LR-RU-012 Class Rules for Low-Flashpoint Fuel Ships

1. Document Position

This document is Lloyd's Register's class rule framework for ships using gases or other low-flashpoint fuels. Its formal title is:

Rules and Regulations for the Classification of Ships using Gases or other Low-flashpoint Fuels, July 2025.

LR-RU-012 is Lloyd's Register's class rule document for low-flashpoint fuel ships, formed by incorporating the IMO IGF Code into LR class rules together with LR supplementary class requirements and fuel-specific appendices. It covers requirements relating to design, construction, testing, operation and training; but operation, training and statutory approval matters must still be confirmed separately against the flag Administration, IMO instruments and project-specific class review comments.

Rule Nature

LR class rules for ships using low-flashpoint fuels.

Regulatory Basis

Incorporates the IMO IGF Code into class rules, with LR supplementary requirements and fuel-specific appendices.

Engineering Aim

To achieve a safety level equivalent to conventional oil-fuelled ships.

Main Fuels and LR Fuel Identifiers (LFPF yy)

This is not only an LNG-fuelled ship rule. It is LR's wider classification framework for low-flashpoint fuel ships. The table below lists the yy fuel identifiers used in LFPF(xx,yy) and GR(yy,z) under LR-RU-012.

Fuel Type	LR Code	Description	Covered in This Note
Natural Gas	NG	Natural gas; may be supplied as LNG or CNG	One of the main fuels covered in depth
Ethane Gas	EG	Ethane gas	Listed for reference only; not expanded in depth
Petroleum Gas	PG	Petroleum gas, including propane, butane or their mixtures; LPG fuel is denoted as PG in LR-RU-012	Appendix LR4
Methyl Alcohol	ML	Methanol	Appendix LR1
Ethyl Alcohol	EL	Ethanol	Appendix LR1
Hydrogen	HY	Hydrogen fuel	Appendix LR3
Ammonia	AM	Ammonia fuel	Appendix LR2

2. Relationship with the IGF Code, Flag Administration and LR

1. Relationship with the IMO IGF Code

IGF Code means the International Code of Safety for Ships Using Gases or Other Low-Flashpoint Fuels.

LR-RU-012 integrates the IGF Code into LR's classification rules. A ship seeking LR low-flashpoint fuel classification must comply with both the IGF Code baseline and the LR supplementary requirements contained in this rule.

2. Meaning of an "LR" Prefix

Where a requirement is prefixed by LR, it is an LR class supplementary requirement, not necessarily a direct quotation from the IGF Code.

In practice, plan approval should not stop at the IMO text. LR appendices, notations, Gas Ready descriptors and risk-assessment requirements also need to be checked.

3. Three Layers of Responsibility

Layer	Role	Main Function
IMO	Develops international codes such as the IGF Code.	Provides the international minimum safety standard.
Flag Administration	Interprets statutory requirements and issues statutory certification.	Determines statutory compliance.
LR	Performs class approval and applies class rules.	Verifies compliance with LR class requirements and related technical criteria.

3. Scope and Boundary of Application

Typical Application

LNG-fuelled container ships
LNG-fuelled bulk carriers
LNG-fuelled ferries
Methanol-fuelled ships
Ammonia-fuelled ships
Hydrogen-fuelled ships
LPG-fuelled ships
Gas Ready ships prepared for future alternative-fuel use

Key Distinction

The rule primarily applies when gas or another low-flashpoint substance is used as ship fuel, not merely carried as cargo.

Case	Regulatory Logic
Using LNG as ship fuel	Normally follows the IGF Code and LR-RU-012.
Carrying LNG as bulk cargo	Normally follows the IGC Code and gas carrier rules.
Hybrid or special-purpose designs	The rule boundary should be confirmed with LR and the Administration.

Important: Do not assume that every "LNG ship" falls under this rule. The key question is whether LNG is used as fuel or carried as cargo.

