Pipe Line Research Articles

The Development of Tidal Power System Can be Installed in Existing Dykes -The Open Channel Experimental Verification

As problems such as difficulties in securing stable energy resources and global warming due to the emission of greenhouse gases due to the use of fossil fuels have emerged, interest in the development of renewable energy is increasing. Since the tidal phenomenon has a regularity that occurs regularly with a certain period, it is possible to predict accurately in advance, which has a advantage in terms of energy recovery. Therefore, various methods have been devised to utilize the tide as an energy source. Tidal power using barrages is a representative method that is widely operated, but the promotion of tidal power generation projects is being delayed or stopped due to the decrease in the level of water in the tidal basin, changes in water quality and in the ecosystem. In this study, a field experiment was conducted to develop and verify the performance of a tidal power device applicable to sea areas where dykes are already installed. As a result of carrying out four cases of experiments using two water tanks, pipe lines, open channels, weirs, and water turbine and generator, the possibility of developing a power generation system capable of 10 kW output or more and 60% efficiency or more was confirmed. These research results can be used for small-scale tidal power by utilizing the existing dykes.

The Development of 10 kW Class Tidal Power Generator System - Focusing on Field Experiments with Pipelines

Along with the growing interest in renewable energy development, Korea’s west coast is one of the favorable regions for tidal power. Tidal power using tidal barrages that work like hydroelectric dams is a representative method of tidal power through long-term operation, but the promotion of tidal power projects is being delayed or stopped due to impacts on ecological changes, reproduction, water column processes and hydrology. In order to reduce the high construction cost and environmental cost problems caused by tidal power using tidal barrages, in this study, field experiments were conducted to develop and verify the performance of tidal power generation devices applicable to sea areas where dykes are already installed. As a result of conducting five cases of experiments using two water tanks, pipe lines, open channels, and water turbine and generator, the possibility of developing a power generation system capable of generating more than 10 kW output and more than 60% efficiency were confirmed. The results of this study can be used for small-scale tidal power by utilizing the existing dykes of the west coast.

ESTIMATING CULVERT CAPACITY TO RESIST FLOOD WATER

Kulasi is one of the main rivers with catchment areas located in eastern part going down Mt. Isarog. The passage of the river crosses important roads and highways within the lower portion of the mountain, made of culverts and mostly were destroyed during the passage of typhoon Ulysses with international name VAMCO. This study describes a situation of the water course crossing after the extreme typhoon event. It derived hydrologic models that will be used to estimate the capacity of the culvert to handle excessive storm water event and it estimated the capacity of the culverts using the derived models. The evidences of culvert failure in different portions were presented. With known data of precipitation, watershed area, river surface slope and other parameters hydrologic modeling was shown to define the discharge capacity of the culvert pipe line at identified portion of the river. The capacity of the culvert pipe line was then computed using the derived hydrologic models. With the presented table, it expressed the capacity that flood water flow be accommodated in terms of actual precipitation and discharge at certain culvert pipe line. The procedure used on this study may be applied in other portions of the river and in other rivers.

Health Risks Assessment from Cured-in-Place Pipe Lining Fugitive Styrene Emissions in Laterals

The aim of this study was to improve the understanding of styrene emissions in sewer laterals, resulting from the installation and steam curing of a resin impregnated cured-in-place-pipe (CIPP) liner, within a sanitary sewer. The study included development and performance assessment of a controlled field test program that measures and records styrene emissions before, during, and after steam-curing a CIPP liner. Measured styrene emissions are then compared with those of published studies and regulatory exposure guidelines to assess the potential risk exposure. The field study measurements confirmed that high styrene concentrations can exist in sewer laterals during the steam-curing of the CIPP liner. They also confirm that water, in proper functioning P-traps, will prevent high styrene emissions from exiting the lateral and into buildings. Fugitive emission modeling shows that the risk of exceeding the acute exposure guideline limits is very low, even when high styrene concentrations exist in a lateral with a dry P-trap, and the styrene odor threshold is exceeded within the building, that is, when the building occupants smell styrene.

Regulatory Significance of Plastic Manufacturing Air Pollution Discharged into Terrestrial Environments and Real-Time Sensing Challenges.

