1、 Standard Practice Guided Wave Technology for Piping Applications 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
2、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 manufacture, sell, or use in connection wit
3、h 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 the use of better procedures or materials
4、. 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 other parties and accepts responsibility f
5、or 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 appropriate health, safety, environmental, and regula
6、tory 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, equipment, and/or operations detailed or referr
7、ed 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 with any existing applicable regulatory requir
8、ements 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 CAUTIONARY NOTICE: NACE standards are subject to periodic review, and may be revised or withdrawn at any time in accordance with NACE technical committee procedures.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, revise, or withdraw this standard no later t
9、han 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 NACE publications by contacting the NACE F
10、irstService Department, 1440 South Creek Dr., Houston, TX 77084-4906 (telephone +1 281-228-6200). Approved 2013-10-2 NACE International 1440 South Creek Drive Houston, Texas 77084-4906 +1 281-228-6200 ISBN 1-57590-264-8 2013, NACE International NACE SP0313-2013 Item No. 21174 SP0313-2013 NACE Intern
11、ational i _ Foreword Since the transportation of hydrocarbons by pipeline began in the 1860s, the primary means of establishing pipeline integrity has been through the use of pressure testing. These tests have been most often performed on completion of the construction of the pipeline. The completed
12、 pipeline segment has been pressurized to a level equal to or exceeding the anticipated maximum operating pressure (MOP). Government regulations, codes, and standards have specified the test pressures, test media, and test durations that must be achieved for pipelines to be permitted to operate with
13、in their jurisdictions. However, until very recently, there have been no regulatory requirements for pipelines to be periodically tested for integrity. Some pipeline operators have traditionally performed periodic integrity assessments in a variety of forms with varying degrees of success. In 1998,
14、pipeline operators began to use a form of instrumented inspection technology that has evolved into what is known at present as guided wave testing (GWT), which detects changes in the cross-sectional area of the pipe wall. Test equipment software provides a percent estimate of the change (gain or los
15、s) and is often expressed as percent estimated cross-sectional loss. Note that some features (such as welds) represent gains in cross-sectional area. These changes include metal loss indications, anomalies, or defects such as corrosion, gouges, etc., or metal pickup such as welds, valves, flanges, e
16、tc. The technology is now in many operators integrity management programs. However, there has been a lack of industry-recognized standards that specify and govern GWT and as a result there has been variability in the expectations and results. When properly applied, GWT can monitor cross-sectional lo
17、ss over time, and provide economic benefits and efficiencies in integrity assessments. This standard practice outlines a process of related activities that a pipeline operator should use to plan, organize, and execute a GWT project. Guidelines pertaining to GWT are included (e.g., site setup, people
18、 and equipment qualifications, performance expectations, accessible and inaccessible facilities, and pipe). Key NACE companion standards include NACE SP0502, 1SP0206, 2and SP0210. 3This standard is intended for use by qualified individuals and teams planning, implementing, and managing GWT projects
19、and programs. These individuals include engineers, operations and maintenance personnel, technicians, specialists, construction personnel, and inspectors. Users of this standard must be familiar with all applicable pipeline safety regulations for the jurisdiction in which the pipeline operates. This
20、 includes all regulations requiring specific pipeline integrity assessment practices and programs. This standard was prepared by Task Group (TG) 410, “Long-Range Guided Wave Ultrasonic Testing.” TG 410 is administered by Specific Technology Group (STG) 35, “Pipelines, Tanks, and Well Casings,” and i
21、t is sponsored by STG 05, “Cathodic/Anodic Protection.” This standard is issued by NACE International under the auspices of STG 35. 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 sh
22、all 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. _ SP0313-2013 ii NACE International _ Standard Practice Guided
23、 Wave Technology for Piping Applications Contents 1. General 1 2. Definitions . 3 3. Preassessment 8 4. Conducting Guided Wave Testing 12 5. Post-Assessment Step 13 6. GWT Service Provider Quality Management System Perspective . 17 7. Guided Wave Testing Records . 18 References 19 Appendix A: Guided
24、 Wave Testing Background, Technical Explanation, and Field Implementation Protocol to Assist Operators . 21 Appendix B: Commonly Used GWT Terminology . 40 Appendix C: Sample Preinspection Questionnaire . 41 Appendix D: GWT Inspector Certification Levels 43 FIGURES Figure 1: Typical volumetric covera
25、ge of a guided wave examination . 2 Figure 2: Examples of different 10% cross-sectional areas flaws 7 Figure 3: Schematic diagram of pulse echo, through transmission, and pitch catch configurations 12 TABLES Table 1: Typical Values of Relative Signal Amplitude . 2 Table 2: General Effects of Appurte
26、nances on GWT 9 Table 3: Example of Acceptance Criteria and Response Plan . 16 Table D1: Descriptions of Responsibilities of Guided Wave Testing Inspector Levels . 43 Table D2: Training Criteria for Guided Wave Testing . 45 _ SP0313-2013 NACE International 1 _ Section 1: General 1.1 This standard is
27、 primarily applicable to GWT tools that are designed to be coupled to the external surface of the pipe. However, this standard can be adapted to GWT technology that couples to the interior of the pipe using deployment tools such as tethered, remotely controlled, internal free-swimming, or permanentl
