1、 Inert Gas Systems 1990 Edition Erratum Some copies o this hook inclucle an incorrect page 5. The correct page is oil the reverse o this sheet. Printed in lhe United Kingdoni by IMO Copyright I IMO 1998 (Publication IMO-860E) 2.2 Flammable limits 2.2.1 A mixture of hydrocarbon gas and air cannot ign
2、ite unless its composition lies within a range of gas in air concentrations knoivn as the “flammable range”. The lower limit of this range, known as the “lower flammable limit” is any hydrocarbon concentration below which there is insufficient hydrocarbon gas to support combustion. The upper limit o
3、f the range, known as the “upper flammable limit” is any hydrocarbon concentration above which there is insufficient air to support combustion. 2.2.2 The flammable limits vary somewhat for different pure hydrocarbon gases and for the gas mixtures derived from different petroleum liquids. In practice
4、, however, the lower and upper flammable limits of oil cargoes carried in tankers can be taken, for general purposes, to be 1% and 10% hydrocarbon by volume, respectively. 2.3 Effect of inert gas on flammability 3 2 a Y 2 Y U Y P I VI U z 4 I 4 U I 2.3.1 When an inert gas is added to a hydrocarbon g
5、aslair mixture the result is to increase the lower flammable limit Concentration and to decrease the upper flammable limit concentration. These effects are illustrated in figure I, which should be regarded only as a guide to the principles involved. FLAMMABLE I - - O 5 10 15 OXYGEN - PERCENTAGE BY V
6、OLUME Figure I 2.3.2 Any point on the diagram represents a hydrocarbon gas/air/inert gas mixture, specified in terms of its hydrocarbon and oxygen content. Hydrocarbon/air mixtures without inert gas lie on the line AB, the slope of which shows the reduction in oxygen 5 INERT GAS SYSTEMS 1990 Edition
7、 INTERNATIONAL MARITIME ORGANIZATION London, 1990 First pithlished in 1982 by the INTERNATIONAL MARITIME ORGANIZATION 4 Albert Embankment, London SEI 7SR Second edition 1983 Third edition 1990 Printed by the International Maritime Organization, London 14 16 18 20 19 17 15 13 ISBN 92-801-1262-7 I IMO
8、PUBLICATION 1 I Sales number: I860E I Copyright 0 IMO 1990 All rights reserved. No pari of this piihlicution muy he rcproducecl, stored in u retrieval systeni or trrinsniitied in ciny .form or by any meuns, electronic, electrosintic, mugnetic tup, niecliunicul, photocopying or otlierwise, without pr
9、ior permission in writing ,from the Internutiunril Muritinie Organizcition. FOREWORD 1 This publication contains the text of guidelines for inert gas systems and relevant IMO documents on inert gas systems and supersedes the publication 860 83.15.E. Provisions of the SOLAS Convention covering applic
10、ation and technical requirements for inert gas systems, together with recent developments on regulations for inert gas systems on chemical tankers are included with a view to setting out the framework as well as details of international requirements for inert gas systems. Part I: Guidelines for Iner
11、t Gas Systems 2 The International Conference on Tanker Safety and Pollution Prevention, 1978, with resolution 5, requested the Organization to re-examine the requirements relating to inert gas systems in regulation 11-2/62 of the 1974 SOLAS Convention, and to develop guidelines to supplement the req
12、uirements of that regulation. 3 The Maritime Safety Committee at its forty-second session approved the Guidelines for Inert Gas Systems (MSC/Circ.282), and at its forty-eighth session adopted amendments to sections 8 and 12 of the Guidelines (MSC/Circ.353). Furthermore, the Maritime Safety Committee
13、 at its fiftieth session adopted revised section 5.5 - cargo discharge - of the revised Guidelines (MSWCirc.387). This part provides the text of the Guidelines for Inert Gas Systems which incorporates all these amendments. Part II: Provisions of application 4 Provisions of application for inert gas
14、systems in the 1974 SOLAS Convention were modified by the 1978 SOLAS Protocol and amended by the 1981 and 1983 amendments. This part contains all the relevant provisions of application as well as clarification of application of inert gas system requirements developed by the Maritime Safety Committee
15、 at its fifty-fifth session (MSC/Circ.485). Part III: Provisions of technical requirements 5 Technical requirements for inert gas systems in the 1974 SOLAS Convention were amended substantially by the 1981 amendments and to a lesser extent by the 1983 amendments. These technical requirements which a
16、re to be applied under the provisions of the SOLAS Convention are contained in this part. Part IV: Regulations for inert gas systems on chemical tankers 6 Regulation 11-2/60 of the 1978 SOLAS Protocol requires new and existing chemical tankers of a certain size, when carrying petroleum products, to
17、be fitted with a fixed inert gas system at specific dates. The Assembly at its twelfth session, recognizing the unique features of chemical tankers, adopted the Interim regulation . 111 for inert gas systems on chemical tankers carrying petroleum products (resolution A.473(XII), and urged Government
