《DEP 30.10.73.32-Gen.pdf》由会员分享，可在线阅读，更多相关《DEP 30.10.73.32-Gen.pdf（31页珍藏版）》请在三一文库上搜索。
1、TECHNICAL SPECIFICATION DESIGN OF CATHODIC PROTECTION SYSTEMS FOR OFFSHORE PIPELINES (AMENDMENTS/SUPPLEMENTS TO DNV RP B401) DEP 30.10.73.32-Gen. July 1996 DESIGN AND ENGINEERING PRACTICE This document is confidential. Neither the whole nor any part of this document may be disclosed to any third par
2、ty without the prior written consent of Shell International Oil Products B.V. and Shell International Exploration and Production B.V., The Hague, The Netherlands. The copyright of this document is vested in these companies. All rights reserved. Neither the whole nor any part of this document may be
3、reproduced, stored in any retrieval system or transmitted in any form or by any means (electronic, mechanical, reprographic, recording or otherwise) without the prior written consent of the copyright owners. PREFACE DEP (Design and Engineering Practice) publications reflect the views, at the time of
4、 publication, of: Shell International Oil Products B.V. (SIOP) and Shell International Exploration and Production B.V. (SIEP) and Shell International Chemicals B.V. (SIC) The Hague, The Netherlands, and other Service Companies. They are based on the experience acquired during their involvement with
5、the design, construction, operation and maintenance of processing units and facilities, and they are supplemented with the experience of Group Operating companies. Where appropriate they are based on, or reference is made to, national and international standards and codes of practice. The objective
6、is to set the recommended standard for good design and engineering practice applied by Group companies operating an oil refinery, gas handling installation, chemical plant, oil and gas production facility, or any other such facility, and thereby to achieve maximum technical and economic benefit from
7、 standardization. The information set forth in these publications is provided to users for their consideration and decision to implement. This is of particular importance where DEPs may not cover every requirement or diversity of condition at each locality. The system of DEPs is expected to be suffi
8、ciently flexible to allow individual operating companies to adapt the information set forth in DEPs to their own environment and requirements. When Contractors or Manufacturers/Suppliers use DEPs they shall be solely responsible for the quality of work and the attainment of the required design and e
9、ngineering standards. In particular, for those requirements not specifically covered, the Principal will expect them to follow those design and engineering practices which will achieve the same level of integrity as reflected in the DEPs. If in doubt, the Contractor or Manufacturer/Supplier shall, w
10、ithout detracting from his own responsibility, consult the Principal or its technical advisor. The right to use DEPs is granted by SIOP, SIEP or SIC, in most cases under Service Agreements primarily with companies of the Royal Dutch/Shell Group and other companies receiving technical advice and serv
11、ices from SIOP, SIEP or SIC. Consequently, three categories of users of DEPs can be distinguished: 1)Operating companies having a Service Agreement with SIOP, SIEP, SIC or other Service Company. The use of DEPs by these Operating companies is subject in all respects to the terms and conditions of th
12、e relevant Service Agreement. 2)Other parties who are authorized to use DEPs subject to appropriate contractual arrangements. 3)Contractors/subcontractors and Manufacturers/Suppliers under a contract with users referred to under 1) or 2) which requires that tenders for projects, materials supplied o
13、r - generally - work performed on behalf of the said users comply with the relevant standards. Subject to any particular terms and conditions as may be set forth in specific agreements with users, SIOP, SIEP and SIC disclaim any liability of whatsoever nature for any damage (including injury or deat
14、h) suffered by any company or person whomsoever as a result of or in connection with the use, application or implementation of any DEP, combination of DEPs or any part thereof. The benefit of this disclaimer shall inure in all respects to SIOP, SIEP, SIC and/or any company affiliated to these compan
15、ies that may issue DEPs or require the use of DEPs. Without prejudice to any specific terms in respect of confidentiality under relevant contractual arrangements, DEPs shall not, without the prior written consent of SIOP and SIEP, be disclosed by users to any company or person whomsoever and the DEP
16、s shall be used exclusively for the purpose for which they have been provided to the user. They shall be returned after use, including any copies which shall only be made by users with the express prior written consent of SIOP and SIEP. The copyright of DEPs vests in SIOP and SIEP. Users shall arran
