Answer
Reference :UR Z21 of IACS and ENGG Circ 1 of 2016 (same as URZ21) replaced 7 of 2013 There are two types of systems.
1.Open Loop System.
2.Closed Loop systems.
a)Water Lubricated.
b)Oil Lubricated System.
Note:In Oil Lubricated system water content max allowed as per IACS is 1%.
Every 6months shore lab analysis is required for both oil lubricated and fresh water systems.
Flanged Propeller : Method 1, 2 &3
Keyless Propeller : Method 1,2 & 3
Keyed Propeller : Method 1 & 2
Method 1: Extensive Procedure involving complete removal of the Propeller shaft.
No records required.
No T MON notation required Propeller taken off the taper.
Shaft withdrawn completely.
NDT (MPI) of the forward 1/3rd of the taper.
Bearings surface condition & wear down clearances with poker gauge or by measurements before & after withdrawal.
Shaft complete examination
Integrity of the inboard & Outboard seals. Especially after reinstallation.
Verification that prop free from damages. Static & dynamic balancing.
Method 2 : Less extensive than method 1
No TS withdrawal. TMO/TCM notation required.
Verification of service records.
Verification of testing records.
Verification that no repair has been carried out.
Only prop taken off the taper
NDE of forward 1/3rd
Bearing wear down measurements taken by poker gauge.
Visual inspection of all the accessible parts as much as possible.
liner condition to be checked by surveyors hammer. Checking of the condition of the packing between the liner and the tailshaft.
Propeller checked free of damages. If required carry out balancing.
Outboard seal liner may need to change position in case of leaking seal.
Seal integrity to be verified.
Verification after reinstallation of the Propeller.
Method 3 : Least extensive
T MON notation required.
No withdrawal of shaft or removal of Propeller.
Verification of service records.
Verification of testing records. Water content limit 1% as per IACS URZ36. Oil sample examination. Bearing weardown readings by poker gauge.
Visual examination of all accessible parts as far as possible.
Verification that no damage on the Propeller (including tip).
Verification that no repair work on TS or Propeller.
IMPORTANT REQUIREMNTS :
The maximum interval between 2 surveys carried out by method 1 or method 2 should not exceed 15 years. Every 15 years, atleast the Propeller has to be taken off the taper once.
In between, we can use method 2 or 3 if all is well.
TS may not be withdrawn for the entire life of vessel.
But a surveyor can insist on method 1 or 2 incase there has been some damage.
Bolts used in the tailshaft are :
High Tensile, Corrosion resistant special marine grade bolts with additional treatments to enhance their strength and the resistance to the marine environment.
Purpose of fitted bolts- Torque transmission.
Q.In case of keyless Propeller what will you check on Propeller part?
Note: Method 2 ,3 applicable only if no service or maintenance was carried out on tailshaft or Propeller.
Flanged Propeller | Keyless Propeller | Keyed Propeller | |
Every 5 yrs | Method 1,2 or 3 | Method 1,2 or 3 | Method 1or 2 |
Extension 2.5 yrs | yes | yes | yes |
Extension 1 yr | yes | yes | yes |
Extension 3 months | yes | yes | yes |
-For extension of surveys vessel should be on EDD scheme and have IWS notation also written confirmation from C/E that shafting system is in good condition.
Method 4
*For open loop FW lubricated system Follow method 1 & integrity of forward seals to be checked.
As per Engg Circular of No.7 of 2013.
There are three types of survey,
1.Normal survey-
Tail shaft is removed along with Propeller .
2.Modified Survey-
Partial withdrawal of shaft to check the aft bearing condition & examination of forward bearing as far as practible. For keyed Propeller NDE for keyless Propeller visual examination & seal integrity check.
T MON File required.
In modified survey every 10yrs have to do complete withdrawal of tail shaft.
3.Partial survey
Extension of 2.5 yrs is given. Propeller backed off from shaft and in keyed Propeller and top half of cone examined.
Propeller Checks tailshaft survey
1.Propeller is free of damages especially tip area.
2.Trueness of both leading edge & trailing edge.
3.Signs of any crack or corrosion and pitting marks.
4.Crack detection of boss.