Abstract The fitness-for-service procedures for local thin areas in pipelines trade complexity for conservatism, with more complex procedures being less conservative. In this paper, we outline a procedure for automating the advanced Level 3 assessment procedure outlined in API 579-1/ASME FFS-1 for local thin areas. The outlined procedure is bundled into a web-enabled, industrial trade tool where the minimum data requirements are the same as those for a Level 2 assessment. The procedure can be applied to an entire in-line inspection scan of UT thickness readings and, after calculation, can identify hotspots of local damage. By reducing the inputs to those of a Level 2 assessment procedure, the Level 3 procedure presents as an attractive alternative to the current Level 2 approaches.

Abstract Polyethylene (PE) pipe has been widely used in the transportation natural gas, and electrofusion (EF) welding is a welding method commonly used in the welding of polyethylene pipes. Defects are likely to occur in electrofusion joints, which lead to significant casualties and economic losses if PE pipes failed during service. However, the assessment of electrofusion joints is made by visual inspection and destructive testing, which can’t detect internal defects directly. This paper introduces two recently developed Chinese standards for nondestructive testing and safety assessment of electrofusion joints. These standards illustrate inspection process, sample block, defect characterization and safety assessment. Some research, applying these standards for inspection and safety assessment of electrofusion joint, is introduced in this paper. Those researches show that ultrasonic detection technology in these standards is suitable for defects inspection, and standards provide standard technical support for the safety of polyethylene pipelines.

Abstract Mandatory Appendix XXVI of Section III of the ASME B&PV Code contains rules for the construction of Class 3 polyethylene pressure piping systems. The scope is limited to buried portions of Class 3 service water or buried portions of Class 3 cooling water systems, consisting of PE4710 High Density Polyethylene (HDPE) materials. The minimum Pennsylvania Notched Test (PENT) rating for the HDPE material is 2,000 hours. Appendix XXVI contains acceptance standards for the maximum allowable depths of gouges, cuts or other surface conditions that are characterized as indentations. The acceptance standards are considered to be very restrictive, in particular for large diameter HDPE pipes. Less restrictive maximum allowable indentation depths for pipes with a minimum PENT rating of 2,000 hours were developed based on use of results from tests performed on pressurized HDPE pipes containing flaws in the parent material. These maximum allowable indentation depths were implemented into the new Section III Code Case N-891 on alternative requirements to Appendix XXVI for inspection and repair. The technical basis for the maximum allowable indentation depths is described in this paper.

Abstract For several decades pressurized water reactors have experienced Primary Water Stress Corrosion Cracking (PWSCC) within Alloy 600 components and welds. The nuclear industry has developed several methods for mitigation of PWSCC to prevent costly repairs to pressurized water reactor (PWR) components including surface stress improvement by peening. Laser shock peening (LSP) is one method to effectively place the surface of a PWSCC susceptible component into compression and significantly reduce the potential for crack initiation during future operation. The Material Reliability Program (MRP) has issued MRP-335, which provides guidelines for effective mitigation of reactor vessel heads and nozzles constructed of Alloy 600 material. In addition, ASME Code Case N-729-6 provides performance requirements for peening processes applied to reactor vessel head penetrations in order to prevent degradation and take advantage of inspection relief, which will reduce operating costs for nuclear plants. LSP Technologies, Inc. (LSPT) has developed and utilized a proprietary LSP system called the Procudo ® 200 Laser Peening System. System specifications are laser energy of 10 J, pulse width of 20 ns, and repetition rate of 20 Hz. Scalable processing intensity is provided through automated focusing optics control. For the presented work, power densities of 4 to 9.5 GW/cm 2 and spot sizes of nominally 2 mm were selected. This system has been used effectively in many non-nuclear industries including aerospace, power generation, automotive, and oil and gas. The Procudo ® 200 Laser Peening System will be used to process reactor vessel heads in the United States for mitigation of PWSCC. The Procudo ® 200 Laser Peening System is a versatile and portable system that can be deployed in many variations. This paper presents test results used to evaluate the effectiveness of the Procudo ® 200 Laser Peening System on Alloy 600 material and welds. As a part of the qualification process, testing was performed to demonstrate compliance with industry requirements. The test results include surface stress measurements on laser peened Alloy 600, and Alloy 182 coupons using x-ray diffraction (XRD) and crack compliance (slitting) stress measurement techniques. The test results are compared to stress criteria developed based on the performance requirements documented in MRP-335 and Code Case N-729-6. Other test results include surface roughness measurements and percent of cold work induced by the peening process. The test results demonstrate the ability of the LSP process to induce the level and depth of compression required for mitigation of PWSCC and that the process does not result in adverse conditions within the material.

