Section
17 Screwshafts, tube shafts and propellers
17.1 Definitions
17.1.1 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:
- continuous metallic, corrosion-resistant liners (Pt 5, Ch 6, 3.9 Bronze or gunmetal liners on shafts),
- continuous cladding,
- multiple layer synthetic coating,
- multiple layers of fiberglass,
- combinations of above mentioned,
- rubber/elastomer covering coating.
The means for protection against corrosion are to be installed/applied according to
LR approved procedures.
17.1.2 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. Fresh Water sample tests are to be carried out at regular
intervals not exceeding six months. The samples are be taken under service
conditions and are to be representative of the water circulating within the
sterntube. The Fresh Water sample test shall include measurement of chloride and
sodium content, pH value and the presence of particles from both metallic and
synthetic materials. Analysis results are to be retained on board.
17.1.3 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.
17.1.4 Oil sample examination. An oil sample examination is a visual
examination of the sterntube lubricating oil taken in the presence of a Surveyor,
with a focus on water contamination.
17.1.5 Service records. Service records are regularly recorded data showing
in-service conditions of the shaft(s) and are to include:
- For Oil Lubricated Stern Bearings: lubricating oil temperature, bearing
temperature and oil consumption records.
- For Closed Loop System Fresh Water Lubricated Bearings: water flow, water
temperature, salinity, pH, make-up water and water pressure (depending on
design).
17.1.6 Survey methods on closed systems. Oil Lubricated Shafts or Closed Loop System
Fresh Water Lubricated Shafts:
- TS Method 1 – Survey of screwshaft, tube shaft and propeller
in accordance with the requirements of TS Method 1, see
Table 3.17.3 Shaft survey methods.
Primarily the shaft is withdrawn and the propeller is removed.
- TS Method 2 – Survey of screwshaft, tube shaft and propeller
in accordance with the requirements of TS Method 2, see
Table 3.17.3 Shaft survey methods. Primarily records are
reviewed, the propeller is removed but the shaft is not withdrawn.
- TS Method 3 – Survey of screwshaft, tube shaft and propeller
in accordance with the requirements of TS Method 3, see
Table 3.17.3 Shaft survey methods. Primarily records are
reviewed, the shaft is not withdrawn and the propeller is not removed.
17.1.7 Survey Methods on Open Systems. Water Lubricated Shafts:
- TS Method 4 – Survey of screwshaft, tube shaft and propeller
in accordance with the requirements of TS Method 4, see
Table 3.17.3 Shaft survey methods. Primarily the shaft is
withdrawn and the propeller is removed.
17.1.8 Tube shaft is a shaft placed between the intermediate shaft and
propeller shaft, normally arranged within a sterntube or running in open water. It
may also be called a sterntube shaft.
17.2 Closed systems – Oil lubricated shafts or closed loop system fresh water lubricated shafts: Frequency of surveys
17.2.2 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 five years in accordance with TS Method 1, 2 or 3.
17.2.3 Shafts with a keyed propeller connection with a keyway that complies fully with the
present Rules are to be surveyed at intervals of five years in accordance with TS
Method 1 or 2; TS Method 3 is not permitted.
17.2.4 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 the
case when one extension for no more than three months is agreed.
17.2.5 For closed loop system fresh water lubricated shafts, the maximum
interval between two surveys carried out according to TS Method 1 shall not exceed
15 years, except in the case when one extension for no more than three months is
agreed.
17.2.7 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 onboard and audited by LR at the Annual Survey.
17.2.9 For oil lubricated arrangements, the descriptive note ShipRightSCM is
not a prerequisite in order to hold TS Method 2 and TS Method 3.
17.2.10 In order to assign and maintain the descriptive note
ShipRightSCM, the requirements of Pt 5, Ch 6, 4 Control and Monitoring 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.
17.2.11 For surveys completed within three months before the Shaft Survey due date, the next
period will start from the Shaft Survey due date.