4. Overall Document Architecture

The rule can be read as a ship life-cycle structure: regulatory position and applicability first, then design, construction and testing, followed by operation and training requirements listed in LR-RU-012, and finally fuel-specific appendices. Part C-1 and Part D are included in the rule, but statutory operation, SMS, STCW and Administration approval must be understood separately from ordinary classification (see Section 9 reminder).

Part	Main Content	Function
Preamble	Purpose, IGF Code relationship, LR additional requirements and Administration responsibility.	Sets the statutory and class context.
Part A: General	Application, definitions, alternative design, goals and functional requirements.	Common basis for all low-flashpoint fuel ships.
Part A-1	Specific design requirements for natural-gas fuelled ships.	Main design-review body for NG natural-gas fuelled ships (LNG or CNG supply form).
Part B-1	Manufacture, workmanship, inspection and testing.	Connects shipyard construction, LR survey and functional testing.
Part C-1	Operation, drills and emergency procedures.	Lists operation and drill requirements; statutory SMS and Administration approval remain with the flag or its authorised RO.
Part D	Crew training.	Lists crew training requirements; STCW certification and Administration approval must still be confirmed separately.
Appendix LR1	Methanol / ethanol fuelled ships.	Translates MSC.1/Circ.1621 into LR class requirements.
Appendix LR2	Ammonia fuelled ships.	Focuses on toxicity, detection, ventilation and personnel protection.
Appendix LR3	Hydrogen fuelled ships.	Focuses on explosion analysis, hydrogen detection, ventilation and separation distances.
Appendix LR4	LPG fuelled ships.	Focuses on propane / butane behaviour, low-level accumulation and dispersion risk.

Layer 1: Regulatory Position
The Preamble explains the relationship among LR, the IGF Code, the flag Administration and class responsibility.

Layer 2: Common Rules
Part A establishes application, definitions, alternative design, functional requirements and risk philosophy.

Layer 3: Natural Gas Requirements
Part A-1 provides the complete design framework for natural-gas fuelled ships.

Layer 4: Manufacture, Operation and Training
Part B-1 mainly addresses construction testing; Part C-1 and Part D list operation, drills and training requirements, but statutory operation, SMS and STCW approval remain within the flag Administration or its authorised RO.

Layer 5: Fuel-Specific Supplements
Appendices LR1 to LR4 add special safety requirements for methanol / ethanol, ammonia, hydrogen and LPG.

5. Front Matter Summary

Cover and publication information

The cover confirms the July 2025 edition and the subject of LR class rules for ships using gases or other low-flashpoint fuels. This matters for edition control, subsequent Notices, contract dates, keel-laying dates and delivery dates.

A guide to the Rules and published requirements

This part explains how LR rules are published and updated:

LR rules are normally published periodically.
Between formal publications, amendments may be issued as Notices.
Special ship types, fuels, arrangements or alternative designs may require direct calculations.
LR may use internal or recognised calculation methods for review.

Preamble

The Preamble is essential because it states that:

The rule aims to ensure low-flashpoint fuel ships can comply with the IGF Code.
The IGF Code text current at publication has been incorporated.
LR additional requirements are marked with the LR prefix.
Interpretation of the IGF Code remains with the flag Administration.
Natural-gas requirements are the most complete; other fuels require equivalent-safety demonstration through alternative design or appendices.

6. Part A: General

Part A is the common foundation for all ships using gases or low-flashpoint fuels. It explains how the rule is applied, which ships are covered, how important terms are defined, how alternative fuels can demonstrate equivalent safety, and what overall safety objective must be achieved.

Chapter 2: General

Clause	Summary	Practical Use
2.1Application	Defines the scope, mainly for ships covered by SOLAS Chapter II-1 Part G.	Helps decide whether the project follows IGF Code / LR-RU-012 or IGC Code logic.
2.1-07Class notation	Defines LFPF(xx,yy) and GR(yy,z).	Used in class certificates, newbuilding contracts, fuel-readiness planning and conversions.
2.1-08Submission	Lists drawings and information such as fuel tanks, test procedures, supporting calculations and conversion descriptions.	Forms the plan-approval submission checklist.
2.2Definitions	Defines accident, bunkering, CNG, LNG, ESD, LEL, MAWP, MARVS and other terms.	Creates a common basis for interpreting later clauses.
2.3Alternative Design	Requires equivalent safety when a fuel or system is not specifically covered.	Common where the IGF Code has no full mandatory chapter; actual route depends on interim guidelines, class appendices and Administration approval (see below).

