Journal of Pipeline Systems Engineering and Practice

Cast iron pipe break rates in North American water distribution systems have increased significantly in the last six years (a 43% increase with respect to 2012). Of the numerous mechanisms that are responsible for these breaks, pipe fracture data from the City of Sacramento indicates that corrosion induced damage followed by pipe flexure due to moisture-induced soil expansion is one of the dominant mechanisms. This mechanism results in full-circle breaks in which fracture occurs transverse to the pipe axis. This paper presents an analytical model to predict such fractures, given a range of parameters that describe pipe configuration, soil conditions, and triggering factors, such as soil saturation, that leads to expansion. The model is based on (1) classical solutions for beams on elastic foundations that are enriched to reflect material nonlinearities in the soil medium, and (2) a corrosion equation to estimate pitting damage in the pipe wall. The model development and validation are supported by a suite of continuum finite-element simulations that simulate detailed interactions between the pipe and soil. The prospective use of the model is outlined in the context of decision-support frameworks to identify pipe segments at a high-risk of fracture. The limitations of the approach are discussed.

In subsea pipeline engineering practice, the total stress or alpha approach, which assumes that the axial resistance to pipeline walking in fine-grained soils such as soft and very soft clays for a specified type of coated pipe varies primarily with the undrained shear strength of the material and contact area, has been increasingly applied in axial stability analyses. The adhesion factor between the subsea pipeline and soil is an important design parameter in the total stress approach. In this paper, a series of axial pipe–soil interaction model tests were conducted to study the effects of the buried depth of a polyethylene (PE)-coated pipe, the undrained shear strength of clays, the pipe diameter, the loading rate, and the setup period on the adhesion factor using full-scale steel pipes coated with PE material. The results reveal that the adhesion factor increases with increasing loading rate, buried depth, and pipe diameter. However, the effect of the pipe diameter on the adhesion factor is not obvious for very soft clay. The range of the adhesion factor of PE-coated pipes is analyzed based on the model test results. Because the displacement-resistance curve of very soft clay shows hardening behavior based on model test results, the adhesion factor associated with the ultimate resistance of very soft clay varies from 0.2 to 0.38. Because the displacement-resistance curve of soft clay shows soft behavior based on model test results, the peak adhesion factor ranges from 0.15 to 0.26, and the residual adhesion factor is approximately 0.85 times the peak adhesion factor for soft clay. Finally, an empirical formula for determining the adhesion factor of PE-coated pipes in soft and very soft clays is recommended based on the model test results. A discussion is also provided to explain to why existing studies based on the Coulomb friction law have generally arrived at seemingly different results.

This paper presents a study of the hydrodynamic stability of a submerged floating pipeline (SFP) under regular waves. Generally, pipelines submerged in water are constructed as the seabed type, using the immersed method. However, in the Turkey and Cyprus Project, which was completed in 2015, pipelines that traverse water depths of up to 1,500 m were constructed using the suspended method for offshore crossings to ensure economic feasibility. This study investigated the behavior and response characteristics of submerged floating pipelines using the buoyancy to weight ratio, the tendon anchoring method, and the wave incidence angle by finite-element analysis. When the influence of the waves increases as the SFP approaches the free surface, the SFP has large deformation due to the material properties of the pipe. Installed depth was very important because the effect of wave for SFP decreases according to increasing of the water depth. The proposed analysis method produced good results. It can be applied as an evaluation of global behavior in the design phase.

Excessive ratcheting deformation is a typical failure mode of pressurized pipeline under repeated loads in practice. There are still very few studies regarding the analytical ratcheting limits of pressurized pipes subjected to reversed biaxial loads. In this work, the ratcheting limits of straight pipes under combined constant internal pressure and repeated bending moment were deduced and verified. Moreover, the effects of the radius ratio and strain hardening were discussed in detail. The results show that the proposed ratcheting limits are better than those obtained from the KTA/ASME and RCC-MR codes. However, the analytical ratcheting limits are still very conservative compared with those experiment data owing to the strain hardening effect of the material. The flow stress was introduced to involve the strain hardening effect, and the results show that the flow stress can be used to estimate the ratcheting limits of strain hardening pipes with high accuracy. Correspondingly, a Bree-like diagram of strain hardening pipeline under combined internal pressure and reversed bending moment was further established for engineering design.

