Site Selection and Design for LNG Ports and Jetties (IP no. 14)
This book is aimed at port developers as a guide to the minimum design criteria required when a port is built or altered to accommodate LNG carriers. It contains operational and design considerations before questioning these in the context of the human element. The consequences of collisions and groundings are studied and methods of limiting the effect of such accidents are offered.
The book outlines the way forward for site selection of LNG terminals, establishes a basis for safe jetty design and considers the safety factors in the port approach. It also considers the existing industry guidelines that cover cargo operations at the ship/shore interface. It is suggested that LNG’s excellent safety record is owing to the existing standards being adopted. As the industry becomes more widespread, continuing success will depend not only on better acceptance of the existing standards but also on future improvements. Some of the newer aspects are described and a checklist can be found in the appendix.
At the time of site selection, the level of marine risk is determined by the position chosen for the terminal and this is particularly true of terminals handling hazardous cargoes such as LNG. Once the port is in operation, the risks identified during planning should be controlled by suitable equipment and pre-arranged procedures. This should include the ongoing need to keep other industries or populations remote from the plant.
As can be seen from much of its earlier work, SIGTTO urge acceptance of a wide range of
equipment and procedures for the reduction of operational risk. To supplement past work, this paper recommends that for new sites the LNG terminal, and its port area, should be examined as a unique risk system. This paper focuses, therefore, on accident exposure and risk management not only during cargo operations alongside, but also during the port transits of LNG carriers.
Implicit in site selection is the recognition of risk. As described elsewhere, risk consists of a
combination of event frequency and consequence. Therefore, port designers are often faced with a number of choices when selecting a site, and these choices can arise from a variety of competing pressures. As described in risk assessment theory, operational solutions are found by acceptance, or non-acceptance, of some categories of risk. However, whatever remote frequencies may be tolerated for a smaller release, there is no acceptable frequency for a large release.
In essence, the issue being addressed is how best to minimise port risks by design factors at the start of a project. As can be seen in the paper, there are three components in this equation. Initially, questions on satisfactory jetty position and design are covered. Operational procedures are then addressed. Thereafter, having questioned the robustness of these procedures with respect to human elements, the consequences of collisions and groundings are studied and methods of limiting the effect of such accidents are considered. By this means, any high risk scenario is identified during design and this then requires special handling to restrict occurrence.
From a navigational standpoint and as alluded to in the above paragraph, the paper suggests that while the human controls called upon during ship manoeuvring deserve high ranking, of themselves, they can never be considered 100% secure. This is because questions of human error can prevail. However, back-up is achieved if it is known that, in a grounding or collision, an LNG carrier’s cargo containment system is most unlikely to be breached. To achieve this end, a detailed study of each port approach is needed and, to give this subject greater clarity, examples are given in Section 10.3. To cover the main risks (as identified), the possibility of liquid spillage during cargo operations at the jetty is also discussed. Here, a three stage solution is offered. First, well deployed moorings.
Second, well engineered and interlinked ESD systems. Third, the fitting of PERCs, with quick-acting valves included on either side. All of these are controlled by an ERS system.
Having addressed all risks — big and small — alongside and in the port approach, an outcome from the risk analysis which makes an accident virtually impossible is clearly the most satisfactory. If, however, the outcome shows consequences of a serious nature then, clearly, it is necessary to draw up detailed contingency plans. But, in some circumstances, such as a large LNG release close to a populated area, it may be impossible to devise a realistic contingency plan because of the nature of the problem. Herein lies a problem which may only be resolved by further reducing the chance of a major release by designing out the problem.
The precautions, as recommended by SIGTTO in this paper, do not offer a single package that reduces operational risk to some quantifiable and acceptable level; indeed it is suspected that the pattern of operational risk is too complex to be easily handled in this way. However, this cautionary note aside, the industry’s objective must be to further reduce risk whenever possible.
Of course, the safety of life is vital, as is continuing public confidence in the trade. However, the enormous financial exposures of LNG projects also must be safeguarded. In some circumstances it is found that the protection given to save life also protects the commercial exposure. In other cases, however, personal safety can be assured while unacceptable business risks remain – so suggesting the improved standards, as recommended in this report, are necessary not only due to personnel hazards but also to protect the business risk.
Important factors such as personnel training, contingency planning or matters of a general safety nature are not covered in this paper; the aim has been to focus more on matters of equipment and issues of navigational interest. Nevertheless, these extra factors are fundamental to future safety in the LNG sector and, as a matter of course, should always be taken into account.
2.1 Port Design
2.2 The Jetty
5 Development of LNG Standards
6.2 Jetty Location
7.1 Root Criteria for Hazardous Liquid Cargoes
7.2 Specific Criteria for LNG
8.1 Port Controls
9 The Human Element
10.1 Hull Damage – a Historical Review
10.2 Risk of Structural Damage to LNG Carriers
The Society of International Gas Tanker and Terminal Operators (SIGTTO) is an international body established for the exchange of technical information and experience, between members of the industry, to enhance the safety and operational reliability of gas tankers and terminals. Learn more: https://www.sigtto.org/about-us/
- Number of Pages:
- Published Date:
- February 1997
- Binding Format:
- Book Height:
- 300 mm
- Book Width:
- 210 mm
- 0.3 kg