1、 Standard Practice Steel-Cased Pipeline Practices 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, whether he or she has adopted the standard or not,
2、 from manufacturing, marketing, purchasing, or using products, processes, or procedures not in conformance with this standard. Nothing contained in this NACE standard is to be construed as granting any right, by implication or otherwise, to manufacture, sell, or use in connection with any method, ap
3、paratus, 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 restriction on the use of better procedures or materials. Neither is thi
4、s standard intended to apply in all cases relating to the subject. Unpredictable circumstances may negate the usefulness of this standard in specific instances. NACE assumes no responsibility for the interpretation or use of this standard by other parties and accepts responsibility for only those of
5、ficial NACE interpretations issued by NACE in accordance with its governing procedures and policies which preclude the issuance of interpretations by individual volunteers. Users of this NACE standard are responsible for reviewing appropriate health, safety, environmental, and regulatory documents a
6、nd for determining their applicability in relation to this standard prior to its use. This NACE standard may not necessarily address all potential health and safety problems or environmental hazards associated with the use of materials, equipment, and/or operations detailed or referred to within thi
7、s standard. Users of this NACE standard are also responsible for establishing appropriate health, safety, and environmental protection practices, in consultation with appropriate regulatory authorities if necessary, to achieve compliance with any existing applicable regulatory requirements prior to
8、the use of this standard. CAUTIONARY NOTICE: NACE standards are subject to periodic review, and may be revised or withdrawn at any time in accordance with NACE technical committee procedures. NACE requires that action be taken to reaffirm, revise, or withdraw this standard no later than five years f
9、rom the date of initial publication and subsequently from the date of each reaffirmation or revision. The user is cautioned to obtain the latest edition. Purchasers of NACE standards may receive current information on all standards and other NACE publications by contacting the NACE FirstService Depa
10、rtment, 15835 Park Ten Place, Houston, TX 77084 (telephone +1 281-228-6200). Revised 2014-06-26 Reaffirmed 2008-03-20 Approved 2000-01-14 NACE International 15835 Park Ten Place Houston, Texas 77084 +1 281 228-6200 ISBN 1-57590-094-7 2014, NACE International NACE SP0200-2014 (formerly RP0200) Item N
11、o. 21091 SP0200-2014 _ Foreword This standard practice details acceptable practices for the design, fabrication, installation, and maintenance of steel-cased metallic pipelines. It is intended for use by personnel in the pipeline industry. The use of cased carrier pipe for pipelines crossing under h
12、ighways and railroads has been common practice in the industry. The first cased crossings were made using large-diameter pipe. The carrier pipe was mechanically coupled and pushed through the casing, and the coupling or collars were in direct contact with it. When coatings came into general use, iso
13、lating spacers were made of hemp rope saturated with pipe-coating enamel. End seals consisting of either concrete or pipe-coating enamel were poured into each end of the casing. The current practice of installing cased carrier pipe has changed only slightly since the beginning of its use. External l
14、oading of the carrier pipe has now been eliminated by the installation of heavy-wall casing pipe, and isolating spacers are used to prevent electrical contact between the casing and the carrier pipe. End seals are used to keep electrolyte (e.g., mud, water) out of the annular space between the carri
15、er pipe and casing. This standard was originally prepared in 2000 by NACE Task Group T-10A-18, a component of Unit Committee T-10A, “Cathodic Protection.” It is based on NACE Publication 10A192, “State of the Art Report on Cased Pipeline Practices,” written by the same task group in 1992. This stand
16、ard was reaffirmed in 2008 by Specific Technology Group (STG) 35, “Pipelines, Tanks, and Well Casings,” and revised in 2014 by Task Group (TG) 012, “Pipelines, Steel-Cased.” It is also sponsored by STG 05, “Cathodic/Anodic Protection.” It is issued by NACE International under the auspices of STG 35.