Class Notation: LFPF(xx,yy)

LFPF means Low Flash Point Fuel. It indicates that the ship's low-flashpoint fuel machinery, systems and arrangements have been designed, constructed, installed and tested in accordance with LR rules.

Field	Meaning	Examples
xx	Applicable rule basis	GF for LR-RU-012 / IGF Code; GC for IGC Code.
yy	Fuel identifier	See the LR fuel identifier table

Examples: LFPF(GF,NG) natural-gas fuelled ship under LR-RU-012 / IGF Code; LFPF(GF,ML) methanol-fuelled ship; LFPF(GF,HY) hydrogen-fuelled ship.

Fuel code reminder: the formal natural-gas identifier in LFPF notation is NG (Natural Gas). LNG and CNG are storage or supply forms, not yy fuel codes.

Gas Ready: GR(yy,z)

GR(yy,z) indicates that the ship has been prepared for a specific low-flashpoint fuel yy under Gas Ready, while z describes the level of preparation or installed scope. Publicly available older LR descriptive notes commonly use z codes such as A, S, T, P and E, where T may indicate that fuel storage arrangements are installed and E may indicate that engineering systems are installed; E may also be followed by M, A, B or I for main engines, auxiliaries, boilers or incinerators. The actual codes and definitions must be taken from the applicable edition of the official LR-RU-012 text.

Note: Gas Ready does not mean that the ship is already allowed to operate on that fuel, nor does it guarantee unconditional future LFPF classification. Future activation must be reviewed under the LR rules, IMO requirements and Administration requirements effective at that time.

Key Terms

Term	Explanation	Engineering Meaning
Low-flashpoint fuel	A gas or liquid fuel with a flashpoint below the normal SOLAS II-2/4 allowance.	Triggers special design, detection, ventilation and safety requirements.
Bunkering	Transfer of fuel to the ship from shore, floating facility or portable tank.	Critical interface for ESD, communication and spill control.
ESD	Emergency Shutdown.	Isolates the fuel system during leakage, fire or abnormal conditions.
LEL	Lower Explosive Limit.	Key basis for gas detector alarm and shutdown settings.
MAWP	Maximum Allowable Working Pressure.	Design basis for pressure vessels, piping and valves.
MARVS	Maximum Allowable Relief Valve Setting.	Basis for fuel tank pressure relief design.
TMIV	Tank Master Isolation Valve.	Important remotely operated isolation valve near the liquefied gas fuel tank outlet.

Alternative Design

For low-flashpoint fuels not yet fully addressed by mandatory chapters of the IGF Code, equivalent-safety demonstration, alternative design procedures, IMO interim guidelines, class fuel-specific appendices and flag Administration / project approval are usually needed in practice to show that safety is not lower than existing requirements. Methanol / ethanol, ammonia, hydrogen and LPG now have interim guidelines or class supplementary requirements to varying degrees, but the applicable approach must still be confirmed against the latest IMO documents, flag requirements and class review results.

HAZID

Hazard Identification.

HAZOP

Hazard and Operability Study.

FMEA

Failure Mode and Effects Analysis.

Explosion Analysis

Assessment of explosion pressure and consequences.

Gas Dispersion Analysis

Assessment of gas cloud extent after leakage.

RBC

Risk Based Certification.

7. Chapter 3-4: Goals, Functional Requirements and General Technical Requirements

Chapter 3: Goal and Functional Requirements

Chapter 3 is the safety philosophy of the rule. It applies a goal-based approach: the system must achieve defined safety functions, not merely satisfy isolated equipment dimensions or arrangements.

