Engineering

Pipeline is the common mode for transporting oil, gas, and various petroleum products. Structural integrity of oil and gas transmission pipelines is often threatened by external interferences such as concentrated load, impact load, and external pressure. These external interferences can cause 'mechanical damage' leading to structural failure in onshore and offshore linepipes. Lateral load is applied as a concentrated load on a small area of pipe segment and can cause local buckling, bend, dent, or out-of-roundness in the pipe. As an example, a concentrated load in buried onshore linepipe can occur if a segment of the linepipe rests on a narrow rock tip or even a narrow hard surface. Such concentrated lateral load may or may not cause immediate rupture or leak in the linepipe; however, it may produce out-of-roundness with or without a dent in the pipe cross section, which can be detrimental to the structural and/or operational integrity of the pipeline. Hence, the pipeline operator becomes concerned about the performance and safety of the linepipe if a pipe section is subject to a sustained concentrated load. A research work using full-scale tests and finite element method (FEM) was undertaken at the Centre for Engineering Research in Pipelines (CERP), University of Windsor to study the influence of various internal pressures and diameter-tothickness ratios on the out-of-roundness of 30 in diameter (NPS 30) and X70 grade pipes with D/t of 90 when subjected to a stroke-controlled concentrated load. This paper discusses the test specimens, test setup, test procedure, test results, and FEM results obtained from this study.

Pipeline is the common mode for transporting oil, gas, and various petroleum products. Buried linepipe can be exposed to various external interferences and corrosive environment and as a result, damage in the form of dent or corrosion or crack or gouge or combination of any of these damages can form in the pipe wall. Such damage or combined damages can reduce the pressure capacity of the pipeline. A defect combining dent and crack, often known as dent-crack defect, can develop in the wall of a buried oil and gas linepipe. This combined defect may lead to a leak or a rupture in the pipe wall and hence, the pipeline operator becomes concerned about the performance and safety of the pipeline when a dent-crack defect is detected in the field pipeline. A long-term research program is currently underway at the Centre for Engineering Research in Pipelines, University of Windsor to study the influence of various parameters such as dent depth and operating line pressure on the pressure capacity or burst strength of 30 inch diameter and X70 grade pipes with D/t of about 90. From the study completed so far, it has been found that the dent depth of 8% with crack depth of 4 mm or more can reduce the pressure capacity by 32%. This paper discusses the test specimens, test setup, test procedure, test results, and data obtained from finite element analyses.

While most in-field non-destructive technologies for structural integrity diagnosis focus on precise crack detection, a novel instrumented indentation technique for non-destructively determining tensile properties in fields is introduced here. The goal of this work is to apply the newly-developed indentation technique to in-field fitness-for-service (FFS) assessment of linepipe cracks. As one step to verify its applicability, tensile properties in base metal and girth weldement of API-X65-graded linepipe were evaluated by this indentation technique and provided for construction of material-specific failure assessment diagrams (FADs). Results are discussed in terms of the accuracy of the indentation data and how the FAD assessment results are affected by the variation in local tensile properties measured by indenting small target regions such as heat-affected zones (HAZs). Based on the results, we suggest that the indentation technique may be useful for reducing possible difficulties in flaw assessment (arising from the use of incorrect tensile properties) by providing reliably practical data for FAD construction.

Integrity management decisions related to operating energy transmission pipelines affected by Stress Corrosion Cracking (SCC) represent a formidable challenge to the pipeline industry. Effective management of SCC damage requires the development of tools and technology to identify the occurrence of SCC and to assess the impact of the SCC on pipeline integrity. Development of practical non-destructive evaluation (NDE) solutions for the measurement and evaluation of SCC, including crack depths, is difficult due to the complexity of crack shapes and their inter-relationship and distribution within crack colonies.

A novel test setup has been used in this study to simulate stress corrosion cracking initiation under a disbonded coating on an X-65 pipeline steel. In this setup, the synergistic effects of cyclic loading, cathodic protection and soil solution environment under disbonded coatings have been considered. When the X-65 pipeline steel was exposed to the test environment, there existed a wide range of corrosion products on the steel surface in the gradient of cathodic protection. Increasing the test time and the maximum stress increased the possibility of stress corrosion cracking initiation in regions with a high susceptibility to pitting corrosion.