Abstract In-line Inspection (ILI) tools are regularly used for inspecting transmission pipelines. However, it is challenging to use such technology for a large portion of pipes; e.g. terminals and pumping stations, because of diameter changes, tight turns, or other pipe/inspection characteristics. Non-contact pipeline magnetic testing (NPMT) is a well-suited technique to inspect potentially non-ILI pipes. This paper presents a new framework for selecting and prioritizing digs-based LSM high severity features. A multi-criteria decision-making approach was developed using pair-wise comparisons which stems from the Analytical Hierarchy Process (AHP). AHP is a structured technique for organizing and analyzing complex decisions to help the decision maker set priorities and make the best decision given available information. In addition to the application of AHP, a cost benefit analysis and evaluation of risk have been conducted in order to support a risk-informed decision-making for selecting the top priority digs. Pipe properties, LSM tool reported data and Subject Matter Expert (SME) opinion were utilized in order to efficiently render a decision regarding prioritization of dig sites. The developed approach can be used as a regular process to prioritize similar dig programs. This method is capable of ranking different dig sites based on SME opinion as well as construction information and LSM reported data.

Abstract Power plant component condition monitoring with respect of fatigue and creep-fatigue requires information about the real operational loading of the component. Load monitoring systems are available on the market for that purpose. The retrieved load information can be further processed in terms of fatigue assessment based on realistic loading. Moreover, the combination of load monitoring, derivation of stress-time-histories for sentinel locations, cycle counting and fracture mechanics based assessment paves the way of substantiated determination and optimization of non-destructive testing (NDT) inspection intervals. This approach enables a continuous structural health monitoring of critical components even in the sense of online-monitoring capabilities. This approach provides — in addition to the established fatigue analysis — concrete decisions for the remaining component lifetime and the maximum inspection intervals. This method can also be used if the previous lifetime consumption is unknown. It basically constitutes an advanced damage tolerance approach. The paper describes a newly developed solution which combines the established Fast Fatigue Evaluation (FFE) approach of Framatome with the THERRI capabilities of TÜV NORD.

Abstract Pressurized water reactor (PWR) steam generator (SG) main steam and feedwater nozzles are classified as ASME Code, Section XI, Class 2, Category C-B, pressure retaining welds in pressure vessels. Current ASME Code requirements specify that the nozzle-to-shell welds (Item No. C2.21 & C2.32) and nozzle inner radius sections (Item C2.22) are to be examined very 10 years. An evaluation was performed to establish a technical basis for optimized inspection frequencies for these items. The work included a review of inspection history and results, a survey of components in the PWR fleet (which included both U.S. and overseas plants), selection of representative main steam and feedwater nozzle configurations and operating transients for stress analysis, evaluation of potential degradation mechanisms, and flaw tolerance evaluations consisting of probabilistic and deterministic fracture mechanics analyses. The results of multiple inspection scenarios and sensitivity studies were compared to the U.S. Nuclear Regulatory Commission (NRC) safety goal of 10 −6 failures per year.

Abstract The Primary Water Stress Corrosion Cracking causes existing ASME BPV Code Section XI inspection and repair methodology to need enhancement. This forms the basis for Code Case N-770 and revisions through 6. The paper includes the bases for examination requirements, examination schedule, and repair criteria.

