Skip to main content

Stern tube leakage

Causes
  • Misalignment of bushes 
  • Poor material, design of liner and seals
  • Contaminated oil supply with foreign materials
  • Fishing net, rope and similar material entering into seal due to defective rope guard.
  • Electro static pitting on shaft due to defective shaft earthing device.
  • Prolonged low speed operation, in which hydrodynamic oil film could not attain.
Remedies
  • Keep good alignment of bushes. 
  • Use good material and an improved seal design.
  • Always maintain L.O level due to draught condition. 
  • Keep sufficient aft peak tank water level.
  • Use good design of rope guard. 
  • Keep earthing device in good order.
Action to be taken at sea to continue the voyage
  • When stern tube seal leaks at sea, minimized as possible. To continue the voyage, following actions are to be taken.
  • Correct the vessel trim, as possible as minimum astern, to certain allowable trim
  • Use more viscous oil (e.g. Cylinder oil)
  • Use lower header tank. If not possible, reduce the oil pressure-head by using a 'temporary header tank with flexible hose to obtain only slight pressure head above SW pressure.
  • If required, reduce rpm to avoid boundary lubrication.
Repair in port
  • Repairs or renewal of aft seal done either in dock or afloat.
  • If vessel is due for dry docking survey or a dry dock facility is available, arrange to enter dry dock and renew both seals.
  • If dry dock facility is not available, renewal of shaft seals done by Bonding method in port without removing propeller and tail shaft.
  • Necessary vessel trim by ahead until propeller shaft exposed to correct position above water level and to set up "scaffolding.
  • Renewal of sealing ring done by cutting and joining it on shaft with special tool and high temperature bonding method.
Insurance Claim
  • When leakage occurs, inform to head office or owner through captain.
  • When arrive in port, invite Class Survey and Underwriter Surveyor.
  • Survey damage and by their recommendation, repair to be carried out as per Class requirement.
  • Quotation of repairs and repair cost submitted to Underwriter Surveyor to negotiate for any reduction appear necessary.
  • Both surveyors will survey the repaired work when completed.
  • For insurance claim purpose, repair cost and bills endorsed by Underwriter Surveyor, but exclude transportation charges.
For insurance claim purpose the following items are necessary,
  • Damage report
  • log abstracts
  • Damage report form for insurance claim
  • Class Surveyor recommendation 
  • Repair bills endorsed by Underwriter Surveyor

Labels:

Comments

Post a Comment

If you have any doubts.Please let me know

Popular posts from this blog

Differences between MC/MC-C and ME/ME-C engines

The electrohydraulic control mechanisms of the ME engine replace the following components of the conventional MC engine: Chain drive for camshaft Camshaft with fuel cams, exhaust cams and indicator cams Fuel pump actuating gear, including roller guides and reversing mechanism Conventional fuel pressure booster and VIT system Exhaust valve actuating gear and roller guides Engine driven starting air distributor Electronic governor with actuator Regulating shaft Engine side control console Mechanical cylinder lubricators. The Engine Control System of the ME engine comprises: Control units Hydraulic power supply unit Hydraulic cylinder units, including: Electronically controlled fuel injection, and Electronically controlled exhaust valve activation Electronically controlled starting air valves Electronically controlled auxiliary blowers Integrated electronic governor functions Tacho system Electronically controlled Alpha lubricators
9 comments
Read more

Main engine interlocks

Interlocks are provided so that the engine can be started or reversed only when certain conditions have been fulfilled. When there is a remote control of engines, it is essential to have interlocks. This reduces the possibility of engine damage and any hazards to the operating personnel. Turning gear Interlock . This device prevents the engine from being started if the Turning gear is engaged. Running Direction Interlock . This prevents the fuel from being supplied if the running direction of the engine does not match the Telegraph. Starting Air Distributor in end position . This prevents starting from taking place if the shifting of the Distributor has not been completed. Main Lube. oil pressure, Piston cooling pressure, Jacket water pressure, and important parameters must be above the required minimum. Auxiliary Blower Interlock . The Auxiliary Blower is provided in case of Constant pressure turbo charging. Air Spring pressure Interlock . In case of the present generation
7 comments
Read more

Why is a man hole door elliptical in shape?

Any opening in a pressure vessel is kept to a minimum and for a man entry an elliptical hole  is lesser in size than the corresponding circular hole. More over it is prime concern to have a  smoothed generous radius at the corners to eliminate stress concentration. Hence other  geometrical shapes like rectangle and square are ruled out.  To compensate for the loss of material in the shell due to opening, a doubler ring has to be  provided around the opening. The thickness of the ring depends on the axis length along the  dirrection in which the stresses are maximum and the thickness of the shell. It is important to  align the minor axis along the length of the vessel, as the stress in this direction is  maximum. Longitudinal stress: Pd/2t where P= pressure inside the vessel, d= diameter of the arc, t=  thickness of the shell plating  Circumferential stress: Pd/4t  More over a considerable material and weight saving is achieved as minor is along the  direction of maximum stress.
20 comments
Read more