17.3 Open systems – Water lubricated shafts:
Frequency of surveys
17.3.1 Survey in accordance with TS Method 4 at intervals of five years is applicable to any
of the following:
- Single shaft operating in fresh water only,
- Single shaft provided with approved adequate means of protection
against corrosion or fabricated from corrosion-resistant material,
- Multiple shaft arrangements.
17.3.2 Single shaft configurations other than listed above are to be surveyed every three
years in accordance with TS Method 4.
17.3.3 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.
17.3.4 For surveys completed within three months before the Shaft Survey due date, the next
survey period will start from the Shaft Survey due date.
17.3.5 For shafts with a keyless propeller connection or a flanged propeller connection
(including controllable pitch propellers for main propulsion purposes), and when the
descriptive note ShipRightSCM is assigned to an open loop water lubricated
shaft, a TS Method 4 survey may be replaced by a TS Method 2 or TS Method 3 survey.
Notwithstanding this, the maximum interval between two surveys carried out according
to TS Method 2 or TS Method 4 shall not exceed 15 years, except in the case when one
extension for no more than three months is agreed.
17.3.6 For shafts with a keyed propeller connection, and when the descriptive note
ShipRightSCM is assigned to an open loop water lubricated shaft, a TS
Method 4 survey may be replaced by a TS Method 2 survey.
17.3.7 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 sterntube 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.
17.4 Survey extensions
17.4.1 For all types of propeller connections, consideration can be given at the discretion
of the Classification Committee to an extension of the interval between two
consecutive surveys after the execution of an extension survey as follows:
- Extension up to a maximum of two and a half years: Only permitted for closed
systems. No more than one extension can be considered. No further extension, of
other type, can be considered.
- Extension up to a maximum of one year: Two consecutive ‘one year extensions’ can
be considered. Where an additional extension is agreed the requirements of the
‘two and a half year extension’ are to be carried out and the Shaft Survey due
date, prior to the previous extension(s), is extended for a maximum of two and a
half years.
- Extension up to a maximum of three months: One ‘three month extension’ can be
considered. In the event an additional extension is agreed the requirements of
the “one year extension” or ‘two and a half years extension’ are to be carried
out and the Shaft Survey due date, prior to the previous extension, is extended
for a maximum of one year or two and a half years.
17.4.2 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.
17.4.3 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.
Table 3.17.1 Summary of survey intervals and extensions – Closed systems
Oil Lubricated
|
|
Flanged Propeller Coupling
|
Keyless Propeller Coupling
|
Keyed Propeller Coupling (see Note
b)
|
Every 5 years
(see Note a)
|
TS Method 1 or
|
TS Method 1 or
|
TS Method 1 or
|
|
TS Method 2 or
|
TS Method 2 or
|
TS Method 2
|
|
TS Method 3
|
TS Method 3 (see Note c)
|
|
Extension 2,5
years
|
Yes (see Note d)
|
Yes (see Note d)
|
Yes (see Note d)
|
Extension 1
year
|
Yes (see Note e)
|
Yes (see Note e)
|
Yes (see Note e)
|
Extension 3
months
|
Yes (see Note f)
|
Yes (see Note f)
|
Yes (see Note f)
|
|
Closed Loop
System Fresh Water Lubricated
|
|
Flanged
Propeller Coupling
|
Keyless Propeller Coupling
|
Keyed Propeller Coupling (see Note
b)
|
Every 5 years (see Note a)
|
TS Method 1 (see Note g) or
|
TS Method 1 (see Note
g) or
|
TS Method 1 (see Note g)
or
|
|
TS Method 2 (see Note g) or
|
TS Method 2 (see Note g)
or
|
TS Method 2 (see Note g)
|
|
TS Method 3
|
TS Method 3
|
|
Extension 2,5 years
|
Yes
(see Note d)
|
Yes (see Note d)
|
Yes (see Note d)
|
Extension 1 year
|
Yes
(see Note e)
|
Yes (see Note e)
|
Yes (see Note e)
|
Extension 3 months
|
Yes (see Note f)
|
Yes (see Note f)
|
Yes (see Note f)
|
|
General notes:
|
For surveys
(TS Method 1, or TS Method 2, or TS Method 3) completed within 3
months before the Shaft Survey due date, the next period will start
from the shaft survey due date.
