Journal of Pipeline Systems Engineering and Practice

Horizontal directional drilling (HDD) plays an important role in pipeline construction. Drilling mud loss, or the maximum allowable drilling mud pressure, in soil and sand layers during HDD has been continuously studied since the 1980s. However, because HDD has been used more often in bedrock, it was realized that there is a lack of studies on this topic for rock HDD projects. In this study, the drilling mud loss risk of a HDD pipeline construction project in competent soft bedrock is studied by numerical modeling. The numerical modeling result shows that, in bedrock, the Delft equation can overestimate the maximum allowable drilling mud pressure when the lateral earth pressure coefficient is less than unity. Through numerical modeling, it is found that tension failure, instead of shear failure, is the main failure mode of bedrock surrounding the borehole. The failure mode in this project looks more like fracturing after expansion, instead of cylindrical expansion. A parametric study is conducted to investigate the required minimum rock mass overburden thickness, effect of overburden stress, and effect of geological strength index (GSI) value.

As an alternative pipe material, ductile iron pipe (DIP) has been more and more widely used in horizontal directional drilling (HDD) because of its excellent mechanical performance and corrosion resistance. The limited capacity of restrained joints to withstand pulling force severely constrains their application in long-distance crossing projects. The finite-element method (FEM) was used to study the mechanism of joint failure as well as the effect of slope angle, based upon which an approximate solution was developed to estimate the maximum pull capacity of joints. The authors found that joint failure started from the spigot and an appropriate increase of slope angle could improve the maximum pull capacity of joints. Considering pipe angular deflection, a new pullback load estimation model was established and its accuracy was verified by a HDD river crossing project.

The paper presents a methodology for the advanced design of buried concrete pipes or assessment of their performance that enables realistic decisions to be taken concerning the safe and cost-effective operation of sewage pipe systems during their service life. In this respect, the influence of microbiologically induced corrosion (MIC) on bearing capacity is modeled as a time-dependant and stochastic problem. The potential of the approach is shown by performing parametric studies concerning the crushing strength of both uncorroded and corroded pipes and by comparing these results with results from tests. Also, a complex analysis of a concrete buried pipe is presented via combined use of finite-element software for concrete structures, its randomization, and degradation phenomena modeling. Using statistical processing, the reliability level can be assessed based on a relevant limit state, and a service-life prognosis can be made. This is in contrast to current methods developed worldwide for the design or assessment of buried concrete sewage pipes based in practice on simplified models; thus, reliability level and service-life issues are not treated.

In the deep sea, pipelines can undergo penetration during the laying process; therefore, lateral soil resistance is of great importance for shallowly embedded pipelines to maintain stability under high-temperature and high-pressure conditions; in this case, a pipeline may buckle due to release of stress, with a large amplitude over several pipe diameters. This paper reports on a series of large-scale plane strain model tests to study the lateral pipe–soil behavior in large-displacement conditions, and a fine sand collected from Bohai Gulf is chosen in view of Bohai sea geotechnical conditions. A 200 mm diameter model pipe section is integrated into a lateral pipe–soil interaction testing system to study the lateral soil resistance response as influenced by pipe weight $W$ and relative embedment $z/D$. From the test results, three characteristic soil resistances are identified, derived from the soil resistance curves, namely, breakout resistance $H_{\mathrm{br}}$, maximum resistance $H_{\max }$, and residual resistance $H_{\mathrm{re}}$. Experimental data indicate that lateral soil resistance depends on the soil passive pressure and berm resistance ahead of the pipe and that $H_{\mathrm{br}}$ is strongly coupled with $H_{\max }$ and $H_{\mathrm{re}}$ in deeper embedments. An observational test was conducted to study the mechanism of breakout resistance $H_{\mathrm{br}}$. Simplifying $H_{\mathrm{br}}$ as the ultimate bearing capacity problem of a shallowly embedded cylindrical foundation under an inclined load, an upper-bound solution is proposed to calculate $H_{\mathrm{br}}$, and both the failure mechanism and corresponding velocity are derived from experiments. Through comparison with existing calculation methods, the upper-bound solution is proven to provide an alternative prediction method for the breakout resistance $H_{\mathrm{br}}$ of pipeline in Bohai Gulf.

Current regional seismic loss estimation models, for example, the United States Federal Emergency Management Agency’s (FEMA) Hazus, typically employ empirical functions for damage assessment of buried pipelines subjected to permanent ground deformation (PGD). These functions are based on a limited number of damage observations to pipelines during past strong earthquakes. They represent the repair rate per unit length in a brittle or ductile pipe segment under average structural and geotechnical conditions and ground failure phenomena. This study aims to propose an analytical method for assessment of vulnerability of ductile energy pipelines traversing permafrost regions and subject to active layer detachment (ALD) landslide hazard. Canadian ALD morphological statistics combined with the probability of pipeline exposure to transverse ALD-caused PGD and the extent of the potential PGD are used as input. A computer program is developed in order to analyze the structural behavior of pipelines and evaluate their vulnerability considering three damage mechanisms: tensile rupture, local buckling, and premature cross-sectional failure. The vulnerability functions associated with PGD, expressed in terms of repair rate, are obtained by applying Monte Carlo simulation to the structural analysis results. The novel vulnerability functions developed herein are specific to permafrost regions and can be incorporated in the Hazus-type platforms for regional seismic risk assessment.

