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LNG bunkering process – standards and rules

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The LNG bunkering process is the transfer of fuel to a ship. In this process, a fuel tanker pumps fuel into the ship’s fuel tanks. It is essential to follow safety rules and regulations during bunkering to prevent accidents and ensure smooth operations.

The LNG bunkering process involves transferring liquefied natural gas (LNG) from a supply vessel to a ship’s storage tanks. The plan includes:

  • assessing safety risks;
  • preparing the bunkering area;
  • connecting hoses or pipelines;
  • transferring LNG;
  • monitoring the process;
  • and completing all necessary documentation.

Compliance with safety regulations and guidelines is essential to ensure a safe and efficient bunkering operation.

Introduction

LNG bunkering is developing worldwide in line with the increase of use of natural gas as a fuel compliant with environmental legislation.

This guideline provides recommendations for the responsibilities, procedures and equipment required for LNG bunkering operations and sets harmonised minimum baseline recommendations for bunkering risk assessment, equipment and operations.

These guidelines do not consider commercial Basic Information about Liquefied Natural Gas Bunkering Operationsaspects of the bunker transfer such as Bunker Delivery Notes and measurement of quantity or quality of LNG.

Purpose

The purpose of these guidelines is mainly to define and cover the additional risks associated with bunkering LNG and to propose a methodology to deal with those additional risks in order to provide a similar level of safety as is achieved for traditional oil fuel bunkering operations.

This document is designed to complement the requirements from the existing applicable guidelines and regulations, such as port and terminal checklists, operator’s procedures, industry guidelines and local regulations. This guide provides guidance to clarify the gaps that have been identified in the existing guidance and regulations. In particular, the following items are covered:

  • The responsibility of different parties involved in the LNG transfer;
  • The LNG bunkering process;
  • SIMOPS;
  • Safety distances;
  • QRA and HAZID.

LNG Bunkering process and guideline structure

LNG bunkering is the process of transferring LNG fuel to a ship from a bunkering facility.

The sequence for a bunkering operation carried out between two parties for the first time is described in the following diagram; the references identify the applicable sections of the guideline.

Bunkering process diagram
Fig. 1 Bunkering process

Applicability

These guidelines are applicable to LNG bunkering operations for:

  • Different methods;
  • Different ship types, and
  • Different locations (in port, off shore and terminal) worldwide.

LNG Bunker Management Plan (LNGBMP)

An LNG Contingency Plans for Liquefied Natural Gas Carrierbunker management plan should be established in order for the involved parties to agree technically and commercially on methodology, flow rate, temperature, pressure of the delivery of LNG and receiving tank. This plan gathers together all the information, certificates, procedures, and checklist(s) necessary for an effective and safe LNG Bunkering operation.

The LNG Bunker Management Plan should be referenced as part of the safety management system of the RSO.

The LNG Bunker Management Plan
Fig. 2 Breakdown of LNGBMP content showing related sections of this guide

Definitions, applicable standards and rules

Terms and definitions

Atmospheric tanks. Atmospheric tanks mean tanks of the types A or B or membrane tanks as defined in:

  • IGC Code, regulations 4.21, 4.22 and 4.24;
  • and IGF Code, regulations 6.4.15.1, 6.4.15.2 and 6.4.15.4.

Bunkering Facility Organisation (BFO). This is the organisation in charge of the operation of the bunkering facility.

Breakaway Coupling (BRC). A breakaway coupling is a safety coupling located in the LNG transfer system (at one end of the transfer system, either the receiving ship end or the bunkering facility end, or in the middle of the transfer system), which separates at a predetermined section at a determined break-load or relative separation distance each separated section containing a self-closing shut-off valve, which seals automatically.

Bunkering facility. A bunkering facility is normally composed of a LNG storage and a LNG transfer installation, a bunkering facility may be (a stationary shore-based installation or a mobile facility, i. e. a LNG bunker ship or barge or a tank truck).

A bunkering facility may be designed with a vapour return line and associated equipment to manage the returned vapour.

Dry disconnect. This applies when the transfer system between two vessels or a vessel and a port facility is disconnected as part of normal operations. The objective is that no LNG or natural gas should be released into the atmosphere. If this objective cannot be achieved, the amount released can be reduced to negligible amounts consistent with safety. Dry disconnect can be achieved by:

  • Draining and inerting process before the disconnection;
  • or use of dry connect/disconnect coupling.

