19th World Conference on Non-Destructive Testing 2016 Application of ultrasonic methods for manufacture of pipelines and maintenance Mitko MIHOVSKI 1, Pavel CHUKACHEV 1, Yordan MIRCHEV 2, Vladimir SERGIENKO 3 1 Institute of Mechanics, Sofia, Bulgaria 2 BGSNDT and Institute of Mechanics - Bulgarian Academy of Sciences, Sofia, Bulgaria 3 V. A. Belyi, Metal Polymer Research Institute of National Academy of Sciences of Belarus, Gomel, Belarus Contact e-mail: nntdd@imbm.bas.bg Abstract. Ultrasonic method is universal for inspection of manufacture and maintenance pipelines. In this paper the features of application and possibilities to obtain correct information about state of pipeline are presented. The following application fields of ultrasonic method are reviewed in work: • QualТtв Мontrol oП manuПaМturОН pТpОs (Обport Мontrol); • InspОМtТon oП аОlНs in pipeline fitting; • AssОssmОnt oП tСО pТpОlТnО statО Тn aНvanМО prОparОН МrТtТМal arОas (usТnР also metallographic analysis, hardness test); • CorrosТon ТnspОМtТon Тn maТntОnanМО usТnР Pipeline internal gauge (PIG) for inspection; Guided wave technique; Convention ultrasonic thickness testing to assessment of corrosion damage in advanced prepared critical areas on pipeline. • AssОssmОnt oП mОМСanТМal strОss statО Тn surПaМО oП pТpОlТnО; • AssОssmОnt oП aНСОsТon between reinforced (repair) material and pipe surface; • InspОМtТon oП qualТtв, mОМСanТМal propОrtТОs anН tСТМknОss oП rОТnПorМОН material for pipelines repair. The information in this work are presented used developed written practice procedures for laboratory testing and for maintenance of pipelines. Introduction In data presented in [1] and in accordance with the strategy for the development of Russia until 2030 the unified system of gas supply, which is the largest in the world, includes 160 000km pipeline and 300 compressor stations. In pipeline material has a significant amount of discontinuities that occurred during the manufacturing of pipes and welds as well as during maintenance. To discontinuities in the manufacturing of pipeline are included: change of integrity, discontinuities in welds and change in physical and mechanical properties. Discontinuities in manufacturing of gas pipelines are associated with problems in pipe laying, break protective coating, mechanical wear and increased mechanical stresses in the material. 1 License: http://creativecommons.org/licenses/by/3.0/ More info about this article: http://ndt.net/?id=19758 In maintenance primarily discontinuities are associated with corrosion and erosion damage, changes in mechanical stress state at environmental influences, fatigue cracks, changes in the material structure in emergency situations and others. Presented data in [2] show that the percentage defects of external corrosion in maintenance are 29%, of internal - 2.5%, wrong manufacturing of pipeline- 23%, of fault in maintenance- 16% and production of pipes in factories- 14%. In defects break integrity of the pipeline has gas leakage, often leads to significant material damage (loss of gas, fires, pollution of the atmosphere) and in many cases, human sacrifices. Based on years of experience in manufacture and maintenance of pipelines has a constructed system for managing the technical condition and defects, which includes: assessing influence of many factors on maintenance of the pipeline, monitoring testing, system for risk assessment and the effective work of transit systems. This system is constructed with consideration of: - Significant date from non-destructive testing and diagnostics; - Development of general and specific standards and regulations. The systems included internal and external pipeline inspection included remote control and diagnostics (for pipeline underground). As most perspective method for non-destructive testing and diagnostics of defects state, mechanical state and the physically-mechanical properties in recent years have ultrasound method with its various applications for internal and external pipeline inspection. The purpose of this work is to present the possibilities of using ultrasound methods at different stages of manufacturing pipelines for transportation, for installation and there maintenance. Conditional in the work are refered the following stages: - Manufacturing of gas pipelines; - Welding of basic pipelines elements; - Assessment state after placing pipes (over- and underground); - Maintenance inspection; - Rapier. All activities of control and diagnostics used ultrasonic methods is regulated by legislation. These documents are shown into reference in work. Special attention is paid to industry standards STO Gazprom, GOST and EN. In table 1 are written name of this standards and procedures in which they are specificities Table 1 Methods and regulations. Methods Traditional and modern 2-2.4-083 methods for ultrasonic 2-2.3-292 