18、s concerned, under the provisions of regula- tion I/5 of the 1974 SOLAS Convention, to apply to chemical tankers as appropriate the Interim regulation as equivalent to regulation 11-2/62 of the 1974 SOLAS Convention. 7 The Assembly at its fourteenth session, recognizing that the extension of the reg
19、ulation in resolution A.473(XII) to cover the carriage of petroleum and other liquid products would be desirable, adopted resolution A.567( 14), the regulation for inert gas systems on chemical tankers, which supersedes resolution A.473(XII). 8 The Assembly at its fourteenth session also adopted dra
20、ft amendments to regulation II-2/55.5 of the International Convention for the Safety of Life at Sea, 1974, as amended (resolution A.566( 14). These amendments were subsequently adopted by the Maritime Safety Committee at its fifty-seventh session and included in the 1989 set of amendments to the SOL
21、AS Convention expected to enter into force on 1 February 1992 and the resolution is also contained in this part. Part V: Application of requirements for inert gas systems for oil tankers by port authorities and terminal operators (MSWCirc.329) 9 At the forty-sixth session of the Maritime Safety Comm
22、ittee, concern was expressed on the stringent oxygen levels insisted on by some terminal operators and port authorities for inerted cargo tanks of oil tankers, and their reluctance to allow the opening of inerted tanks for dipping, measuring and sampling. The Committee, in MSWCirc.329, noting the co
23、ncern, urged Governments to encourage port authorities and terminal operators to comply with international requirements. iv CONTENTS Foreword . PART I PART II 1 2 3 4 5 PART III 1 2 3 PART IV 1 2 PART V Guidelines for Inert Gas Systems (MSUCirc.282 as amended by MSYCirc.353 and MSC/Circ.387) Provisi
24、ons of Application 1974 SOLAS Convention 1978 SOLAS Protocol 1981 Amendments to the 1974 SOLAS Convention . 1983 Amendments to the 1974 SOLAS Convention . Clarification of inert gas system requirements under SOLAS 1974. as amended (MSC/Circ.485) . . Provisions of Technical Requirements . 1974 SOLAS
25、Convention 1981 Amendments to the 1974 SOLAS Convention . 1983 Amendments to the 1974 SOLAS Convention . Regulations for Inert Gas Systems on Chemical Tankers Regulation for inert gas systems on chemical tankers (resolution A.567(14). Draft amendment to regulation 11-2155.5 of the International Conv
26、ention for the Safety of Life at Sea, 1974. as amended (resolution A.566( 14) Application of Requirements for Inert Gas Systems for Oil Tankers by Port Authorities and Terminal Operators (MXYCirc.329) . Page . 111 1 1 50 50 54 58 63 65 66 66 68 75 76 76 84 87 V PART I GUIDELINES FOR INERT GAS SYSTEM
27、S (adopted by the Maritime Safety Committee at its forty-second session and amended at its forty-eighth and fiftieth sessions) CONTENTS 1 Introduction 1.1 Purpose 1.2 Application 1.3 Definitions 2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 3 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 Pr
28、inciples General Flammable limits Effect of inert gas on flammability Sources Quality Methods of gas replacement General policy of cargo tank atmosphere control Function and design considerations Description of an inert flue gas system Function of inert gas scrubber Design considerations for inert g
29、as scrubber Function of inert gas blowers Design considerations for inert gas blowers Function of nonreturn devices Design considerations for nonreturn devices Inert gas distribution system Design considerations for valves and pipework in inert gas systems Gas pressure regulating valves and recircul
30、ating arrangements Arrangements for inerting, purging and gas-freeing Isolation of cargo tanks from the inert gas deck main Liquid-filled pressurehacuum breakers Instrumentation and alarms Effluent and drain piping Seawater service 4 Operation of inert gas plant 5 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 App
31、lication to cargo tank operation Inerting of tanks Discharge of water ballast Loading Loaded condition Cargo transfer and cargo sampling Crude oil washing Ballasting of cargo tanks Ballast condition 1 5.9 5.10 5.1 5.12 5.13 6 6.1 6.2 6.3 6.4 6.5 7 7.1 7.2 7.3 7.4 7.5 7.6 8 9 9.1 9.2 9.3 9.4 9.5 9.6
32、9.7 9.8 10 10.1 10.2 10.3 10.4 11 12 Tank cleaning Purging prior to gas-freeing Gas-freeing Tank entry Re-inerting after tank entry Product carriers Carriage of products having a flashpoint exceeding 6OoC Product contamination by other cargoes Contamination of cargoes by inert gas Contamination of c
33、argoes by water Additional purging and gas-freeing Combination carriers Slack holds Leakage Ballast and void spaces Inert gas distribution system Application when carrying oil Application when carrying cargoes other than oil Emergency procedures Maintenance and testing General Inert gas scrubber Ine
34、rt gas blowers Deck water seal Nonreturn valve Scrubber effluent line Testing of other units and alarms Suggested maintenance programme Training General Personnel requiring training Location of training Some training methods Instruction manual(s) Some safety considerations with inert gas systems 12.
