Oil tanker operations
Oil Tanker operation : Procedure and basic guidance
Tankers are specialized vessels that include crude oil, product, chemical,
LNG, and other tanker types. Tankers spend considerable time in ballast
given the typical one -way nature of the underlying trades. Tankers are
selfdischarging and most are equipped with a series of pumps that allow
for a fast turnaround in port.
When carrying certain oil types, many tankers will be asked to heat the
cargo (using the ship’s heating coils) to reduce the cargo’s viscosity.
World trade relies on tankers. There are different categories of oil tankers
—a crude tanker is used for transporting bulk volume of unrefined crude
oil from the oil extraction facilities to the refineries. The movement and
storage of crude oil in large volume requires the largest sized tankers.
Those in the tanker industry are familiar with methods for describing the
vessels. For example: Very Large Crude Carriers (VLCC) – which range
between 150,000 – 320,000 deadweight tons. Large crude oil tankers can
carry in excess of 2,000,000 barrels of oil and even a vessel of 120,000
deadweight tons may be considered a modest size tank vessel today.
Suezmax and Aframax tankers – which range between 75,000 - 150,000
deadweight tons. Their smaller size allows for greater flexibility in the
ports called.
tanker deck area
Product tankers – the larger ones being around 60,000 – 90,000
deadweight tons while the smaller so called “handy” sized vessels load
between 20,000 and 50,000 tons. Product tankers are used to carry
refined products from oil refineries to the markets/consumer facilities.
Specialized parcel tankers with stainless steel tanks and segregated
pumping systems allow for the carriage of a variety of sensitive liquid
cargos while reducing the risk of commingling and contamination.
There are other tanker types. For example, a replenishment tanker is used
for refueling ships at sea and old nonoperational oil tankers may be used
as floating oil storage units.
The largest tankers are unable to berth in port and must load and
discharge at offshore platforms. Vessels can load at very fast rates and
can easily turnaround in port in less than a day. Tankers are also fitted
with special systems, not found on dry bulk ships, such as IGS (inert gas
systems) and COW (crude oil wash). Obviously, there are pronounced
environmental regulations that crew and shore side staff must be
concerned with.
The tanker market has historically been dominated by the oil majors
(Exxon, Shell, BP, etc.) as well as large state owned oil companies such as
Saudi Aramco, Pemex, and others. Like Amoco, many of these majors
owned large fleets of vessels (their proprietary fleet) which was
supplemented by chartering tankers owned by independent tanker
owners. In recent years the trend is for the oil companies to reduce their
proprietary fleets and rely more on vessels owned by independents.
So tankers and the tanker trades are special. However, a tanker is after all
a ship and tanker owners are routinely tasked with the same concerns
that their dry cargo counterparts must address, such as crewing,
maintenance, drydocking, insuring, chartering, etc. Nevertheless, the
special nature of tankers – as outlined above – present unique concerns.
External Links
1. The International Association of Independent Tanker Owners
(INTERTANKO) is a voice for independent tanker owners (non-oil
companies and non-state controlled tanker owners). Independent
tanker owners operate about 80% of the world's tanker fleet.
2. Stolt Nielsen, Ltd. and its related “Stolt” companies is one of the
largest tanker owners specializing in chemicals and other products.
They have offices in Connecticut and worldwide.
3. Fairfield Chemical Carriers has offices in Connecticut and controls a
large fleet of chemicals carriers.
4. Teekay is the largest operator of mid-sized tankers including
suezmax, aframax, and long range two (LR2) vessels.Teekay and its
related companies is probably the largest tanker owner in the world
and earns revenues in the billions annually. They have offices in the
USA and abroad.
5. AET has offices world wide including an office in Houston. They
operate a large fleet of crude oil tankers.
6. International Seaways, Inc. is engaged in the ownership and
operation of crude, product, and chemical tankers around the world
and has offices in Manhattan. is one of the largest tanker companies
worldwide providing energy transportation services for crude oil and
petroleum products in International Flag markets. International
Seaways owns and operates a fleet of 40 vessels, including 13
VLCCs, two Suezmaxes, five Aframaxes/LR2s, 13 Panamaxes/LR1s
and 5 MR Tankers.
Major oil companies such as Shell Oil, Exxon Mobil, and bp (among others)
own and operate large fleets of crude oil and product tankers.