testing: - Guided Wave - TOFD - Phased array - Tandem Assessment of mechanical 2-2.3-220 stress state 2-2.3-238 12503 14782 28702 52330-2005 52890-2007 52731-2007 2 EN EN ISO 16810 EN ISO 17640 EN ISO 11666 EN ISO 10963 EN ISO 16828 EN ISO 17635 1. Manufacturing of pipes 1.1. Automated ultrasonic testing of seamless and welded (except submerged arc-welded) steel tubes for the detection of longitudinal and/or transverse imperfections The tubes shall be tested by using an ultrasonic shear wave technique for the detection of longitudinal and transverse imperfections. Lamb wave technique may be applied for the detection of longitudinal imperfections. The requirements for testing are in accordance with standard EN ISO 10893-9:2011 [16]. 1.2.Ultrasonic testing on plate edges The longitudinal strip/plate edges shall be 100 % ultrasonically tested for the detection of laminar imperfections over a width of at least 15 mm, plus, if appropriate, the total width of edge material which shall be removed from each original strip/plate prior to seam welding, in order to detect the relevant minimum imperfection length, Lmin, as given in Table 2 in standard EN ISO 10893-9:2011 [17]. 1.3. Mechanical stress testing in predefined critical areas in pipe during maintenance In the system of Russian legislation are presented two standards [7], [8], which regulate the application of ultrasonic methods, for evaluation of the mechanical stress. 52890-2007 [7] regulates the basic requirements for determining the mechanical stress. Use volume ultrasonic waves that propagate in radius direction on controlled pipes. The standard is applicable to pipes of steel (seam and seamless) with ratio the wall thickness to the outer diameter 20 times and to pipes with a diameter greater than 325mm. In the process of measurement is recorded the initial velocities (time of propagation) in the material in the absence of mechanical stresses, taking into account the acoustic anisotropy of the material, microstructure etc. factors. Depending on the measurement conditions, the current primary acoustic state of the material is carried on specially prepared samples or on the test pipes. 1.4.Measurements of velocities and attenuation for spreading ultrasonic waves in medium Measurements are realized with specialized equipment with high accuracy when measuring the velocity and times of volumetric ultrasonic waves. Emitted and received of the waves is realized with special transducers for transverses polarized waves and normal transducers for longitudinal waves. Increasing accuracy of measurement can be achieved using method of multiple echoes. The attenuation measurement is written in EN ISO 16823. 1.5. Assessment of mechanical characteristics- elastically modulus The determination of longitudinal and transverse velocity of sound in a material makes it possible to approximately calculate tСО PoТsson’s ratio- , ВonР’s moНulus oП ОlastТМТtв- E and shear modulus- G. The formulas for calculating these factors are as follows 3 C 1 2 t Cl C 2 1 t C l Ct2 (3Cl2 4Ct2 ) , , G Ct 2 , E 2 2 2 C C l t 2 (1.5.1) where is density, Cl , Ct are ultrasonic longitudinal and transverse velocity. The elastically modulus is used for assessment of allow pressure in transits petroleum pipelines. 1.6. Ultrasonic thickness measurement in point on critical areas, where is conducted monitoring during the maintenance of pipe Ultrasonic thickness measurement is done by pulse-echo method, according to standard EN 14127 [15]. This standard specified procedures for determining the thickness including and thinning and detection and characterization of discontinuity encountered in general and pitting corrosion. In these procedures, information characteristics of the echo in determining the thickness are: time distribution of information received ultrasonic signal and the location of the probe on the contact surface. The measurements are done on points in area, where is most possibility thinning of pipe wall from different factors during work conditions. The good accuracy for measured thickness is achieved used ultrasonic electromagnetic acoustical probes and equipment with A-scan presentation of signals. Automated ultrasonic thickness testing is done according requirements of standard EN ISO 10893-12 [20]. 2. Welding of pipe in main pipelines 2.1.Automated ultrasonic testing used normal and angular beam probes for welds and head affected base material This technique is mainly used for the pre service inspection of pipelines. The ultrasonic techniques and settings will be selected according diameter, weld thickness and preparation (chamfer) to be inspected. The scan movement consists of a single line scan along the weld. In accordance with EN ISO 10893-11 weld seam of the tube shall be tested using an ultrasonic shear wave technique for the detection of longitudinal and/or transverse imperfections. Unless otherwise agreed on by the purchaser and manufacturer, testing shall be carried out in two opposite directions of sound propagation for the requested type of inspection, clockwise and anticlockwise for the detection of longitudinal imperfections and forward and backward for the detection of transverse imperfections. The application, restriction and acceptance level are written in EN ISO 10893-11 [19]. 