On completing this chapter you will have an understanding of how the next voyage
order decides the tanker operations in the ballast voyage my cargo tank
inspections are required routinely in ballast voyages why crude oil washing
machines need to be tested for functionality regularly why ballast
voyages are suitable for the most critical tanker operations in terms of
safety of personnel the function of the ODM ii and why it is to be constantly
switched on whether being used or not how does the next voyage order decide a
crude oil tankers operational activity as soon as she is free of cargo the
voyage order is normally received from the owner or charterer as soon as
possible after she is free of her previous cargo
in any event the vessels next destination port by the for loading or
for awaiting orders has to be instructed to the master in all cases it is
received prior to arriving at the next loading port in order to ensure a
sufficient quantity of Bunker oil for the laden voyage if the discharge port
is not known prior to departure from the loading port the consequence may be
extra quantity of Bunker oil in stock which may reduce the cargo intake or the
vessel may have to call at a port for bunkers during the voyage depending on
the duration of the voyage to the loading port maintenance and ballast
change activities can be undertaken
you
why our target tanks required internally imbalanced voyages reduced
thickness of high-tensile steel in modern double hull tankers can cause
corrosion holes or pitting and oil leaks into ballast tanks and from there
overboard also to be considered our metal fatigue and stress that threaten
the integrity of the whole structure
classification societies such as Lloyd's or DMV certify that ships are in class
for insurance companies who otherwise will not let the owners buy insurance
policies from them for the hull and machinery depending on the treatment and
trade the frequency of cargo tank inspection is therefore an agreement
between the shipping company and the classification Society
how often a car required the company's PMS which is
approved by the class defined the frequency of cargo tank inspections for
some companies the policy is to have all cargo tanks inspectors within the 24
months period for oil tankers inspection of cargo tanks should be made at
intervals not exceeding 2.5 years ballast tanks are to be inspected
annually
you
after how many usages must each crew washing-machine be tested for correct
functioning as required by the pms for Marple and classification society
requirement the multiple regulations require fixed tank equipment like deck
mounted and submerged crude oil washing machines to be regularly inspected for
functionality and maintenance this function check shall be performed after
sixth usages of the machine but the interval of checks shall not exceed
twelve months
when does this testing require water washing of the tank even in new
double-hull tankers it is acceptable to verify the function of submerged tank
washing machines from outside the tank either by a rotation indicator or by
observing the impact sound when the machine is working the deck mounted
crude oil washing machines can easily be lifted out of the tank for inspection
and testing the new generation of double hull crude oil tankers have by design
achieved smooth and plain bulkheads in the cargo tanks the majority of
longitudinal webs and stiffness have been moved to the double hull side of
the longitudinal bulkheads thus reducing the number of protrusions and
constructions which made it difficult to clean the tank earlier in order to
achieve the cleaning coverage required by marco the new generation of crude oil
tankers will still have to fit submerged crude oil washing machines for instance
to cover under sides of stringer decks either in the fall or after part of the
tank and in the slot tanks where the function cannot be verified from outside
of the tank the tank must be water washed gas freed and the machines be
inspected from inside of the tank while they are working with water pressure
each occasion of testing of the crude oil washing machines must be recorded in
supplement to for the oil record book
for detailed information on inspect of crude oil washing machines see cbt
number zero five four
you
why is the ballast voyage suitable for the most critical operation in a crude
oil tanker in terms of safety of personnel the ballast voyage is normally
the most suitable time to carry out maintenance on the vessels cargo
equipment after a discharge with crude oil washing there will always be need
for repairs and overhaul of equipment used the vessels pls contains full
details on each individual instrument or piece of equipment like the
manufacturer's recommended maintenance schedule periodic overhaul history etc
difficult a tank needs to be water washed and gas freed in order to check
submerged crude oil washing machines and for internal tank inspection this will
involve both the pump man and bosun with deck crew gas freeing and entering a
cargo tank is the most critical operation on a crude oil tanker
you
what is the function of the oil discharge monitoring and control system
in a balanced voyage the Oh DME is a system used on ballast voyages to ensure
that no oil is discharged into the sea when draining out water collected on
board during cargo tech washing the oily water is allowed to first settle in the
slop tank where the oil separates out above the clean water which is then
monitored carefully while being pumped into the sea
you
the Oh DME is a complicated instrument that consists of some four systems the
oil content meter that measures oil in the water stream by ppm the flow meter
measures flow rate of oily water through the discharge pipe
the monitoring and controlling computer that calculates oil discharge rate in
liters per nautical mile total quantity together with date and time
identification the freeway Overboard valve control system that enables to
stop the discharge when the permissible limit has been reached the latest models
of Oh DME has become very advanced and require little maintenance by the
vessels crew the maintenance is limited to changing the printer paper roll and
ink
why is the Oh DME required to be on at all times where the draining out
slots are not the oil content meter sensors and the flow meter are
permanently connected to the overboard discharge system piping and valves and
must continuously monitor that no illegal oily discharge has taken place
deliberately or inadvertently at any time from an oil tanker
the Oh DME shall at all times be switched on and we're not in operating
mode it must be switched to standby motors as
it automatically carries out calibration and cleaning operation
you
the printer paper rolls must be still on board retention time three years all
service and maintenance work on the system is to be recorded in the oil
record book
for detailed information on DMV see CVT number zero five five