3.16 STARTING CARGO
Starting up cargo is one of the most critical periods of any cargo
operation. Extraordinary vigilance and care both onshore and onboard
are mandatory. Special attention should be paid to pipeline pressures
and pressure venting systems. Frequent checks must be made to detect
any leakages to the sea, on deck, or into other tanks/spaces.
When the chief officer is satisfied that his vessel is ready to load
cargo, that all necessary personnel are available to start loading,
and that all required inspections have been completed and documented,
then the first manifold valve can be opened and he can advise the shore
terminal operator that he is ready to load cargo. This must be done
in a way which clearly indicates which manifold valve is open to receive
the first cargo. If all manifold valves are not open at the start, that
fact must be clearly indicated to the person in charge at the shore
A product tanker was moored at an oil terminal near Houston, preparing
to load heating oil. When all preparations were complete, the tanker's
cargo watch officer advised the berth supervisor that they were 'ready
to load'. However the manifold valves had not yet been opened. The dock
supervisor instructed the shore control room operator to start the heating
oil pump to the ship. Before the ship's crew could open their manifold
valve, the 20,000 bbl./hour pump was started. The loading arm could
not withstand the hydraulic surge of heating oil against the closed
valve. It failed catastrophically, showering the berth area with heating
oil. The operator of a push tug in the adjacent berth started his engines
to back clear of the spill. A source of ignition in the tugs engine
room ignited the oil vapours. The tug exploded and sank with its two
crew. The dock and port stern of the tanker were enveloped in flame.
Quick action by the ship's crew, helped by a favourable wind, soon contained
and extinguished the fire on deck. The refinery fire brigade extinguished
the dock fire.
The essential cause of this incident was a failure of ship-shore
communications. During the pre-loading conference, the communications
protocol to be used for all basic and emergency cargo communications
should be discussed. The shore superintendent must receive a clear indication
that the ship is ready to load and that the necessary manifold
valve is open. A suitable exchange would be as follows:
Ship to shore: "Berth three, this is the Neverspill.
We are ready to load fuel oil in our Starboard loading line."
Shore to ship: "Neverspill this is berth three, understand you
are ready to begin loading fuel oil on your starboard line. Is your
manifold valve open?"
Ship to shore: "Berth three, this is Neverspill, our fuel
oil manifold valve is open; you may start the pump."
Shore to ship: "Neverspill, this is berth three, we are
opening the shore tank and will advise you when we have started the
Ship to shore: "Berth three, this is Neverspill, Roger,
Shore to ship:(later): "Neverspill, this is berth three,
we have started the pump; please advise when you are receiving cargo."
Ship to shore: "Berth three, this is Neverspill, we are
receiving cargo at (time)."
This may seem like an unnecessary number of words for
such a simple operation, but considering the consequences of the incident
described above, a few extra words seems like a good investment! The
important point is that positive feedback, verification, and disciplined
communications procedures are essential to properly conducting the start
and all aspects of every cargo operation.
3.16.1 Starting samples
In 1982, a vessel loading two grades of gasoline, leaded and unleaded,
discovered upon completion of loading that there was substantial contamination
of the unleaded parcel by the leaded parcel. When the case reached the
Canadian courts, five years later it was essentially decided on statements
of probability by expert witnesses and by the presence of a single sample
drawn from the dock which showed the unleaded line was contaminated
In this case, a single sample, not even drawn by dock or ship's staff,
provided a precariously thin exhibit on which to base the ship's defence.
Thousands of dollars in legal and expert witness fees would have been
avoid if the cargo had been thoroughly sampled according to standard
procedures. While a product tanker may have paid scrupulous attention
to the preparation of its tanks and pipelines for the cargo, there is
no guarantee that the shore has done the same. A line displacement may
have been incorrectly calculated, or the wrong hose used. Either error
can contaminate a tank or parcel of cargo.
When each product grade is started, the cargo watch officer must have
a crew member standing by the sampling connection at the manifold, to
sample the first flow of oil into the ship. This sample should be suitably
labelled and retained along with the other cargo samples.
Refined products should be started on one tank only, until it is verified
that the correct product is being loaded. If the wrong product is received,
only one tank will have been contaminated and only one tank will require
cleaning before the correct grade can be loaded. Where no manifold sample
point is fitted, cargo should be loaded into one tank and a 'frame sample'
or bottom sample drawn and tested as soon as possible.
