1、 Standard Practice Metallurgical and Inspection Requirements for Offshore Pipeline Bracelet Anodes 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, w
2、hether 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 otherwise,
3、 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 restricti
4、on 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 o
5、f 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 Int
6、ernational 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 pr
7、oblems 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 cons
8、ultation 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 CAUTIONARY NOTICE: NACE International standards are subject to periodic review, and may be revised or withdrawn at any time wit
9、hout prior notice. 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 standards may receive current informa
10、tion on all standards and other NACE International publications by contacting the NACE FirstService Department, 1440 South Creek Drive, Houston, Texas 77084-4906 (telephone +1 281228-6200). Reaffirmed 2006-07-18 Reaffirmed 1999-04-28 Approved April 1992 NACE International 1440 South Creek Drive Hous
11、ton, Texas 77084-4906 +1 (281) 228-6200 ISBN 1-57590-080-7 2006, NACE InternationalNACE Standard SP0492-2006 (formerly RP0492-99) Item No. 21056 SP0492-2006 NACE International i _ Foreword The purpose of this standard practice is to set minimum physical quality and inspection requirements for cast g
12、alvanic anodes for offshore pipeline applications. The objectives are to standardize an industry-wide practice that can be used by consultants, manufacturers, and users to define the physical requirements of anodes and to be sufficiently specific to assist inspection authorities in their task of con
13、firming that anodes comply with the physical requirements. This standard is applicable to typical half-shell or segmented bracelet-type anodes. This standard was originally prepared in 1992 by Task Group T-7L-9, a component of Unit Committee T-7L on Cathodic Protection. It was reaffirmed by T-7L in
14、1999, and in 2006 by Specific Technology Group (STG) 30 on Oil and Gas ProductionCathodic Protection. This standard is published under the auspices of STG 30. In NACE standards, the terms shall, must, should, and may are used in accordance with the definitions of these terms in the NACE Publications
15、 Style Manual, 4th.ed., Paragraph 7.4.1.9. Shall and must are used to state mandatory requirements. The term should is used to state something considered good and is recommended but is not mandatory. The term may is used to state something considered optional. _ SP0492-2006 ii NACE International _ N
16、ACE International Standard Practice Metallurgical and Inspection Requirements for Offshore Pipeline Bracelet Anodes Contents 1. General . 1 2. Definitions . 1 3. Physical Requirements of Anodes 2 4. Documentation of Inspection 5 References 6 _ SP0492-2006 NACE International 1 _ Section 1: General 1.
17、1 This standard defines minimum physical quality and inspection requirements for bracelet galvanic anodes for offshore pipeline applications, including risers and J-tubes. 1.2 This standard is applicable to the majority of bracelet-type anodes used on offshore pipelines, i.e., anodes of half-shell o
18、r segmented configurations. For other anode designs, such as semi-cylindrical segments with cast-in longitudinal notches, an experienced corrosion specialist should be responsible for defining the acceptance criteria. 1.3 This standard does not specify particular anode alloy compositions or define s
19、hort- or long-term performance tests. 1.4 This standard does not specify particular anode or anode insert designs. An experienced corrosion specialist should be responsible for anode and anode insert design. 1.5 Although some aspects of this standard may be relevant to other types of galvanic anodes
20、, it is not intended to apply to platform, hull, tank, or extruded-type anodes. 1.6 This standard does not address electrochemical or other anode performance test procedures. NACE Standard TM01901gives a standardized short-term potential and capacity determination test procedure for quality control
21、purposes in international laboratories. 1.7 The manufacturer is responsible for meeting the quality levels specified in this standard. The purchaser shall determine the extent of inspection to be conducted by the purchasing organization to prove compliance with the quality specified. _ Section 2: De
22、finitions Bracelet Anodes: Galvanic anodes with geometry suitable for direct attachment around the circumference of a pipeline. These may be half-shell bracelets consisting of two semi-circular sections or segmented bracelets consisting of a large number of individual anodes. Certificate of Conformi
23、ty: A statement from the manufacturers representative (executive) and endorsed by a representative of the purchaser affirming that the anodes listed comply with the requirements of the order. Cold Lap: (1) Discontinuity caused by solidification of the meniscus of a partially cast anode as a result o
24、f interrupted flow of the casting stream. The solidified meniscus is covered with metal when the flow resumes. Cold laps can occur along the length of an anode. (2) A protective film consisting of one or more coats, applied in a predetermined order by prescribed methods to an as-specified dry film t
25、hickness, including any reinforcing material that may be specified. Cold Shut: Horizontal surface discontinuity caused by solidification of a portion of a meniscus during the progressive filling of a mold, which is later covered with more solidifying metal as the molten metal level rises. Cold shuts
26、 generally occur at corners remote from the point of pour. Cracking: Fracture of metal along an irregular path producing a discontinuity similar to a ragged edge. It can occur during the solidification of the anode (hot cracking), during the contraction of the anode after solidification, or under ex
27、ternally applied loads. Hot cracking may be associated with the shrinkage depression that can occur in open-topped molds. Dulling of Steels: Deterioration in the appearance of shot-blasted inserts due to oxidation that causes darkening of the surface but not rust discoloration (see Rust Discoloratio
