Crude Oil Tanker Basics - The Theory and Practice of Crude Oil Cargo Operations

The topics covered in this book range from the basics of crude oil chemistry to the economics of the oil market. Fundamentals of cargo operations, such as calculating cargo quantity, are explained in both theory and practice. This ensures that the basics of operating crude oil tankers and their related activities are not neglected; readers will be equipped with the required knowledge to perform operations fully and correctly.

The book is supported by photographs taken on board a new build VLCC.

This textbook covers everything from the basics of crude oil chemistry to the economics of the oil market. As I read the book, I was so impressed that I must provide some highlights of its contents, to illustrate why I believe this book to be the best on the market.

Loss control and cargo measurements, since they are often taken by shoreside metering and verified by independent inspectors, may be easily overlooked in day to day cargo operations. Nevertheless, modern measurement systems may fail or have errors. Ships might often be blamed for losses that result from these errors unless measurement theories are understood and put into practice. Volumes loaded, transported and discharged must be carefully measured and monitored by ships so that differences in volumes and contaminations can be identified, resolved and notices of protest appropriately issued. ‘Measurement of Cargo Quantity’ and ‘Calculating Cargo Quantity’ each spell out theories, recommended processes and commercial implications of good measurement techniques aboard ships, therefore ensuring sound cargo custody practices and saving loss claims against the ship.

‘Loading Rates and Venting’ explains the critical relationship between ship and shore. Priceless rules of thumb include ‘…a tank filling rate of 5 cm (2 inches) per minute is considered to be a reasonable loading rate for topping off …’. Implementing this can only be done if terminal staff are given long enough notice time to slow down shoreside pumping systems. Venting systems on tankers protect ships’ tanks from over pressurisation that can be generated at flow rates generated by high volume terminal pumps. Ships’ officers must understand tank vents, ensure that they are operating and properly set and monitor them as carefully as tank volumes. Explanations of different venting systems, vapor recovery apparatus and other details remind ships’ officers of the importance of this equipment.

Loading and discharging cargo are critical operations, during which an accident might compromise the safety of the crew, the ship or the environment. Well thought out plans, carefully reviewed and implemented, that contain standing instructions, specific instructions and emergency procedures go a long way to successful cargo operations. They also provide maximum flexibility to commercial operators, allowing changes to load or discharge sequences generated by unforeseen circumstances. Finally, requirements for adequate rest periods for officers and crews are not only mandated by STCW, but also make good practical sense and ensure safe operations.

First time cargo officers are often timid about raising loading rates during the early stages of loading and reducing loading rates to top off at the end of loading operations. ‘Old timers’ can become complacent and make assumptions. ‘The Loading Operation’ is full of guidelines and reminders of procedures and checks necessary during initial loading, full rate loading, topping off and completion to ensure a safe and successful outcome. Armed with such knowledge that aft loading tanks will fill faster when the vessel is trimmed by the stern and that, as a rule of thumb, the time taken for hydraulic valves to close is about the same as the diameter of the valve in millimetres (a 550 mm valve will take about 55 seconds to close) will enhance confidence. Easily accessed checklists and suggested procedures will remind cargo officers that successful cargo operations are a matter of good planning, well managed operations and good old common sense. Ample warnings built into this chapter will also remind experienced officers that complacency can lead to disaster.

Success often depends on a theoretical understanding blended with practical experience. Crude tanker pumping systems transfer large volumes quickly; tanker officers’ success with these systems will be enhanced through basic understanding of pump theory. ‘Cargo Discharge Operation’ becomes straightforward once the reader is armed with critical pump theories. The impact of discharge time on charter party performance can have a major impact on voyage profitability. Good records, well kept logbooks, carefully monitored, maintained and logged discharge pressure and well implemented plans that maximise bulk pumping time, while keeping low volume stripping to a minimum, will ensure that any demurrage claims are valid and give charterers little ammunition to refute them.

Inert gas systems are complicated, requiring attention to safety, monitoring, and carefully coordinated operation so that they protect the crew and the ship without endangering either. ‘Inert Gas’ shows how these systems operate with theoretical and practical illustrations and explanations.

Properly performed crude oil washing (COW) benefits both the ship and the cargo owners. Hazards include ignition, pollution and chemical reactions that can quickly end a life or a career. Clues and suggestions will help readers to use COW successfully and profitably.

Ballast water on tankers is considered so critical that MARPOL, SOLAS and Loadline Conventions all regulate it. The author shares his rich experience with personal insights to handle ballast water safely, in a pollution free manner and in various classes of crude oil tankers. For example, properly maintained and operated ODMEs, required under MARPOL, are complex instruments that may provide crucial evidence to exonerate (or implicate) a tanker with an oil pollution. ‘Ballasting, Deballasting and Oil Content Discharge Control’ is loaded with nuggets of information and suggestions, pointing out mandatory requirements for handling ballast water.

Cautious owners with well run tankers remain the core of the world’s tanker industry. Effectively maintained tankers ensure safe operations, good cargo custody, charter party compliance and satisfied charterers, therefore a profitable revenue stream to owners. None of these can be achieved unless the hazardous atmosphere in cargo tanks, pipelines and (potentially) ballast systems are cleaned for entry, repairs, inspections and preventative maintenance. Tank atmosphere management is critical to all of these operations. ‘Preparing for Maintenance’ walks readers through washing, gas freeing, gas detection and sludge removal. With easily understood procedures, instrument explanations and precautions, as well as how to mitigate personal risk and equipment damage, this chapter will ensure safe maintenance preparation, satisfied owners, safe custody of cargo and therefore repeat charterers.