|
If the
extension survey is carried out within 1 month of the shaft survey
due date then the extension will take effect from the shaft survey
due date. If the extension survey is carried out more than 1 month
prior to the shaft survey due date, then the period of extension
counts from the date when the extension survey was completed.
|
Notes:
Note a.
Unless an Extension (Extension 2,5 years, Extension one year,
Extension three months) is applied in between.
Note b. TS Method 3
not allowed.
Note c. The maximum
interval between two surveys carried out according to TS Method
1 or TS Method 2 shall not exceed 15 years, except in the case
when one extension for no more than 3 months is agreed.
Note d.
No more than one extension can be considered. No further
extension of other type can be considered.
Note e. Two
consecutive extensions can be considered. Where an additional
extension is agreed the requirements of the ‘2,5 year extension’
are to be carried out and the shaft survey due date, prior to
the previous extension(s), is extended for a maximum of 2,5
years.
Note f. Extension up
to a maximum of 3 months: One “3 month extension” can be
considered. In the event an additional extension is agreed the
requirements of the ‘one year extension’ or ‘2,5 years
extension’ are to be carried out and the shaft survey due date,
prior to the previous extension, is extended for a maximum of
one year or 2,5 years.
Note g. The maximum
interval between two surveys carried out according to TS Method
1 (or TS Method 2 for arrangements where ShipRightSCM was
assigned) shall not be more than 15 years, except in the case
when one extension for no more than 3 months is
agreed.
|
Table 3.17.2 Summary of survey intervals and extensions – Open systems
- Single shaft operating exclusively in fresh water.
- Single shaft provided with adequate means of corrosion
protection, single corrosion-resistant shaft.
- All kinds of multiple shaft arrangements.
|
Other shaft
configuration.
|
|
All kinds of propeller coupling (see
Note d)
|
|
All kinds of propeller coupling (see
Note d)
|
Every 5 years (see Note a)
|
TS Method 4 (see Note
e)
|
Every 3 years (see Note a)
|
TS Method 4
|
Extension 1 year
|
Yes (see Note b)
|
Extension 1 year
|
Yes (see Note
b)
|
Extension 3 months
|
Yes (see Note
c)
|
Extension 3 months
|
Yes (see Note c)
|
General notes:
|
For surveys
(TS Method 4) completed within 3 months before the shaft survey due
date, the next period will start from the shaft survey due date.
|
If the
extension survey is carried out within 1 month of the shaft survey
due date then the extension will take effect from the shaft survey
due date. If the extension survey is carried out more than 1 month
prior to the shaft survey due date, then the period of extension
counts from the date when the extension survey was completed.
|
Notes:
Note a.
Unless an extension (Extension 1 year, Extension 3 months) is
applied in between.
Note b. No more than
one extension can be considered. No further extension, of other
type, can be considered.
Note c. One extension
can be considered. In the event an additional extension is
agreed the requirements of the 1 year extension are to be
carried out and the shaft survey due date prior to the previous
extension is extended for a maximum of 1 year.
Note d. For keyless
propeller connections the maximum interval between two
consecutive dismantling and verifications of the shaft cone by
means of non-destructive examination (NDE) shall not exceed 15
years.
Note e. Unless
descriptive note ShipRightSCM is assigned.
|
17.5 Shaft survey methods
17.5.1 For the survey methods see
Table 3.17.3 Shaft survey methods
below.
