Chapter 2 Survey Requirements of Steel Ship
2.3 Propeller Shaft and Tube Shaft Surveys
(ii) Detailed information or drawings of constructions and arrangement indicated in the item (c) below together with their colour photographs and detailed instruction for inspection of such constructions and arrangements; and
(iii) Other data, if deemed necessary.
(c) Constructions and arrangement
The constructions and arrangements of ships which are intended to be subjected to an in-water survey are to comply with the following:
(i) Anodes are to be attached in such a manner as to be easily replaced where necessary.
(ii) Rudder is to be provided with the means of facilitating the measurement of cle arances in way of each pintle. Liners on rudder stock and pintles are to be marked in such a way so that any relative movements can be checked.
(iii) Rope guard ring plates are to be of such constructions as to facilitate the inspection of shafts between propeller hubs and stern frame boss.
(iv) In case of water lubricating type stern-tube bearings, the devices which may indicate the clearance of propeller shaft strut and stern bearings are to be provided.
(v) In case of oil lubricating type stern-tube bearings, suitable means of ascertaining the performances of stern-tube bearings including oil sealing devices are to be provided.
(vi) Suitable means of ascertaining the position and identifying each blade of propellers from inboard are to be provided.
(vii) Sea connections are to be provided with the means of blanking their openings to the sea from outboard so that the sea connections may be opened up from inboard for examination and repairs.
Grating of sea suctions are to be of hinged type as far as practicable.
(viii) To the hull below load water line, provision is to be made for ready identification of the position of bulkheads and transverses (including indication of the number of transverses). To bottom shell plating, provision is to be made for ready identification of the flat bottom an d of ship's lengthwise (fore and aft) and athwartship (port side or starboard side) direction.
(d) Performance of in-water survey
(i) The in-water survey is to be carried out in sufficiently clear and calm waters. The ship is to be as light as possible. The shell sides below the waterline and the bottom are to be sufficiently clean.
(ii) The in-water survey is to be carried out in the presence of the Surveyor, and there is to be satisfactory two-way communication between the Surveyor and the diver.
(iii) The underwater pictures on the surface monitor screen are to offer reliable technical information such as to enable the Surveyor to judge the parts surveyed.
(iv) The in-water survey is to provide the information normally obtained from a bottom survey in dry dock. It at least covers an examination of the bottom and side plates of the shell plating, including any attachments and the rudder, an external examination of propellers as well as propeller shafts, and the cleaning condition of sea chests.
(v) If the in-water survey reveals damage or deterioration that requires early attention, the Surveyor may require that the ship be dry-docked in order that a further survey can be undertaken and the necessary work carried out.
(e) Firms engaged in In-Water Survey of ships are to comply with the requirements of "Guidelines for Approval of Service Suppliers."
2.3 Propeller Shaft and Tube Shaft Surveys
2.3.1 Tapered ShaftsThe following survey details, apply to a shafting arrangement where the propeller is taper fitted to the shaft.
(a) Water-lubricated bearings
2.3 Propeller Shaft and Tube Shaft Surveys
The survey is to consist of removing the propeller and drawing in and examining the entire shaft. During each survey, the shaft is to be examined by a surface crack-detection method (such as magnetic particle or dye penetration) all around the shaft from the after edge of the liner for one -third of the length of the taper, including forward end of keyway (if fitted).
(b) Oil-lubricated bearings
The survey may be carried out as described in (a) above. Alternatively, on the basis of satisfactory service record, lubricating oil analysis, bearing weardown and the condition of the inboard and outboard seal assemblies, the survey may consist of removing the propeller to expose the forward end of the taper and performing a nondestructive examination by a surface crack- detection method (such as magnetic particle or dye penetration) all around the shaft in way of the forward portion of the taper section, including the end of key-way (if fitted).
2.3.2 Flanged propeller shafts
The surveys detailed below are applicable where the propeller is fitted to the shaft by means of a coupling flange.
(a) Water-lubricated bearings
The survey is to consist of withdrawing the shaft in its entirety.
(b) Oil-lubricated bearings
The survey may be carried out as described above. Alternatively, the survey may consist of the verification of a satisfactory service record, lubricating oil analysis, stern bearing wear down, shaft seal effectiveness, and for controllable pitch propellers, a blade seal leak and function test.
(c) Coupling bolts and flange radius
Whenever the coupling bolts of any type of flange-connected shaft are removed or the flange radius is made accessible in connection with overhaul or repairs, the coupling bolts and flange radi us are to be examined by means of a surface crack detection method.
2.3.3 Miscellaneous propellers
(a) Controllable pitch propellers where fitted are to be opened up and the working parts examined, together with the control gear.
(b) Directional propeller units are to be dismantled for examination of the propellers, shafts, gearing and control gear.
(i) Lubrication oil samples are to be taken and sent to a recognised laboratory for analysis at regular intervals, not exceeding 3 months. Records of lubrication oil analysis are to include trends of previous analysis, and be available onboard at all times. A representative oil sample is to be taken before the filters and with the unit in its normal running condition. Oil analysis is to detect iron (Fe) and other solid contamination in addition to possible water content. Acceptance criteria for wear particles and water content are set by the relevant thruster maker (in case thruster maker criteria are not available due to e.g. bankruptcy of gear thruster maker, the water content due to condensation is normally not to exceed 0.5%). The oil analysis is to cover all of the following areas, if applicable:
(1) lubrication oil for gears, bearings;
(2) sealing boxes;
(3) steering gear; and (4) propeller.
If the propeller shafts seal oil systems do not allow for sampling unless the vessel is in dry dock, a representative oil analysis is to be taken in connection with the bottom survey in dry-dock.
