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Two aft split oil lubricated stern-tube seals type, SeaQual
size 23, was recently installed on the M/V "Ragnhild
Knutsen". On October 19-20th, during a period of 36 hours,
two service engineers from "Cedervall & Söner
AB" dismounted the existing seals and mounted the new
SeaQual seals on the 530mm shafts.
The remarkable thing was not the fact that a customer selected
to exchange the
existing seals for the new SeaQual, this has become more and
more frequent, but the fact that it was done at such speed
and with the ship afloat. The twinscrew tanker "Ragnhild
Knutsen" was moored to a buoy at the entrance to Europort
in Rotterdam with the North Sea at the back and with swell
from passing ships making the job more exiting.
The building of the platforms, trimming of the ship as well
as removal and remounting of the rope guards were carried
out by the crew and local companies.
An owner that selects the SeaQual is, as can be seen from
above story, more flexible in choosing the location of the
site for a retrofit and will benefit from the big advantages
of the new seal that Cedervall is proud to present:
SeaQual, that has a revolutionary new feature; the built in
pressure equalizer. SeaQual is the first stern-tube seal ever
with this kind of device. The pressure equalizer compensates
for the pressure variations that normally occur in the
stern-tube. Cedervall seals have always been designed to tolerate
axial and radial shaft movements normally experienced in the
shaft line. Now, with the SeaQual, we can alsoaccept and compensate
pressure pulses that occur. The ability to ensure that the
stern-tube is pressurised only by static pressure from the
gravity tank, provides an excellent and trouble free operation
of the system.
The SeaQual is equipped with separate sealing faces. This
enables easy mounting and dismounting of spare parts.
Separate free-floating sealing faces provide great benefits
to the face-to-face seal principle. Besides acting as stator
the white metal face functions as a working surface for the
newly developed X-ring. This means that two sealing surfaces
have been combined in to one component, thus reducing the
number of spare parts.
The SeaQual is of course made in a fully split execution,
which enables complete dismounting and/or mounting - without
shaft or propeller removal.
The conclusion is that SeaQual represents a lifetime guarantee
against undesired shaft removals.
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