17、 In NACE standards, the terms shall, must, 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
18、recommended, but is not considered mandatory. The term may is used to state something considered optional. _ NACE International i SP0200-2014 _ Standard Practice Steel-Cased Pipeline Practices Contents 1. General 1 2. Definitions 1 3. Design . 1 4. Installation . 3 5. Maintenance And Repair . 5 6. M
19、onitoring 6 References 8 Bibliography . 8 APPENDIXES Appendix A: Options for Mitigation of Carrier Pipe Corrosion In the Casing Annulus (Nonmandatory) . 10 Appendix B: Monitoring Techniques (Nonmandatory) 14 Appendix C: Clearing a Shorted Casing (Nonmandatory). 28 Appendix D: Removing a Casing (Nonm
20、andatory) . 30 Appendix E: Guidelines for Selection of Indirect Inspection Tools for Cased Pipe (Nonmandatory) . 32 FIGURES Figure B1: Potential Survey Measurement 14 Figure B2: Internal Resistance Test 15 Figure B3: Four-Wire IR Drop Test (Calibrating the Inside Terminals) . 18 Figure B4: Establish
21、ing a circuit for a Four-Wire IR Drop Test (U/S End) . 19 Figure B5: Four-Wire IR Drop Test (Establishing the Circuit) (D/S End) 19 TABLES Table B1: Example 1: Electrical Isolation . 23 Table B2: Example 2: Electrical Isolation . 23 Table B3: Example 3: Electrically Shorted Condition . 24 Table B4:
22、Pipe Data 25 Table E1: Inspection Tools for Cased Pipe . 32 _ ii NACE International SP0200-2014 _ Section 1: General 1.1 Steel casings are used to install and maintain pipeline crossings such as those at road and railroad right-of-ways. This standard details acceptable practices for the design, fabr
23、ication, installation, maintenance, and monitoring of steel-cased pipelines. 1.2 The use of cased crossings should take into account load considerations, unstable soil conditions, protection from third-party damage, sound engineering practices, and regulatory requirements. 1.3 This standard does not
24、 imply that utilization of casings is mandatory or necessary. 1.4 This standard does not imply that cased crossings, whether electrically isolated or electrically shorted, contribute to corrosion of a carrier pipe within a cased crossing. However, cased crossings may adversely affect the integrity o
25、f the carrier pipe by shielding cathodic protection (CP) current to the pipe or reducing the CP effectiveness on the pipe in the vicinity of the casing, including if the casing is coated and electrolytic contact exists between the casing and carrier pipe (see Paragraph 3.2.3 in Casing Design). 1.5 T
26、he practices contained in this standard may or may not be applicable to casings installed prior to its issuance. It is presumed that all practices described in this standard are performed in a safe manner. _ Section 2: Definitions Carrier Pipe: A pipe inside a casing, which carries a product such as
27、 a gas and/or a liquid. Casing: A metallic pipe used to protect the carrier pipe. Also referred to as Encasement Pipe. Dogleg: A term used to describe a vent pipe that is offset, which may cause the below-ground portion to appear to be shaped like the rear leg of a dog. The vent is offset as necessa
28、ry to place the above-ground portion in a more acceptable location (e.g., to locate it off a right-of-way or to locate it where it is less susceptible to potential damage). End Seal: A dielectric material to seal the end of a casing to assist in preventing water and soil ingress. Electrolytic Couple
29、: Ionic contact between two metallic structures via an electrolyte. Electrolyte inside the casing that is in contact with the carrier pipe is an example of electrolytic couple. Filler: A product placed in the annular space between the carrier pipe and the casing pipe to inhibit corrosion and assist
30、in preventing the ingress of electroyte. Isolator or Spacer: A dielectric device specifically designed to electrically isolate a carrier pipe from a casing and provide support for the carrier pipe. Metallic Short: Direct metallic contact between two metallic structures. Split Sleeve: A method of in
31、situ casing installation by welding two halves of the casing (split sleeve) together around the carrier pipe. Test Leads: Electrical wiring attached to the casing and or carrier pipe for conducting electrical tests. NACE International 1 SP0200-2014 _ Section 3: Design 3.1 Carrier Design 3.1.1 Unless
32、 prohibited by regulation or right-of-way agreement, consideration should be given to adding supplementary carrier pipe wall thickness or pipe burial depth, in lieu of casing (refer to API(1)RP 11021or other applicable standards). 3.1.2 The carrier pipe shall be effectively coated, with consideratio