Feature of Coastal tanker ASPERITY
(According to The Motor Ship June 1997)
The double-hulled coastal tanker ASPERITY was built by Singmarine
Dockyard and Engineering, Singapore. A major feature of the cargo tank
arrangement is the elimination of the centreline bulkhead to reduce
discharge time to halve the number of tanks to pump. In the result, the
ship has five cargo tanks of varying size, which allow small parcels of
differing product grades to be transported. Each cargo tank is equipped
with the Wärtsilä Svanehoej variable speed deepwell pump with a
capacity of 550 m3/h at 90m liquid column. Loher 174 kW explosion proof
motors are sited on the trunk top and drive the pumps using Cardan shaft.
Fig: Oil tanker at sea
All cargo lines and tank fittings are made of stainless steel. Cargo valves
are stainless steel high-performance butterfly valves. Cargo stripping and
tank washing valves are stainless steel ball valves. The cargo control
system comprises a loading computer, tankradar and temperatures
probes, ballast, bunker, fresh-water and draught gauging and an
independent hi-hi tank alarm system.
Two computer monitors with light pens control the five deepwell cargo
pumps, the slop pump and ballast pumps. Other details monitored are
cargo tank ullages and pressures, slop tank ullage and pressure, tank
temperatures. The control system has mimic diagrams and monitors the
control plan and two-valve segregation parameter. Dynamic colouring of
pipelines indicates flow and the opening of valves. Continous information
of tank levels is provided to the Kockumation loading computer for a
continuous update of tank status and ship stability.
A main engine develops 2000kW at 825 rev/min. It drives a 3.3m diameter
CP propeller at 160 rev/min through a gearbox. An arrangement of
clutches allows the shaft alternator to be used as the emergency
propulsion, providing a “get-you-home” speed of 9 knots. Length, oa:
88.76m, Length, bp: 82.20m, Breadth, moulded 16.50m, Depth, moulded:
7.65m, Draught: 5.60m, Displacement: 5490t, Lightweight: 1712t,
Deadweight: 3778dwt, Service speed: 12.5 knots, Cargo capacity:
4266m3.
Oil tanker more safety guideline: The operation of modern oil tankers
involve numerous complexities and careful consideration will need to be
made for various shipboard activities. Our site is a quick guide to finding
tanker vessel operation related information.
How to ensure safe working atmosphere onboard oil tankers
The basic procedure - Restriction of Smoking, other Burning activities and
Naked Lights
The basic procedure of ship to ship transfer
For dealing with Unforeseen Emergencies, such events can be contained
and their effects minimized by preparing the ship’s crew through a system
of drills
Pumproom inspection procedure for oil tanker
A pump room contains the largest concentration of cargo pipelines of any
space within the ship and leakage of a volatile product from any part of
this system could lead to the rapid generation of a flammable or toxic
atmosphere
How to ensure safe working area onboard oil tankers
Before work, the conditions of working area, such as the density of
inflammable gas and fire, shall be positively managed, and the work shall
be started after necessary safety of the work is confirmed
Tanker operation : Matters That Require Attention At Sea
Maintenance of Vent Line System, Cautions about Sparks from Funnel,
Avoidance of Thunder Storms, Ballasting and Cargo Oil Transfer
Operations
Tanker operation: Inert gas system
The oxygen content of the Inert Gas supplied to cargo tanks should be 5%
or less. However, it is to be noted that too less content of oxygen in the IG
would introduce other impurities into the cargo tanks
Safety preparation for oil tanker prior entering freezing area
The Master shall ensure that the appropriate measures have been taken
to prevent damage to Vessel, Machinery, Pipelines and Equipment prior
entry into areas with Freezing Conditions
Daily soundings of tanks and bilges
Bilge (Hold, Engine Room, Cofferdam, Void space, Chain Locker,
Emergency Fire Pump Room, Bow Thruster Room, etc.),Ballast Water
Tanks , Fresh Water Tanks
Oil pollution control
Equipment For Oil pollution Control, Equipment for Oil Pollution Mitigation,
Guidelines For Prevention Of Oil Pollution Mitigation, Action by Duty
Officer, Plugging Deck Scupper Plugs
Gas freeing procedure onboard oil tanker
It is generally recognized that Tank cleaning and Gas freeing is the most
hazardous period of tanker operations. This is true whether Washing for
clean ballast tanks, Gas freeing for entry, or Gas freeing for Hot work.
