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| Lloyd's Register improves Shaft alignment rules |
We have compared regulations July 2006 with the corresponding of July 2000.
The main distinctions are as following.
- Shaft alignment calculations are to be submitted to
LR for approval where the screwshaft has a diameter of 250 mm or greater.
(Formely 300 mm)
- Shaft alignment calculations are to be submitted to
LR for approval for all geared installations.(Formely all multi-engined, geared installations)
- The shaft alignment calculations are to take into
account the effect of filling the aft peak ballast tank upon the bearing loads. (New!)
- Limitation of relative slope between the propeller shaft and aftermost sterntube bearing 3x10^4 rad
is patently refered to static conditions. (Formely conditions were not specified)
- Bearings of synthetic material are to be verified as being
within tolerance for ovalilty and straightness, circumferentially
and longitudinally, after installation. (New!)
- The sterntube forward bearing static load is to be
sufficient to prevent unloading in all static and dynamic
operating conditions, including the transient conditions
experienced during manoeuvring turns and during
operation in heavy weather.(New!)
- The system bearing load measurements are to be
carried out to verify that the design loads have been achieved.
In general the measurements will be carried out by the jack-up
measurement technique using calibrated equipment.(New!)
- For the first vessel of a new design an agreed
programme of static shaft alignment measurements is to be
carried out in order to verify that the shafting has been
installed in accordance with the design assumptions and to
verify the design assumptions in respect of the hull deflections
and the effects of machinery temperature changes. The
programme is to include static bearing load measurements in
a number of selected conditions. Depending on the ship type
and the operational loading conditions that are achievable
prior to and during sea trials these should include, where
practicable, combinations of light ballast cold, full ballast cold,
full ballast hot and full draught hot with aft peak tank empty
and full. (New!)
- For vessels of an existing design or similar to an
existing design where evidence of satisfactory service
experience is submitted for consideration and for subsequent
ships in a series a reduced set of measurements may be
accepted. In such cases the minimum set of measurements is
to be sufficient to verify that the shafting has been installed in
accordance with the design assumptions and are to include
at least one cold and one hot representative condition. (New!)
The other changes done to achieve more exact wordings and text consistency.
See LR Rules and Regulations for the Classification of Ships, July 2006 Part 5, Chapter 8, Section 5.
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