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Risk Assessment on Liquefied Natural Gas Tanker

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Conducting a thorough risk assessment for LNG vessels is crucial to ensure the safe transportation of liquefied natural gas. Such assessments typically involve analyzing potential hazards such as leaks, fires, and collisions, considering factors like vessel design, operating conditions, and route selection. By identifying and mitigating risks proactively, stakeholders can minimize the likelihood of accidents and protect both the environment and human life.

Reference SIGTTO “LNG Shipping Suggested Competency Standards”, Sections:

1 Have an awareness of the requirement to carry out risk assessment:

  • Definition of risk assessment and hazard;
  • Purpose of a risk assessment;
  • When to carry out a risk assessment.

2 Know and understand the process to carry out risk assessment of planned operations:

  • Risk assessment elements (process);
  • How to identify hazards;
  • How to determine risk;
  • How to establish “likelihood” and “severity”;
  • How to decide if the risk is tolerable;
  • How to prepare a risk control action plan.

Definition of risk assessment and hazard

A risk assessment is a systematic and careful examination of items that could cause injury, harm or damage, so that decisions can be made as to whether sufficient precautions have been taken to minimise the risk or whether further remedial action is necessary. For example, for many operations, a permit to work (PTW) will be required to be completed. The aim is to minimise accidents and the impact to health on board ship and at the terminal.

The requirements and procedures for Common Hazards and Risk Assessment in Oil and Gas Industryrisk assessment should be clearly defined within the company SMS. The assessment will depend on the type of ship, the nature of the operation and the type and extent of specific hazards. A hazard is a source of potential injury, harm or damage.

Purpose of a risk assessment

The assessment should first establish the hazards that are present and then identify the risk level arising out of any activities. The assessment should consider existing precautions to control the risk, such as permits to work, restricted access, use of warning signs or personal protective equipment (PPE).

Man welding steel
Example of the risky task
Source: pixabay.com

A risk assessment must address risks to the health an.d safety of workers, the use of PPE, the use of equipment, manual handling operations and any recommended measures to address those risks (for example, environmental impact, economic impact, etc.).

When to carry out a risk assessment

A risk assessment should be seen as a continuous process. In practice, risks in the workplace should be assessed before work begins on any task for which no valid risk assessment exists. An assessment must be constantly reviewed and updated as necessary while carrying out any task to ensure that it reflects any changes.

Risk assessment elements (process)

The main elements of the risk assessment process are:

  • Classification of work activities;
  • Correct and accurate identification of all hazards;
  • Identification of personnel who may be harmed, and how;
  • Determination of the likelihood that harm may arise and the severity of the harm;
  • Deciding if the risk is tolerable and disregarding inconsequential risks;
  • Deciding on control measures, as appropriate, recording findings and preparation of an action plan;
  • Reviewing the adequacy of the action plan.

One type of approach to risk assessment is known as the four level process. This involves:

  • Level 1 – generic risk assessments, contained within the company SMS;
  • Level 2 – task based risk assessments of normal activities on board each ship;
  • Level 3 – toolbox talk. This is another form of risk assessment and all matters of the job should be talked through;
  • Level 4 – personnel assessment of risk.

Risks identification

How to identify hazards. Asking these three questions should help to identify whether there is a hazard:

  • Is there a source of harm?
  • Who (or what) could be harmed?
  • How could harm occur?

To help with the process of identifying hazards it is useful to categorise hazards in different ways, for example by topic, e. g.:

  • Mechanical;
  • Electrical;
  • Physical;
  • Radiation;
  • Substances;
  • Fire and explosion.

A complementary approach may be to develop a “prompt list” that considers whether the following hazards could exist:

  • Slips/falls on the level;
  • Falls from a height;
  • Falls of tools, materials, etc., from a height;
  • Inadequate headroom;
  • Inadequate ventilation;
  • Hazards from plant and machinery associated with assembly, commissioning, operation, maintenance, modification, repair and dismantling;
  • Hazards from manual handling, etc.

