Liquefied Gas Handling Principles on Ships and in Terminals, (LGHP4) 4th Edition
- Product Review (submitted on 9 September 2016):
SIGTTO Updates LNG/LPG guide
Everything you need to know about handling liquefied gas cargoes on board ship and at the terminal ship-shore interface can be found between the covers of the updated fourth edition of Liquefied Gas Handling Principles, flagship publication of the Society of International Gas Tanker and Terminal Operators (SIGTTO).
The guide has come a long way since its 160-page first edition launched in 1986 and the previous, 275-page third edition, published in 2000. The latest edition of the book, nicknamed LGHP4 by the SIGTTO community, has been revised to accommodate the many advances taking place in gas shipping and terminal technology and now weighs in at 530 pages and 2.5kg.
Liquefied Gas Handling Principles deals with handling liquefied gases carried in bulk, including LNG, LPG and chemical gases, and is a valuable reference work for everyone involved in design, construction and operation of gas carriers and terminals.
Like previous publications in the series, however, the new edition has been written primarily for serving ships’ officers and terminal staff responsible for cargo-handling operations, and for those who oversee these operations.
SIGTTO now has 139 full members, 48 associates and 27 non-contributory members. It drew on this broad resource base to compile LGHP4. The job of editing and structuring that input into the latest revisions fell to SIGTTO technical adviser Rick Boudiette, who submitted the final draft for peer review and endorsement by members of SIGTTO’s General Purposes Committee and several subject-matter experts.
The guide stresses the importance of understanding the physical properties of liquefied gas cargoes in relation to the operation of gas-handling equipment and systems on the ship and at loading and discharge jetties. Operators need to know how and why each gas behaves the way it does, and the associated hazards, across a range of operating scenarios, to appreciate the role of the shipboard and terminal equipment they are controlling.
LGHP4 features a revised and extended section on liquefied gas properties. Chapter two has been divided into three major subsections; the chemistry of liquefied gases, the physics of liquefied gases and gas laws, thermodynamic principles and reliquefaction.
For a newcomer there is much vital information to assimilate. A modern multigas carrier is constructed to carry upwards of 15 different cargoes, each with its own flash point, flammability range, auto-ignition temperature, boiling point, critical pressure, reactivity characteristics, density, viscosity and chemical compatibility with inert gas.
Once these properties are assimilated, it is necessary to understand the concepts of specific heat, enthalpy, entropy, phase change and saturated vapour pressure, and the basic laws of thermodynamics.
Safe and efficient handling of cargoes – and adhering to procedures that mitigate against the risks posed by their carriage in bulk – requires a basic appreciation of these liquefied gas properties and principles of gas behaviour.
LGHP4 may weigh heavily on the scales, but it brings a light touch to the complexities of handling liquefied gases and is above all a reader-friendly publication. The running commentary, with its straightforward explanations and numerous section breaks, incorporates colour-coded blocks of text.
Blue-shaded boxes contain information of an operational nature that offers useful hints for planning purposes. Yellow-shaded boxes contain cautionary information regarding operations. Grey-shaded boxes with a red border denote information considered to be of particular importance. These cautions are relatively rare and merit special attention.
One blue-tinted box contains LGHP4’s statement that certain chemical gases such as diethyl ether, propylene oxide and isoprene, which are not strictly liquefied gases, are carried under high vapour pressures. This fact, coupled with the health and flammability hazards, has led to these and similar compounds being listed in both the International Gas Carrier (IGC) and International Bulk Chemical (IBC) Codes.
These cargoes are most often shipped in gas carriers but when carried on chemical tankers, such cargoes will often be required to be stowed in independent tanks. They are also subject to many of the handling principles covered in LGHP4.
Readers will find the visual material in LGHP4 invaluable. Most of the book’s 325-plus figures are new or are updated versions of earlier visuals. Rick Boudiette and staff at Witherby developed the figures that required amendment or configuration from scratch.
The figures range from flow, equilibrium, schematic and process diagrams and depictions of refrigeration and reliquefaction cycles to photos of gas ship types, cutaways of containment systems and key cargo-handling equipment, propulsion system overviews and pictures of ship and terminal safety systems and damage that can be caused by unwanted reactions such as polymerisation and hydrate formation.
The figures are augmented by detailed tables, including those that encapsulate the key physical and chemical property data of the many gas carrier cargoes.
Notwithstanding the expanded coverage of liquefied gas physical and chemical properties, the increased LGHP4 page count reflects technological advances during the 16 years since the third edition appeared. And so offshore operations, a range of new propulsion systems and environmental stewardship get the LGHP treatment for the first time.
Ship-to-ship (STS) cargo transfers have become a routine commercial operation over the past decade, thanks to the rising popularity of floating storage and regasification units
(FSRUs) as LNG-receiving terminals. And as the first floating LNG production (FLNG) vessels come into service, similar transfers will become part of the operating scenario at offshore loading facilities, prompting LGHP to review the various STS systems available.
Considerations of propulsion systems and environmental stewardship cross over, as the need to meet new, mandated standards of higher energy efficiency benefits from the introduction of dual-fuel, gas-burning engines. Two-stroke engines offer the highest propulsive efficiencies of marine power plants and manufacturers have succeeded in developing dual-fuel versions of these units and, over the past 18 months, in winning the majority of LNG carrier newbuilding propulsion system orders.
Technical innovation has also manifested itself in other, more subtle ways across the gas cargo-handling spectrum. New two and four-stroke dual-fuel engines have required new types of equipment to be fitted on board LNG carriers, including gas combustion units (GCUs), reliquefaction plants and other systems for controlling boil-off gas (BOG).
LGHP4 also considers the differences between warm and cold ballast voyages, highlighting the key role of GCUs for the former and reliquefaction plants for the latter.
In the cargo containment-system section the new edition reviews the refinements that Gaztransport & Technigaz (GTT) has introduced in recent years with its No 96 and Mark III membranes, spurred by the drive to reduce cargo BOG rates and to enhance membranes’ ability to withstand sloshing loads.
For the Mark III membrane these goals have been achieved through the development of Mark III Flex. In the case of the No 96 design, using different insulating materials provides lower BOG rates and strengthened insulation boxes increase the ability to sustain higher sloshing loads without system damage.
The fourth edition of Liquefied Gas Handling Principles is available from Witherby Publishing; www.witherbys.com, priced £275