Near neutral pH Stress Corrosion Cracking (NNpHSCC) associated with external corrosion of pipelines is an issue facing industry today. Determining areas of NNpHSCC susceptibility is crucial to developing Integrity Management Programs and inspection dig schedules. This research involved collecting pertinent field data (inspection dig reports, failure reports, loading histories) and developing a predictive model to help identify areas and lines most susceptible to NNpHSCC. The predictive model focused on the loading history (in this case, SCADA data) patterns to classify different groups of loading conditions. Hydrogen has been identified and established in previous literature to be a major contributor to NNpHSCC. Different Hydrogen Enhancement Factors (HEF) were applied based on how the mechanisms of hydrogen embrittlement react to the respective loading conditions. The predictive model illustrated a dormancy behaviour, similar to the one seen in field conditions and a mechanically a...

Pipeline corrosion is a common problem for polyethylene (PE) tape-coated oil and gas transmission pipes buried under ground. It is often seen under cathodic protection (CP) shielding coating disbondments, where a wrinkle filled with ground water could be formed. This study investigates corrosion of X-65 pipeline steel under a simulated CP shielding coating disbondment with a gap size of 1 cm. Results showed that the corrosion rate of pipeline steel under the CP shielding coating disbondments is a function of carbon dioxide (CO2) and level of CP at the holiday of the coating disbondment, and could be significantly different to that in bulk environments.

This project developed and validated models that will allow the industry to predict the overall benefits of hydrotests. Such a prediction is made with a consideration of various characteristics of a pipeline including the type of operation, stage of cracking, environmental susceptibility, steel metallurgy, and operation history. When hydrotesting is necessary, the model will help operators select the parameters that would generate the most effective crack remediation.

This investigation was initiated to provide governing equations for crack initiation, crack growth, and service life prediction of pipeline steels in near-neutral pH (NNpH) environments. This investigation has focused on the crack initiation and early-stage crack growth. The investigation considered a wide range of conditions that could lead to crack initiation, crack dormancy, and crack transition from a dormant state to active growth. It is concluded that premature rupture caused by stress cracking at a service life of about 20 to 30 years previously observed during field operation could take place only when the worst conditions responsible for crack initiation and growth have been realized concurrently at the site of rupture. This also explains the reason that over 95 pct of NNpH cracks remain harmless, while about 1 pct of them become a threat to the integrity of pipeline steels.

This paper reports the crack growth behavior of pipeline steels in near-neutral pH environments. Crack growth data were obtained using compact tension (CT) specimens exposed to two near-neutral pH environments. The surface of CT specimens was masked either with or without coatings. The coverage of sample surface reduces the generation of hydrogen resulting from free corrosion of iron. This has caused a substantial reduction of crack growth rate and a different dependence of crack growth behavior on Kmax, ΔK, loading frequency and environments. The growth rate data were further analyzed based on recent developed true corrosion fatigue model for pipeline steels in near neutral pH environments, from which the relative contribution of dissolution to cracking and hydrogen facilitated cracking was determined.

Integrity assessments for internal or external corrosion damage on an exposed pipeline are only as accurate as the methods which measure the extent of the damage. Inaccuracies in measurement can lead to unnecessary repairs or non-conservative assessments. This paper describes the development and use of three systems used to reliably and efficiently measure corrosion damage on both internal and external pipe surfaces of exposed in-service pipeline segments. They are based upon the application of laser optics, magnetic flux leakage and ultrasonics. The use of these systems allows for more accurate corrosion damage assessments, thereby reducing the number of unnecessary repairs and cut-outs, and reducing the risk of non-conservative assessments. The laser-based and ultrasonic systems provide contour maps of corroded areas. Software that incorporates the RSTRENG method is used to assess the significance of the damage from the data. Examples of the applications of all systems on large-di...