17、ge for DEPs to be held in safe custody and SIOP or SIEP may at any time require information satisfactory to them in order to ascertain how users implement this requirement. All administrative queries should be directed to the DEP Administrator in SIOP. NOTE: In addition to DEP publications there are
18、 Standard Specifications and Draft DEPs for Development (DDDs). DDDs generally introduce new procedures or techniques that will probably need updating as further experience develops during their use. The above requirements for distribution and use of DEPs are also applicable to Standard Specificatio
19、ns and DDDs. Standard Specifications and DDDs will gradually be replaced by DEPs. DEP 30.10.73.32-Gen. July 1996 Page 2 TABLE OF CONTENTS PART IINTRODUCTION.4 1.1SCOPE 4 1.2DISTRIBUTION, INTENDED USE AND REGULATORY CONSIDERATIONS4 1.3DEFINITIONS 4 1.4ABBREVIATIONS5 1.5CROSS-REFERENCES5 1.6GUIDANCE F
20、OR USE.5 PART IIDESIGN PHILOSOPHY6 1.1GENERAL 6 1.2CONCEPTUAL DESIGN.6 1.3DETAILED DESIGN6 PART IIIAMENDMENTS/SUPPLEMENTS TO DNV RP401, 1993 EDITION7 2.SCOPE 8 3.DEFINITIONS, SYMBOLS AND ABBREVIATIONS9 3.1PARTIES AND RESPONSIBILITIES.9 5.GENERAL DESIGN CONSIDERATIONS.10 6.DESIGN PARAMETERS.11 6.1GEN
21、ERAL 11 6.2DESIGN LIFE11 6.3DESIGN CURRENT DENSITIES11 6.4COATING BREAKDOWN FACTOR .12 6.5PIPELINE COATINGS.13 6.5.5Replace this section by:.14 6.6SACRIFICIAL ANODE MATERIAL PERFORMANCE.14 7.DESIGN TASK.15 7.2SUB-DIVISION OF OBJECT.15 7.5CURRENT DRAIN CALCULATIONS15 7.9DETAILED ANODE DESIGN15 7.10DI
22、STRIBUTION OF ANODES.15 7.11ANODE MOUNTING AND PROVISIONS FOR ELECTRICAL CONTINUITY15 7.12ENGINEERING DOCUMENTATION16 8.MANUFACTURING OF SACRIFICIAL ANODES.18 8.2QUALIFICATION OF ANODE MANUFACTURING18 8.3STANDARDS.18 9.INSTALLATION OF SACRIFICIAL ANODES.19 9.3DOCUMENTATION.19 10.IMPRESSED CURRENT CA
23、THODIC PROTECTION SYSTEMS20 10.1GENERAL 20 10.2CURRENT SOURCES AND CONTROL.20 10.4SYSTEM DESIGN.20 10.5MONITORING EQUIPMENT.20 10.7DOCUMENTATION.22 11.INSPECTION AND MONITORING OF CATHODIC PROTECTION.23 PART IVREFERENCES24 APPENDICES APPENDIX 1SPECIMEN COPY OF REQUISITION SHEET25 APPENDIX 2DESIGN EX
24、AMPLES.26 APPENDIX 3ELECTROCHEMICAL TEST PROCEDURES FOR SACRIFICIAL ANODES28 DEP 30.10.73.32-Gen. July 1996 Page 3 PART IINTRODUCTION 1.1SCOPE This DEP specifies requirements and gives recommendations for the design of cathodic protection systems for offshore pipelines. This DEP may also be applied
25、to submerged pipeline sections of on-shore pipelines. Short “offshore“ pipelines or pipeline sections (e.g. loading lines) may sometimes be protected by onshore based (impressed current) cathodic protection installations. For such installations reference is made to DEP 30.10.73.31-Gen. This DEP is b
26、ased on DNV Recommended Practice RP B401, 1993 edition. Part III of this DEP gives amendments and supplements to RP B401. 1.2DISTRIBUTION, INTENDED USE AND REGULATORY CONSIDERATIONS Unless otherwise authorised by SIOP and SIEP, the distribution of this DEP is confined to companies forming part of th
27、e Royal Dutch/Shell Group or managed by a Group company, and to Contractors and Manufacturers/Suppliers nominated by them (i.e. the distribution code is “F“ as defined in DEP 00.00.05.05-Gen.). This DEP is intended to be used for new offshore pipeline construction projects in relation to oilandgaspr
28、oductionfacilities,oilrefineries,chemicalplants,gasplantsand supply/marketing installations. This DEP is not intended to be used for retrofitting of cathodic protection systems on existing offshore pipelines. If national and/or local regulations exist in which some of the requirements may be more st
29、ringent than in this DEP the Contractor shall determine by careful scrutiny which of the requirements are the more stringent and which combination of requirements will be acceptable as regards safety, environmental, economic and legal aspects. In all cases the Contractor shall inform the Principal o
30、f any deviation from the requirements of this DEP which is considered to be necessary in order to comply with national and/or local regulations. The Principal may then negotiate with the Authorities concerned with the object of obtaining agreement to follow this DEP as closely as possible. 1.3DEFINI
31、TIONS 1.3.1General definitions The Contractor is the party which carries out all or part of the design, engineering, procurement, installation, and commissioning or management of a project or operation or maintenance of a facility. The Principal may sometimes undertake all or part of the duties of t
32、he Contractor. The Manufacturer/Supplier is the party which manufactures or supplies equipment and services to perform the duties specified by the Contractor. The Principal is the party which initiates the project and ultimately pays for its design and construction. The Principal will generally spec
33、ify the technical requirements. The Principal may also include an agent or consultant, authorised to act for the Principal. The word shall indicates a requirement. The word should indicates a recommendation. 1.3.2Specific Definitions Anode Manufacturer/Supplier - the manufacturer/supplier of sacrifi