28、y installed inspection devices. 1.2 This standard is applicable to a variety of industries that use metallic pipelines and piping systems to transport natural gas and hazardous liquids, including those containing anhydrous ammonia, carbon dioxide, water (including brine), liquid petroleum gases (LPG
29、), isotopes, and other services that are not detrimental to the function and stability of GWT tools. 1.3 This standard provides specific guidance based on successful, industry-proven GWT practices. 1.4 This standard requires the service provider to determine the attenuation levels for GWT examinatio
30、ns for each pipe. In practice, GWT attenuation levels should not be greater than 1 dB/m (0.4 dB/ft) during testing. When attenuation levels are greater than 1 dB/m (0.4 dB/ft), the service provider must have an equipment-specific procedure tailored to the piping configuration and target corrosion me
31、chanism of the pipe to be tested. As such, use of this standard as a stand-alone practice on such piping should only be used as a guideline. 1.5 This standard is primarily intended for use on above- and/or below-ground pipelines installed along a right-of-way, plants, pump/compressor station piping,
32、 and for subsea pipelines and flow lines. The general process and approach may be applied to other facilities such as hydrocarbon distribution and gathering systems, water injection systems, station piping, and isolated crossings of railroads, highways, or waterways. 1.6 GWT is a nondestructive test
33、ing technique that provides for the rapid screening of lengths of pipe from each test location in order to achieve inspection coverage of a pipe in a cost-effective manner and to target suspect areas for closer examination by local nondestructive testing (NDT) techniques. With this process, the redu
34、ction of access costs is a significant positive factor. This method also has the ability to examine pipe lengths that are inaccessible for more conventional NDT methods, such as road or rail crossings, by testing from the nearest accessible location, thereby increasing the proportion of any pipe sys
35、tem that can be inspected. 1.7 GWT is similar to the use of Lamb waves in conventional Lamb wave testing, which may be generated in plates and in common pipe thicknesses. Currently, piezoelectric and magnetostrictive transducers are used to generate and receive ultrasonic signals that travel through
36、 the pipeline wall, and changes in time of flight can be used to detect imperfections, features, and defects in the short segments of the pipeline system under inspection. To generate the appropriate wave modes, guided waves are several orders of magnitude lower in frequency than that which is used
37、for normal ultrasonic tests. Typically, frequencies of approximately 50 kHz are used in GWT, compared to approximately 5 MHz for conventional thickness testing. These waves can travel many meters with minimal attenuation and offer the potential to test large areas from a single point using a pulse-e
38、cho transducer bracelet wrapped around the pipe. This principle is shown in Figure.1. The transducer transmits a controlled pulse GWT along the pipe. Any changes in the thickness of the pipe, either on the inside or the outside, cause reflections, which are detected by the transducer. Hence, metal l
39、oss indications from corrosion/erosion inside the pipe or corrosion on the outside of the pipe may be detected. The detection of additional mode converted signals from defects aids discrimination between pipe features and metal loss. Knowledge of the speed of the guided waves as they travel along th
40、e pipe allows the distance from the transducer tool to the corrosion to be measured so that its position can be determined. SP0313-2013 2 NACE International Figure 1: Typical volumetric coverage of a guided wave examination. (Inspection can be conducted in either direction or both simultaneously fro
41、m the transducer collar.) 1. 8 GWT does not provide a direct measurement of wall thickness, but it is sensitive to cross-sectional changes, a combination of the depth and circumferential extent of any metal loss, as well as the axial length. This is a result of the transmission of a guided wave fron
42、t along the pipe wall, which interacts with the annular cross-section of the pipe at each point. It is the change in this cross-section to which GWT is most sensitive. Commercial test systems employ further analysis of the signals received to estimate the depth and extent of any imperfections detect
43、ed. 1.9 In GWT, it is common for response amplitudes to be compared to reference levels derived from distance amplitude correction (DAC) curves or by time-controlled gain (TCG) amplitude levels. These allow responses to be compared to known features. The reference levels may be set from responses fr
44、om the girth weld between sections of pipe. Table 1 shows typical values of relative signal amplitude: Table 1 Typical Values of Relative Signal Amplitude Relative Signal Amplitude Percentage (dB) Reflection from weld (approximate) 20% (14 dB) Reflection from 10% cross-sectional area (CSA) discontin
45、uity 10% (20 dB) Maximum acceptable background noise level for detection of 5% CSA discontinuity 2.5% (32 dB) 1.10 These values assume a linear relationship between change in cross-section and reflection amplitude. Different manufacturers may have specific instructions for more advanced relationship
46、s between the change in cross-section and reflection amplitude as well as calibration. 1.11 The principal benefits of GWT are that pipe may be examined in a manner to determine whether areas of potential degradation are present and that areas inaccessible for direct inspection may be tested. Applica
47、tion of quantitative methods should be used to provide more detailed information about the imperfections detected. 1.12 GWT may be used as a stand-alone assessment method for pipelines provided that the operator provides a separate engineering procedure. See Appendix A (Nonmandatory) for complementa
48、ry use of GWT technology. SP0313-2013 NACE International 3 _ Section 2: Definitions (1)Anomaly: Any deviation from nominal conditions in the wall of a pipe. See also Imperfection and Defect. Appurtenance: A component that is attached to the pipeline: e.g., valve, tee, casing, connection, etc. Axi-Symmetric Mode: Guided wave for which the principal pattern of vibration is uniform around the circumference of a cylindrical test object. NOTE: The principal effect