33、n being given to the application of supplementary coating. See NACE SP01691for details. 3.1.3 The carrier pipe shall be properly supported inside and outside the casing to prevent metallic contact between the casing and the carrier pipe. See NACE SP02862for details. 3.2 Casing Design 3.2.1 The casin
34、g should be kept as short in length as possible. 3.2.2 For pipelines 200 mm (8.0 in) in diameter and larger, the diameter of the casing should be a minimum of 100 mm (4.0 in) larger than that of the carrier pipe. For pipelines smaller than 200 mm (8.0 in) in diameter, the diameter of the casing is n
35、ormally a minimum of 50 mm (2.0 in) larger than that of the carrier pipe. 3.2.2.1 Selection of casing diameter should also take into consideration the dimensions of isolators and thickness of coatings to be installed on the carrier pipe. This is particularly important if there are additional coating
36、s, such as concrete or epoxy-polymer concrete. 3.2.2.2 Casing diameter selection must also consider adequate clearance for pipe with bell and spigot joints, flange joints, etc. 3.2.3 Casings can be coated or uncoated. However, the use of coated or nonmetallic casings may result in shielding problems
37、. 3.2.4 Vent pipes should be installed on both ends of a casing, one on top of the casing at the high elevation end and one on the bottom of the casing at the low elevation end. The vents should be positioned so that they are not directly over or under any isolating spacer or end seal. Care should b
38、e taken that the casing vents are not blocked during installation of the carrier pipe. 3.2.5 The casing vent hole should be at least one-half the diameter of the vent pipe (25 mm 1.0 in minimum). The casing vent pipe should be a minimum of 50 mm (2.0 in) in diameter. 3.2.6 The casing and carrier pip
39、e shall be properly supported for the entire length of the pipe, especially near the ends, to prevent sagging, metallic contact, and carrier pipe stress. Refer to Paragraphs 4.3 and 4.4. 3.2.7 Casing end seals shall be designed to prevent ingress of water and debris. 3.2.8 Vent pipes shall be design
40、ed, using standard industry methods, to prevent intrusion of water and debris. 3.3 Metallic Isolation Design 3.3.1 Sufficient electrically nonconductive spacing material shall be specified to prevent metallic contact between the carrier pipe and the casing, provide adequate support, and minimize coa
41、ting damage during installation. Refer to Paragraph 4.4. 3.3.2 Casing isolators shall be carefully selected to ensure they have the mechanical strength required to withstand the actual installation, considering all conditions including pipe weight, length of casing, weight of the product the carrier
42、 pipe will be conveying, conditions of weld beads, deflections in the casing, and other field conditions. Selection should include an evaluation of the ability of the casing isolators to provide electrical isolation after enduring the rigors of installation, and to position the carrier pipe for prop
43、er end seal application. (See NACE SP0286 for additional information.) (1)American Petroleum Institute (API), 1220 L St. NW, Washington, DC 20005-4070. 2 NACE International SP0200-2014 3.3.3 The selection of the appropriate end seal depends on the position of the carrier pipe at the end of the casin
44、g. Most watertight seals, such as modular mechnical seals, require that the carrier pipe be positioned in the center of the casing, whereas most rubber boots allow for some amount of off-centered positioning. Other considerations (such as temperature, materials, and pressure capabilities) should be
45、considered (See Appendix A). 3.3.4 Electrical testing facilities shall be designed to permit verification of metallic isolation after installation. Refer to Paragraph 4.5 and Section 6. 3.4 Other Design Considerations for Mitigation of Carrier Pipe Corrosion in the Casing Annulus 3.4.1 CP may be con
46、sidered in some situations and designed for the casing as required by conditions or regulations. See NACE SP0169 for details. 3.4.2 Consideration may be given to placing inhibited dielectric filler in the annular space. Refer to Appendix A (nonmandatory), Filling the Casing Annulus with Petrolatum W
47、ax or Petroleum-Based Compounds, Paragraph A2. 3.4.3 Consideration may be given to using multiphase vapor or gel corrosion inhibitor systems. Refer to Appendix A (nonmandatory), Treating the Casing Annulus with Corrosion Inhibiting Products, Paragraph A3. 3.4.4 Sound engineering practices shall be u
48、sed in the selection of casing materials. 3.4.5 When there are HVAC power lines over the pipeline, electrical system grounding, and/or counterpoise in close proximity to the pipeline, these conditions may create possible electrical safety hazards and an increased risk for AC corrosion. When present, additional precautions should be evaluated. Bonding of the carrier pipe to the casi