How to determine risk

Risk has two elements:

  • The likelihood that harm or damage may occur;
  • The potential severity of the harm or damage.

These two components should be assessed independently.

How to establish “likelihood” and “severity”

Likelihood of harm. In order to establish the likelihood of harm, the adequacy of control measures already in place should be reviewed. Guidance provided in publications such as the Code of Safe Working Practices for Merchant Seamen (COSWP) and other marine safety publications can be of additional value when assessing the Flammability, Explosion and other Hazards of Liquefied Gascontrol of specific hazards.

In this process, the following issues should typically be assessed:

  • Number, location(s) and experience of personnel exposed;
  • Availability of safe access to work location(s);
  • Frequency and duration of exposure to the hazard;
  • Effects of failure of power or water supply;
  • Effects of failure of plant and machinery components and safety devices;
  • Exposure to environmental conditions;
  • Protection afforded by personal protective equipment and its availability, adequacy limitations;
  • Possibility of unsafe acts by persons who, for example:
    • May not be aware of the potential hazards;
    • May not have the knowledge, physical capacity, or adequate skills for the intended task;
    • Underestimate risks to which they are exposed;
    • Underestimate the practicality and benefits of safe working methods.

Severity of harm. When seeking to establish the potential severity of harm, the following should be considered:

  • Low – may cause minimal harm i. e. superficial injuries, requiring minor treatment/first aid on the ship;
  • Moderate – may cause more significant harm with potentially lasting consequences i. e. injuries requiring treatment ashore;
  • Severe – may lead to permanent or long term harm i. e. severe injuries, amputations, etc.;
  • The possibility of death.

How to decide if the risk is tolerable

The following table shows a simple method for estimating risk levels and deciding whether risks are tolerable. Risks are classified according to their estimated likelihood and potential severity of harm. However, other approaches may be developed, according to the nature of the operation.

Estimating Risk Levels
Slightly harmfulHarmfulExtremely harmful
Highly unlikelyMinor riskTolerable riskModerate risk
UnlikelyTolerable riskModerate riskSubstantial risk
LikelyModerate riskSubstantial riskIntolerable risk
Note: In this context “tolerable” means that the risk has been reduced to the lowest level that is reasonably practicable.

How to prepare a risk control action plan

Having determined the significant risks, the next step is to decide what action should be taken to improve safety, taking account of precautions and controls already in place.

Risk categories form the basis for deciding whether improved controls are required and the timescale for action. The following table suggests a possible simple approach. This shows that the effort made to control a risk should reflect the seriousness of that risk.

Risk Categories
Action and Timescale
MinorNo action is required and no documentary records need be kept.
TolerableNo additional controls are required. Consideration maybe given to a more cost effective solution or improvement that imposes no additional cost burden. Monitoring is required to ensure that the controls are maintained.
ModerateEfforts should be made to reduce the risk, but the costs of prevention should be carefully measured and limited. Risk reduction measures should be implemented within a defined time period. Where the moderate risk is associated with extremely harmful consequences, further assessment may be necessary to establish more precisely the likelihood of harm as a basis for determining the need for improved control measures.
SubstantialWork should not be started until the risk has been reduced. Considerable resources may have to be allocated to reduce the risk.Where the risk involves work in progress, urgent action should be taken.
IntolerableWork should not be started or continued until the risk has been reduced. If it is not possible to reduce the risk even with unlimited resources, work has to remain prohibited.
Note: In this context, “tolerable” means that the risk has been reduced to the lowest level that is reasonably practicable.

To ensure that all personnel Involved In any operation are aware and understand the hazards and associated risks, it is important to conduct a toolbox talk before work commences.

When you are controlling the risks identified in a risk assessment,you may come across some of the following methods (ordered here from most to least effective):

  1. Elimination (removing the hazard completely, e. g. electrical isolation).
  2. Substitution (i. e. a less hazardous alternative).
  3. Prevention of access to the hazard (e. g. enclosure/guarding).
  4. Adequate training and effective supervision.
  5. Use of PPE (to be utilised last, i. e. where controls 1-4 are not effective).