Table 3.17.3 Shaft survey methods
|
TS METHOD 1
|
TS METHOD 2
|
TS METHOD 3
|
TS METHOD 4
|
GENERAL
|
|
|
|
|
Drawing the shaft and examining the entire
shaft (including liners, corrosion protection system and stress
reducing features, where provided), sealing system and
bearings
|
X
|
|
|
X
|
SHAFT
|
|
|
|
|
Visual examination of all accessible parts
of the shafting system in situ
|
|
X
|
X
|
|
For keyed and keyless propeller
connections, removing the propeller to expose the forward end of the
taper
|
X
|
X
|
|
X
|
For keyed and keyless propeller
connections, perform a non-destructive examination (NDE) by an
approved surface crack-detection method around the after end of the
cylindrical part of the shaft and the forward one-third of the shaft
cone, including the keyway with the key removed (if fitted); for
shafts provided with liners the NDE shall be extended to the after
edge of the liner
|
X
|
X
|
|
X
|
For flanged connections, whenever the
coupling bolts of any type of flange-connected shaft are removed or
the flange radius is made accessible in connection with overhaul,
repairs or when deemed necessary by the Surveyor, the coupling bolts
and flange radius are to be examined by means of an approved surface
crack detection method
|
X
|
X
|
X
|
X
|
Visual examination of all accessible parts
of the shafting system following re-installation of the
shaft
|
X
|
|
|
X
|
PROPELLER
|
|
|
|
|
Visual examination of the
propeller. Examination of the edges and roots of the propeller’s
blades by an approved surface crack detection method, if deemed
necessary by the Surveyor
|
X
|
X
|
X
|
X
|
Controllable pitch propellers, where
fitted, are to be opened up and the working parts examined, together
with the control gear. Propeller to be examined upon
reassembly
|
X
|
X
|
|
X
|
Operational test of pitch
functionality to its full range, including visual confirmation of no
leakage in the CPP seals
|
X
|
X
|
X
|
X
|
Examination of the propeller following
re-installation
|
X
|
X
|
|
X
|
BEARING CLEARANCES
|
|
|
|
|
Checking, recording and verification of
bearing clearances
|
X
|
|
|
X
|
Recording the bearing weardown measurements
after re-installation, if applicable
|
X
|
|
|
|
Checking and recording the bearing weardown
measurements
|
|
X
|
X
|
|
SEALING SYSTEM
|
|
|
|
|
Examine the inboard and outboard seals with
shaft removed and following the re-installation of the shaft and
propeller
|
X
|
|
|
X
|
Examine the inboard and outboard
seals
|
|
X
|
X
|
|
Examination of seal liner
|
|
X
|
X
|
|
OTHERS
|
|
|
|
|
Stationary supporting structure and any
erosion protection inserts or doublers are to be examined in way of
any propulsion devices
|
X
|
X
|
X
|
X
|
Verification of no unapproved repairs by
grinding or welding of shaft and/or propeller
|
X
|
X
|
X
|
X
|
SERVICE RECORDS
|
|
|
|
|
Review of service records
|
|
X
|
X
|
|
Review of test records of Lubricating Oil
Analysis (for oil lubricated shafts), or Fresh Water Sample Test
(for closed system fresh water lubricated shafts)
|
|
X
|
X
|
|
Oil Sample Examination (for oil lubricated
shafts), or Fresh Water Sample Test (for closed system fresh water
lubricated).
|
|
X
|
X
|
|
17.6 Other systems
17.6.1 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 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.
17.6.2 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
Pt 5, Ch 9, 5.3 Propulsion shafting 5.3.7.
17.6.3 Dynamic positioning and/or thruster-assisted mooring and athwartship thrust
propellers and shaftings are to be surveyed at intervals not exceeding five 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.
17.6.4 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 five
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.
17.6.5 Stationary supporting structure and any erosion protection inserts or doublers are to
be examined in way of any propulsion devices.
17.7 Alternative arrangements
17.7.1 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.
|