Emergency Release Systems, Liquefied Gases, Vapour Return and High-Pressure Gas Systems, - First Edition

Developed with the input of manufacturers, terminal operators and LNG shippers, this publication takes a risk-based approach to emergency release systems (ERS), covering their design, risk assessment and operation. It provides guidelines and best practices for ERS associated with liquefied gases, vapour return and high-pressure gas systems, including applications for LNG, LPG, ammonia and CO₂.
This publication updates and replaces SIGTTO’s ‘LNG Emergency Release Systems - Recommendations, Guidelines and Best Practices’, covering additional products and services, including high-pressure gases, and additional assets such as LNG FPSOs, FSRUs and FSUs. It also includes guidance on maintenance and competence.

Introduction

Emergency release systems (ERSs) form part of a terminal’s safety equipment. They may be fitted to cargo transfer equipment to protect it from damage by enabling rapid disconnection from the ship in the event of an emergency or when activated by the terminal operator.

As with any safety equipment, ERSs may occasionally not work as intended, eg fail to operate when required or activate unintentionally when not required. They may introduce additional risk if not designed, maintained and operated properly.

To help improve industry safety, this document provides guidance for the life cycle of different ERSs, focusing on the following aspects:

• Specification, design and failure modes

• maintenance and testing

• operations and personnel competence

• risk assessment considerations.

The document benefits from advances in safety, technological improvements, new applications, such as floating storage and regasification units (FSRUs), and lessons learnt. It replaces SIGTTO’s LNG Emergency Release Systems - Recommendations, Guidelines and Best Practices, which has been withdrawn.

Scope

This document is useful for conventional onshore and floating terminals, the latter including floating storage units (FSUs), FSRUs and liquefied natural gas (LNG) floating production, storage and offloading (FPSO) units.

The document discussed ERSs installed in marine loading arms (MLAs) and flexible hoses, both of which are used to handle liquefied gases (such as LNG, liquefied petroleum gas (LPG) and ammonia), vapours or high pressure gases. For other products, such as carbon dioxide (CO2), additional considerations may be required because of their properties or specific trade.

The information provided is based on ERSs that use instrumented systems1 and covers their design, operation and maintenance. Passive systems such as breakaway or double check valves are not addressed. Pressure containment and strength aspects of the ERSs or the cargo transfer equipment, such as material selection, the pressure and temperature rating, or quality requirements, are also excluded.

The level of technical detail of the document assumes that the reader is familiar with the design and operation of liquefied gas terminals.

Introduction and Scope
1.1 Introduction
1.2 Scope
2 Overview of Cargo Transfer Equipment
2.1 Transfer System Equipment
2.2 Operating Envelopes
3 Overview of Emergency Release Systems
3.1 Functional Description
3.2 Subsystems and Components
3.3 Construction Types
4 Specification
4.1 Regulations, Codes and Standards
4.2 Design Integrity
4.3 Actuation System
4.4 Suggested Minimum Information on the Specification Data Sheet
5 Design
5.1 General Engineering
5.2 Actuation System
5.3 Controls and Instrumentation
5.4 Integrity Assessment
5.5 Suggested Spurious Failure Modes
5.6 Suggested Minimum Information on the Manufacturer’s Data Sheet
6 Fabrication and Installation
6.1 Fabrication
6.2 Factory Acceptance Test
6.3 Installation and Commissioning
6.4 Site Acceptance Test
7 Operations and Maintenance
7.1 Structured Management Systems
7.2 Operations
7.3 Testing
7.4 Maintenance
7.5 Lessons Learnt
8 Competence and Training
8.1 Critical Activities and Competence Scheme
8.2 Suggested Competence Standards
9 Risk Assessment
9.1 Cargo Hazards
9.2 Top Events
9.3 Consequences
9.4 Risk Tolerability
9.5 Initiating Events
9.6 Barriers
9.7 Frequency Modifiers
9.8 Risk Reduction of the Emergency Release System
9.9 Spurious Failure of the Emergency Release System
9.10 Example Risk Assessment for the Cargo Transfer System of an Onshore LNG Terminal
9.11 Example Risk Assessment for the High-Pressure Gas Transfer System of an FSRU
Annexes
Annex 1 – Integrity Life-Cycle Management Flow Chart
Annex 2 – Functional Safety and IEC Approach
Annex 3 – Legend for Tables 2 to 5 – Suggested Spurious Failure Modes
Annex 4 – Glossary of Terms and Abbreviations
Annex 5 – Reference List

The Society of International Gas Tanker and Terminal Operators (SIGTTO) is a non-profit making organisation dedicated to protecting and promoting the mutual interests of its members in matters related to the safe and reliable operation of gas tankers and terminals within a sound environment. The Society was founded in 1979 and was granted consultative status at the International Maritime Organization in November 1983.