If noise easily interferes with acoustic pipeline leak detection technology, false alarms and missing alarms result. This paper proposes a denoising method for the acoustic leak signal sensed by a dynamic pressure transducer (DPT), which is a kind of widely used acoustic sensor. Compared with the normal signal, the leak signal detected by the DPT has stronger energy in low-frequency components. Based on this observation, a numerical integrator was added to the wavelet denoising method for acoustic signal denoising. The numerical integrator can enhance the low-frequency component of a signal. When used for denoising, the wavelet low-pass filter can remove the high-frequency noise first, and then the numerical integrator can enhance the low-frequency leak signal. Therefore, the signal-to-noise ratio (SNR) of the leak signal can be improved. Based on the analysis of the amplitude frequency response of several common numerical integrators, the trapezoidal integrator was selected, which is easy to achieve in engineering. The field experiments show that the method can help reduce the sensitivity of the signal preprocessing result to key parameters of the denoising method including the wavelet basis function and the decomposition scale. Therefore, the stability of signal denoising result can be increased and the robustness of the pipeline leak detection system can be improved.

Self-cleansing is a design criterion for drainage systems that mitigates the continuous deposition of sediments at the channel bottom. In recent decades, in order to improve the knowledge for determination of self-cleansing conditions applicable for drainage system design, laboratory experimental studies on sediment transport in rigid-boundary channels have been conducted. In this study, according to the definition of self-cleansing, the main studies in the literature are classified and projections for future studies are drawn. This review is limited to laboratory experimental studies that used noncohesive sediments. A brief comparison of existing equations are presented and discussed. It is found that a major discrepancy exists among performances and applicability of existing self-cleansing models from a variety of data sources. This fact can be attributed to the subjective definition of different sediment-transport conditions, channel cross-sectional shape, range of experimental data, and parameters used for the model development. It is expected that this review will be helpful for researchers looking for an integrated and classified literature review on sediment-transport studies in rigid-boundary channels and drainage systems.

Buried gas pipelines in seismic-prone regions may suffer leaks or breaks as a consequence of an earthquake, especially if the pipeline is subjected to large differential displacements due to geotechnical failures (e.g., landslide or liquefaction). This paper presents a methodology to assess the risk of a gas pipeline infrastructure at a regional level in the aftermath of a seismic event. Once earthquake characteristics, such as magnitude and epicenter, are known, seismic intensity measures (IMs), such as peak ground acceleration (PGA) and peak ground velocity (PGV), are estimated at the location of each pipe through a simulation-based procedure. The potential updating from real-time data coming from accelerometric stations is considered. These IMs are then used to study the cascading landslide and liquefaction hazards, providing a hybrid empirical-mechanical-based estimation of permanent ground displacements (PGD). With the aid of damage and fragility functions from the literature, loss figures and damage maps are derived as decision-support tools for network managers and stakeholders. Losses provide a preliminary estimation of repair costs, whereas damage maps support the prioritization of inspections in the aftermath of the event. The risk methodology is a novel combination of cutting-edge and consolidated approaches. Firstly, different cross-correlation models between PGA and PGV are included. Secondly, a new three-phase back-to-back geotechnical approach is provided for both landslide and liquefaction, representing (1) the susceptibility, (2) the triggering, and (3) the PGD estimation phases. The 1976 Friuli earthquake and the high-pressure gas network of northeast Italy are used as a test-bed scenario for the risk methodology aimed at emphasizing pros and cons of the different alternative options investigated.

Data mining is performed on the last 21 years of United States pipeline accident data to illustrate the trends in different pipeline accident types and their consequences, namely financial losses, fatalities, and volume of oil spill. An objective ranking is introduced to identify the states with most pipeline accidents, losses, fatalities, and oil spills. The influence of meteorological season, temperature, and precipitation on pipeline accidents is investigated. The contiguous United States (excluding Alaska, Hawaii, and Puerto Rico) is partitioned into six accident zones with equal amounts of accidents (equi-accident zones) and the most frequent pipeline accident type in each zone is identified. Among all the pipeline accident types, material/equipment/weld failure is found to be the most frequent, expensive, and environmentally unfriendly pipeline accident type. Pipeline accidents due to natural force damage increase dramatically during winter season. Among the six equi-accident zones, Zone 2, located in the southern United States, is the smallest zone with the highest density of accidents.

