1、SP0169-2007 Standard Practice Holiday Detection of Fusion-Bonded Epoxy External Pipeline Coatings of 250 to 760 m (10 to 30 mil) 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
2、any respect preclude 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 International standard is to be construed as granting any right
3、, by implication or otherwise, 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
4、 be interpreted as a restriction 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 f
5、or the interpretation or use 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 volu
6、nteers. Users of this NACE International 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
7、potential health and safety 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
8、protection practices, in consultation 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
9、 or withdrawn at any time in accordance with NACE technical committee procedures.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. Purchas
10、ers 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 Drive, Houston, Texas 77084-4906 (telephone +1 281 228-6200). Reaffirmed 2007-08-07 Reaffirmed
11、 March 2001 Reaffirmed March 1995 Approved April 1990 NACE International 1440 South Creek Drive Houston, Texas 77084-4906 +1 281/228-6200 ISBN 1-57590-119-6 2007, NACE International NACE SP0490-2007 (formerly RP0490-2001) Item No. 21045 SP0490-2007 NACE International i _ Foreword Detection and corre
12、ction of defects in protective coatings are important factors in an effective corrosion control program. High-voltage electrical inspection of pipeline coatings prior to installation is one method in general use. Prior to issuance of this NACE International standard, there had been no U.S. standard
13、for electrical inspection of fusion-bonded epoxy pipeline coatings. Although several specifications have been written by operating companies for high-voltage electrical inspection of protective coatings, they apply only to specific coatings. This standard is intended to serve the needs of pipeline o
14、wners, coating applicators, coating inspectors, and other interested parties in the electrical inspection of fusion-bonded epoxy pipe coatings. This standard practice was originally prepared in 1990 by NACE International Work Group T-10D-9c on Electrical Inspection and its parent, Task Group T-10D-9
15、 on Coating Inspection, a component of Unit Committee T-10D on Protective Coating Systems. This standard was developed through the joint efforts of representatives of coating manufacturers and applicators, holiday detector equipment manufacturers, corrosion specialists, and others concerned with the
16、 construction of underground pipeline facilities. Unit Committee T-10D reaffirmed the standard in 1995. This standard was reaffirmed in 2001 by Specific Technology Group (STG) 03 on Protective Coatings and Linings Immersion/Buried. It was reaffirmed by STG 03 in 2007 and is issued by NACE Internatio
17、nal under the auspices of STG 03. These recommendations apply only to fusion-bonded epoxy pipeline coatings, which are generally applied at a dry-film thickness of 250 to 760 m (10 to 30 mil). For other types of patching materials and joint wrap, the manufacturer of the material should be consulted
18、for holiday detection voltages. Conformance to the principles of this standard improves methods of holiday detection and, therefore, the effectiveness of the coating. In NACE standards, the terms shall, must, should, and may are used in accordance with the definitions of these terms in the NACE Publ
19、ications 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. _ SP0490-2007 ii NACE Internati
20、onal _ NACE International Standard Practice Holiday Detection of Fusion-Bonded Epoxy External Pipeline Coatings of 250 to 760 m (10 to 30 mil) Contents 1. General . 1 2. Definitions. 1 3. Testing Voltages . 1 4. Grounding. 2 5. Exploring Electrode . 3 6. Travel Speed of Exploring Electrode . 3 7. Te
21、st Voltage Measurements 3 8. Condition of Coating Surface.3 9. Care of Equipment. 4 References 4 Table 1. 2 _ SP0490-2007 NACE International 1 _ Section 1: General 1.1 This standard presents recommended techniques in the operation of holiday detector equipment currently used on fusion-bonded epoxy (
22、FBE) pipeline coatings following shop application of the coating and prior to on-site installation of the coated pipeline. It also presents recommended voltages for various coating thicknesses. Guidelines for establishing minimum requirements to ensure proper application and performance of plant-app
23、lied, fusion-bonded epoxy coatings are presented in NACE Standard RP0394.11.2 Electrical inspection (holiday detection) is a test of the continuity of a protective coating. This type of inspection is not intended to provide information on coating resistivity, bond, physical characteristics, or the o
24、verall quality of the coating. It detects voids, cracks, foreign inclusions, or contaminants in the coating that are of such size, number, or conductivity to significantly lower the electrical resistance or dielectric strength of the coating. 1.3 Use of a holiday detector shall be under the directio
25、n of a qualified coating inspector, such as a NACE-certified coating inspector. An initial holiday detector inspection, performed as soon as practical after the application of the coating, assists in verifying conformance to specifications for the materials and the application procedures. Before the
26、 coated pipe is placed in the ground, a final electrical coating inspection discloses coating discontinuities or damage that may have occurred during the shipping, storage, or construction period. _ Section 2: Definitions Continuous Direct Current (DC) Voltage Holiday Detector: A holiday detector th
27、at supplies a continuous DC test voltage. The continuous DC-type holiday detector is often used in very arid, sandy, or rocky areas and in coating plants where moisture and contamination conditions are controlled. The continuous DC test voltage holiday detector cannot be used where continuous moistu