Emergency Shut-Down (ESD). These are systems installed as part of the LNG transfer system that are designed to stop the flow of LNG and or prevent damage to the transfer system in an emergency. The ESD may consist of two parts, they are;

  • ESD – stage 1, is a system that shuts the LNG transfer process down in a controlled manner when it receives inputs from one or more of the following; transfer personnel, high or low level LNG tank pressure alarms, cables or other means designed to detect excessive movement between transfer vessels or vessel and an LNG bunkering facility, or other alarms.
  • ESD – stage 2, is a system that activates decoupling of the transfer system between the transfer vessels or between a vessel and an LNG bunkering facility. The decoupling mechanism contains quick acting valves designed to contain the contents of the LNG transfer line (dry break) during decoupling.

Emergency Release Coupling (ERC). The ERC is normally linked to the ESD system where this may be referred to as ESD2 as per SIGTTO «ESD arrangements & linked ship/shore systems for liquefied gas carriers».

An emergency release coupling is activated:

  • By excessive forces applied to the predetermined section, or
  • By manual or automated control, in case of emergency.

Emergency Release System (ERS). A system that provides a positive means of quick release of the transfer system and safe isolation of receiving vessel from the supply source.

Flash Gas. Boil-off Gas instantly generated during LNG transfer due to the warmer temperature of the receiving ship tanks, sudden pressure drop or friction.

HAZOP. A structured and systematic examination of a planned or existing process or operation in order to identify and evaluate problems that may represent risks to personnel or equipment, or prevent efficient operation. A HAZOP is a qualitative technique based on guide-words and is carried out by a multi-disciplinary team of experts during a set of meetings.

HAZID. Hazard identification exercise, there are a number of recognised methods for the formal identification of hazards. For example: a brainstorming exercise using checklists where the potential hazards in an operation are identified and gathered in a risk register these will then be assessed and managed as required.

Hazardous zones. Bunkering-related hazardous zone means any hazardous area zone 1 or zone 2 defined for:

  • The receiving ship in accordance with IGF Code, regulation 12.5;
  • The bunkering ship in accordance with IGC Code, regulation 1.2.24 and where gas may be present as a result of the bunkering operation; and
  • The bunkering shore facility or truck tanker facility in accordance with IEC 60079-10-1.

IAPH. International Association of Ports and Harbours.

IGC Code. International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk (Gas Carrier Code). The revised IGC Code was adopted by Resolution MSC.370(93). It will enter into force on 1 July 2016.

IGF Code. International Code of Safety for Ships using Gases or other Low-Flashpoint Fuels. IGF Code refers to Resolution MSC.391(95). It will enter into force on 1 January 2017.

LNG Bunkering. The process of transferring LNG to be used as fuel on board the receiving ship.

Vapour return line. A vapour return line is a connection between the bunkering facility and the receiving ship to allow excess vapour generated during the bunkering operation to be returned to the bunkering facility and remove any need to vent to atmosphere. It is used to control the pressure in the receiving tank due to the liquid transfer, flash gas and boil-off gas generation.

LNG transfer system. A system consisting of all equipment contained between the manifold used to deliver LNG bunker (and to handle vapour return) and the manifold receiving the LNG (and delivering vapour return) including but not limited to:

  • Loading arms and supporting structures;
  • LNG articulated rigid piping;
  • Hoses, swivels, valves, couplings;
  • Emergency Release Coupling (ERC);
  • Insulating flanges;
  • Quick connect/disconnect couplings (QC/DC);
  • Handling system and its control/monitoring system;
  • Communication system;
  • ESD Ship/Shore Link or Ship/Ship Link used to connect the supplying and receiving ESD systems.

It can also include the compressors or blowers intended for the boil-off gas handling system where provided depending on the design of the transfer system. However, liquefaction systems used to maintain pressure in the bunker vessel tanks are not to be considered as part of the LNG transfer system.

MARVS. Maximum Allowable Relief Valve Setting.

MSC. Maritime Safety Committee of the IMO.

Person in Charge (PIC). The Person in Charge (PIC) is a person who is responsible for the overall management of the bunkering operation. The PIC may also be referred to as Person in Overall Advisory Control (POAC).

PPE. Personal Protective Equipment.

Qualitative Risk Assessment (Qual RA).

A risk assessment method using relative measure of risk value based on ranking or separation into descriptive categories such as low, medium, high; not important, important, very important; or on a scale, for example from 1 to 10 or 1 to 5.

Quantitative Risk Assessment (QRA). This is a formalised statistical risk assessment method for calculating a numerical risk level for comparison with defined regulatory risk criteria.

Receiving Ship. Receiving ship is the ship that receives LNG fuel.

Receiving Ship Operator (RSO). The receiving ship operator (RSO) is the company responsible for the operation of the receiving ship, in particular during the bunkering operations.

Risk. A combination of the likelihood of an event and the consequences if the event occurs.

Risk matrix. A risk matrix is a tool for displaying combinations of likelihood and consequence, used as the basis for risk determination. Multiple consequence categories can be included:

  • impact on people;
  • assets;
  • environment and reputation.