This paper reports on an experimental study on the scouring of pipe materials on the outside of leaks caused by soil fluidization. A base experiment was designed consisting of a 3 mm diameter hole angled at 45° to the horizontal in a 110 mm diameter unplasticized polyvinyl chloride (uPVC) pipe. Five parameters were investigated in a sensitivity analysis: soil particle size, leakage flow rate, leak orientation, cover depth, and pipe material. The development of the scour patterns was measured at regular intervals. It was found that the leak jet orientation had the greatest impact on the scouring rate, followed by the leakage flow rate, sand particle size, pipe material, and cover depth.

This paper presents a defect-based model for assessing risk of failure for sewer pipelines. The proposed model deploys a Sugeno fuzzy inference system to create a risk index from which inspection and replacement activities may be prioritized. To determine the likelihood of failure, dynamic Bayesian network (DBN) was used as an inference engine to predict the likelihood of sewer pipeline failure based on both probable defects that could occur and some pipeline characteristics. The consequences of failure were determined using an economic loss model that assumed both costs resulting from the failure of sewer pipelines and benefits from avoiding such failures. An ArcGIS tool was created using the Python programming language to perform the Sugeno fuzzy inference method and determine the risk of failure by combining both the likelihood and consequences of failure. Actual data for inspected sewer pipelines in Doha, Qatar, were used to validate the tool; in the validation, the pipelines from the model were compared with the inspected pipelines. It was found that, if deployed, the proposed tool could save more than 77% over the current inspection practices followed by municipalities. It is expected that the resulting risk map would help key personnel in municipalities to identify sewer pipelines that require immediate interventions and would assist in better planning for inspection programs, especially in cases of limited funds.

Internal corrosion in pipelines is a persistent problem in the oil and gas industry. Available conventional rehabilitation techniques to stop corrosion losses and prolong the life of the pipeline use an internal lining system to isolate the corrosive medium from the host pipe’s inner surface. To overcome many of the shortcomings associated with conventional lining technologies, a Kevlar-reinforced flexible polymer composite liner has been recently developed. This flexible liner was installed in several stages and is of interest in understanding the mechanisms behind the installation process and, more specifically, in determining the forces and stresses at each stage of the installation process. Hence, the objective of the current study is to build a nonlinear finite element (FE) model to simulate the full installation process of this new liner. The FE model is further validated using physical tests, making it a reliable tool for simulating the entire installation process of this liner in an arbitrary pipeline network.

Flexible pipelines such as high density polyethylene pipes (HDPE) and bonded pipes for seawater intake systems are often subjected to oscillations, due to the combined action of the wave and current in a shallow water region. Rigid pipe materials like aluminum or stainless steel are not economically viable for a seawater desalination project and steel pipes are susceptible to corrosion. This paper focuses on the application of glass fiber reinforced polymers (GFRP), considering their various merits for submarine pipelines in lieu of other pipe materials. The proposed GFRP pipe cannot be buried because of the coral seabed in the shallow water region and exposed to high marine environmental loads. A new methodology was developed to design the GFRP pipe drawing inference from various standards. A suitable winding angle of 30° and a 18.46-mm wall thickness of GFRP pipe were achieved. Pipe specimens were manufactured and tested to validate the design parameters. This paper mainly focuses on the design process for the GFRP pipeline in complex marine environment conditions, where direct methods and standards are not available for unburied submarine pipelines and qualification of GFRP pipe by conducting laboratory and prototype tests.

Scouring phenomena below a pipeline exposed to waves is intrinsically a stochastic process. There is a huge level of uncertainty due to effective parameters on the scour depth prediction and mathematical shape of traditional equations for the scour depth prediction. With inspiration from previous investigations, Shields parameter ($\theta$), Keulegan–Carpenter number ($KC$), and ratio of embedded depth to pipe diameter ($e/D$) were considered as effective parameters governing on this process. Furthermore, effective parameters mentioned in this study were taken into account as random variables and the general structure of empirical equations extracted from the literature have been regarded to develop stochastic methods such as generalized likelihood uncertainty estimation (GLUE) and sequential uncertainty fitting (SUFI). Having obtained statistical error indices values such as root-mean square error (RMSE), mean absolute percentage of error (MAPE), and agreement coefficient ($d$) from the training and testing phases, it was found that both improved stochastic methods have provided adequate accuracy for predicting pipeline scour depth. Moreover, performance of the developed stochastic models and genetic programing (GP) approach were compared with those obtained using deterministic techniques using the total improvement ($I{M}_T$) index. Quantitative comparisons of the proposed stochastic models indicated that the GLUE method ($I{M}_T=21.5$ and 24.73%) was the most efficient model in clear-water and live-bed conditions with large values of $e/D$. In terms of various conditions of scouring process, the highest and least improvement occurred in the clear-water and live-bed conditions with small values of $e/D$, respectively. Ultimately, the developed stochastic methods were more efficient compared with the deterministic models in prediction of wave-induced pipeline scour depth with consideration of uncertainty.