1、 Standard Practice Control of External Corrosion on Underground or Submerged Metallic Piping Systems This NACE International standard represents a consensus of those individual members who have reviewed this document, its scope, and provisions. Its acceptance does not in any respect preclude anyone,
2、 whether he or she has adopted the standard or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not in conformance with this standard. Nothing contained in this NACE International standard is to be construed as granting any right, by implication or otherwis
3、e, to manufacture, sell, or use in connection with any method, apparatus, or product covered by Letters Patent, or as indemnifying or protecting anyone against liability for infringement of Letters Patent. This standard represents minimum requirements and should in no way be interpreted as a restric
4、tion on the use of better procedures or materials. Neither is this standard intended to apply in all cases relating to the subject. Unpredictable circumstances may negate the usefulness of this standard in specific instances. NACE International assumes no responsibility for the interpretation or use
5、 of this standard by other parties and accepts responsibility for only those official NACE International interpretations issued by NACE International in accordance with its governing procedures and policies which preclude the issuance of interpretations by individual volunteers. Users of this NACE I
6、nternational standard are responsible for reviewing appropriate health, safety, environmental, and regulatory documents and for determining their applicability in relation to this standard prior to its use. This NACE International standard may not necessarily address all potential health and safety
7、problems or environmental hazards associated with the use of materials, equipment, and/or operations detailed or referred to within this standard. Users of this NACE International standard are also responsible for establishing appropriate health, safety, and environmental protection practices, in co
8、nsultation with appropriate regulatory authorities if necessary, to achieve compliance with any existing applicable regulatory requirements prior to the use of this standard. CAUTIONARY NOTICE: NACE International standards are subject to periodic review, and may be revised or withdrawn at any time i
9、n accordance with NACE technical committee procedures. NACE International requires that action be taken to reaffirm, revise, or withdraw this standard no later than five years from the date of initial publication. The user is cautioned to obtain the latest edition. Purchasers of NACE International s
10、tandards may receive current information on all standards and other NACE International publications by contacting the NACE International FirstService Department, 1440 South Creek Drive, Houston, Texas 77084-4906 (telephone +1 281-228-6200). Revised 2013-10-04 Reaffirmed 2007-03-15 Reaffirmed 2002-04
11、-11 Reaffirmed 1996-09-13 Revised April 1992 Revised January 1983 Revised September 1976 Revised January 1972 Approved April 1969 NACE International 1440 South Creek Drive Houston, Texas 77084-4906 +1 281-228-6200 ISBN 1-57590-035-1 2013, NACE International SP0169-2013 (formerly RP0169) Item No. 210
12、01 SP0169-2013 NACE International i _ Foreword This standard presents methods and practices for achieving effective control of external corrosion on underground or submerged metallic piping systems. These methods and practices are also applicable to many other underground or submerged metallic struc
13、tures. It is intended for use by corrosion control personnel concerned with the corrosion of underground or submerged piping systems, such as those used for the transport of oil, gas, water, and other fluids. This standard describes the use of electrically insulating coatings, electrical isolation,
14、and cathodic protection (CP) as they relate to external corrosion control. This standard does not include corrosion control methods based on injection of chemicals into the environment, on the use of electrically conductive coatings, or on the use of nonadhered polyethylene encasement (refer to NACE
15、 Publication 10A292).1 The standard contains specific provisions for the application of CP to existing uncoated, existing coated, and new piping systems. Also included are methods for control of stray currents on pipelines. This standard should be used in conjunction with the practices described in
16、the following NACE standards and publications, when appropriate (use latest revisions): SP05722 SP01773 SP02854 SP02865 SP01886 TPC 117 TM04978 For accurate and correct application, this standard must be used in its entirety. Using or citing only specific paragraphs or sections can lead to misinterp