2.2.Automatic ultrasonic testing of welding with TOFD and Phased array methods TOFD is considered a non-amplitude technique but some minimum and maximum sensitivity must be established and a method of duplicating scan level from system to system should be incorporated into the procedures. TOFD sensitivity may be configured by setting the amplitude of the lateral wave or by setting the response off a calibration target such as a tip diffractor or a side-drilled hole. 4 Application of both TOFD and phased array techniques together for zone discrimination of welds, decrease time testing and increase probability of detection for various type and location discontinues in welds. Engineering Critical Assessment (ECA also called Fracture Mechanics, Fitness-For-Service or Structural Integrity) is used to evaluate discontinues on scan image from phased array technique. TOFD technique is used for crack detection in welds and is well written in standard EN ISO 16828 [21]. 2.3. Assessment of mechanical stress state in area around welding used normal beam probe for longitudinal ant transverse waves spread to radial direction Measurements shall be done with certified equipment. Normal probe for emitted of longitudinal and transverse ultrasonic waves is used. The measurements are usually in the echo-pulsed mode. Surface in the measuring zone mast be a roughness Ra2.5m. As contact medium is used an epoxy resin. Mandatory is monitoring the temperature of the test material. In order to increase the accuracy of the method is used multiple echoes signals received in an area of a plane opposing walls in the pipe and in the absence of signals from a discontinuity in the volume of the material. 2.4. Assessment of mechanical stress state in surface and subsurface of welds and head affected base material by Rayleigh and creeping waves Assessment is done used calibration dependences for material between ultrasonic velocities of spread surface waves CR and mechanical stress- . The dependence between them is give with next relationship C R . , (2.1.4.1) where CR=CR-CR0 (CR0 velocity in material without mechanical), is acousticallymechanical coefficient specific for investigated material and head treatment. 2.5. Assessment of adhesion of insulating protection coating of pipe used longitudinal, transverse and Stonely’s waves Echo-pulse method is used with normal duel and angular probes. Adhesion contact state is assessment with information characteristics amplitude and phase of echo signal. When echo signal in material is reflected from air layer (delimitation between protection coating and basic pipe material) with thickness more than 2-3µm at frequency around 4MHz, amplitude is decrees and phase is shifted at 180 compare to reflected signal from acoustical denser medium(good adhesion contact between protection coating and basic pipe material). 3. Ultrasonic testing during maintenance (monitoring) 3.1. Ultrasonic testing for volumetric and surface discontinuities and corrosion damaged used internal pipeline non-destructive evaluation systems Usually internal pipeline inspection are used three different tools: one gauge tool, one cleaning tool and the in-line inspection tool, which maps potential corrosion and metal loss as well as the exact curvature of the lines via an inertial navigation system. The gauge tool is used to detect substantial anomalies of the internal diameter along the pipeline which may potentially obstruct the inline inspection tool during its run. The cleaning tool is sent through the pipe to remove small particles of dust that may have 5 accumulated in the pipeline during the operating time and tiny particles of coating material from the pipelines inside that may have become loose. The main inspection tasks are performed by what is commonly referred to as an intelligent combo tool since it combines arrays of sensors to perform different integrity inspection tasks. The tool constantly measures its distance travelled via wheels rolling along the inner pipe walls – which helps map measurement along the length of the pipeline. 3.2. Ultrasonic thickness measurement in predefined critical areas (monitoring) Monitoring of thickness in critical areas is important information about assessment of corrosion process in pipe wall during services of pipelines. 