Section 12 Periodical Survey Regulations – Screwshafts, tube shafts and propellers

12.1.1 Adequate means for protection against corrosion. An adequate means for protection against corrosion is an approved means for full protection of the shaft against sea water intrusion and subsequent corrosion attack. Such means are used for the protection of common steel material against corrosion, particularly in combination with water lubricated bearings. Typical means are to be, for example:

1. continuous metallic, corrosion-resistant liners (see Rules and Regulations for the Classification of Ships, July 2022 Pt 5, Ch 6, 3.9 Bronze or gunmetal liners on shafts);
2. continuous cladding;
3. multiple layer synthetic coating;
4. multiple layers of fiberglass;
5. combinations of above mentioned;
6. rubber/elastomer covering coating.

The means for protection against corrosion are to be installed/applied according to LR approved procedures.

12.1.2 Fresh Water sample test. At the Screwshaft Survey, a sample of the fresh water in a closed loop fresh water lubricated shaft is to be taken in the presence of a Surveyor. The requirements for Fresh Water sample tests are given in the ShipRight ProcedureMachinery Planned Maintenance and Condition Monitoring.

12.1.3 Lubricating oil analysis. Lubricating oil analysis is to be carried out at regular intervals not exceeding six months. The documentation on lubricating oil analysis is to be available on board. Oil samples, to be submitted for the analysis, are to be taken under service conditions.

12.1.4 Oil sample examination. An oil sample examination is a visual examination of the stern tube lubricating oil taken in the presence of a Surveyor, with a focus on water contamination.

12.1.5 Service records. Service records are regularly recorded data showing in-service conditions of the shaft(s) and are to include:

1. for Oil Lubricated Stern Bearings: lubricating oil temperature, bearing temperature and oil consumption records;
2. for Closed Loop System Fresh Water Lubricated Bearings: water flow, water temperature, salinity, pH, make-up water and water pressure (depending on design).

12.1.6 Survey Methods on Closed Systems. Oil Lubricated Shafts or Closed Loop System Fresh Water Lubricated Shafts:

1. TS Method 1 – Survey of screwshaft, tube shaft and propeller in accordance with the requirements of TS Method 1, see Table 3.12.3 Shaft Survey Methods. Primarily, the shaft is withdrawn and the propeller is removed.
2. TS Method 2 – Survey of screwshaft, tube shaft and propeller in accordance with the requirements of TS Method 2, see Table 3.12.3 Shaft Survey Methods. Primarily, records are reviewed, the propeller is removed but the shaft is not withdrawn.
3. TS Method 3 – Survey of screwshaft, tube shaft and propeller in accordance with the requirements of TS Method 3, see Table 3.12.3 Shaft Survey Methods. Primarily, records are reviewed, the shaft is not withdrawn and the propeller is not removed.

12.1.7 Survey Methods on Open Systems. Water Lubricated Shafts:

1. TS Method 4 – Survey of screwshaft, tube shaft and propeller in accordance with the requirements of TS Method 4, see Table 3.12.3 Shaft Survey Methods. Primarily, the shaft is withdrawn and the propeller is removed.

12.1.8 Tube shaft is a shaft placed between the intermediate shaft and propeller shaft, normally arranged within a stern tube or running in open water. It may also be called a stern tube shaft.

12.2.1 Oil lubricated shafts fitted with approved oil glands and closed loop system fresh water lubricated shafts fitted with approved adequate means of protection against corrosion or fabricated from corrosion-resistant material are to be surveyed in accordance with Pt 1, Ch 3, 12.2 Closed Systems - Oil Lubricated Shafts or Closed Loop System Fresh Water Lubricated Shafts: Frequency of surveys 12.2.2 to Pt 1, Ch 3, 12.2 Closed Systems - Oil Lubricated Shafts or Closed Loop System Fresh Water Lubricated Shafts: Frequency of surveys 12.2.5

12.2.2 Shafts with a keyless propeller connection or a flanged propeller connection (including controllable pitch propellers for main propulsion purposes) are to be surveyed at intervals of 5 years in accordance with TS Method 1, 2 or 3.

12.2.3 Shafts with a keyed propeller connection with a keyway that complies fully with the present Rules are to be surveyed at intervals of 5 years in accordance with TS Method 1 or 2; TS Method 3 is not permitted.

12.2.4 For oil lubricated keyless shafts, the maximum interval between two surveys carried out according to TS Method 1 or TS Method 2 shall not exceed 15 years, except in cases when one extension of no more than 3months is agreed. The Classification Committee may accept alternative arrangements based on the low running hours of offshore units.

12.2.5 Closed loop system fresh water lubricated shafts may be surveyed in accordance with TS Method 2, or for keyless shafts TS Method 3, only if the descriptive note ShipRight SCM is assigned. Notwithstanding this, the maximum interval between two surveys carried out according to TS Method 1 shall not exceed 15 years, except in cases when one extension of no more than 3months is agreed. The Classification Committee may accept alternative arrangements based on the low running hours of offshore units.

12.2.6 Shaft configurations other than those listed in Pt 1, Ch 3, 12.2 Closed Systems - Oil Lubricated Shafts or Closed Loop System Fresh Water Lubricated Shafts: Frequency of surveys 12.2.2 to Pt 1, Ch 3, 12.2 Closed Systems - Oil Lubricated Shafts or Closed Loop System Fresh Water Lubricated Shafts: Frequency of surveys 12.2.5 above are to be surveyed at intervals of 3 years in accordance with TS Method 1.