A study was conducted to evaluate the use of E-glass/epoxy composite materials for reinforcement of large-diameter elbows. Using a combination of sub-scale and full-scale testing, the study demonstrated that when properly designed and installed, composite materials can be used to reduce strain in reinforced elbows considering bending loads of up to 3.6 million ft-lbs (4.88 million N-m), cyclic pressures between 720 psi (4.96 MPa) and 1,440 psi (9.93 MPa), and burst testing. The stresses measured in the composite material were well below designated ASME PCC-2 design stresses for the composite materials. During testing, there was no evidence that previously applied bending loads reduced the overall burst pressure capacity of the composite-reinforced elbows. Finite element modeling was used to optimize the geometry of the composite reinforcement. The resulting design guidance from this study was used to provide direction for possible reinforcement of large-diameter elbows for in-servic...

Integrity assessments for external corrosion damage on an exposed pipeline are only as accurate as the methods used to quantify the extent and severity of the damage. Inaccuracies in measurement can lead to unnecessary repairs or nonconservative assessments. This paper describes the development and use of the second-generation Laser Pipeline Inspection Tool (LPIT). The LPIT is used to reliably and efficiently measure and assess corrosion damage on external surfaces of exposed in-service pipeline segments. To overcome the limitations of the previous system, Mark II LPIT utilizes a spot laser sensor that allows scanning of up to 103 degrees of pipe circumference. The sensor is mounted on a magnetic-wheeled crawler, which permits scanning of unlimited lengths of pipe in any clock position with high acquisition rates. Furthermore, the system has the ability to auto-steer at all orientations about the pipe. Typical pipeline characteristics such as dents, bends, bulges and welds formerly impeded corrosion measurement. New sophisticated software (CorrosionPro98) easily accommodates such features allowing the system to provide an accurate and precise measurement of corrosion. CorrosionPro98 software incorporates the RSTRENG analysis that is used to assess the significance of the damage from the data and calculate the predicted failure pressure. The LPIT system provides colour-coded contour maps of corroded areas.

Geographical Information Systems, Data trending, and Risk Assessment Software are now available to help pipeline operators execute safe, cost effective maintenance programs. However, to use these analytical tools effectively, large amounts of data pertaining to the integrity of the pipeline system and its environment are required. For this reason, pipeline rehabilitation programs have evolved into complex data collecting procedures, the success of which depends on the ability to efficiently obtain reliable, consistent and accurate information. This article will describe new software technology and Quality Control programs, relating to inspection personnel, which have been developed to increase the efficiency and reliability of the information collected during a pipeline excavation. The pertinent functions of software programs discussed will involve compatibility between databases, on site data validation, code calculations, communications and CAD drawings for a comparison with In Li...

The toggle switch consists of a cocking lever that is pinned to a fixed frame at A and held in place by the spring which has an unstretched length of 200 mm. Determine the magnitude of the resultant force at A and the normal force on the peg at B when the lever is in the position shown.

Medicine subjects were similar to pediatrics subjects in baseline demographic characteristics. Satisfaction with the EHR implementation was very high for both sets of subjects, but internal medicine residents were significantly less likely to be satisfied with ...

This paper proposes an uncertain data clustering approach to quantitatively analyze the complexity of prefabricated construction components through the integration of quality performance-based measures with associated engineering design information. The proposed model is constructed in three steps, which (1) measure prefabricated construction product complexity (hereafter referred to as product complexity) by introducing a Bayesian-based nonconforming quality performance indicator; (2) score each type of product complexity by developing a Hellinger distance-based distribution similarity measurement; and (3) cluster products into homogeneous complexity groups by using the agglomerative hierarchical clustering technique. An illustrative example is provided to demonstrate the proposed approach, and a case study of an industrial company in Edmonton, Canada, is conducted to validate the feasibility and applicability of the proposed model. This research inventively defines and investigates product complexity from the perspective of product quality performance with design information associated. The research outcomes provide simplified, interpretable, and informative insights for practitioners to better analyze and manage product complexity. In addition to this practical contribution, a novel hierarchical clustering technique is devised. This technique is capable of clustering uncertain data (i.e., beta distributions) with lower computational complexity and has the potential to be generalized to cluster all types of uncertain data.

Computers are one of the most used things in the world. Many jobs require computers. All computers usually include the internet. The internet has really shaped the modern age in many ways, for example one of the big things that came from the internet is social media. Social media is Twitter, Face Book, Instagram, Snapchat and many others.