Permit to work

Permit to work (PTW) systems provide a structured and auditable approach to safe working. They help safeguard all those who may be affected by a particular task and ensure compliance at the work location with safety requirements. A PTW will often be identified during a risk assessment to control and reduce hazards. There are no exemptions.

The main features of a PTW are:

  • It provides a detailed and clear job description;
  • It identifies who is undertaking and who is authorising the work;
  • It requires a named individual to confirm that the risks have been properly assessed and precautions taken;
  • It ensures that responsible personnel are aware of any work to be carried out within their area of responsibility.

The PTW process can be simplified into the following four steps:

  1. Assessing;
  2. Authorising;
  3. Monitoring;
  4. Cancelling.

Before authorising and issuing a permit, the permit issuer, often the Master or Chief Engineer, should discuss with the permit holder the hazards of the work, the controls that have been put in place and the precautions to be taken during the work.

Read also: Everything you need to know about Permit-to-Work System, Manual about PTW

Ideally, this discussion should take place at the worksite. Where required, the Safety Officer should be consulted for specialist advice on the availability and use of protective clothing and equipment.

In preparing the permit, the applicant (the ultimate permit holder) will detail:

  • Location of the worksite – if necessary providing an Enclosed Space Entry Certificate, Working Aloft Certificate or Lifting Certificate;
  • Identification and status of the equipment – if necessary providing an Electrical Isolation Certificate, Process Isolation Certificate, Mechanical Isolation Certificate or Safety Systems Isolation Certificate;
  • A description of the work to be conducted;
  • Any equipment to be used that is not specifically detailed on the form;
  • Any supporting plans or information that must be attached to the permit;
  • The names of personnel will undertake the work;
  • The estimated time the task will take.

After discussing the details of the work, preparations, made and the controls specified on the permit, the permit issuer and permit holder sign to authorise the permit.

Categories of work covered under the permit to work system

Work that is covered under the permit to work (PTW) system is categorised as either hot work or cold work.

Hot work involves a positive or potential source of ignition, for example:

  • Welding, flame cutting and grinding;
  • Use of electrical/electronic equipment not certified for use in flammable atmospheres;
  • Opening and working on live electrical systems;
  • Use of powered steel wire brushes, needle gunning;
  • Dry grit/shot blasting.

Cold work refers to all other types of work where there is no How to Prevent Fire and Explosion or How to Minimize Effects of itrisk of ignition but there is still a high risk potential. These tasks may be covered by an individual PTW or a generic Cold Work Permit. Examples include:

  • Pressure testing;
  • Work affecting safety or emergency systems;
  • Enclosed space entry or entry into space where the oxygen level may be below 20,9 %;
  • Working aloft or over the ship’s side;
  • Diving operations;
  • Non-routine lifting operations;
  • Opening or disconnection of any closed pipeline or tank.

Other permit types include:

  • A pressurised systems/equipment permit, which must be completed before undertaking invasive work on pressurised systems or equipment;
  • A working aloft, over the side or at height permit, which must be completed whenever there is a need to work at a height where there is a risk offal ling, e. g. near a tank top, over or at the ship’s side, at a mast or at the top of a stairwell.

When creating, reading or signing a permit to work (PTW), always ensure you understand fully:

  • The work scope and how that work is to be carried out;
  • The hazards and the required precautions;
  • The actions to be taken in the event of an emergency;
  • The responsibilities of yourself and others.

It is important that the permit holder copy is readily available for reference by the work party and by anyone conducting inspections of the work. If there is a change in conditions to the work, the work should be stopped and a new permit to work (PTW) issued.

Note that no one person is allowed to issue a permit to themselves as this would defeat one of the prime objectives of a permit to work (PTW) system, that of having a “second pair of eyes” to critically review the proposed controls.

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Март, 28, 2024 46 0
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