Despite preceding studies of transients in non-Newtonian fluids that use two-dimensional (2D) models to predict the velocity gradient required to estimate unsteady losses, this study proposes an efficient one-dimensional (1D) approach. To this aim, Zielke’s solution of unsteady friction is adopted for power-law and Cross fluids. The Hagen–Poiseuille profile is assumed for variations of axial velocity at each cross section, thus allowing for the computation of the shear rate to describe the viscosity in a specific non-Newtonian fluid (e.g., using power-law). The calculated transient viscosity updates the weight function of Zielke’s model at each time increment in an iterative process. To verify the proposed numerical solution, the computational results are compared with available experimental data from literature and with an alternative 2D numerical solution. The comparisons demonstrate that although the proposed method is extremely simpler for practical applications, it is efficient and provides reasonable results.

Hydrostatic joint performance for infiltration is a key design requirement for a reinforced concrete pipe (RCP) to withstand in situ groundwater pressure. However, current standards and test methods adopted by RCP manufacturers do not adequately consider this requirement, leading to higher risk of leaky joints. Moreover, existing in-field evaluation methods conducted during pipe installation commissioning have several limitations. Although RCP joint leakage highly depends on the installation quality, both the ultimate capacity and operating resistance against infiltration of commonly used joints and gasket profiles are still unknown. The authors have recently developed a new test method to evaluate RCP joint performance against infiltration. This paper analyzes the data collected from 85 full-scale infiltration tests measuring the ultimate and operating capacity of RCP ranging from 600 to 1,200 mm in diameter. The analysis demonstrates that critical parameters including the joint gap, gasket mass, annular space influence ratio, and time-dependent behavior significantly affect the RCP resistance to infiltration. The large testing program confirms that the new test method is simple, robust, safe, and reliable for measuring the infiltration capacity of RCP joints. Thus, it can be considered for routine quality control testing.

The purpose of this paper is to present a new kind of fast structural damage-detection method based on structural vibration responses that can be used for aboveground pipelines. This study proposes the use of structural health monitoring (SHM) for aboveground pipelines using the inner product vector (IPV) method. The IPV can be calculated from the vibrational responses signals (displacement or velocity or acceleration) under band pass white noise excitation. The vibrational responses signals were measured before and after damage. The case study is a type 304 stainless steel pipe with an internal defect. Because of difficulties in creating internal defects in practice, numerical simulation was used. This was achieved by the use of three-dimensional (3D) finite element (FE) modeling software (ABAQUS CAE version 6.10) with MATLAB R2015b (version 8.6) used to calculate the IPV method. To verify the simulation method, the results obtained from modeling in ABAQUS are compared with our previous experimental results that showed good agreement. The results indicate that the IPV method can be used for detecting damage in aboveground pipeline.

Due to the potential severity of oil and gas pipeline accidents, the accurate assessment of defective pipelines is a critical focus in petroleum engineering. Some parameters in the assessment standards are, however, limited in their technologies. This essay provides a new modification method for the safety factor (SF) of the widely accepted ASME Manual for Determining the Remaining Strength of Corroded Pipelines (B31G-2012). In the provided method, the SF is modified considering critical factors based on pipeline big data, using two big data analysis techniques, namely, correlation analysis and the analytic hierarchy process (AHP), to improve the previous one in which only the pressure of the pipeline was used during calculation. In this paper, data from an in-service pipeline is manipulated as a case to show how the modified SF is calculated. Comparative analysis with the previous results provides clear evidence that the new results are more accurate and that the SF changes according to different risk levels.

