NACE TM0190-2012 Impressed Current Laboratory Testing of Aluminum and Zinc Alloy Anodes (Item No 21221).pdf

1、 Standard Test Method Impressed Current Laboratory Testing of Aluminum and Zinc Alloy 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, whether

2、 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, to ma

3、nufacture, 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 restriction on

4、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 of this

5、 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 Internati

6、onal 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 problems

7、 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 consultati

8、on 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 in accord

9、ance 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 and subsequently from the date of each reaffirmation or revision. The user is cautioned to obta

10、in the latest edition. Purchasers of NACE International standards may receive current information on all standards and other NACE International publications by contacting the NACE International FirstService Department, 1440 South Creek Dr., Houston, TX 77084-4906 (telephone +1 281-228-6200). Revised

11、 2012-10-05 Reaffirmed 2006-07-18 Revised 1998-06-26 Approved April 1990 NACE International 1440 South Creek Drive Houston, TX 77084-4906 +1 281-228-6200 ISBN 1-57590-060-2 2012, NACE International NACE Standard TM0190-2012 Item No. 21221 TM0190-2012 ii NACE International TM0190-2012 NACE Internatio

12、nal i _ Foreword This standard test method describes a quality assurance procedure for determining the potential and current capacity characteristics under laboratory conditions for aluminum and zinc alloy anodes used for cathodic protection (CP). Field performance of anodes should be evaluated to c

13、orrespond to actual anode performance. This standard is intended primarily for users, designers, and manufacturers involved with the application of CP in marine environments. This standard can be used by manufacturers and users of aluminum and zinc anodes for quality control verification. The most c

14、ommon usage is expected to be by manufacturers to meet quality control requirements requested by the purchasing user. This standard is based on experiences from the paper by J.F. Brown Jr., Quality Control Testing of Aluminum Anodes: T-7L-2 Task Group Progress Report,1 and from ANSI/NACE SP0607/ISO

15、15589-2,2 and Military Specification MIL-A-18001.3 This standard was originally prepared in 1990 by NACE International Task Group T-7L-2 on Aluminum Anode Quality Control, a component of Unit Committee T-7L on Cathodic Protection, in conjunction with ASTM(1) Task Group G01-09-02 T-1. This standard w

16、as revised by Task Group T-7L-12 in 1998, and was reaffirmed by Specific Technology Group (STG) 30, Oil and Gas Production: Cathodic Protection, in 2006, and was revised in 2012 by Task Group (TG) 459, Review and Revise as Necessary NACE Standard TM0190-2006. It is issued by NACE under the auspices

17、of STG 30. These committees are composed of industry representatives, including producers, consumers, and interested individuals. 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 shal

18、l 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 mandatory. The term may is used to state something considered optional. _ (1) ASTM International, 100 Barr Harbor Dr., West Conshohocken

19、, PA 19428-2959. TM0190-2012 ii NACE International _ NACE International Standard Test Method Impressed Current Laboratory Testing of Aluminum and Zinc Alloy Anodes Contents 1. General 1 2. Summary of Test Method 2 3. Test Apparatus 2 4. Reagents . 5 5. Preparation of Test Specimens . 6 6. Preparatio

20、n of Apparatus for Test . 6 7. Procedure 7 8. Calculation of Efficiency 8 References 9 FIGURES Figure 1: Hydrogen Evolution Test Set-Up 3 Figure 2: Alternate Test Cell Set-Up (Without Hydrogen Evolution Test) . 4 Figure 3: Sacrificial Copper Plate and Copper Coulometer 4 Figure 4: Wiring Diagram 5 T

21、ABLES Table 1: Nominal Alloy Composition Ranges for Anodes Tested . 1 Table 2: Range of Evaluation Results . 1 _ TM0190-2012 NACE International 1 _ Section 1: General 1.1 This standard test method describes a laboratory procedure for determining the potential and current capacity characteristics of

22、aluminum and zinc alloy anodes used for CP. It provides a means for screening various heats or lots of anodes to determine performance consistency on a regular basis from lot to lot. Items such as sampling frequency and performance criteria (i.e., test values and intermediate times) are left to the

