Seam 4 Lecture topic

1. “COMMON DAMAGE/ DEFECTS
THAT MAY OCCUR ON
WATERTIGHT TRANSVERSE
BULKHEADS SITUATED AT THE
ENDS OF DRY CARGO HOLDS OF
A BULK CARRIER"
PRESENTED BY: CAIPANG, HANNA MARE P.
BSMT 2-ANTARES

2. Fractures
The following are examples of the more common
damage/defects that may occur:
Corrosion
Buckling

3. Fractures at the boundaries of
corrugations and bulkhead stools,
particularly in way of shelf plates,
shedder plates, deck, inner bottom, etc..
1.

4. 2. Buckling of the plating/corrugations,
leading to the failure and collapse of the
bulkhead under water pressure in an
emergency situation.

5. 3. Excessive wastage/corrosion, in particular
at the mid-height and bottom of bulkheads,
which may look in deceptively good condition.
This is created by the corrosive effect of
cargo and environment, in particular when the
structure is not coated. In this respect
special attention should be given to the
following areas:

6. Bulkhead plating adjacent to the shell plating;
Bulkhead trunks which form part of the venting, filling
and discharging arrangements between the topside tanks
and the hopper tanks;
Bulkhead plating and weld connections to the lower/upper
stool shelf plates;
Weld connections of stool plating to the lower/upper
stool shelf plates and inner bottom;
In way of weld connections to topside tanks and hopper
tanks;
Any areas where coatings have broken down and there is
evidence of corrosion or wastage. It is recommended that
random thickness determination be taken to establish the
level of diminution; and
Other structures, e.g., diaphragms inside the stools,
particularly at their upper and lower weld connections.

7. Side Shell Plating
Connection of Bulkhead plating to side shell.
Connection of side shell frame & end brackets to the shell plating and hopper side
tank plating by close-up inspection.
Connection of side shell frame & end brackets to the shell plating and topside tank
plating.
Fracturing of the Structural members of a transverse bulkhead of a Bulk carrier are:
1.
2.
3.
4.
Actions you would take as a Chief
Officer to avoid the detrimental
effects on bulk carriers due to
corrosion, fatigue and improper
cargo handling:

8. Routing Cargo Hold & Hatch Cover Structural Members Inspection & Planned
Maintenance.
Identifying the areas that are vulnerable to stress and fatigue
Make sure the survey area is easily accessible, keeping in mind that it
needs to be spotless and well-lit.
There is a careful planning of the surveys to be conducted with
participation from all staff.
When a ship's primary hull structure on one side develops a fracture that
was not brought on by contact damage, the comparable structure on the
other side should be investigated to see if a similar fatigue has taken
place. Such fractures are concerning, particularly when corrosion is
linked to failure and may have been a contributory factor.
Actions to control
structural stresses and
fatigue:

9. Routine Inspections.
Planning Surveys
Surveys of known defects.
Classification surveys.
Annual surveys
Intermediate Surveys
Special surveys
Condition Surveys
CAP Surveys
Life extension surveys, etc.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Structural Surveys
include:

10. Fatigue cracking occurs at points such as hatch covers where stresses are locally
high.
Such cracking is the result of cumulative damage caused by cyclic loading of
structure & invariable starts at welded joints.
The fatigue life is the time required in service for the structure to experience
enough stress cycles for a crack to occur. A bulker is so designed that with
proper maintenance cracking should not occur until a fatigue life span of 20
years.
Fatigue life span once used up cannot be regained except by complete replacement
of welded joints.
Therefore, it is very essential that the welded joints of an overstressed
structure are replaced, before proceeding with life exterior surveys/ programmes.
Fatigue cracking have been most frequently observed in the bracket toes at the
connection of the main frames to the hopper and topside tanks and in the
boundaries of the vertically corrugated transverse bulkheads with upper stools,
lower stools and topside tanks.
Fatigue cracking of steel
structures:

11. The tank/hold coating is the main defense against structural deterioration
aboard ships, particularly in the extremely corrosive environment of water
ballast tanks and, to a somewhat lesser extent, cargo holds. Since the
implementation of ESP, all new ships' CH and water ballast tanks are
required to be completely covered. Such coatings ought to be durable and,
ideally, light in color.
An essential component of managing structural conditions is maintaining a
high grade of coating. The structure will be adequately protected if the
coatings are maintained, and the original scantlings will be available to
withstand "service loads" and "stresses."
Therefore, during routine inspections, sea employees should seriously
report the status of tank/hold coatings and for the same to be recorded in
the company PMS system.
Structural deterioration and
corrosion:

12. The best way to safeguard a bulk carrier's structure is
to keep coatings in good condition and perform repairs
as soon as they break down.
Installation of anodes is an efficient backup that will
stop rapid corrosion in the path of local coating
failure, provided the tank is routinely ballasted.
When doing coating repairs in the tanks, such as
freshwater washing, surface preparation, and coating
application, the most effective time to do so is during
a routine repair period of manageable duration.