Plotting the intersection of the two considerations on the matrix provides an estimate of the risk. Acceptable levels of risk are normally shown by color coding the boxes.

Safety zone. The safety zone is a zone around the bunkering facility, the bunkering station of the receiving ship and the LNG transfer system.

The purpose of the zone is to set an area that is put in place during LNG bunkering and within which only essential authorised and qualified personnel are allowed and potential ignition sources are controlled.

Security zone. The Security Zone is the area around Risk Assessment in the Liquefied Natural Gas Bunkering Operations, Hazard Identificationthe bunkering facility and receiving ship where ship traffic and other activities are monitored (and controlled) to prevent entry and provide a «stand-off» distance during the bunkering operation; this will be larger than the safety zone.

  • The security zone may also be referred to as the «exclusion zone».
  • The security zone is site dependent and is often determined by the Port Authorities.

SIGTTO. Society of International Gas Tanker and Terminal Operators.

Simultaneous Operations (SIMOPS). Carrying out LNG bunkering operations concurrently with any other transfers between ship and shore (or between ships if ship-to-ship bunkering method is used). This includes:

  • loading or unloading cargo operations;
  • dangerous goods loading or unloading and any kind of other goods loading or unloading (i. e. stores and provisions);
  • passenger embarkation/disembarkation;
  • chemical and other low flash product handling, bunkering of fuels other than LNG;

and any other activity that can impact or distract from bunkering operations (e. g. cargo movements on board, heli-ops, etc.).

Read also: Ship to Ship Bunkering Operations of the Liquefied Natural Gas

Special attention is to be paid to any of the above activities occurring within the bunkering safety zone as well as any on board testing that may impact on the bunker operation.

STCW Code IMO Code for Seafarers’ Training, Certification and Watchkeeping.

Independent Type A, B, C and Membrane tank. These tank types are defined in the IGC and IGF Code.

Standards and rules. The following tables provide an overview of existing standards related to LNG and risk assessment. The lists are not exhaustive.

Standards and rules for LNG
No.ReferenceTitle
1EN 1160General characteristics of liquefied natural gas
2EN 1473Design of onshore installations
3EN ISO 16904:2016Design and testing of marine transfer systems. Design and testing of transfer arms
4EN 1474-2Design and testing of marine transfer systems. Design and testing of transfer hoses
5EN 1474-3Design and testing of marine transfer systems. Offshore transfer systems
6EN 12308Suitability testing of gaskets designed for flanged joints used on LNG piping
7EN 12838Suitability testing of LNG sampling systems
8EN 13645Design of onshore installations with a storage capacity between 5 t and 200 t
9EN ISO 28460Ship-to-shore interface and port operations
10ISO 16903Characteristics of LNG influencing design and material selection
11ISO/TS 18683Guidelines for systems and installations for supply of LNG as fuel to ships
12CSA Z276Standard for production, storage and handling of LNG in Canada
Draft Standards and rules for LNG
13ISO 20519Specification for bunkering of gas fuelled ships
14CTACRecommendations for LNG Unmanned Barge Policy Letter
Standards for Risk Analysis
15ISO/IEC Guide 73Risk Management – Vocabulary
16ISO/TS 16901Guidance on performing risk assessments in the design of onshore LNG installations including the ship/shore interface
17ISO 31000Risk Management – Principles and Guidelines
18ISO 31010Risk Management – Guidelines on principles and implementation of risk management
Other standards & guidelines
19SGMFGas as a marine fuel – Bunkering safety guidelines
20IEC 60079Explosive Atmosphere Standards
21IEC 60092-502Electrical installations in ships – Tankers – Special features
22EN13463-1Non electric equipment for use in potentially explosive atmospheres
23SIGTTOESD arrangements & linked ship/shore systems for liquefied gas carriers
24USCG (CGOES) Policy Letter No. 01-15Guidelines for Liquefied Natural Gas Fuel Transfer Operations and Training of Personnel on Vessels using Natural Gas as Fuel (19 Feb 2015)
25USCG (CGOES) Policy Letter No. 02-15Guidelines Related to Vessels and Waterfront Facilities Conducting Liquefied Natural Gas (LNG) Marine Fuel Transfer (Bunkering) Operations (19 Feb 2015)
26USCG CG-521
Policy Letter 01- 12
Equivalency Determination: Design Criteria for Natural Gas Fuel Systems
27NFPA 52Vehicular Gaseous Fuel Systems Code
28NFPA 59AStandard for the Production, Storage, and Handling of LNG
2949 CFR 193Liquefied Natural Gas Facilities: Federal Safety Standards (DOT)

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