Safety, reliability and dependability should be equivalent to new conventional oil-fuelled main and auxiliary machinery.
The probability and consequences of fuel-related hazards should be minimised through arrangement, ventilation, detection and safety actions.
Safety measures must not create unacceptable loss of power.
Hazardous areas should be limited as far as practicable.
Equipment in hazardous areas should be minimised and properly certified.
Unintended accumulation of explosive, flammable or toxic gas should be prevented.
System components should be protected from external damage.
Ignition sources in hazardous areas should be reduced.
Fuel storage, supply and bunkering systems should safely receive, store and transfer fuel.
Control, alarm, monitoring, shutdown, fixed gas detection and fire safety systems are required.
Technical documentation must demonstrate compliance.
A single failure must not lead to an unsafe or unreliable condition.

Engineering interpretation: Safety is not delivered by tank thickness, valve rating or pipe material alone. It depends on a controlled system response during leakage, fire, explosion, blackout, valve failure, ventilation failure, detector activation and ESD initiation.

Chapter 4: General Requirements

Chapter 4 turns the functional requirements into the overall safety requirements used before detailed design. It is typically linked to the following documents and analyses:

Safety Analysis Documents

Risk assessment report
Explosion analysis
Gas dispersion analysis
Equivalent-safety demonstration for alternative design

Design and Control Documents

Hazardous area plan
System safety concept
Arrangement plans
ESD cause-and-effect

8. Part A-1: Requirements for Natural-Gas Fuelled Ships

Part A-1 is the most complete technical body of the rule. It mainly addresses ships using natural gas (NG; LNG or CNG supply form) as fuel. Other fuels may borrow its design logic, but cannot simply copy it because fire, explosion, toxicity, cryogenic and leakage characteristics differ by fuel.

Chapter 5

Ship Design and Arrangement

Covers fuel tanks, machinery spaces, tank connection spaces, fuel preparation rooms, bunkering stations, accommodation, control stations, hazardous areas and escape routes.

Practical impact: Affects GA plan, tank location, hazardous area boundary, bunkering station and ventilation outlet arrangement.

Chapter 6

Fuel Containment System

Covers tank type, primary and secondary barriers, insulation, interbarrier space, supports, relief arrangements, loading limits and cryogenic protection.

Practical impact: Used for Type C tanks, independent tanks, membrane tanks, LNG fuel tanks and secondary barrier design.

Chapter 7

Material and General Pipe Design

Covers low-temperature materials, pipe strength, pressure ratings, double-wall pipes, ducts, welding, valves, external damage protection and fire endurance.

Practical impact: Main basis for fuel supply piping, bunkering lines, GVU piping, pipe supports and penetrations.

Chapter 8

Bunkering

Covers bunkering station, bunkering piping, bunkering control, communication, ESD, leak detection, overflow protection and connection methods.

Practical impact: Important for truck-to-ship, shore-to-ship and ship-to-ship bunkering.

Chapter 9

Fuel Supply to Consumers

Covers the supply system from storage tank to main engines, auxiliaries, boilers, fuel cells or other consumers.

Practical impact: Reviews FGSS, GVU, double-wall piping, master gas fuel valve, purging, venting and pressure control.

Chapter 10

Power Generation and Gas Consumers

Covers dual-fuel engines, gas-only engines, auxiliaries, boilers, fuel cells, gas turbines and other gas consumers.

Practical impact: Focuses on fuel changeover, pilot fuel, engine shutdown, power redundancy and single-failure safety.

Chapter 11

Fire Safety

Covers fire detection, fire separation, fire main, water mist, dry powder, fixed fire-extinguishing systems and protection of fuel-related spaces.

Practical impact: Affects fire control plan, fire piping, bunkering station fire protection and fuel preparation room extinguishing arrangements.

Chapter 12

Explosion Prevention

Covers hazardous area classification, ignition source control, explosion pressure relief, gas accumulation prevention and separation distance.

Practical impact: Closely connected to hazardous area plan, Ex equipment list, explosion analysis and ventilation design.

Chapter 13

Ventilation

Covers ventilation for tank connection spaces, fuel preparation rooms, bunkering stations, ducts, airlocks and machinery spaces.