3.16.2 Loading rates and static generative cargoes
Cargo should be started slowly, by gravity flow from the shore whenever
possible. A crew member (the same one taking the starting sample), should
remain at the manifold connection, observing it for any leakages. When
cargo is seen to be entering the tanks by gravity, the shore operator
can be instructed to start the shore pumps. The manifold connection
must be under continuous observation until the full loading rate is
Ships on charter are required by their charter parties to load cargo,
whether single or multi grade, as fast as they can safely receive it.
It is up to the master to determine how fast the ship can safely load
a particular cargo at a facility. To make this decision, he must give
full consideration to the recommendations of the International safety
guide for oil tankers and terminals (ISGOTT), to the owner's instructions
and to any special circumstances.
Loading rates for non-static accumulator cargoes are limited by the
physical ability of the vessel's tank structure, vent and cargo piping
systems to withstand the loading pressures. The pressure in the pipelines
must not exceed the maximum permitted pressures
(normally 125 psi) and pressures in the tanks should not exceed 1400
mm (2 psig).
The vent line pressure should not exceed that indicated by the designer/builder
and must be closely monitored at terminals where loading rates are high.
(The builder's maximum vent pressure is based on rates for loading all
tanks simultaneously. Rates must be reduced accordingly for a smaller
number of tanks being loaded).
The final consideration in setting a maximum loading rate is the competence
of the cargo watch officers. Maximum possible loading rates should not
be used if the deck officers have recently been changed, lack experience,
or are unfamiliar with the vessel.
Acceptable maximum loading rates are normally rates which produce between
six and ten meters per second pipeline velocity.
Static accumulator oils are distillates (clean oils) with low conductivity
and a corresponding slow dissipation of any static electricity charge
acquired through handling. Kerosene and Kerosene based jet fuel (JP-1),
are two of the most significant static accumulator oils. Others are
indicated in the ISGOTT manual. Any distillate must be treated as a
static accumulator unless the product contains an antistatic additive.
Static accumulator oils must be loaded with procedures which minimise
static charge generation and accumulation. When a static accumulator
oil, such as natural gasoline or naphtha is loaded, the initial loading
rate must be a flow of less than one meter per second in the cargo pipelines.
For a vessel with 510 mm (24") loading branch lines, this flow
rate would be less than 676 cubic meters per hour. The initial slow
loading of static accumulator oils must continue until the bottom longitudinals
and the cargo tank oil inlet are covered and all splashing and surface
turbulence has stopped. Since the surface of the cargo in closed-loading
tanks cannot be observed, the chief officer will have to indicate in
the cargo orders the ullage which corresponds to the required slow filling
rate level. The cargo level must be measured by permanently installed
tank gauging equipment. Portable gauging equipment should not be introduced
into a tank while loading a static accumulator oil or for thirty minutes
after loading stops.
After the tank bottom is covered as required, the flow rate can be increased
to the maximum safe rate.
If an IGS system is fitted, tanks to receive static accumulator cargoes
should always be inerted prior to loading.
Loading rates must be checked regularly by ship's personnel to ensure
that the agreed loading rates are being maintained. Rates may increase
without warning, especially at terminals where the same grade of cargo
is being loaded to more than one vessel.
3.16.3 Bottom samples
Where the specifications of the cargo are critical and particularly
if there is any question regarding the suitability of the ship's preparations
to receive and carry the cargo, then loading should be stopped after
tank bottoms have been placed in each cargo tank. Tank bottom samples
('frame samples'), should be taken and sent ashore for quality analysis.
If the sample test results are acceptable, the ship may continue to
load. If the samples are 'off-test' but by a small margin, the ship
may resume loading with the expectation that the dilution of the bottoms
with a full cargo of 'on-test' product will produce a cargo which will
be uniformly 'on-test'. The master must be informed of any 'off-test'
bottom sample results and he must contact charterers to obtain their
advice. He must be a party to all discussions regarding the 'off-test'
cargo and should note his protest of the situation. If samples are significantly
'off-test', the terminal may reject the ship for further loading. Alternatively,
the master may refuse the cargo and should do so unless advised by charterer's
in writing to continue.
3.16.4 Tank flushing
Where cargo quality is critical, particularly with respect to water,
the use of flushing oil is often required. Use of flushing oil will
normally be indicated in the vessel's cargo orders. When the ship is
ready to load, about 50 cubic meters of flushing oil is loaded into
the designated tanks. The flush oil is then stripped ashore or to a
collection tank where it may be loaded on top. The collection tank is
measured to confirm that it has all been recovered. The ship is then
ready to load the critical cargo into the flushed tanks.
Where flushing oil is required for preparing cutback asphalt tanks for
loading, fuel oil is normally used. The recovered flush oil may be loaded
on top with fuel oil, or used as bunkers.