35、1 Backflow of cargo gases 12.2 Health hazards 12.3 Tank pressure 12.4 Electrostatic hazards 12.5 Repair of inert gas plant 12.6 Hazards from pyrophoric iron sulphide 2 1 INTRODUCTION 1.1 Purpose The International Conference on Tanker Safety and Pollution Prevention held in February 1978 passed resol
36、ution 5 recommending that the International Maritime Organization develop Guidelines to supplement the requirements of amended regulation 62 of chapter 11-2 of the 1974 SOLAS Convention* by taking into account the arduous operating conditions of inert gas systems and the need to maintain them to a s
37、atisfactory standard. In addition regulation 62.1 requires that an inert gas system shall be designed, constructed and tested to the satisfaction of the Administration. These Guidelines have accordingly been developed to supplement and complement the Convention requirements for inert gas systems. Th
38、ey are offered to Administrations to assist them in determining appropriate design and constructional parameters and in formulating suitable operational procedures when inert gas systems are installed in ships flying the flag of their State. 1.2 Application 1.2.1 The status of these Guidelines is ad
39、visory. They are intended to cover the design and operation of: .1 inert gas systems that are required on new tankers by regulation 60 of chapter 11-2 of the 1978 SOLAS Protocol and in accordance with regulation 62; inert gas systems that are required on existing tankers by regulation 60 of chapter
40、11-2 of the 1978 SOLAS Protocol and in accordance with regulation 62.20; inert gas systems which are fitted but not required to comply with the requirements of regulation 60 of chapter 11-2 of the 1978 SOLAS Protocol. .2 .3 1.2.2 However, for existing inert gas systems the Guidelines are directed pr
41、imarily at operational procedures and are not intended to be interpreted as requiring modifications to existing equipment other than those which are required on ships to which regulation 62.20 applies. 1.2.3 The content of these Guidelines is based on current general practice used in the design and
42、operation of inert gas systems using flue gas from the uptake from the ships main or auxiliary boilers, and installed on crude oil tankers and combination carriers. The Guidelines do not exclude other sources of inert gas, such as systems incorporating independent inert gas generators, other designs
43、, materials or operational procedures. All such divergences should be carefully assessed to ensure that they achieve the objectives of these Guidelines. * Any reference to regulation 62 in these Guidelines means the new text of regulation 62 of chapter 11-2 of the 1983 SOLAS amendments, as adopted b
44、y the Maritime Safety Committee at its forty-eighth session in June 1983. 3 1.3 Definitions 1.3.1 insufficient oxygen to support the combustion of hydrocarbons. Inert gas means a gas or a mixture of gases, such as flue gas, containing 1.3.2 Inert condition means a condition in which the oxygen conte
45、nt throughout the atmosphere of a tank has been reduced to 8% or less by volume by addition of inert gas. 1.3.3 pressurize, monitor and control delivery of inert gas to cargo tank systems. Inert gaspfant means all equipment specially fitted to supply, cool, clean, 1.3.4 Inert gas distribution system
46、 means all piping, valves, and associated fittings to distribute inert gas from the inert gas plant to cargo tanks, to vent gases to atmosphere and to protect tanks against excessive pressure or vacuum. 1.3.5 Inert gas system means an inert gas plant and inert gas distribution system together with m
47、eans for preventing backflow of cargo gases to the machinery spaces, fixed and portable measuring instruments and control devices. 1.3.6 Inerting means the introduction of inert gas into a tank with the object of attaining the inert condition defined in 1.3.2. 1.3.7 Gas-freeing means the introductio
48、n of fresh air into a tank with the object of removing toxic, flammable and inert gases and increasing the oxygen content to 21% by volume. 1.3.8 Purging means the introduction of inert gas into a tank already in the inert condition with the object of: 1 further reducing the existing oxygen content;
49、 and/or .2 reducing the existing hydrocarbon gas content to a level below which combustion cannot be supported if air is subsequently introduced into the tank. 1.3.9 Topping up means the introduction of inert gas into a tank which is already in the inert condition with the object of raising the tank pressure to prevent any ingress of air. 2 PRINCIPLES 2.1 General With an inert gas system the protection against a tank explosion is achieved by introducing inert gas into the tank to keep the oxygen content low and reduce to safe proportions the