13. Ships can be and are frequently damaged during discharging discharging over this especially if
the operation is carried out by grabs or payloaders making heavy contact with the ship’s
structure.
Local overloading, when bulk corners are loaded in ways not for seen by their classification
society or shown in their loading manual, resulting in cracking of deck plating at the hatch
covers & backing of plating between the hatchways.
A faulty distribution of weight can occur when:-
A ship jump loads to her tropical marks and corner less than full bunkers. In that situation
some or all of the strengthened holds are subjected to greater tonnage of cargo than they
were designed to carry.
Particular holds are loaded with greater tonnage then the tonnage for which the hold was
designed.
The vessel is block loaded – i.e., where two or more adjoining holds are heavily loaded with
adjacent holds empty. Although it is imperative that the longitudinal stresses are
negligible but still the vessel suffers structural damage of the cross deck structures which
separates adjacent cargo hatchways at the upper deck level.
Failure to Trim cargo reasonably:-
Cargoes with a low angle of repose are particularly liable to dry surface movement aboard
ship.
To overcome this problem the code states that such cargoes should be trimmed as reasonably
Damage to ship structure by improper
cargo handling:

14. Importance of assessing
defects and damage to cargo
spaces:
It is important that the protective coatings in cargo holds and water ballast tanks are maintained. Therefore, it
is imperative that the cargo holds and deck areas should be inspected by ship’s deck officers upon completion of
cargo operations to identify any signs of Physical Damage, corrosion or coating damage to the ship’s structure.
Where hull damage is identified, which may affect the integrity of the hull structure and sea-worthiness of the
ship, it should be reported accordingly to the classification society.
The internal hold structure and protective coatings in the cargo hold and adjacent double bottom spaces are
vulnerable to damage when the cargo is discharged by using grabs. Grabs are made from toughened steel material
and when carelessly used can cause considerable damage to the ship’s structure.
Chipping (sharp indentations) and the local buckling or detachment of side frames and end brackets at lower
connections could lead to cracking of the side shell plating which would allow the ingress of water into the
cargo spaces.
1.
2.
3.
4.

15. 5. The protective coating which may be required to be applied in the cargo hold are also subject to
deterioration caused by the corrosive nature of the cargo, high temperature cargoes, cargo settlement
during the voyage and abrasive action of the cargo.
6. Where no protective coating has been applied or the applied protective coatings have broken down, the
rate of corrosion in that area will greatly increase, especially when carrying corrosive cargoes such as
coal.
7. Corrosion will weaken the ship’s structure and may eventually seriously affect the ship’s structural
integrity. The severity of the corrosion caused by a structural member may not be easily detected, without
close-up inspection or until the corrosion causes serious structural problems such as the collapse or
detachment of hold frames, resulting in cracks propagating in the side shell.

16. It is therefore extremely important for a
close-up inspection of the cargo spaces,
after discharge operations when such
corrosive and high temperature cargoes are
being carried.
When the main grab discharge is ended, front end loaders (Pay Loaders)
are usually lowered into the hold to gather the cargo from the ends and
wings and pile it in the square of the hatch, to facilitate easy discharge by
the grab.

17. Also, trimmers men are employed to shovel up the
last of cargo from the position which front end
Payloader, cannot reach, i.e. all the
inaccessible places, elsewhere by the Payloader,
in order to assist in discharge of final
remaining cargo.
Standards of trimming vary considerably and ship’s officers are therefore encouraged to inspect the holds, thoroughly, whilst
the trimmers are working in the hold, in order to remove as much residual cargo as possible. Thereby, utilizing the maximum
efficiency and preparing hold for hold cleaning preparations.
The final inspection, after each cargo operation should include that no bilge gratings or manhole cover plates are missing
that the securing bolts have not been damaged, that all the sounding pipes, airpipes and ballast lines and their pipeguards
are intact, that no new indents can be seen in the plating of the tanktop, lower or upper hopper sides, or athwart ship
bulkheads, that the side frames are regular and undamaged with brackets undamaged and that the hold ladders platforms, rails
are complete and undamaged.
Any damage to the tank top plating, hopper sides, shell plating and framing, hatch coamings, hatch covers, bulkheads, stools
and upper deck plating, air and sounding pipes, which could affect the sea-worthiness of the vessel, should be directly
reported to the classification society.

18. Be safe always!
THE END
CAIPANG, Hanna Mare P.
DATE
SUBJECT SEAM4R Cargo Handling and
Stowage (Dangerous Goods and
Inspections)
September 21, 2022