17、retation and misapplication of the practices contained in this standard. This standard does not designate practices for every specific situation because of the complexity of conditions to which underground or submerged piping systems are exposed. This standard is not intended to apply to offshore pi
18、pelines and structures. For these facilities, the recommended NACE standards are NACE SP0607/ISO 15589-29 for offshore pipelines, and SP017610 for offshore structures. Definitions of onshore and offshore vary, and it is the responsibility of the user to determine which of the above standards apply t
19、o pipelines across coastal boundaries. This standard was originally published in 1969, and was revised by NACE Task Group T-10-1 in 1972, 1976, 1983, and 1992. It was reaffirmed in 1996 by NACE Unit Committee T-10A, “Cathodic Protection,” and in 2002 and 2007 by Specific Technology Group (STG) 35, “
20、Pipelines, Tanks, and Well Casings.” It was revised in 2013 by Task Group (TG) 360, “Piping Systems: Review of SP0169-2007 (formerly RP0169), Control of External Corrosion on Underground or Submerged Metallic Piping.” This standard is issued by NACE International under the auspices of STG 35, which
21、is composed of corrosion control personnel from oil and gas transmission companies, gas distribution companies, power companies, corrosion consultants, and others concerned with external corrosion control of underground or submerged metallic piping systems. In NACE standards, the terms shall, must,
22、should, and may are used in accordance with the definitions of these terms in the NACE Publications Style Manual. The terms shall and must are used to state a requirement, and are considered mandatory. The term should is used to state something good and is recommended, but is not considered mandator
23、y. The term may is used to state something considered optional. _ SP0169-2013 ii NACE International _ Standard Practice Control of External Corrosion on Underground or Submerged Metallic Piping Systems Contents 1. General 1 2. Definitions, Abbreviations, and Acronyms . 1 3. Determination of Need for
24、 External Corrosion Control 7 4. Piping System Design . 9 5. External Coatings 12 6. Criteria and Other Considerations for Cathodic Protection . 17 7. Design of Cathodic Protection Systems 22 8. Installation of CP Systems 25 9. Control of Stray Currents . 28 10. Operation and Maintenance of CP Syste
25、ms . 30 11. External Corrosion Control Records . 32 References 34 Bibliography . 40 Appendix A: External Coatings Tables . 44 Appendix B: Review of International Standards . 48 FIGURES Figure 1: Residual Corrosion Rate of Carbon Steel Specimens as a Function of AC and CP Current Density. Laboratory
26、Tests Performed in Simulated Soil Conditions. . 19 Figure 2: SCC Range of Pipe Steel in Carbonate/Bicarbonate Environments. 20 TABLES Table 1a: Generic External Coating Systems for Carbon Steel Pipe with Material Requirements and Recommended Practices for Application for Underground and Submerged Pi
27、pe (Field- and Shop-Applied) 13 Table 1b: Generic External Coating Systems for Ductile Iron Pipe with Material Requirements and Recommended Practices for Application 14 Table 2: Common Reference Electrodes and Their Potentials and Temperature Coefficients 22 Table A1: References for General Use in t
28、he Installation and Inspection of External Coating Systems for Underground or Submerged Piping . 45 Table A2: External Coating System Characteristics Relative to Environmental Conditions . 45 Table A3(a): External Coating System Characteristics Related to Design and Construction 46 Table A3(b): Exte
29、rnal Coating System Characteristics Related to Design and Construction: Design and Construction Factor Recommended Test Methods 47 Table A4: Methods for Evaluating Field Performance of External Coatings 48 Appendix B: Review of International Standards . 48 _ SP0169-2013 NACE International 1 _ Sectio
30、n 1: General 1.1 This standard presents accepted methods and practices for the control of external corrosion on buried or submerged steel, stainless steel, cast iron, ductile iron, copper, and aluminum piping systems. 1.2 This standard is intended to serve as a guide for establishing requirements fo
31、r control of external corrosion on the following systems: 1.2.1 New piping systems: A proven method of corrosion control (e.g., coating supplemented with CP) should be provided in the initial design and maintained during the service life of the piping system, unless investigations indicate that corr
32、osion control is not required. Consideration should be given to the construction of piping in a manner that facilitates the use of in-line inspection (ILI) tools. 1.2.2 Existing coated piping systems: CP should be provided and maintained (which includes the maintenance of coating as necessary), unle
