Introduction to the Design and Maintenance of cargo system pressure relief valves onboard gas carriers

Introduction to the Design and Maintenance of cargo system pressure relief valves onboard gas carriers

This title supersedes the 1992 "Guidelines on the Maintenance of Pressure Relief on board Gas Carriers" that were developed after an incident involving relief valve failure occurred during the loading of a semi-pressurised LPG carrier.

Using an incident that involved relief valve failure during loading of a semi-pressurised LPG carrier as an example, this book advises on PRV maintenance and testing, emergency closure and operating problems and faults. The example was with a propane cargo where the PRVs were set to operate at 11 bar gauge. During the final stages of loading, and at a pressure of only 7 bar gauge, one of the two PRVs lifted and failed to re-seat and there were no guidelines available, onboard or at the terminal, on emergency methods of closing the valve. This book is a direct response to that incident.

1. Introduction
2. Requirements For Pressure Relief Valves
2.1 General
2.2 Valve Design Requirements
2.3 Design And Installation
3. Types Of Pressure Relief Valves
3.1 Pilot Operated Valves
3.2 Spring Operated Pressure Relief Valves
4. Preventative And Planned Maintenance Procedures For Pressure Relief Valves
4.1 Scope
4.2 Pressure Relief Valve Preventative Maintenance Philosophy
4.3 Pressure Relief Valve Preventative Maintenance Frequency
4.4 Pressure Relief Valve Maintenance And Inspection
4.5 Maintenance And Care Of Diaphragms
4.6 Spare Parts
5. Emergency Closure Of Pressure Relief Valves
5.1 Emergency Closure
6. Operating Problems And Faults
6.1 Operating Problems
6.2 Faults
6.3 Chloride Stress Corrosion Cracking
7. In-Service Testing
Appendix 1 Imo Igc Code – Extracts From Chapter 8 Cargo Tank Vent Systems
Appendix 2 Definitions And Terminology Used In Regard To Pressure Relief Valves
Appendix 3 Metal To Metal Seat Valves – Precautions And Hints For Lapping Seats
Appendix 4 Pressure Levels
Appendix 5 Fire Activated Pressure Relief Systems
References