3.3. Guided wave ultrasonic testing for wall thinning Guided wave offers an alternative application for ultrasound wall thickness of pipes. At this stage there is no European standard for its application. Individual companies have developed documented procedures for control with guided wave technique. This technique The application of this technique is performed by an ultrasonic system, consisting of: array circular ring with a number of transducers, equipment for controlling the circular array (multiplexer) and notebook with program product for displaying the signal in the scan image and control the multiplexer. Four most produced guided wave systems are developed and presented to the market until now from Plant Integrity Ltd (www.plantintegity.com), TWI, Guided Ultrasonic Ltd (www.guided-ultrasonics.com), MKC Korea (www.mkckorea.com/english.html) and the new systems from company OLYMPUS. Restrictions for guided wave are related to the following characteristics of the manufacture, installation and operation of controlled pipeline: geometry and components, insulation, content of fluid in the pipeline, the pipeline status, noise around the pipeline and others. 3.4. Assessment of mechanical stress state in assumed area with discontinuity for prediction of method and materials for pipeline fiber-reinforced composite repairs. Assessment of mechanical characteristic of used composite material Assessment of mechanical stress state in area with discontinues in services of pipeline give initial characteristic used for numerical calculation of necessary pressure applied from outside to inside of pipe for safety work with working pressure. When value of pressure, mechanical and geometrical characteristic of pipeline and working pressure is known is define elastically and mechanically characteristics and dimensions of material used for reinforced (repair) of pipeline. 3.5. Acoustic emission testing for monitoring and localization of discontinues Acoustic emission (AE) is an excellent tool for detecting and locating leaks in buried pipelines. Access to the pipeline is required only locally for mounting AE sensors. Pipeline is pressurized and AE tested in 600m-1000m long sections at a time. The AE sensors detect the turbulent flow at the leak orifice, and with the use of digital AE systems and specialized software, the position of the leak is provided. The technical description and the physics of the AE leak detection technique, presents the application, limitations and requirements of the method is describes in 52727 [3]. 6 Conclusion In this work are presented the possibility of different techniques for application of ultrasonic testing of manufacturing pipelines for petroleum industry and assessment of pipeline state during maintenance. References [1] А . ., .Ю. . А ” , [2] К . ., К NDT, 2013, №2, 42-54; [3] 52727-2007. . [4] 52330-2005. К [9] 52079-2003. . 12503-75. . 52890-2007. К . 52731-2007. К ; 153-39.4-010-2002. [10] 153-34.0-10.673-2005. [5] [6] [7] [8] [11] 08.00-60.30.00-К . . Х ”, , , 2009, №9, 42-49; . А e . . А ; . - . К . ., . . , . . А . . -046-1-05. . [12] 2-2.3-066-2006. К К А ” ”. [13] EN 12737:2001.Gas infrastructure. Welding steel pipework. Functional requirements. [14] EN 10160:2001. Ultrasonic testing of steel flat product of thickness equal or greater than 6 mm (reflection method) [15] EN 14127. Non-destructive testing - Ultrasonic thickness measurement [16] EN ISO 10893-8:2011. Non-destructive testing of steel tubes - Part 8: Automated ultrasonic testing of seamless and welded steel tubes for the detection of laminar imperfections (ISO 10893-8:2011) [17] EN ISO 10893-9:2011. Non-destructive testing of steel tubes - Part 9: Automated ultrasonic testing for the detection of laminar imperfections in strip/plate used for the manufacture of welded steel tubes (ISO 10893-9:2011) [18] EN ISO 10893-10:2011. Non-destructive testing of steel tubes - Part 10: Automated full peripheral ultrasonic testing of seamless and welded (except submerged arc-welded) steel tubes for the detection of longitudinal and/or transverse imperfections (ISO 10893-10:2011) [19] EN ISO 10893-11:2011. Non-destructive testing of steel tubes - Part 11: Automated ultrasonic testing of the weld seam of welded steel tubes for the detection of longitudinal and/or transverse imperfections (ISO 10893-11:2011) [20] EN ISO 10893-12:2011. Non-destructive testing of steel tubes - Part 12: Automated full peripheral ultrasonic thickness testing of seamless and welded (except submerged arc-welded) steel tubes (ISO 1089312:2011) [21] EN ISO 16828:2014. Non-destructive testing - Ultrasonic testing - Time-of-flight diffraction technique as a method for detection and sizing of discontinuities (ISO 16828:2012) [22] EN ISO 17405:2014. Non-destructive testing - Ultrasonic testing - Technique of testing claddings produced by welding, rolling and explosion (ISO 17405:2014) [23] EN ISO 16810:2014. Non-destructive testing - Ultrasonic testing - General principles (ISO 16810:2012) 7