TS-114
T081 Reliability and Ecological Safety of Ship Propulsive Systems.
Pavel M. Lyssenkov* and Nikolay A. Reshetov**
ABSTRACT
The analysis of reliability of ship propulsive system components is given. The technical, economic and ecological consequences of their unsufficient reliability are described. Here you can find the proof of an opportunity and description of the ways of creating the "ideal" ship propulsive system. Methods to ensure the ecological safety of stern-tube arrangements including the application of ecologically friendly lubricant-coolant are considered.
Key Words: Ship, Propulsion system, Propeller, Shaft, Stern-tube, Bearing, Seal, Lubricating, Ecology
The standard definition of a concept "The ship propulsive system" (SPS) does not exist. In Russian and in English by virtue of the certain traditions this expression is perceiving not equally. Therefore it is offered to concretize it as the array of the following basic elements (Fig.1):
- the propeller;
- the propeller shaft;
- propeller shaft bearings;
- the lubricating and cooling liquid;
- the stern tube;
- stern tube seals;
- the propeller seal;
- the lubricating and cooling system.
SPS is located in the area, inaccessible to the people, is not technically served and is not subject to repair while a vessel acts. The failure of any listed components, as a rule, results in impossibility of the SPS operation, and a vessel, quite often creates an emergency dangerous to the people life. SPS rightly is considered as one of the most frequently of damaged objects of a vessel, which failure brings significant damage to the shipowner.
The Russian Maritime Register of Shipping (further Register) has executed the special scale research of SPS components reliability. The "normal" damages were considered only, the emergency cases were not included in the statistical analysis. 5300 (!) certificates of survey of the various type vessels were investigated within 5 years. The depressing picture of the failure rate of SPS components is shown in a fig.2.
The character of damages of SPS components is the following.
The cracks and corrosion ulcers on the propeller shafts body caused by corrosion-fatigue processes and by the water affect can be observed. These processes are active when bronze liners and coatings of the propeller shafts are damaged or when the outer water is pierced in the oil system of the stern tube.
Unmetal propeller shaft bearings of water lubricating systems have the increased natural wear. The wear is stimulated by an influence of the scale factor (the increasing is directly proportional to the propeller shaft diameter).
Outer and inner stern tube seals both radial and face-to-face type for systems with oil lubricants are failed mainly owing to the wear of the metal and unmetal surfaces of glands. It is shown in increased oil leakage from a ship board and in piercing of water into stern tube oil system.
Let's have analysed the statistical data received by the Register.
First of all, the reliability both the primary information and conclusions is obvious. The Register fixed in this case only the presence of the fact of a damage (by a principle "is present - is not present") and did not describe the reasons. Therefore received numerical values of the failure rate based on rather representative sample (5300 certificates), looks more than convincingly. The universality of the received data is based also on the investigating of commercial vessels practically of all designations and in a wide range of the sizes. The such convincing statistical data give the basis to the declaration, that the SPS reliability problem has not "the Russian colour".
* The Center of Technological Researches,
E-mail: ecoilsgm@hotmail.com
** Russian Maritime Register of Shipping