33、ss investigations indicate that CP is not required. 1.2.3 Existing uncoated piping systems: Studies can be made to determine the extent and rate of corrosion on existing uncoated piping systems. When these studies indicate that corrosion affects the safe or economic operation of the system, adequate
34、 corrosion control measures shall be taken. 1.3 The provisions of this standard are intended to be applied under the direction of competent persons who, by reason of knowledge of the physical sciences and the principles of engineering and mathematics, acquired by education and related practical expe
35、rience, are qualified to engage in the practice of corrosion control on underground or submerged metallic piping systems. Note: Such persons might be, but are not limited to, registered professional engineers or persons recognized as Corrosion Specialists or CP Specialists by NACE, if their professi
36、onal activities include suitable experience in external corrosion control of underground or submerged metallic piping systems. 1.4 Special conditions in which CP is ineffective or only partially effective sometimes exist (see Paragraph 6.2.1.4 for examples). Deviation from this standard might be war
37、ranted in specific situations provided that corrosion control personnel in responsible charge are able to demonstrate that the objectives expressed in this standard have been achieved. 1.5 This standard is not intended for use in the control of internal corrosion. _ Section 2: Definitions,(1) Abbrev
38、iations, and Acronyms Definitions: Amphoteric Metal: A metal that is susceptible to corrosion in both acid and alkaline environments. Anode: The electrode of an electrochemical cell at which oxidation occurs. (Electrons flow away from the anode in the external circuit. It is usually the electrode wh
39、ere corrosion occurs and metal ions enter solution.) Anode Bed: One or more anodes installedunderground or submergedfor the purpose of supplying cathodic protection. It is often called a groundbed. Backfill: Material placed in a hole to fill the space around the anodes, vent pipe, and buried compone
40、nts of a cathodic protection system. For the purposes of this standard, “backfill” is also defined as the material (native or imported) used to fill a pipeline trench. Beta Curve: A plot of dynamic (fluctuating) stray current or related proportional voltage (ordinate) versus the corresponding struct
41、ure-to-electrolyte potentials at a selected location on the affected structure (abscissa). For the purposes of this standard, (1) Definitions in this section reflect common usage among practicing corrosion control personnel and apply specifically to how the terms are used in this standard. In many c
42、ases, in the interests of brevity and practical usefulness, the scientific definitions are abbreviated or paraphrased. SP0169-2013 2 NACE International “Beta Curve” is defined as a correlation between the pipe-to-soil potential of the affected pipeline and the open-circuit potential between the affe
43、cted pipeline and the stray current source. Cable: One conductor or multiple conductors insulated from one another. Casing: A metallic pipe (normally steel) installed to contain a pipe or piping. Cathode: The electrode of an electrochemical cell at which reduction is the principal reaction. (Electro
44、ns flow toward the cathode in the external circuit.) Cathodic Disbondment: The destruction of adhesion between a coating and the coated surface caused by products of a cathodic reaction. Cathodic Polarization: (1) The change of electrode potential caused by a cathodic current across the electrode/el
45、ectrolyte interface; (2) a forced active (negative) shift in electrode potential. See Polarization. Cathodic Protection: A technique to reduce the corrosion of a metal surface by making that surface the cathode of an electrochemical cell. Cathodic Protection Criterion: Standard for assessment of the
46、 effectiveness of a cathodic protection system. Coating: (1) A liquid, liquefiable, or mastic composition that, after application to a surface, is converted into a solid protective, decorative, or functional adherent film; (2) (in a more general sense) a thin layer of solid material on a surface tha
47、t provides improved protective, decorative, or functional properties. Coatings used in conjunction with cathodic protection are electrically isolating materials applied to the surface of the metallic structure that provides an adherent film that isolates the metallic structure from the surrounding e
48、lectrolyte. The thickness and structure of the coating type vary according to the environment and application parameters. Coating Disbondment: The loss of adhesion between a coating and the pipe surface. Coating System: The complete number of coats and type applied to a substrate in a predetermined order. (When used in a broader sense, surface preparation, pretreatments, dry film thickness, and manner of applicati