Owing to large differences in the stiffness of pipelines and soil, their movements cannot be coordinated under vibrational loads. Therefore, pipe-soil interaction is an extremely important factor in studying pipeline failure, and many researchers have performed detailed investigations on pipe-soil interactions in straight pipelines. In this paper, pipe bending tests were performed using unplasticized polyvinyl chloride (PVC-U) pipes on a shaking table and earth pressures at an elbow were obtained under different site conditions. Experimental results were compared with those obtained from particle flow code in two dimensions (${\mathrm{PFC}}^{2\mathrm{D}}$) simulations and empirical equations, which proved the reliability of the experimentally obtained results. In this paper, the change rule of earth pressure at an elbow was analyzed, relevant regular curves obtained for different soil types were fitted, and the relationship between earth pressure at an elbow and transverse and longitudinal earth pressures for straight pipes were determined. Then five external factors influencing the earth pressure of pipe bending, including pipe buried depth, pipe diameter, bending angle, loading frequency, and loading peak, were investigated. Finally, based on experimental equations of earth pressure for straight pipes, experimental equations were derived for elbow earth pressure calculation, and the reference values for the calculation of the earth pressure of pipe bending were given.

This study is interested in executing an optimal wavelet transform (WT) to interpret the continuous leak acoustic emission signal precisely. Thus, this paper proposes detailed guidelines on how to select an optimal mother wavelet. The recurring dominant signal patterns were first isolated from the raw leak AE signal. Having their correlation similarity with available standard mother wavelets led to the optimal choice of mother wavelet. The WT spectrogram with mother wavelet cmor1-1.5 presents an excellent leak frequency band and peak leak frequency in comparison with other mother wavelets. Cross-correlation tests were further carried out to evaluate the ability of cmor1-1.5 for locating the leak source with WT coefficients on the leak characteristic frequency. Furthermore, through directly transferring the raw leak AE signals into the cross-correlation function to recalculate their time difference of arrival (TDOA), the location results of the leak source have a huge deviation or are fundamentally impossible. Thus, comparison incredibly indicates the significance of the choice of suitable mother wavelet, which also further highlights that having an optimal choice of the mother wavelet in the proposed method led to the accurate location for the leak source.

In this paper, a new application of tire-derived aggregate (TDA) backfill around corrugated steel plate (CSP) pipe culverts is proposed and its feasibility is explored experimentally and numerically. Pressure distribution around buried structures depends on the relative stiffness of the structure and the surrounding backfill material. Accordingly, earth pressure around buried culverts can be reduced by installing a layer of compressible material such as TDA above the culverts, developing a positive arching mechanism, causing the earth pressure above the culverts to be less than the theoretical value of the weight of the soil prism above them. Four full-scale tests were conducted to evaluate the effectiveness of using a layer of TDA material in different backfill envelope configurations around 600-mm CSP culverts. In addition, three-dimensional (3D) finite-element models of the tests were developed and verified against the experimental results to study the interaction mechanisms in the considered problem. An intensive parametric study was also conducted to examine the effect of the TDA backfill envelope configuration around the culvert, the influence of the stiffness of the top granular backfill, the performance of the proposed system beneath rigid pavement, the effect of the culvert burial depth, and the performance of the proposed system under embankment loads. The results show that the proposed system can be effectively used to decrease culvert stresses and deformations.