Practical impact: Affects fan capacity, vent positions, ventilation failure alarms and automatic shutdown logic.

Chapter 14

Electrical Installations

Covers Ex type, certification, installation, cable penetrations, lighting and power safety for electrical equipment in hazardous areas.

Practical impact: Must align with IEC 60079, IEC 60092-502, Ex equipment selection and hazardous area classification.

Chapter 15

Control, Monitoring and Safety Systems

Covers gas detection, fire detection, pressure / temperature / level monitoring, alarms, ESD, interlocks and cause-and-effect logic.

Practical impact: Core chapter for ESD logic, alarm list, FMEA, commissioning tests and sea trials.

Bunkering reminder: the bunkering station should generally be located on open deck to ensure natural ventilation. If located in an enclosed or semi-enclosed space, risk assessment should consider segregation, forced ventilation, leak detection, airlock, CCTV or direct line-of-sight monitoring.

9. Part B-1 / Part C-1 / Part D: Manufacture, Operation and Training

Part C-1 / Part D scope reminder: Although Part C-1 and Part D are included in LR-RU-012 and cover operation, drills and crew training requirements, statutory operational requirements, SMS, STCW training certification and Administration approval remain within the responsibility of the flag Administration or its authorised RO. LR may review related documents and arrangements under class requirements or within the RO's authorised scope, but this should not be understood as meaning that all operational matters fall directly under ordinary classification.

Part B-1: Chapter 16 Manufacture, Workmanship and Testing

Chapter 16 is about proving that the installed system actually matches the approved design.

Main Content

Manufacturing quality
Welding requirements
Material certificates and traceability
Fuel tank tests
Pipe pressure tests
Leak tests
Double-wall pipe or duct tests
ESD testing
Commissioning and sea trial

Common Shipyard Deliverables

Inspection and Test Plan (ITP)
Welding Procedure Specification (WPS)
Procedure Qualification Record (PQR)
Pressure test report
Leak test report
ESD valve closing-time test
Cold and hot commissioning records for the fuel system

Testing focus: the outer pipe or duct of a double-wall fuel pipe must also be pressure-tested to show that it can withstand the maximum expected pressure after inner pipe rupture. ESD valves in liquefied gas piping should close smoothly and completely within the required time.

Part C-1: Chapters 17-18 Operation and Drills

Chapter	Topic	Focus
Chapter 17	Drills and Emergency Exercises	Fuel leakage, fire, bunkering accident, ESD activation, ventilation failure and gas detection alarm drills.
Chapter 18	Operation	Normal operation, fuel changeover, bunkering, purging, inerting, venting, maintenance, inspection and emergency procedures.

Typical onboard documents include:

Fuel Handling Manual
Bunkering Procedure
Emergency Shutdown Procedure
Gas Freeing Procedure
Maintenance Manual
Permit to Work Procedure
Enclosed Space Entry Procedure
Emergency Response Plan

Part D: Chapter 19 Crew Training

Chapter 19 requires the company to ensure that relevant crew members receive appropriate training according to their responsibilities, aligned with the STCW Convention and Code.

Personnel	Training Focus
General deck and engine-room personnel	Fuel hazards, alarm meanings, basic response, escape and PPE.
Personnel responsible for fuel operations	Bunkering, fuel changeover, purging, ESD and leak response.
Engineers and chief engineers	Fuel supply system, main / auxiliary machinery operation, maintenance and troubleshooting.
Masters and senior officers	Bunkering command, risk management, emergency response and regulatory responsibility.
Bunkering personnel	Ship-shore communication, ESD link and bunkering checklist.

10. Fuel-Specific Appendices

NG Natural Gas: natural-gas fuel system (LNG or CNG supply form)

Natural gas is the fuel most fully covered by the IGF Code, so Part A-1 is the main body for NG natural-gas fuelled ships.

NG fuel tank type and location (LNG or CNG supply form)
Fuel supply piping and GVU
Double-wall pipe or duct
Ventilation and gas detection
Bunkering station
Fire safety, explosion prevention, control / monitoring and ESD
LNG Bunker Delivery Note

Appendix LR1: Methanol / Ethanol

Applies to ships using methyl alcohol (methanol) or ethyl alcohol (ethanol) as fuel.