Abstract Probabilistic analysis is becoming increasingly adopted by pipeline integrity management practices in recent years. The practice employs reliability engineering methods to address pipeline integrity and safety concerns. At present, the industry is beginning to pair reliability methods with numerical methods to estimate probabilities of failure ( PoF ) for individual defects, or features, in a pipeline. The effort required for this can be intensive, since it must be repeated on hundreds of thousands of features, which need to be analyzed on a regular basis. This poses a challenge for pipeline reliability engineers, given limited human and computational resources. In the meantime, machine learning applications in many industries have grown significantly due to advancements in algorithms and raw computing power. With massive amounts of raw data available from inline inspection (ILI) tools, and artificial data available through simulation techniques, pipeline integrity reliability becomes a promising field in which to apply machine learning technology to fast-track PoF estimation. Since a large population of reported features have low PoF s and pose low risk to integrity and safety, they can be safely screened out using fast machine learning models to free up engineers who can be dedicated to in-depth analysis of more critical features, which could have a much larger impact on pipeline operational safety. In this paper, two machine learning models are proposed to address the pipeline integrity reliability challenges. The regression model was able to predict features with low PoF s with 99.99% confidence. The classification model was able to conservatively predict PoF s so that no high PoF feature was misclassified as being low PoF , while correctly filtering out 99.6% of the low PoF features. The proposed approach is presented and validated through pipeline integrity simulated case studies.

Abstract Researchers at Northrop Grumman Innovation Systems (NGIS) have been pursuing the application of additive manufacturing (AM) technology in pressure vessel manufacture for several years. We gained significant insight after the design, analysis, fabrication, and qualification of a 1.8 liter propellant tank with additive manufactured shell in 2017. A Space Propulsion 2018 summary paper titled Additive Manufactured Pressure Vessel Shell included a description of the research and its development progress as of May 2018. Importantly, the authors discussed several items for further examination, including developing a material data base, developing fracture inspection techniques, developing fracture data to facilitate fracture analyses, assessing consistency in material properties, and examining material shedding. In this summary paper, we review the continuing AM research and development (R&D) activities within NGIS and provide a progress update. The summary paper has three sections. Section 1 contains program background and a description of the evolving NGIS R&D program. In Section 2, we present a progress update. In Section 3, we conclude with a review of our vision towards the implementation of AM technology in space borne pressure vessel manufacture.

Abstract A comprehensive study is conducted on finite element modeling and stress analysis techniques of above ground atmospheric bulk liquid storage tanks with foundation settlements. Both 2-D and 3-D modeling are examined for their applicability and limitations. Simple elastic analysis and 3-step method using a hybrid elastic-plastic procedure are explored and compared. In addition, data processing techniques are proposed to extract effective settlements from tank inspection measurements, which could be used for proper reconstruction of a settled foundation in finite element model. Procedures and practices are proposed and demonstrated to improve the finite element modeling and analysis of storage tanks.

Abstract This paper discusses when new SIF and k-Factors from ASME B31J-2017 should be used for operating and new piping systems. Screening guidelines are provided to help plant owners know when current operating facilities may be subject to through-wall leaks as they approach given life milestones. The paper also shows when these same guidelines can be used in new system designs to require the use of more applicable SIF data, of qualified vendor lists and additional inspections.

Abstract Research shows how the impact of inaccurate fatigue calculations (SIFs), poor quality materials and manufacturing shortcuts will eventually result in pipe content leaks that will cause significant business interruption costs and potentially casualties in a very small population of operating piping systems. B31J-2017 corrects many of these inaccurate SIFs but has been slow to be implemented by the piping user community because failures due to thermal overstresses occur much closer to the end of the piping system life than the beginning. Fortunately for the owner this leaves time to correct for any errors once they have been recognized. Relatively simple screening is described that allows the owner and designer to identify the relatively small population of piping systems that should be addressed.