28、re is present on the surface of the coating. For proper inspection using continuous DC output test voltage, other than in coating plant operations, the fusion-bonded epoxy coating surface must be dry. Generated Test Voltages: With two types of commercially available detectors, generated output test
29、voltages are used for the electrical inspection of fusion-bonded epoxy pipeline coatings. They are commonly described as pulse-DC and continuous-DC test voltages. Holiday: A discontinuity in a protective coating that exposes unprotected surface to the environment. For the purpose of this standard, t
30、he term is used interchangeably with discontinuity. Holiday Detector: An electrical device that locates discontinuities in the protective coating. Pulse-DC Voltage Holiday Detector: A holiday detector that supplies a high DC voltage pulse of a very short duration (such as 0.0002 seconds at a rate of
31、 30 pulses or more per second). The pulse-type holiday detector is the most common type used in the industry. _ Section 3: Testing Voltages 3.1 All holiday detector output test voltages in this standard refer to pulse-DC and continuous-DC values. 3.2 The minimum effective applied output test voltage
32、 is dependent on coating thickness, atmospheric conditions, electrode configuration, and grounding conditions. Therefore, the applied test voltage varies from case to case. 3.3 To determine the minimum effective applied test voltage for a given set of field conditions, the following field calibratio
33、n should be performed daily: 3.3.1 Make a holiday 790 m (0.031 in.) in diameter through the FBE coating. Ensure that the hole extends completely through the coating to the metal substrate. 3.3.2 Start with the lowest test voltage setting of the holiday detector and slowly increase the test voltage u
34、ntil the manufactured holiday can be positively detected at normal operating speeds (see Paragraphs 5.3 and 9.2 and Section 6). 3.3.3 This method of test voltage adjustment shall be performed while the exploring electrode and grounding are in the expected operating positions. If the above SP0490-200
35、7 2 NACE International conditions change, it may be necessary to readjust the test voltage setting. 3.4 Alternatively, the pipe-to-electrode test voltage can be adjusted to the minimum test voltages described in Paragraph 3.5, which are commonly used in the pipeline industry. Output test voltages ma
36、y be somewhat higher than these test voltage settings; the differential depends on grounding conditions and detector type. 3.5 The minimum testing voltage for a particular coating thickness shall be within 10% of the value determined by Equation (1): TKV VoltageTesting = (1) where V = peak voltage i
37、n volts, T = nominal coating thickness in m, and K = 104 (constant)(1)Table 1 gives calculated voltages for coating thicknesses of 250 to 760 m (10 to 30 mil). TABLE 1 Recommended Test Voltages for Various FBE Coating Thicknesses Coating Thickness Test Voltage(A)250 m (10 mil) 1,650 V 280 m (11 mil)
38、 1,750 V 300 m (12 mil) 1,800 V 330 m (13 mil) 1,900 V 360 m (14 mil) 1,950 V 380 m (15 mil) 2,050 V 410 m (16 mil) 2,100 V 510 m (20 mil) 2,350 V 640 m (25 mil) 2,650 V 760 m (30 mil) 2,900 V _ (A)Rounded to the nearest 50 V. 3.5.1 The test voltage should be verified periodically (see Paragraph 3.3
39、.3). 3.5.2 If an outerwrap is applied over the primary coating, the thickness and dielectric strength of the outerwrap material must be considered when determining or specifying the test voltage. Certainouterwrap materials may have electrical insulating properties equal to or greater than the coatin
40、g. 3.5.3 Consumer-specified test voltages used at the coating site at the time of coating application shall not be exceeded during the on-site electrical inspection of the coating. _ Section 4: Grounding 4.1 Proper electrical grounding of the holiday detector to the coated pipe under inspection is n
41、ecessary to complete the electrical circuit. 4.1.1 The coated pipe metal must have electrical contact to earth at one or more points. An electrical ground of the pipe can be made by electrically connecting the pipe metal to a metal grounding rod driven into the earth to a depth of 0.6 to 0.9 m (2 to
42、 3 ft). 4.1.2 The holiday detector can, in most cases, be effectively grounded electrically by the use of a flexible ground wire of approximately 9 m (30 ft) in length that is connected to the ground terminal of the holiday detector and trailed along the surface of the earth. The first 1 to 1.5 m (4
43、 to 5 ft) of the ground wire extending from the ground terminal of the holiday detector must be adequately insulated to prevent possible electrical_ (1)For coating thickness in mils, use K = 525. SP0490-2007 NACE International 3 shock to the operator. In some instances, the bare end of the ground wi
44、re must be attached to an independent driven earth rod to ensure adequate electrical grounding. 4.1.3 In arid, sandy, or rocky areas where earth resistivity prevents effective holiday detection bycreating high circuit resistivity, a direct wire connection between the pipe metal and holiday detector
45、ground terminal shall be maintained. Additional ground wire (0.324 mm222 AWG minimum) of any length may be used in making connections between the holiday detector ground terminal and the pipe metal. _ Section 5: Exploring Electrode 5.1 The exploring electrode is the means by which the electrical pot
46、ential is applied to the surface of the coating. 5.2 Typically, electrical holiday detector exploring electrodes are manufactured in two basic forms. The most common electrode is the full-circle wire spring type, which, when placed around the coated pipe in operating position, allows for complete ci
47、rcumference inspection with one pass by rolling the spring electrode over the coated surface. The second type is in the form of a brush made of conductive rubber or brass bristles such that there is no more than 250m (10 mil) lateral distance between the spring coils or brass bristles at the area where the electrode contacts the coated surface. 5.3 The exploring electrode shall maintain contact with the coated surface at all times. 5.4 The exploring electrode shall b