12.2.7 TS Method 2 and TS Method 3 are only permitted where the prerequisite service records and data specified for those methods are to be provided. If at the time of survey, the attending Surveyor is not satisfied with the service records and data presented, then the shaft may be required to be withdrawn. The service records and data are to be retained on board and audited by LR at the Annual Survey.

12.2.8 For oil lubricated arrangements, the descriptive note ShipRight SCM is not a prerequisite in order to hold TS Method 2 and TS Method 3 surveys.

12.2.9 In order to assign and maintain the descriptive note ShipRightSCM, the requirements of Pt 5, Ch 6, 4 Control and Monitoring of the Rules for Ships and ShipRight Procedure Machinery Planned Maintenance and Condition Monitoring, Section 4, are to be complied with, including the requirements therein for onboard maintenance of records and review of them by the attending Surveyor at Annual Survey.

12.2.10 For surveys completed within 3 months before the Shaft Survey due date, the next period will start from the Shaft Survey due date.

12.2.11 See Summary of Survey Intervals and Extensions for closed systems in Table 3.12.1 Summary of Survey Intervals and Extensions - closed systems.

12.3.1 Survey in accordance with TS Method 4 at intervals of 5 years is applicable to any of the following:

1. single shaft operating in fresh water only;
2. single shaft provided with approved adequate means of protection against corrosion or fabricated from corrosion-resistant material;
3. multiple shaft arrangements.

12.3.2 Single shaft configurations other than those listed above are to be surveyed every 3 years in accordance with TS Method 4.

12.3.3 For shafts subject to five-yearly surveys with keyless connections, at the Surveyor’s discretion removal of the propeller and NDE of the shaft taper, as required by TS Method 4, need only be carried out every 15 years, subject to a satisfactory visual inspection of all accessible parts of the shafting system at the intervening surveys.

12.3.4 For surveys completed within 3 months before the Shaft Survey due date, the next survey period will start from the Shaft Survey due date.

12.3.5 At the discretion of the Classification Committee, consideration may be given to accept special arrangements to monitor the condition of the screwshaft, bearings, sealing devices and the stern tube lubricant system so as to allow an extension to the interval between withdrawals of the screwshaft required by TS Method 4. This is subject to the shaft being provided with approved adequate means of protection against corrosion or being fabricated from corrosion-resistant material.

12.3.6  See Summary of Survey Intervals and Extensions for open systems in Table 3.12.2 Summary of Survey Intervals and Extensions - open systems.

12.4.1 Consideration can be given at the discretion of the Classification Committee to extend the intervals between surveys. This will be based on:

1. a satisfactory diver’s/ROV external examination of the shaft bearing and outboard seal area including weardown check as far as is possible;
2. internal examination of the shaft area (inboard seals) in propulsion room(s);
3. confirmation of satisfactory lubricating oil records (oil loss rate, contamination);
4. shaft seal elements are examined/replaced in accordance with seal’s manufacturer’s recommendations;
5. low running hours.

12.4.2 If the extension survey is carried out within one month of the shaft survey due date then the extension will take effect from the Shaft Survey due date.

12.4.3 If the extension survey is carried out more than one month prior to the Shaft Survey due date, then the period of extension will take effect from the date on which the extension survey was completed.

12.5.1 For the survey methods see Table 3.12.3 Shaft Survey Methods

12.6.1 Directional propeller and podded propulsion units for main propulsion purposes, inclusive of the propellers, shafts, gearing, control gear and the primary electrical components including any control and protection devices, are to be surveyed at intervals not exceeding five years. They are to be dismantled if considered necessary, and generally examined as far as practicable. Non-destructive examination on blade/fin roots is to be carried out as considered necessary by the Surveyor. Consideration may be given to condition monitoring schemes for determining the condition of the unit.

12.6.2 Podded propulsion unit screwshaft roller bearings are to be renewed when the calculated life at the maximum continuous rating no longer exceeds the survey interval, see the Rules and Regulations for the Classification of Ships, July 2022 Pt 5, Ch 9, 5.3 Propulsion shafting 5.3.7.

12.6.3 Dynamic positioning and/or thruster-assisted mooring and athwartship thrust propellers and shaftings are to be surveyed at intervals not exceeding 5 years. They are to be generally examined so far as possible in dry dock and tested under working conditions afloat for satisfactory operation. All accessible parts, including sealing, locking and bearing faces, and any other moving parts are to be examined. Non-destructive examination is to be carried out as considered necessary by the Surveyor on blade/fin roots. Consideration may be given to condition monitoring schemes for determining the condition of the unit.

12.6.4 Water jet units for main propulsion purposes, including the impeller, casing, shaft, shaft seal, shaft bearing, inlet and outlet channels, steering nozzle, reversing arrangements, and control gear are to be surveyed at intervals not exceeding 5 years, provided the impeller shafts are made of approved corrosion-resistant material or have approved equivalent arrangements. They are to be generally examined so far as practicable.

12.6.5 Stationary supporting structure and any erosion protection inserts or doublers are to be examined in way of any propulsion devices.

12.7.1 The Classification Committee will be prepared to give consideration to the circumstances of any special case upon application by the Owner, where the level of safety achieved is equivalent to that obtained by the survey methods described in this Section.