Ambient-temperature liquid; lower cryogenic risk than LNG
Still a low-flashpoint fuel requiring vapour control
Methanol toxicity requires exposure control and personnel protection
Focus on tank, leakage collection, ventilation, bunkering and ESD
Specific filling-limit requirements apply

Appendix LR2: Ammonia

The key issue for ammonia is not only fire or explosion, but toxicity.

Toxic area plans and personnel exposure risk
Ammonia detector location and alarm settings
Relative location of air intakes, accommodation, control stations and machinery openings
PPE, breathing apparatus and escape routes
Vent outlet location
Cause-and-effect diagram
Safe sequential shutdown of the fuel supply system

Appendix LR3: Hydrogen

Hydrogen risk centres on leakage tendency, wide flammable range, low ignition energy and explosion risk.

High-pressure hydrogen or liquid hydrogen storage
Material compatibility
Hydrogen detection and flame detection
Ventilation and separation distance
Explosion analysis and hazardous area classification
Purging, venting and ESD
PFD, P&ID, HAZID, HAZOP and FMEA

Appendix LR4: LPG / PG

LPG usually includes propane, butane or mixtures of both.

Vapour is usually heavier than air
Leakage may flow to and accumulate in low areas
Deck recesses, drains, bilges and ventilation dead zones must be analysed
Focus on tank, piping, valves, leak detection and isolation
Complete P&ID, cause-and-effect, FMEA, manuals and test plans are needed

11. Integrated Technical Themes

1. Core Risks of Low-Flashpoint Fuel Ships

Risk	Description	Typical Fuels
Fire	Flammable fuel ignites after leakage.	Natural gas, methanol, hydrogen, LPG.
Explosion	Flammable gas or vapour may accumulate in enclosed or semi-enclosed spaces and explode if ignited.	Natural gas, hydrogen, LPG, methanol / ethanol vapour, etc.
Toxicity	The fuel itself harms personnel.	Ammonia, methanol.
Cryogenic hazard	Liquefied fuel leakage causes frostbite or steel embrittlement.	LNG, liquid hydrogen, some liquefied gases.
Asphyxiation	Gas displaces oxygen.	LNG vapour, hydrogen, inert gas.
Loss of power	ESD or fuel system failure affects propulsion or power generation.	All low-flashpoint fuel ships.

2. Typical Safety Layers

Leak Prevention and Consequence Reduction

Safe arrangement
Primary containment
Secondary containment
External damage protection
Cryogenic protection

Detection, Isolation and Response

Ventilation
Gas detection
ESD
Ex-certified equipment
Fire safety systems
Procedures and training

3. Common Design Document List

Design Statement
Concept of Operation (ConOp)
General Arrangement Plan
Fuel Tank Arrangement
Process Flow Diagram (PFD)
Piping and Instrumentation Diagram (P&ID)
Hazardous Area Plan
Gas Detection Layout
Ventilation Arrangement
Fire Safety Plan
Explosion Analysis
Gas Dispersion Analysis
Risk Assessment
HAZID / HAZOP Report
FMEA
Cause-and-effect Diagram
ESD Logic
Alarm List
Fuel Handling Manual
Bunkering Procedure
Inspection and Test Plan
Commissioning / Sea Trial Test Procedure

12. Practical Application for Different Users

For Shipyards

Confirm whether the notation is LFPF or GR
Confirm the fuel type and relevant appendix
Control piping fabrication, welding quality and material certificates
Prepare pressure tests, leak tests and ESD tests
Complete tests before first bunkering
Coordinate LR survey hold points and sea trial items

For Designers

Check early GA against tank and bunkering station requirements
Validate hazardous area classification
Check conflicts between vents and accommodation or control stations
Confirm secondary containment for fuel piping
Make ESD cause-and-effect clear
Support alternative fuels with risk assessment

For Owners and Managers

Gas Ready does not mean ready for operation
Future conversion still requires review
Crew competence must match the fuel risk
Bunkering procedure must be complete
Drills should be incorporated into SMS
Crew must understand toxicity, explosion and cryogenic risks

13. Common Misunderstandings

1. LR-RU-012 is not just the IGF Code text

LR-RU-012 includes the IGF Code and LR's additional class requirements. An LR prefix indicates a supplementary LR requirement.