28、n). Electrochemical Properties: Those properties of potential and current capacity that characterize a sacrificial anode and can be assessed by quantitative tests. Former: A length of pipe of diameter appropriate to the cast anode bracelet that can be used as a form to mechanically straighten a defo
29、rmed casting. Galvanic Anode: A metal that provides the sacrificial protection to another metal that is more noble when electrically coupled in an electrolyte. This type of anode is the electron source in one type of cathodic protection. Gas Holes: Evidence of bubbles within the solidifying metal. T
30、he holes can indicate that moisture was on the mold or insert prior to casting or that the liquid metal contained a high level of hydrogen that formed bubbles during cooling of the metal. Heat: Also called a melt or cast, it is the unit that defines molten metal and identifies the anodes cast from i
31、t. A heat is the product that is cast to a planned procedure in one melting operation in one furnace, without significant interruption. If the casting sequence is interrupted, the anodes produced before, between, and after the interruption constitute batches. SP0492-2006 2 NACE International Insert:
32、 The form over which the anode is cast. This is sometimes referred to as a core. Low-Carbon Steel: Steel having less than 0.30% carbon and no intentional alloying additions. Nonmetallic Inclusions: Particles of oxides and other refractory materials entrapped in liquid metal during the melting or cas
33、ting sequences. Porosity: Uniformly distributed fine holes caused by gas bubbles, shrinkage (formed by the starvation of eutectic material within the dendrite arms during “unfed” solidification), or a combination of the two mechanisms when hydrogen in solution diffuses into the lower-pressure shrink
34、age voids. Protrusion: Extraneous material on the anode surface. It may interfere with the anode-to-structure fit, appear unattractive, and be a safety hazard if there are sharp edges. Protrusions can be formed by careless filling of the mold or the flash from imperfect fitting of mold sections. Rim
35、med Steel: An incompletely deoxidized steel. Also called Rimming Steel. (See ASM(1)Handbook, Desk Ed.,2for a detailed definition.) Rust Discoloration: A brown bloom of iron oxide. Sacrificial Anodes: See Galvanic Anode. Sample: A representative specimen. Shrinkage Depression: The natural concave sur
36、face produced when liquid metal is allowed to solidify in a container without the provision of extra liquid metal to compensate for the reduction in volume that occurs during the liquid-solid transformation. The term also applies to the concave surface produced when liquid metal is solidified in a c
37、losed mold in such a manner that the area is not “fed” by the liquid metal provided by the riser of the casting. Tap Sample: A specimen taken from a molten metal stream. Such samples may be taken at the commencement of pouring and then at regular intervals until a final sample is taken at the end of
38、 the pour. Voids Adjacent to Insert: Visible spaces between anode and anode insert materials. These can be caused by surface evaporation of moisture from the insert, contraction of the insert, or movement of the insert during casting caused by uneven heating and expansion that distorts the insert an
39、d prevents it from returning to its original, desired position within the anode. _ Section 3: Physical Requirements of Anodes 3.1 Samples for Chemical Analysis 3.1.1 Representative tap samples shall be taken at the beginning and end of each heat. All samples shall be hard stamped or engraved with th
40、e heat number and retained for the contract period. 3.1.2 The samples shall be analyzed to prove compliance with the agreed chemical composition limits of the alloy being produced. 3.2 Anode Identification 3.2.1 Each anode individual casting shall be marked with its unique heat number and the manufa
41、cturers mark. For as-treated anodes, a heat treatment batch number shall be provided on each anode. 3.3 Anode Weight 3.3.1 The net weight of individual anode castings shall be greater than 97% of the design net weight. 3.3.2 An agreed sample of anode castings shall be weighed, either individually or
42、 in small batches, to confirm general compliance with Paragraph 3.3.1. 3.3.3 The total supplied net weight shall not be below the nominal net contract weight. 3.4 Anode Dimensions and Straightness 3.4.1 Dimensions shall conform to the following: 3.4.1.1 The mean length of the anode casting shall be
43、3% of nominal length or 25 mm (1.0 in.), whichever is smaller. 3.4.1.2 Anode internal diameter shall conform to the following dimensional tolerances (for semi-cylindrical, see Paragraph 1.2): (a) -0/+4 mm (0.16 in.) for pipeline diameters 305 mm (12.0 in.); (b) -0/+6 mm (0.24 in.) for pipeline diame
44、ters 305 mm (12.0 in.) and 610 mm (24.0 in.); and (c) -0/+1% for pipeline diameters 610 mm (24.0 in.). 3.4.1.3 The dimensional tolerance on the anode thickness shall be 3 mm (0.12 in.). 3.4.2 Anodes shall be free from excessive bowing or _ (1)ASM International (ASM), 9639 Kinsman Rd., Materials Park
45、, OH 44073-0002. SP0492-2006 NACE International 3 twisting. This shall be verified on a completely assembled bracelet by fitting to a full-length former or by another agreed method. The external diameter shall not exceed the summation of the tolerances given in Paragraphs 3.4.1.2 and 3.4.1.3. 3.4.3
46、For all anodes, the anode and anode insert dimensions shall be suitable for the proposed fitting requirements. 3.4.4 The number of samples to be measured to prove compliance with Paragraphs 3.4.1 and 3.4.2 shall be subject to agreement prior to manufacture. 3.5 Insert Dimensions and Position 3.5.1 A
47、ny special provisions needed to make the insert a suitable means of attachment shall predominate in the requirements of Paragraphs 3.4, 3.5, 3.6, and 3.7. 3.5.2 Anode insert cross-section dimensions shall comply with the appropriate specification for the insert material used. 3.5.3 Tolerances on ins
48、ert position within the anode shall be subject to agreement prior to manufacture. 3.5.4 Anode insert protrusions, fixing centers, and any other critical dimensions specified in the contract pursuance of Paragraph 3.5.1 shall be measured on samples of all anodes of each type. The number of samples shall be agreed on prior to manufacture. 3.6 Insert Material 3.6.1 I
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