1、 Standard Test Method Cathodic Disbondment Test for Coated Steel Structures Under Cathodic Protection This NACE International (NACE) 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
2、 anyone, 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 standard is to be construed as granting any right, by implication or otherwise, to
3、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 restriction o
4、n 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 assumes no responsibility for the interpretation or use of this standard by
5、 other parties and accepts responsibility for only those official 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 appropriat
6、e health, safety, environmental, and regulatory documents and 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, equi
7、pment, and/or operations detailed or referred to within this 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 wit
8、h any existing applicable regulatory requirements prior to 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 CAUTIONARY NOTICE: NACE standards are subject to periodic review, and may be revised or withdrawn at any time in accordance with NACE technical committee procedures.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, r
9、evise, 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 obtain the latest edition. Purchasers of NACE standards may receive current information on all standards and other
10、 NACE publications by contacting the NACE FirstService Department, 15835 Park Ten Place, Houston, TX 77084-5145 (telephone +1 281-228-6200). Approved 2015-03-14 NACE International 15835 Park Ten Place Houston, Texas 77084-5145 +1 281-228-6200 ISBN 1-57590-315-6 2015, NACE International NACE Standard
11、 TM0115-2015 Item No. 21269 TM0115-2015 NACE International i _ Foreword This NACE International standard test method specifies procedures to evaluate cathodic disbondment resistance of the steel structure coating systems under cathodic protection, such as buried or submerged pipeline and tank lining
12、s. The standard covers all test specimen geometries and test temperatures. This standard also takes into consideration all test parameters with the goal of the standard to be used during the selection of protective coating systems for use under cathodic protection. This test method is intended for u
13、se by facility owners, coating applicators, and coating manufacturers. This test method was prepared in 2015 by Task Group (TG) 470, “Cathodic Disbondment Test for Coated Steel Structures Under Cathodic Protection.” TG 470 is administered by Specific Technology Group (STG) 03, “Coatings and Linings,
14、 ProtectiveImmersion and Buried Service.” This standard is issued by NACE under the auspices of STG 03. 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 sta
15、te 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. _ TM0115-2015 ii NACE International _ NACE International Standard Test Method Cathodic Dis
16、bondment Test for Coated Steel Structures Under Cathodic Protection Contents 1. General 1 2. Definitions 1 3. Coating Materials 2 4. Sample Preparation . 2 5. Test Solution 3 6. Test Specimens . 3 7. Apparatus 3 8. Test Procedure 6 9. Report 8 References 10 FIGURES Figure 1: Typical Test Setup for A
17、ttached Cell Method 4 Figure 2: Typical Test Setup for Salt Bath Method . 5 Figure 3: Four Radial Direction Cuts for Evaluation of Disbonded Coating 7 Figure 4: Levering Action Used to Evaluate Extent of Disbondment 8 TABLES Table 1: Example Test Report 10 _ TM0115-2015 NACE International 1 _ Sectio
18、n 1: General 1.1 This test method describes an accelerated test procedure for determining comparative resistance to cathodic disbondment of protective coating systems applied to the exterior of steel pipes and structures that are buried in soil or submerged. This test method is intended for use with
19、 specimens of coated tube, a specimen cut from a section of coated pipe, or flat coated steel plates. 1.2 This test method also is applicable to tank linings with an internal cathodic protection system. 1.3 This test method is not intended for tape or sleeve coatings with a soft adhesive that may fl
20、ow at the test temperature. 1.4 This test method is intended to cover all service temperatures from ambient to elevated temperatures. 1.5 The test results obtained in this method will serve as a ranking of the candidate coating systems in their cathodic disbondment resistance at different service te
21、mperatures. This standard test method is not intended to simulate field conditions or predict service life. 1.6 There are many test parameters that may affect the cathodic disbondment test results. This test method has taken all test parameters into consideration, and all the test parameters shall n
22、ot be modified to satisfactorily meet the requirements of this standard. _ Section 2: Definitions 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 where corrosion occurs and metal ions
23、enter solution.) Anode Isolation: The placement of the anode such that the chlorine gas from the anodic reaction is kept away from the drilled holiday of the test specimen. The chlorine gas may react with the alkaline of the reaction product at the drilled holiday to form hypochlorite, which may att
24、ack organic coatings and affect the test results. This phenomenon does not occur in the field because the anode and cathode are far apart and will not produce the hypochlorite. In the laboratory testing of cathodic disbondment, the anode shall be isolated to prevent the dissolved anolyte chlorine ga
25、ses from migrating to the cathodic sites. Attached Cell: A cylindrical cell made of plastic or glass that is placed on top of a coated flat or curved plate to hold electrolyte for a cathodic disbondment test. Cathodic Disbondment (CD): The destruction of adhesion between a coating and the coated sur
26、face caused by products of a cathodic reaction. Cathodic Protection: A technique to reduce the corrosion rate of a metal surface by making that surface the cathode of an electrochemical cell. Coating System: The complete number and types of coats applied to a substrate in a predetermined order. Refe
27、rence Electrode: An electrode having a stable and reproducible potential, which is used in the measurement of other electrode potentials. Room Temperature (RT): An indoor temperature generally between 20 and 25 C (68 and 77 F). Salt Bath: A reservoir containing a 3% by weight NaCl solution. TM0115-2
