klaveness vessels were
used as one side of the new composite. The class
society, DNV, carried out extensive analysis
prior to execution of the work.
Since they were built at the end of the 1980s,
the Klaveness self-discharging Handymax
designs Bauta and Ballangen have served their
owners well. Frequent maintenance of thedouble-bottom tanks had ensured that the
coating systems were in good condition;
however, the constant wear and erosion from
cargo and handling equipment led to the steel
tanktops coming close to the minimum allowed
thickness. Rather than re-assess alternate
loading possibilities, Klaveness decided to
re-instate the tanktops.
'There were three key reasons for using SPS
overlay', says Sverre Grønn, technical manager
at Klaveness. 'First, the need for a predictable
schedule for the work was essential. Second,
we avoided the need to clean and then
re-coat the double-bottom ballast tanks, saving
considerable inconvenience and work. Last, but
not least, the final tanktops would be more
durable and resistant to damage than their
predecessors, minimising future deformation,
allowing for easier discharge and cleaning'.
Klaveness approached DNV for approval of
the use of SPS Overlay, and the class society's
major concern was not the sandwich design
itself, but its termination at the base of the
hopper tanks and stools. As the double bottom is
a major contributor to longitudinal strength, the
transfer of stresses between the conventional
structure and the sandwich was seen as a
possible hotspot for future through-life fatigue.
Considerable time savingsDNV conducted a detailed finite-element
method (FEM) analysis, and working together
with IE, a satisfactory solution was found. Stuart
Rolland, from Intelligent Engineering, observes,
'Torvald Klaveness avoided lengthy deviation
and time out of service by conducting the repair
at Malta Shipyards rather than travelling to the
Far East. The repair took 23 days rather than an
estimated 56 to crop and replace the tops, and
deviation was only eight days each way. With
charter rates as they currently stand, the
opportunity costs savings could not be ignored'.
The work was conducted in Malta in
conjunction with IE's field engineers. In total,
3025m2 of SPS Overlay on Bauta was
completed in just 23 days in a number of steps.
The process involved cleaning and grit-blasting
the tanktops; attaching the perimeter bars and
top plates, and injection of polyurethane
elastomer, which cures to form a solid core
within three hours. A similar programme of
work was also carried out on Ballangen.
IE points out that the steel repairs on the
Klaveness bulkers demonstrated how SPS
Overlay can also be used to repair bulk
carrier bulkheads. On Ballangen, excessive
diminution of the bulkhead between hold No 5
and the engineroom was repaired using
the technology. The extra work involved
integrating 225m2 of SPS Overlay bulkhead
repair, extending to a height of 8m, with over-
steelwork to the hatch coamings and the side
shell.
The non-intrusive nature of the SPS process
meant that the repair could be carried out at
the same time as other work and avoided a
requirement for extensive and time-consuming
fuel tank cleaning in the engineroom and
double bottom. Moreover complex cable and
pipework on the engineroom side of the
bulkhead remained intact throughout the
repair. At the same time, a slight design
modification made possible by the use of SPS
Overlay enabled water ingress alarm sensors
to be installed with additional protection.
IE points out that SPS Overlay can provide
fire protection equivalent to A60 and so can
satisfy fire regulations for insulation between
flammable cargoes such as fertilisers, and the
ship's fuel tanks. Furthermore, it can be used
to strengthen existing tanktops to enable
higher point loads, so increasing cargocarrying capacity for cargoes such as steel
coil.
IE is now working on another notable bulk
carrier repair project, this time involving
Gayle Eustace, for an American owner. This
work is being carried out in Mexico at a yard
in Vera Cruz, and is the second occasion
where the bulker has been upgraded using
SPS.
Speeding up bulk carrier repairs
An overhead view of re-instatement work, using Intelligent Engineering's SPS Overlay, in progress
at Malta Shipyards on the bulk carrier Bauta .
SPS Overlay was additionally used to make repairs to the bulkhead between No 5 hold and the
engineroom on Ballangen .