Oil spills may occur from human error or from equipment failure. Containing any oil spilled on ships’ decks, returning it to the cargo tanks and cleaning up residual volumes must be done thoughtfully, quickly and consistently with well thought out plans and procedures. The reader will gain new insights and be reminded of tried and true ways to overcome IGS failure, ODME failure, contaminated ballast, cargo leakage, cargo overflows and oil spills. The author reminds readers of mandatory reporting requirements and good communication during any oil spill emergency. Badly managed oil spills will damage a ship’s reputation for many years and could result in criminal proceedings against responsible individuals. The author gives readers many hints which, if studied, retained in officers’ memories and implemented, can mitigate these bad results.

Often a mystery even to careers ship officers, ‘Crude Trade, Voyage Fixing and Economics’ provides concise explanations of commercial and contractual aspects of the tanker business. Ships’ officers need to understand communications, impacts of ship delays on demurrage, freight billings and other commercial terms and requirements to run their ships effectively. Commercial references throughout Crude Oil Tanker Basics come to a head in this chapter.

Five appendices very nicely round off this excellent book. These appendices give readers detailed explanations and examples for cargo calculations, wedge formula, cargo loading plan, cargo system checklist and pressure conversion units.

Crude Oil Tanker Basics puts many years of experience into a concise, technical yet easy to read format. Every tanker officer should be handed a copy to be read and re-read until its contents become second nature in day to day cargo and ballast operations.

In a world where an accidental oil spill can put the Captain or cargo officer in jail, it is essential for every tanker officer to read and understand this book before setting foot on a tanker’s deck. Your career and your freedom may depend on it.

Tom Allen

1 Crude Oil Extraction

2 Crude Oil Chemistry
2.1 Classification of Crude Oil
2.2 Properties of Crude Oil

3 Measurement of Cargo Quantity
3.1 Level Measurement (Tank Gauging)
3.2 Temperature Measurement
3.3 Detecting Water

4 Calculating Cargo Quantity
4.1 Calculating the Cargo Requirement
4.2 Calculating the Weight of Cargo
4.3 Calculating the Volume of Cargo
4.4 Cargo Distribution
4.5 Load Port Calculations
4.6 Calculation of Cargo Loaded and Discharged
4.7 Calculating Residual Quantities
4.8 Comparing Onboard Quantities with Bill of Lading (B/L) Figures

5 Loading Rates and Venting
5.1 Maximum Loading Rate
5.2 Minimum Loading Rate
5.3 Topping off Loading Rate
5.4 Cargo Tank Vetting During Loading

6 Preparing for Cargo Transfer
6.1 Planning
6.2 Testing and Checking Equipment

7 The Loading Operation
7.1 Initial Loading Phase
7.2 Full Rate Phase
7.3 Topping off and changing Over Tanks
7.4 Completing Phase

8 Pumping and Pump Theory
8.1 Pressure and Head
8.2 Pump Suction Conditions
8.3 Pump Discharge Conditions
8.4 Construction and Principles of Operation of Centrifugal Pumps
8.5 Pump Suction Conditions
8.6 Discharge Conditions
8.7 Water Hammer
8.8 Stripping Systems

9 Cargo Discharge Operations
9.1 Commencement of Discharge
9.2 Discharging at Full Rate
9.3 Stripping
9.4 Stripping Line Contents

10 Inert Gas
10.1 Chemistry of Inert Flue Gas
10.2 Production and Processing of Inert Flue Gas
10.3 Preparing the IG System
10.4 Primary Inerting
10.5 Purging
10.6 Monitoring Gas Concentrations
10.7 Operation of the IG System during Cargo Discharge
10.8 Cold Weather Precautions when Using the IG System

11 Crude Oil Washing (COW)
11.1 The Chemistry of COW
11.2 Hazards of COW
11.3 COW Methodology
11.4 Programming COW Machines

12 Ballasting, Deballasting and Crude Oil Content Discharge Control
12.1 Ballast Tank Arrangements
12.2 Piping and Pumps
12.3 Venting Arrangement
12.4 Oil Discharge Monitoring and Control Equipment (ODME)
12.5 Ballasting and Deballasting Segregated Ballast Tanks (SBTs)
12.6 Ballasting and Deballasting Cargo Tanks
12.7 Decanting
12.8 Ballast Exchange

13 Preparing for Maintenance
13.1 Tank Cleaning / Washing
13.2 Line Washing
13.3 Gas Freeing
13.4 Gas Detection and Measurement
13.5 Operations Requiring Tank Cleaning and Line Washing

14 Contingencies and Emergencies
14.1 Cargo Equipment or Systems Failure
14.2 Problems during Pumping
14.3 Inert Gas System Failure
14.4 Cargo or Ballast Leakage
14.5 Marine Pollution
14.6 Oil Outflow due to Hull Damage

15 Crude Oil Trade, Voyage Fixing and Economics
15.1 Crude Oil Trading
15.2 Chartering
15.3 Charter Types
15.4 Voyage Economics
15.5 Crude Oil Trade

Captain Paul Armitage

Following his appointment as Fleet Operations Manager with Acomarit UK, Captain Armitage progressed to ship Master with Vela International Marine, a role he held for 21 years. In education since 1966, in 2018 Captain Armitage became Visiting Lecturer at City, University of London.