28、015 2 NACE International Test Temperature: The temperature of the steel substrate during the test. Test Specimen: Prepared portion of a sample or coupon upon which a test is intended to be performed. (Also known as a specimen.) _ Section 3: Coating Materials 3.1 Coating Systems All nonmetallic coati
29、ngs can be tested except for materials that flow at the test temperature, such as wax, petrolatum and thermoplastic elastomer, and tape/sleeve coatings with a soft adhesive layer. Coating systems application methods and the environment during application shall be in accordance with manufacturers pro
30、duct data sheet (PDS). 3.2 Coating Surface If the attached cell method (Paragraph 7.1.1) is used, the coating surface should be sufficiently smooth to provide a leak-free seal with the attached cell. 3.3 Degree of Cure All coatings shall be allowed to cure in accordance with the manufacturers produc
31、t data sheet before testing. _ Section 4: Sample Preparation 4.1 Steel Surface Pretreatment and Surface Preparation Steel surface preparation has a significant impact on the test results. When preparing test specimens, surface cleanliness and profile shall be in accordance with the coating manufactu
32、rers recommendations. The surface cleanliness, profile, and any other chemical treatment (if required in the coating specification) shall be included in the test report. If the surface preparation is unknown, this shall be stated in the test report. 4.2 Coating Dry Film Thickness (DFT) Measurement A
33、 minimum of five DFT measurements over the possible maximum disbonded area shall be conducted in accordance with ASTM(1) D70911 before and after the cathodic disbondment (CD) test, and the average DFT shall be used to report the coating DFT. Some coating samples may experience change in DFT as a res
34、ult of chemical attack during the test. The coating DFT measurements taken before and after the CD test shall be recorded in the test report. 4.3 Holiday Inspection The test specimen shall be holiday inspected with a low-voltage wet sponge in accordance with NACE SP0188.2 The specimens with holidays
35、 shall be discarded and replaced with specimens free of holidays. (1) ASTM International (ASTM), 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959. TM0115-2015 NACE International 3 _ Section 5: Test Solution The electrolyte shall be 3% by weight NaCl in deionized water or distilled water. _ Se
36、ction 6: Test Specimens 6.1 Specimen Geometry 6.1.1 The specimen may be either flat, curved panel, or tube. If the tube-shaped samples are used, one or both ends of the tube shall be sealed with nonmetallic end caps. 6.1.2 For polyurethane foam insulated pipe samples, the foam insulation layer shall
37、 be removed before the installation of the attached cell. For other rigid and thick pipeline coating specimens, the DFT should be machined down to less than 3 mm (0.125 in). 6.2 Number of Test Specimens Three specimens (minimum) shall be tested for each test condition. 6.3 Specimen Size 6.3.1 Attach
38、ed cell methodThe minimum specimen size for flat steel panels shall be 100 x 100 x 6 mm (4 in x 4 in x 0.25 in). For curved panels, the minimum size is 100 x 100 mm (4 in x 4 in) x pipe wall thickness. 6.3.2 Salt bath methodThe minimum tube outside diameter is 50 mm (2 in). Minimum tube length shall
39、 be 100 mm (4 in). The minimum specimen size is 100 x 150 x 3 mm (4 in x 6 in x 0.125 in) for flat panels. 6.4 Drilled Holiday Size For all coating specimens, the drilled holiday diameter shall be 6 mm (0.25 in) to be drilled in the center of the specimen with a flat head end mill bit. The maximum d
40、epth of the drilled holiday into the steel substrate shall be 0.5 mm (0.02 in). The drilled holiday shall be free of all coating and metal scraps before testing. For each sample only a single drilled holiday shall be prepared. _ Section 7: Apparatus 7.1 Test Vessel 7.1.1 Attached Cell Method 7.1.1.1
41、 Cell Construction: The attached cell material shall be either plastic (acrylic, polycarbonate, polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), etc.), or a glass tube of 75 to 100 mm (3 to 4 in) in inner diameter (ID), 100 mm (4 in) in length. The plastic or glass tube is centered o
42、ver the drilled holiday and adhered to the coating specimen surface by a silicone adhesive with adequate temperature resistance. A glass vessel with an O-ring groove can also be used to attach it to the specimen surface with a mechanical clamp. For higher testing temperatures, a condenser should be
43、installed to minimize water evaporation. Figure 1 illustrates an example of a typical test setup of an attached cell. TM0115-2015 4 NACE International Figure 1: Typical Test Setup for Attached Cell Method 7.1.1.2 Electrolyte Volume: During the course of testing, 300 mL (10 oz) (minimum) electrolyte
44、shall be maintained. Either deionized or distilled water shall be added into the cell to maintain the electrolyte volume. A condenser may be used to maintain electrolyte volume, particularly for elevated temperature testing. 7.1.1.3 Heating Method 7.1.1.3.1 If the test temperature is RT, the specime
45、n shall be heated by a hot plate, heating mat, or in an oven. If heated by a hot plate, a sand bath of a minimum of 12 mm (0.5 in) depth should be placed between the cell and the hot plate to improve thermal stability. The electrolyte shall also be heated with a heating coil or external hot water ci
46、rculation system. The temperature difference between the steel as measured by a thermocouple embedded in the steel for onshore coatings and the thermometer placed on the top of the coating surface in the electrolyte shall be within 2 C (4 F). For offshore coatings, the electrolyte temperature shall
47、be agreed upon between the end user and the testing laboratory. The electrolyte temperature for offshore pipelines shall be 30 5 C if no specified test temperature is given. 7.1.1.3.2 If the test temperature is 95 C (203 F), the specimen shall be heated on a hot plate. A sand bath of a minimum of 12 mm (0.50 in) depth shall be placed between the cell and hot plate. The electrolyte shall be maintained at 95 2 C (203 4 F) by an immersed cooling coil or other adequate device for onshore coatings. Alternatively, the test specime