Abstract Liquid penetrant testing (PT), magnetic particle testing (MT) and ultrasonic testing (UT) have been used as nondestructive testing methods for the welded tubular joints of reactor cooling systems. The PT and the MT that are applied to the surface test of the specimen have been experiencing problems such as specimen contamination, hazardous chemical exposure risk for the inspector, and the inspector’s extended time in the nuclear power plant due to the long testing time (increased risk of radiation exposure). This study is about the applicability of an alternative nondestructive examination (ANDE) method to solve the aforementioned problems. According to the requirements of ANDE, the NDE technology should be applied with the same or better sensitivity and shorter inspection time than the conventional inspection methods of PT and MT. In order to satisfy these requirements, a flexible-type multi-sensor array was developed in order to scan a certain welding area and complete the inspection in a short time. The static and time-varying magnetic fields were applied to the test specimen and the magnetic flux density distribution was measured by solid state magnetic sensors. Each sensor is arranged with a spatial resolution of less than 2 mm, and the shape can be varied according to the shape of the bead. By using the measured data, the magnetic flux density distribution according to the presence or absence of defects and shapes can be visualized in real time, and stored into the database.

Abstract The erect pipe is a dangerous one with a special double concentric pipes, in which the inner pipe and outer pipe are both corroded on the offshore platform so that a effective corrosion inspection is needed to measure the thinning to the inner pipe and outer pipe at the same time. In addition, because of the narrow space in the offshore platform, it is difficult for the digital X-ray tangential photography (DR) to be implemented during the operation because of the larger X-ray dose that is enough to threaten the personal safety according to the standards in China. Hence, a special inspection tech is demanded to obtain the wall thicknesses of erect pipe which is the most important information to the corrosion management. In this article, A new measuring tech is proposed for the concentric multi-pipe structure to dissolve the bottleneck on the inspection of the offshore erect pipeline. Through the tangential scanning and a wall boundary identifying algorithm, the tech can accurately measure the wall thicknesses of erect pipe, and the ray dose can also be decreased about to the one thousandth of traditional DR, which can guarantee the safety of a inspection and monitoring during the operation in a narrow space as the offshore platform. Besides, the low dose of ray doesn’t influence the accuracy of the measurement which can still be kept into 0.2mm according to the theoretical analysis and experimental data.

Abstract The integrity of transmission oil pipelines are often managed through in-line inspections (ILI) at regular intervals. For the last two decades, such ILI-based integrity programs along with excavations and field non-destructive testing (NDE) have proven their effectiveness in terms of reliability. In a few cases, some pipes contain; for example, a unique cracking mechanism exhibited by short, deep axial cracks located in the vicinity of girth welds. These attributes pose sizing difficulties for ultrasonic crack ILI tools. Accordingly, operators may lean on supplemental integrity activities to prove the safety of the pipelines such as; but not limited to, hydrostatic testing, laboratory testing of cut-outs, qualitative ranking of features, borehole leak detection analysis, Just-Missed-Flaw (JMF) or Just Surviving Flaw (JSF) analysis, discharge and/or point pressure restrictions, and/or a mix between all the previous techniques. Moreover, it is the operators’ responsibility to evaluate the risk associated with their integrity plans. Hence, it is important to be able to analyze the reliability of such integrity activities quantitatively. This paper presents an event-tree approach which can augment standard ILI or hydrostatic test results and probabilistic analysis with non-ILI integrity measures under one umbrella. In this approach, the likelihood of failure for both leak and rupture modes can be comprehensively estimated. The event tree approach is used herein as an inductive analytical diagram in which failure events are analyzed using Boolean logic to examine a chronological series of subsequent integrity actions and consequences. The proposed approach is also designed to capture subject matter experts’ opinion into the analysis as part of the integrity management program. The work discusses a real practical application along with verification and validation elements of the proposed integrated approach.