Operators of North America’s potable water systems are facing numerous challenges in meeting the current needs and future expectations. Even though utility management experts started building customer-driven asset management systems to prioritize the water mains’ maintenance and replacement, the gap between the utility experts’ and end users’ perspectives still exists due to the lack of technical knowledge in terms of assessing the water quality. Therefore, this paper proposes a service-based asset management framework that evaluates the factors associated with the level of service (LOS) of the water supply networks and maps it to the physical condition. In this paper, the LOS for water supply networks is an indicator that measures the ability of a municipality to continuously supply the end users with adequate water quality to ensure fewer customer complaints and higher end-user satisfaction. The framework revolves around three phases: (1) data collection; (2) model implementation, which comprises LOS assessment and LOS and condition mapping models; and (3) results and analysis. To assess the LOS, a questionnaire was designed and analyzed using the best-worst method. Furthermore, an artificial neural network model was developed to map the relationship between the LOS and condition. Water quality, customer complaints, pressure, and continuity of water supply were used as mapping metrics between the LOS and condition. Toward the end, the framework was applied to the water distribution network of Montreal, Canada and it showed promising results in estimating the corresponding LOS from the condition. In addition, a cross-validation was carried out and the results displayed an 0.871 coefficient of determination ($R^2$), which implies a strong existing relationship between the model inputs and outputs. This framework enables the utility experts to understand the customer perception of the service, optimize the budget allocation, and forecast the LOS based on the network condition.

The leak localization in a water pipeline system plays a vital role in pipeline system modeling. The leak location is identified by estimating the time difference between two sensor signals placed on either side of the leak. The time difference estimation is achieved using the cross-correlation technique. The conventional cross-correlation technique fails to detect the leak when the vibrated sensor signal is corrupted by noise as well as convoluted with the impulse response of the pipe. In this paper, adaptive independent component analysis-based cross-correlation techniques along with empirical mode decomposition are implemented for processing the noisy and convolved impulse response output from acousto-optic sensors for locating the leaks in the water pipeline. The preprocessing of empirical mode decomposition is used to decompose the leak signal into several intrinsic mode functions (IMFs), and the external noise in the leak signal can be eliminated by removing the uncorrelated IMFs. The adaptive nature of independent component analysis in the proposed method makes the algorithm more robust in a real-time scenario. The probable benefit of using adaptive independent component analysis is to achieve a strong decorrelation and separation of the real-time vibrated sensor signal from the convoluted impulse response of the pipe along with noise. The proposed algorithm has been experimentally tested from a specially erected leak-detection facility located at Universiti Tunku Abdul Rahman Research site in Malaysia. The test result shows that the proposed method offers more than 95% accuracy of leak localization compared with conventional cross-correlation methods.

Central heating is the main heating method in cities in northern China in winter, and it is also an important part of urban utilities. The safety of the heating pipe network operation is an important livelihood issue. Temperature fatigue damage of the central heating pipeline has a severe impact on the safe operation of the system, and reasonable estimation of the number of fatigue cycles during the service life of the pipeline is an essential link in the pipeline design of a district heating (DH) system. The temperature data of five typical secondary networks of heat exchanger stations in Jiancao District of Taiyuan City in four heating seasons were collected. The frequency of temperature change during operation was counted, and the maximum total temperature difference cycle number of pipelines was estimated. In this paper, the regression analysis method is adopted to fit the design equation of the number of temperature cycles of water supply and return pipelines in 30 years of service life, which provides a way of thinking for predicting the number of temperature difference fatigue cycles of pipelines in the design stage. In the calculation of the number of maximum total temperature difference cycles, the different values of temperature difference defining parameter $b$ and reference temperature difference $\mathrm{\Delta }{T}_{\mathrm{ref}}$ are analyzed. The results show that the selection of temperature difference defining parameter $b$ can effectively distinguish the effect of large and small temperature difference on the number of fatigue cycles of pipelines; at the same time, the cyclic temperature difference is normalized within a specific range of design temperature difference, which overcomes the problem of simplifying the guidance of the operation parameters of the central heating system and makes the predicted maximum total temperature difference cycle have universal guiding significance in a specific heating area.

Augmented reality (AR) has been identified as a technique that can enhance information extraction from the virtual world to the real world and improve the access and utilization of information. The main challenge in creating a reliable and adaptive outdoor AR system is the accurate registration of virtual objects in the real world. There is currently limited research using outdoor AR for collecting underground utility inventory and evaluating the accuracy. Because of the limited accuracy of smartphones, this study used external GPS devices to reduce positional error. The main objective of this research was to evaluate the horizontal accuracy of the captured data used by the AR phone application XR-GIS, developed by the authors. This study used root-mean-square error (RMSE), average Euclidean error (AEE), and central error (CE) in the evaluation of two smartphones and two popular GPS devices on 16 survey location points. Leveraging a Trimble S5 robotic total station, a geodetic base point and the location points used in the study were authoritatively measured. The results show that the smartphone accuracies were significantly different compared with smartphones linked to external GPS devices. Generally, the results suggest that current smartphones cannot be adopted in the underground construction industry without higher-accuracy integrated GPS devices.