23、discretion of the user of the test method. 1.2 One test method for anode potential evaluation and two test methods for anode current capacity evaluations are described. 1.3 The actual values obtained in these tests should not be used for design purposes because they represent laboratory testing. 1.4

24、 This procedure can be validated by using zinc anode samples as a reference in the test to verify results of aluminum anodes tested. Zinc samples shall be as defined in ASTM B4184 or Military Specification MIL-A-18001 for zinc anodes. 1.5 This procedure was evaluated by testing alloys of Al-Zn-Sn, A

25、l-Zn-Hg, Al-Zn-In-Mg, and MIL-A-18001 zinc of the respective nominal alloy composition ranges shown in Table 1. The results of the test are reported in Paper No. 346 presented at CORROSION/84. 1.6 The precision of the test has not been validated. The scatter in the test results is considered to resu

26、lt from heterogeneities in aluminum alloy anode materials in general, as tested, rather than the test method itself. Only anode materials exhibiting good, reproducible performance (in accordance with this test method) and meeting manufacturer or user specifications are acceptable. 1.6.1 Ranges of pe

27、rformance from those alloys tested are listed in Table 2. Table 1 Nominal Alloy Composition Ranges for Anodes Tested (%) Al-Zn-Sn Al-Zn-Hg Al-Zn-In-Mg Zinc (MIL-A-18001) Zn 6.0 to 8.0 1.25 to 2.00 1.0 to 3.0 Remainder Sn 0.10 to 0.20 Si 0.125 max. Hg 0.030 to 0.08 Pb 0.006 max. Mg 0.50 to 1.0 In 0.2

28、0 Fe 0.10 max. 0.10 max. 0.10 max. 0.005 max. Cd 0.025 to 0.15 Cu 0.003 max. 0.003 max. 0.010 max. 0.005 max. Al Remainder Remainder Remainder 0.10 to 0.50 Table 2 Range of Evaluation Results Alloy Operating Potential (SCE(A)-mV) Hydrogen Evolution (% Efficiency) Impressed Current Capacity A-h/kg A-

29、h/lb Al-Zn-Sn 940 to 1,176 70 to 94 1,014 to 2,711 460 to 1,230 Al-Zn-Hg 830 to 1,114 96 2,623 to 2,949 1,190 to 1,338 Al-Zn-In-Mg 1,032 to 1,140 90 2,354 to 2,742 1,068 to 1,244 Zinc 969 to 1,051 98 754 to 804 342 to 365 (A) Saturated calomel electrode. TM0190-2012 2 NACE International 1.6.2 Al/Zn/

30、In alloys have been found suitable for this test method (see ANSI/NACE SP0607/ISO 15589-2 and Military Specification MIL-DTL-24779).5 _ Section 2: Summary of Test Method 2.1 A 16,000 mm3 (1.0 in3) sample of alloy anode material shall be immersed in synthetic seawater (see ASTM D11416) at ambient tem

31、perature for two weeks (336 h), while anodically polarized at an impressed current density value of 6.2 A/m2 (4.0 mA/in2). Potentials shall be measured periodically and current capacity determined by the method(s) described in Paragraph 2.4. 2.2 The test shall be conducted with the synthetic seawate

32、r electrolyte at room temperature of 23 3 C (73 5 F), or other temperature specified by the client, and shall be recorded each time potential measurements are made. 2.3 Anode potentials shall be measured with a standard reference electrode, such as an SCE, at 3 h, 24 h, 48 h, 72 h, and 336 h. Potent

33、ials may be taken more frequently if desired. 2.3.1 For tests conducted at temperatures other than room temperature, consideration should be given to the impact of the test temperature on the potential measurement. 2.4 Anode current capacity shall be determined by the Mass Loss Method. This method m

34、ay be supplemented by the Hydrogen Evolution Method. 2.4.1 Mass Loss Method: The total current passed through the system shall be measured by a coulometer. Anode mass loss shall be determined at the end of the two-week test when the samples are removed, cleaned, and weighed. Mass loss current capaci

35、ties shall be determined from knowledge of the total charge passed through the system and the mass loss of the anode samples. 2.4.2 Hydrogen Evolution Method: Hydrogen that evolved from the anode as a result of local cell action under impressed conditions shall be collected in a graduated buret afte