Abstract A periodic inspection of a reactor pressure vessel in refinery was scheduled. Prior to that inspection, criteria need to be established to determine what flaw indication would be tolerable so that the vessel can safely be put back in to service in a timely manner, or in the worst case, identify what flaw indication would create a very strong case for repair or replacement criteria for the vessel. A flaw tolerance criterion that can be applied to the refinery inspection process was developed for numerous potential flaw locations in this vessel. The finite element alternating method was used to determine the appropriate fracture parameters to assist in this flaw assessment procedure. These computational efforts involved examining the fracture response of the system in preparation for planned inspections. Stress intensity factors were evaluated for a total of ten (10) cracks inserted into the refinery pressure vessel at several locations and crack orientations. Most of the cracks had depth to thickness ratios of 0.25 and a half width 3 times this depth. The crack sizes are chosen based on the assumed maximum initial flaw sizes expected to be found from NDI. The stress intensity factor for residual stress loading was conservatively estimated by placing a unit tensile pressure on the crack face for all 10 cracks. The approximation of crack face pressure loading to simulate residual stress is also shown to be accurate. Therefore, one can estimate the contribution to stress intensity factor by multiplying the residual stress value of K by the estimated residual stress ratio. The final estimate of crack driving force for a crack, K I , is obtained by adding the contributions of the pressure loading with the residual stress contribution. Internal pressure loading of this vessel is the only significant source of loading in this vessel.

Abstract Repeated weld joints leaks were observed in newly commissioned non insulated low temperature carbon steel anhydrous ammonia pipes after few months of operations. A detailed investigation was carried out to identify the root cause which found to be usage of high strength filler wire which leads to stress corrosion cracking (SCC) and weld joints failure. Also, An Online advance inspection via Phased Array Ultrasonic Test (PAUT) was conducted to assess the condition of weld joints in anhydrous ammonia pipe loops. Moreover, three different samples of leaked weld joints were submitted for metallurgical failure analysis laboratory. The paper explains the root cause of the damage, Online PAUT inspection and the challenges faced during development of the rectification procedure and implementation.

Abstract Polyethylene pipe has been used widely in gas transportation and nuclear safety-related cooling water applications due to its exceptional resistance to corrosion and erosion. Butt fusion joint is one of the main welding forms for polyethylene pipes. Ultrasonic technique is a typical nondestructive examination technique. To overcome the coupling problems when inspecting butt fusion structures, an inspection technique of ultrasonic phased array using water wedge is proposed to solve the coupling matching and to increase the ultrasound amplitudes. The influences on the imaging of the parameters (such as the angle and height of the water wedge), the array element specifications, and the aperture, were investigated via simulations. The parameter optimization was conducted to establish a suitable detection process. After that, the related probe and a simulated water wedge were designed based on the results and manufactured, in which the simulated wedge as a specific probe holder could adjust its own incident angle and array height. Meanwhile, a typical DN315 pipe of PE 100 was made with some typical artificial defects in it. Experiments were conducted, and the results showed that the proposed water-wedged ultrasonic phased array technique is suitable for butt fusion joint inspection.

Abstract In recent years, there has been a growing interest of using Leak-Before-Break (LBB) concept in the refining industry. LBB methodology has been applied in the nuclear industry for decades, but generally for elimination of hardware for dynamic rupture control at the design stage. However, in the refining industry the purpose of the LBB application could be quite different than for the nuclear industry. In the refining industry the purpose of LBB is to show in-service leakage can be detected well ahead the potential for rupture allowing for ample time for safe replacement of piping. This paper explores conditions in which LBB can be applied to refinery piping. Initially, the analysis was conducted using a finite element model of a typical pipe system with its design boundary conditions under operating loadings, i.e., gravity, pressure, thermal and hanger loadings. The results with various circumferential crack sizes show a displacement-controlled manner (LBB is easy to satisfy) for the pipe system mainly due to higher secondary stresses, i.e., thermal loadings. However, the pipe system behaved in a load-controlled manner (LBB is harder to satisfy) when some of the boundary conditions were changed simulating a possible support failure and/or hanger failure. This paper investigates how boundary conditions can change a displacement-controlled LBB behavior to load-controlled LBB for a representative pipe system and the implications regarding leak rate detection capability. The effect of material’s toughness reduction due to high-temperature hydrogen-attack (HTHA) damage was also included in these analyses. The procedure outlined here can be applied to a piping system to identify piping supports that are critical for inspection to demonstrate LBB, and the anticipated leak rate before reaching critical flaw size.