Quantitative measurements are necessary to support accurate assessments of culverts; however, the choice of which sensor to employ to support these assessments is often not clear. An in-service corrugated steel culvert with a 3.1-m span was tested under static truck loading and monitored with fiber-optic strain sensors, a total station, digital image correlation (DIC), and lidar. Distributions of strains around the circumference were successfully captured by fiber-optic sensors, showing how the position of the peak thrust depended on the truck location, and that the peak flexural stress was double the peak hoop stress (contrary to strength limits considered within North American design codes). The peak thrust and moment occurred when the truck wheel pair was directly over the crown, as inferred in previous studies. The live load was found to be distributed nonuniformly along the longitudinal axis. Both the total station and DIC were feasible options for measuring displacements at the crown, while lidar was highly effective at recording the overall geometry.

Hole cleaning is a significant issue in well drilling, and this problem becomes more severe in horizontal directional drilling (HDD). One of the main functions of the drilling fluid is to transport cuttings from the borehole to the ground surface. A better understanding of the rheological properties of drilling fluid is essential to predict its hydraulic behavior in the annulus and choosing the optimal drilling fluid for hole cleaning in HDD. In this paper, the authors explore the rheological properties of drilling fluids with various bentonite concentrations through laboratory tests. A six-speed rotational viscometer was used to obtain the shear stress and shear rate relationships of drilling fluids, and both the Bingham plastic (BP) model and the Herschel-Bulkley (H-B) model were adopted to describe the rheological properties. The effect of increasing bentonite concentration on the conventional hole-cleaning capacity index, yield point to plastic viscosity ratio (YP/PV), was calculated using the YP and PV values obtained from the BP model. Based on the cuttings transport mechanism and flow patterns, the hole-cleaning capacity of drilling fluid was divided into two components: the carrying (suspension) capacity and the sweeping capacity. The rheological parameters and the hydraulic parameters, such as the width of the flattened velocity profile (plug width, $h$), the frictional pressure loss ($\mathrm{\Delta }P$), and wall shear stress (${\tau }_w$), are used together to reflect the hole-cleaning performance of drilling fluid from the two aspects. The results showed that as the concentration of bentonite increased, YP, PV, and H-B yield stress (${\tau }_y$) increased significantly, while the $k$ and $n$ values (H-B model) varied in a narrow range. The YP/PV, $\mathrm{\Delta }P$, and ${\tau }_w$ values increased as more bentonite was added, while $h$ increased first and then plateaued after 3.5% concentration. Although the high values of YP/PV, $h$, ${\tau }_y$, and ${\tau }_w$ will theoretically benefit the cuttings transport, the accompanying high frictional pressure losses may raise concerns about borehole stability.

In recent years, incorporation of recycled material in the production of large-diameter plastic drainage pipes for nonagricultural purposes has gradually increased. With this new development, AASHTO began allowing corrugated high-density polyethylene (HDPE) pipes manufactured with postconsumer recycled (PCR) materials to be installed as culverts under major highways, despite the fact that such pipes may contain impurities and their long-term behavior still is not fully understood. This paper presents a test program in which HDPE pipes with varied recycled material contents were subjected to forced long-term constant vertical deflection of 20%. Eight HDPE pipe specimens with inside diameter of either 610 mm (24 in.) or 762 mm (30 in.) were kept in a compressed state in the laboratory for 2 years. The maximum tensile strain was found to be about 3% for all pipes. No cracks were seen in the 0% and 49% PCR-content pipes during the 2-year test duration. However, the 98% PCR-content pipe developed longitudinal cracks at the crown position inside after 101 days and additional longitudinal cracks at the springline position outside after 131 days. In addition, tensile strength tests were performed on dog-bone specimens taken from untested HDPE pipe specimens with PCR contents of 0%, 49%, and 98%. The results showed that the tensile test behaviors were similar in the 0% and 49% PCR-content HDPE materials, but the material ductility significantly diminished at 98% PCR content.