2. Fuels other than natural gas cannot simply copy natural-gas rules

Fuel	Main Risk
NG Natural Gas (LNG/CNG forms)	Cryogenic hazard, flammable gas and explosion.
Methanol	Flammable liquid, toxicity and hard-to-see flame.
Ammonia	Toxicity, corrosiveness and leakage dispersion.
Hydrogen	Leakage tendency, wide flammable range, low ignition energy and explosion.
LPG	Heavy vapour, low-level accumulation and explosion.

3. Gas Ready is not full fuel classification

GR only describes certain reservations, approvals or installed items. It does not mean the ship can operate on the fuel. Actual operation still requires the applicable LFPF notation and Administration approval.

4. Procedures cannot replace hardware safety requirements

Alternative design can demonstrate equivalent safety, but crew procedures alone cannot replace required equipment, material, segregation or safety systems.

5. Risk assessment is not a formality

Risk assessment directly influences:

Bunkering station design
Fuel preparation room arrangement
Tank connection space design
Ventilation capacity and detector location
ESD logic and hazardous area classification
Fire separation, vent outlet position and crew exposure risk

14. Suggested Study Path

Step 1: Understand the document position
Read the Preamble, Chapter 2 Application, Definitions and Alternative Design.

Step 2: Understand the safety philosophy
Read Chapter 3 Goal and Functional Requirements and Chapter 4 General Requirements.

Step 3: Enter the natural-gas fuelled ship design body
Read Chapters 5-9 to understand fuel storage, bunkering, transfer and consumers.

Step 4: Strengthen the safety systems
Read Chapters 11-15 for fire safety, explosion prevention, ventilation, Ex electrical design, control / monitoring and ESD.

Step 5: Understand construction and operation
Read Chapters 16-19 for fabrication, testing, operation, drills and training.

Step 6: Check the appendix by fuel
Use LR1 for methanol / ethanol, LR2 for ammonia, LR3 for hydrogen and LR4 for LPG.

15. Summary and Engineering Judgement

One-sentence summary:
LR-RU-012 is Lloyd's Register's class rule document for low-flashpoint fuel ships, formed by incorporating the IMO IGF Code into LR class rules together with LR supplementary class requirements and fuel-specific appendices. It covers requirements relating to design, construction, testing, operation and training; but operation, training and statutory approval matters must still be confirmed separately against the flag Administration, IMO instruments and project-specific class review comments.

Core Review Points

Document position: LR class rule document for low-flashpoint fuel ships (IGF Code incorporation plus LR supplementary requirements and fuel-specific appendices).
Regulatory basis: IGF Code incorporated into class rules, with LR supplementary class requirements.
Responsibility split: Part C-1 / Part D list operation and training requirements, but SMS, STCW and statutory approval remain with the flag or its authorised RO; LR review is limited to class requirements or RO-authorised scope.
Application: ships using gas or low-flashpoint substances as marine fuel.
Key distinction: using LNG as fuel is different from carrying LNG as cargo.
Formal class notation is LFPF(xx,yy).
Gas Ready is GR(yy,z), but it is not full fuel classification.
Safety philosophy: goal-based standards and equivalent safety.
Main risks: fire, explosion, toxicity, cryogenic hazard, leakage, loss of power and human error.
Design focus: fuel tanks, piping, bunkering, fuel supply, ventilation, explosion prevention, fire safety, control / monitoring and ESD.
Construction focus: welding, materials, pressure tests, leak tests, ESD tests and commissioning.
Operation focus: fuel handling manual, bunkering procedure, emergency procedure, drills and maintenance as required by class rules.
Training focus: crew competence requirements within class rules; STCW / flag requirements must be confirmed separately.