34、cial anodes and related materials Cathodic protection design Contractor - the party responsible for the design of the cathodic protection system and ultimately responsible for the functioning of the cathodic protection system. DEP 30.10.73.32-Gen. July 1996 Page 4 Cathodic protection installation Co
35、ntractor - the party responsible for the installation of the cathodic protection system in accordance with the design and with this DEP. Coating breakdown factor - the ratio between the surface area of exposed metal due to coating breakdown and the total surface area under consideration. The factor
36、is used to determine the average current density on coated metal from current densities compared with that for bare steel. Conceptual design - early design phase, preceding detailed design. Foreign structures/pipelines - metal structures, or pipelines other than the pipeline under consideration, in
37、contact with the same electrolyte as the pipeline, and which (may) come under the influence of the pipelines cathodic protection system. Foreign structures/pipelines may be owned by the Principal or other companies and may or may not be equipped with cathodic protection. Pipe to (sea)water potential
38、 - the difference in electrochemical potential between a pipeline or foreign structure/pipeline and a specified reference electrode in contact with the electrolyte. Similar terms such as structure to (sea)water potential, pipe to electrolyte potential and pipe to soil potential are sometimes used as
39、 applicable in the particular context. Requisition - the data/requisition sheet(s) DEP 30.10.73.94-Gen., to be used by the Principal and completed by the Contractor. A specimen copy for information is included in Appendix 1. The actual sheets can be found in the requisitioning binder (DEP 30.10.01.1
40、0-Gen.). 1.4ABBREVIATIONS Ag/AgClSilver/silver chloride as used for the Silver/silver chloride type of reference electrode. Cu/CuSO4Copper/copper sulphate as used for the Copper/copper sulphate type of reference electrode. ACAlternating current Ah/kgAmpere-hours per kilogram DCDirect current DNVDet
41、Norske Veritas GREGlass reinforced epoxy PEPolyethylene SCESaturated calomel electrode 1.5CROSS-REFERENCES Where cross-references to other parts of this DEP are made, the referenced section is shown in brackets. Other documents referenced by this DEP are listed in (Part IV). 1.6GUIDANCE FOR USE Part
42、 III contains amendments/supplements which are directly related to equivalent sections in DNV RP B401. For clarity, the section numbering of DNV RP B401 has been used. Where sections in DNV RP B401 are referenced in this DEP, those sections as amended/supplemented by this DEP are meant. Sections in
43、DNV RP B401 that are not amended/supplemented by this DEP shall remain valid as written. DEP 30.10.73.32-Gen. July 1996 Page 5 PART II DESIGN PHILOSOPHY 1.1GENERAL Offshore pipelines shall be protected from sub-sea corrosion using a combination of external coatings and cathodic protection. The catho
44、dic protection system shall be designed to maintain the exposed pipeline metal surfaces within an electrochemical potential range which controls corrosion within acceptable limits without causing material damage. The recommended cathodic protection system for newly constructed offshore pipelines fea
45、tures bracelet-type sacrificial anodes. The use of impressed current is not recommended except where successfully in use for existing pipelines and for retrofit purposes when sacrificial systems are not feasible. For offshore pipelines the pipe-to-sea water “ON“ potential is used as a criterion for
46、effective cathodic protection. “OFF“ potentials may be applicable to impressed current systems in high-resistivity waters. The cathodic protection system shall maintain the pipe-to-sea water potential of pipelines between - 800 and -1100 mV with respect to an Ag/AgCl reference cell. The effect of ca
47、thodic protection on corrosion resistant steels and some high strength steels depends on the susceptibility of the material to hydrogen induced stress cracking. Practical potential levels obtained from cathodic protection systems using Zinc or Aluminium sacrificial anodes are such that polarisation
48、more negative than the above overprotection limit is avoided. Therefore, the use of materials, welded or not welded, susceptible to hydrogen embrittlement within the specified potential range shall not be used in conjunction with cathodic protection. Magnesium anodes or impressed current cathodic pr
49、otection shall not be used for high strength steels or corrosion resistant steels. The cathodic protection system shall be designed for the full design life of the pipeline. Electrical pipeline isolation between compatible sacrificial anode cathodic protection systems installed on platforms and pipelines is not required. Offshore pipelines shall, however, be electrically isolated from on-shore pipelines and shore installations, structures equipped with impressed current systems and structures operated by third parties. For new construction projects, the design of the cathodic protection syste