Slip resistance of soil on buried pipelines develops from movement caused by faults, subsidence, and landslides. In areas with underground mining where subsidence is projected at the ground surface, pipelines crossing the subsided area will be subject to compressive and tensile stresses due to horizontal displacements in addition to vertical displacements. The soil–pipe interaction as well as slip resistance developed at the interface depends on surface roughness, backfill conditions, pipe displacement rate, and pipe depth. In this study, a total of six pipe jacking tests were performed on coal tar–coated pipes buried at depths of 1.2–1.8 m surrounded by clayey to sandy backfill materials. The test pipes were installed using typical pipeline construction practices and were exposed to expected rates of movement from longwall mining. Overall, the results from these field tests showed that for the same pipe depth, the slip resistance in clayey backfill sites was higher than at the sandy backfill site. The slip resistance of pipes under various displacement rates was measured and compared with empirical design guides. The analyses were also compared with results of pullout tests on buried pipes under similar conditions.

The process of installing and maintaining buried pipelines can be disruptive to the local traffic along with other undesirable impacts such as airborne emissions from the construction equipment used and workers’ safety concerns. City engineers have the option of using traditional open-cut installation or trenchless technology methods known as horizontal directional drilling (HDD) at their disposal. A waterline relocation project by the City of Enid in Oklahoma to relocate and replace more than 1,100 ft of an existing waterline is used in this study to build empirical evidence of the benefits of HDD over open-cut method based on production rate, airborne equipment emissions, traffic disruption, and workers’ safety features. Field data using human observers and wireless sensors on production, airborne emissions of equipment used, traffic disruption, and workers’ safety from the two separate installations were collected and analyzed. The airborne emissions of the equipment used in the HDD and open-cut installations were comparable, with a lower carbon-monoxide level in the HDD installation accompanied by a sudden spike during the last hour of work. There was no evidence in favor of HDD having less traffic disruption with comparable traffic flow rates and average vehicle speeds at the intersections of the neighboring streets. There were no accidents or incidents recorded during the period of observation.

When developing a methodology for assessing the risks of Russian pipelines, it is necessary to take into account the difficult conditions for the passage and functioning of fuel energy facilities. Given the Russian realities, the accident risk weights were modified at the East Siberia–Pacific Ocean (ESPO) pipeline section. To assess the risks, the bow-tie method was used, as well as a standard checklist questionnaire. The largest pipeline accidents in the world in recent times were analyzed. The main accidents reasons were corrosion and anthropogenic factors. Methods for visualizing accident information with subsequent optimization of risk indicators during operation of trunk pipelines are proposed. It also is proposed to take into account the hydrographic coefficient, which shows the difficulty of laying the pipeline in rough terrain. Future efforts should concentrate on the development of software for assessing the risks of accidents on the ESPO pipeline.

Adjoint methods integrated with computational fluid dynamics (CFD) tools can be used to tackle geometric optimization in processes and equipment in an industrial environment. This work presents a workflow for geometric optimization on a typical pipe elbow geometry using an adjoint–CFD methodology. It uses the ANSYS Fluent CFD and discrete adjoint solver in a stepwise way to guide shape modification to decrease pipe pressure drop. Finally, it discusses the effect of the optimized shape configuration on the predictions of three well-known erosion models. For the majority of gas velocity conditions investigated, a decrease occurred in the peak values and area spread of the erosion spots for the shape-optimized geometry. For some of the velocity conditions investigated a new erosion spot was predicted for the optimized geometry.