7.2.1 The
completed water jet unit is to undergo a tightness test in which an
internal hydrostatic pressure of 1,5 bar above the maximum working
pressure of the unit is to be applied.
7.2.2 In cases
where the impeller is fitted to the shaft using an interference fit,
the bedding of the impeller with the shaft is to be demonstrated in
the shop to the satisfaction of the LR Surveyor. Sufficient time is
to be allowed for the temperature of the components to equalise before
bedding. A contact marking between the bore of the impeller boss and
the shaft surface of better than 80 per cent is to be demonstrated
when the contact marking ink is spread thinly on the surface of the
shaft. Alternative means for demonstrating the bedding of the impeller
will be considered.
7.2.3 Means
are to be provided to indicate the relative axial position of the
impeller boss on the shaft. Permanent reference marks are to be made
on the impeller boss, shaft and any nut to indicate angular and axial
positioning of the impeller. Care is to be taken in marking the inboard
end of the shaft taper to minimise stress-raising effects.
7.2.4 A copy
of the fitting curve, relative to temperature, and means for determining
any subsequent movement are to be placed on board.
7.2.5 The
impeller running clearances are to be checked following the installation
of the unit in the ship.
7.2.6 The
thrust bearing clearances in the water jet system are to be verified
against the required design values. This is to be done following the
installation of the unit in the ship.
7.2.7 The
piping systems are to be adequately flushed in accordance with the
manufacturer’s recommendations and the final levels of contamination
recorded. Similarly, pressure testing of the piping systems is to
comply with Vol 2, Pt 7, Ch 1 Piping Design Requirements.