Oil handling procedure
Bunkering Operation, Measures during Extreme Weather, Restrictions on
Use of Fire, smoking, and other General Precautions to the Crew
General safety measures against oil pollution accident
Working system and preparation , Planning for Cargo Oil Operations ,Pre-
safety meeting , Effective Communication ,Promote techniques of Hazard
Prediction Training, Preparation of Watch Schedule & PIC of Oil Transfer
Operations, Have a complete meeting beforehand with terminal ,Cargo Oil
Transfer Check Lists ,Ship / Shore Safety Checklist ,Pre Arrival
Checks ,Check Operational Conditions and Training of Crew
Preparations For Oil Loading
Preparation of the Cargo Plan, Preparing of Ballast Pumps,Cargo Oil
Transfer Check Lists, Hose Connection,Display of warning notices and
signs, Cargo Oil Transfer Meetings with Terminal representative,Dry
Survey / OBQ survey,Lining up Pipelines and Valves,Precautions for
Loading Heated Cargo, Personnel arrangement
Tanker Standard Equipment Of Prevention Of Oil Spillage
Cargo Tank Level Measuring System and Level Alarm System, Emergency
Hydraulic Hand Pump, “Software”/Guidelines For Prevention Of Oil Spillage
,Operation Guidelines for Cargo / Ballast valves, Prevent Erroneous
Operation of Valves, Valve Handling with Avoiding Liquid Hammer,
Securing Indication for Closed Valves
Loading operation onboard oil tankers
Line up of the Vent lines, Safety Confirmations and Clearance,Leakage
Monitoring System ,Cargo Loading Rates , De-Ballasting of Segregated
Ballast, Preparation for Topping Off ,
Guidelines For Toxic Gases Hazards
HYDROCARBON VAPORS Characteristic ,Toxic Hazards of H.C. Vapors ,
HYDROGEN SULFIDE (H2S), H2S Gas Concentration, Precautions for
Hydrogen Sulfide (H2S), Health Concerns in connection with Benzene,
Health Concerns of Inert Gas, Oxygen-deficient atmosphere
Crude oil washing procedure
Supervision Of Crude Oil Washing (COW) Operations, Discharging Strategy
,Advance Notice In Port ,Safety Measures For Crude Oil Washing
Operations , Confirming Atmosphere in Tanks to be Crude Oil Washed,
Pressure Test
Standard Procedures for Tank Cleaning, Purging and Gas free Operation
Gas-Freeing for Cargo Tank entry ,Safety Precautions ,Non Flammable
Atmosphere , Atmosphere Control during Tank Cleaning
Operations ,Purging with Inert Gas (IG),Forced Air Ventilation
Matters that require attention while loading and discharging oil and ballast
water
Control Of Discharge Of Oily Mixture Originating From Cargo Oil From
Tankers & Restriction of carriage of oil and water ballast
Tanker vessel : Operations during laden voyage
Water And Cargo Oil Measurement, Vapor Control, Topping Up Operation,
Cargo Oil Heating, Line Pressure Test
General Precautions Confirming Working Area Onboard Oil Tanker
Confirming Working Area, Anti-Electrostatic Clothes and Shoes for Ship’s
crew, Permission of Hot Work ,Use of Explosion-proof Type Electric Torch
equipment, Use of Hand Tools, Prohibition of Carrying Unnecessary Tools,
Attention to Shock Sparks by Lighter Metals, handling of Aluminum
Products
Preparation for discharge onboard oil tankers
Preparation of the Cargo Plan, Cargo Equipment, Cargo Oil Transfer Check
Lists, Display of Warning Notices and Signs, Hose Connection, Cargo Oil
Transfer Meetings with Terminal representative, Ullage measurement and
Cargo Quantity Calculation, Lining up Pipelines and Valves
Oil Cargo Discharging Operations
Supply of I.G to cargo tanks being discharged, Line up of the IGS, Safety
Confirmations and Clearance, Deck Watch and Personnel Arrangement
Tanker operation : Personnel for Cargo Handling
Watch Schedule, Supervision Of Operations, Personnel Arrangement
During Cargo Operations
Measures For Handling Cargo Oil Having A Flash Point Exceeding 60c
Ensure that sufficient reliable evidence available that the flash point of the
cargo oil is above 61° C and the temperature of the cargo oil does not
exceed 5° C less than the flash point.
Tanker operation : Disposal for Spilled Oil and Prevention for Secondary
Disaster
Tanker Standard Equipment For Disposal Of Spilled Oil & Secondary
Disaster Prevention Slop Dump (Surface) Valve Arrangement (Emergency
drains)
Tanker operation : Inspection Of Cargo Work Equipment And Machinery
The Chief Engineer and Chief Officer shall jointly be responsible for the
inspection and maintenance of the cargo oil transfer equipment and
machinery before entering port
Tanker operation : Measures For Pump room entry
Entry Permit into Enclosed Space ,Atmosphere Control, Effective
communication ,Gas Monitoring , Maintenance Work in Pump Room