(ii) The thrusters are to be subjected to complete survey every 5 years. The complete survey is to include:
(1) evaluation of oil analysis of gear lubrication oil, propeller hydraulic system oil and sealing system oil as specified in 2.3.3(b)(i) above.
2.3 Propeller Shaft and Tube Shaft Surveys
(2) opening up of protection covers.
(3) inspection of power transmission gear, bearings, visible parts of shafts and general condition of housing internally. Gear clearance and axial play of bearings shall be measured .
(4) examination of controllable pitch mechanism oil transmission system and feedback system.
(5) full stroke ahead and astern are to be verified and correct blade position feed -back and indication verified.
(6) examination of steering column and related sealing and bearing.
(7) running test at MCR (max continuous rating).
(iii) Inboard parts of the thruster accessible from the inside, such as drive motors, shafting system, gear transmissions, pumps and piping systems, alarm, safety and control systems are covered by the class surveys of machinery. This will be applicable for e.g. Voith-Schneider and pump type thrusters.
(iv) If the thruster is overhauled at the time of the complete survey, NDT for TIFF (tooth interior fatigue fracture) shall be carried out according to maker's requirements and acceptance criteria. If the thruster is overhauled during the interval between two scheduled surveys, satisfactory documentation for NDT (TIFF) performed according to maker's requirements and acceptance criteria is to be submitted to the attending surveyor at the next survey. Mounting of the thruster on board is to be verified and function tested.
(c) Water jet units are to be dismantled for examination of the impeller, casing, shaft, shaft seal, shaft bearing, inlet and outlet channels, steering nozzle, reversing arrangements and control gear.
2.3.4 Propeller shaft condition monitoring
(a) Where oil lubricated shaft with approved oil glands are fitted, a class notation PCM may be assigned, if its monitoring manuals or maintenance manuals of preventive maintenance system together with relative diagrams, are submitted and approved by the Society. The management systems are to comply with the following:
(i) Lubricating oil analysis is to be carried out regularly at intervals not exceeding six months. The lubricating oil analysis documentation is to be available on board. Each analysis is to include the following minimum parameters:
(1) Water content;
(2) Chloride content;
(3) Bearing material and metal particles content; and (4) Oil ageing(resistance to oxidation).
Oil samples are to be taken under service conditions and representative of the oil within the stern-tube.
(ii) Oil consumption is to be recorded monthly.
(iii) Bearing temperatures are to be recorded daily, (two temperature sensors with alarm or other approved arrangements are to be provided).
(iv) Facilities are to be provided for measurement of bearing wear down.
(v) Oil glands are to be capable of being replaced without withdrawal of the propeller shaft or removal of the propeller.
(b) For maintenance of the PCM notation, annual survey is to be carried out as follows:
(i) Satisfactory operating conditions of the propeller shaft are to be confirmed, including th e verification of the records of lubricating oil analysis, lubricating oil consumption, bearing temperatures and wear down readings.
(c) Where the notation PCM has been assigned, the propeller shaft need not be withdrawn at surveys as required by 1.6.8 provided all condition monitoring data is found to be within permissible limits and all exposed areas of the shaft are examined by a magnetic particle crack detection method. Where the Surveyor considers that the data presented is not entirely to his satisfaction the shaft will be required to be withdrawn in accordance with 1.6.8.
2.3 Propeller Shaft and Tube Shaft Surveys
(d) For vessels with PCM notation, the propeller shaft survey interval required by 1.6.8(a)(ii) of this Part will be extended up to 15 years provided:
(i) Annual surveys are carried out to the satisfaction of the attending Surveyors, and
(ii) The followings are carried out at each propeller shaft survey due date required by 1.6.8(a)(ii) (1) Bearing weardown measurement.
(2) Verification that the propeller is free of damage which may cause the propeller to be out of balance.
(3) Verification of effective inboard seal.
(4) Renewal of outboard seal in accordance with manufacturer's recommendation.
(5) For keyed propellers, the fore part of the shaft taper and shaft keyway are to be examin ed by an appropriate surface crack detection method(such as magnetic particle or dye -penetration), for which dismantling of the propeller and removal of the key will be required.
(e) Initial survey for existing vessels obtaining PCM notation
(i) All systems required by 2.3.4(a) of this Part are to be examined and tested in accordance with the approval plans, and
(ii) Propeller shaft survey as per 2.3 of this Part will be required if the last propeller shaft survey was carried out more than 5 years prior to the initial survey, or
(iii) The propeller shaft survey may be waived subject to satisfactory review of the following records:
(1) Six-monthly records of stern bearing oil analysis for water and metal contents, covering the last 5 years.
(2) Monthly records of stern bearing oil consumption, covering the last 5 years.
(3) Monthly records of stern bearing temperature monitoring, covering the last 5 years.
(4) Propeller shaft, stern bearing assembly and propeller operation and repair records, if available.
(5) Records of stern bearing clearance and weardown measurement from new building and last dry docking.
2.3.5 Survey in place
The scope of a survey of propeller shafts and tube shafts in place consists of:
(a) Checking of the clearances of the stern tube shafts, (b) Checking of the tightness of the oil sealing glands, (c) Examination of propeller,
(d) Where a controllable pitch propeller is fitted, it is to be ascertained that the pitch control device is in good working order, and if considered necessary, the device is to be opened up for further examination.
2.3.6 Wear-down Limits
(a) The maximum allowable wear-down limit of aft lignum-vitae bush is to be as follows:
(i) For machinery placed amidships:
C = 5+D/100 when D 400 mm C = 9 when D > 400 mm where:
D = Diameter of propeller shaft, in mm.
C = Max. allowable wear-down limit, in mm.
(ii) For machinery placed aft, the clearance is to be 1.5 mm less than the above values.