36、r 72 h of testing, and the anode efficiency shall be calculated. The volume of gas collected during the collection time, the elapsed time, and the current flow through the anode samples shall be used for hydrogen evolution efficiency calculations. 2.4.3 For tests conducted at temperatures other than

37、 room temperature, consideration should be given to the impact of the test temperature on the current capacity values. 2.5 The causes of noble (more positive) potential results or low current capacity, or both, measured on a particular lot of anodes relative to established benchmarks for a particula

38、r alloy, should be investigated. 2.6 Zinc anode samples conforming to ASTM B418 should be used in the test as a reference material. Instructions for cleaning zinc samples before testing are given in ASTM G1.7 _ Section 3: Test Apparatus 3.1 Anode Test Cell: The container (1.5 L 0.40 gal), shown in F

39、igure 1 with a titanium sample support rod, steel screen cathode, and gas buret for hydrogen collection, shall be filled with synthetic seawater to a level 13 mm (0.50 in) from the top. A minimum distance of 19 mm (0.75 in) between the anode sample and the cathode screen should be maintained. 3.1.1

40、If the steel cathode is galvanized, the coating shall be removed from the screen prior to the first test. This may be accomplished by immersing the screen in 10% nitric acid (HNO3, 90 parts water, 10 parts nitric acid by volume) at 49 to 66 C (120 to 150 F) until the coating is removed. The screen s

41、hould be rinsed in reagent water (see ASTM D1193)8 to remove the acid. The nitric acid solution shall be handled with care. 3.1.2 A stainless steel beaker or carbon steel container may be used as a cathode, or a plastic test cell with stainless steel or carbon steel mesh cathode may be used as shown

42、 in Figure 2. 3.2 Copper Coulometer: The coulometer (such as the type shown in Figure 3) shall be filled with copper coulometer solution as described in Paragraph 4.3. Copper plates shall be a minimum of 99.9% purity. TM0190-2012 NACE International 3 3.2.1 An electronic coulometer of sufficient prec

43、ision ( 1%) may be substituted for the copper coulometer. 3.3 Power Supply: A constant-current direct current (DC) power supply should be used in conjunction with the DC milliammeter, as shown in Figure 4. The DC impressed current required in this test shall be 24 0.2 mA. 3.3.1 A voltage-regulated D

44、C power supply capable of regulation at 24 mA with a 1% deviation of full-scale adjustment may be substituted for the constant current supply. 3.4 Any number of anode samples may be tested at one time by wiring multiple test cells in series in the circuit, as shown in Figure 4, provided that the pow

45、er supply is capable of supplying sufficient voltage to maintain the impressed current at 24 0.2 mA through each test cell. . Figure 1: Hydrogen Evolution Test Set-Up TM0190-2012 4 NACE International Figure 2: Alternate Test Cell Set-Up (Without Hydrogen Evolution Test) Figure 3: Sacrificial Copper

46、Plate and Copper Coulometer Anode Sample Cathode Stainless or Carbon Steel (or Plastic Container) Connection to Anode Sample Sample Support (non -Conductive) Connection from Cathode Titanium Rod SS Mesh or Carbon Steel Mesh Cathode (Option, if Plastic Container is used) 13 mm (0.50 in) Rubber Stoppe

47、r 108 mm (4.25 in) 6.4 mm (0.25 in) 16 mm (0.63 in) Thick 51 mm (2.0 in) 127 mm (5.00 in) Sacrificial Copper Plate 57.2 mm (2.25 in) Coulometer Glass Jar 127 mm (5.00 in) Long 2.680 mm (12 Gauge) Copper Wire Sacrificial Copper Plates 16 mm (0.63 in) Thick 25 mm (1.0 in) ( ) ( + ) ( + ) TM0190-2012 NACE International 5 Figure 4: Wiring Diagram _ Section 4: Reagents 4.1 Anode Precleaning Solution: 50 g of sodium hydroxide (NaOH) shall be dissolved in 1 L of reagent water. 4.2 Synthetic Seawater Electrolyte: The electrolyte shall be prepar