Cured-in-place-pipe (CIPP) is an onsite plastic manufacturing technology used in the U.S. and has not been evaluated for regulatory compliance with federal air pollution laws. The practice involves the discharge of manufacturing waste into the environment. The study goal was to estimate the magnitude of volatile organic compounds (VOCs) discharged into the atmosphere for styrene and nonstyrene composite manufacture and examine low-cost air monitoring sensor reliability. Time-resolved emission analysis revealed that VOC emission was not only isolated to the thermal curing period but also occurred before and after curing. In addition to the styrene monomer, other gas-phase hazardous air pollutants regulated under the Clean Air Act were also emitted. Based on typical CIPP installations, 0.9 to 16.6 U.S. tons of emitted VOCs were estimated for styrene CIPPs, and 0.09 to 1.6 U.S. tons of emitted VOCs were estimated for nonstyrene CIPPs. Because the number and size of CIPPs manufactured in a single community can vary, the total air pollution burden will significantly differ across communities. Low-cost VOC sensors commonly utilized near CIPP manufacturing activities did not accurately quantify styrene and should not be relied upon for that purpose. Up to several thousand-fold detection differences were observed. Regulatory evaluation of CIPP air pollution and PID sensor reliability assessments are recommended.

On Sources of Damping in Water-Hammer

Various potential causes of damping of pressure waves in water-hammer-like flows are discussed, with special attention being paid to their qualitative influences on measured pressure histories. A particular purpose is to highlight complications encountered when attempting to interpret causes of unexpected behaviour in pipe systems. For clarity, each potential cause of damping is considered in isolation even though two or more could exist simultaneously in real systems and could even interact. The main phenomena considered herein are skin friction, visco-elasticity, bubbly flows and porous pipe linings. All of these cause dispersive behaviour that can lead to continual reductions in pressure amplitudes. However, not all are dissipative and, in such cases, the possibility of pressure amplification also exists. A similar issue is discussed in the context of fluid–structure interactions. Consideration is also given to wavefront superpositions that can have a strong influence on pressure histories, especially in relatively short pipes that are commonly necessary in laboratory experiments. For completeness, attention is drawn towards numerical damping in simulations and to a physical phenomenon that has previously been wrongly cited as a cause of significant damping.

Axial stresses in pressure pipe liners spanning joints with initial gap, opening as a result of differential ground movements

The mechanical behavior of a pressure pipe liner is studied where it stretches across a ring fracture or joint. Peak axial stresses are calculated for the case where there is an initial gap between the ends of the host pipe, and/or when the gap extends as a result of ground movements. A finite element model is established and evaluated against results from available solutions. The minimum difference between the finite element and the existing closed form solution is 0.15%, and the maximum difference is 6.79%. A parametric investigation is presented considering various values of initial gap width, liner diameter, internal fluid pressure, friction coefficient between the liner and host pipe, and the liner thickness. Finally, a simplified equation for the maximum axial stress in the liner is fitted from 524 data sets. The results show that when there is an initial gap, longitudinal bending leads to development of a tensile stress on the outer face of the liner, which peaks at the midpoint of the gap, and compressive stress occurs on the outside of the liner at the edges of the gap. The initial gap can significantly reduce the ability of the liner to tolerate ground movements that subsequently lead to gap extension. The new equation for maximum axial stress can be used to predict the liner stress when a host pipe with an initial gap (which previous existing solutions do not address) experiences gap extension.

Buckling Behavior of Loosely Fitted Formed-In-Place Pipe Liner in Circular Host Pipe under External Pressure

The formed-in-place pipe (FIPP) is a trenchless technology used for pipeline rehabilitation. It is a folded PVC pipe that expands through thermoforming to fit tightly inside the host pipe. However, the deficiencies during the construction of FIPP liners such as insufficient inflation, pipe misalignment and initial deformation will lead to elliptical deformation of the FIPP liner, which affects the load-bearing performance of the liner and makes it susceptible to buckling failure. In this paper, the buckling behavior of loosely fitted FIPP liners under uniform external pressure was investigated by the external pressure resistance test and finite element model. The pre- and post-buckling equilibrium paths verified the finite element model. The results indicated that the value of the dimension ratio will significantly reduce the critical buckling pressure. With the increasing value of liner major axis ratio to host pipe, the reduction effect on the critical buckling pressure caused by the increase in the ovality will diminish. Different values of liner major axis ratio to host pipe and ovality changed the range of the detached portion, which affected the critical buckling pressure. The parametric studies modified the design model from ASTM F1216, which was established to predict the critical buckling pressure of a loosely fitted FIPP liner and reduced the average difference rate from 23.43% to 5.52%.

GAS LIQUID FLOW IN HILLY TERRAIN PIPELINES-SINGLE AND MULTIPLE SECTIONS

A new way of calculating severe slugging behavior for hilly terrain pipe lines is presented. Analysis is based on the analytical solution of a single line/riser system and treats each section as a single system, using the results of the analytical solution. Yet interaction is needed since the "outlet pressure" in each section is calculated iteratively. The present modification leads to a more elegant and reliable solution. In addition, the modified model takes into account the inclusion of gas within the liquid in the risers. The solution presents the variation of pressure and liquid level in each inclined line with time, the maximum inlet pressure, the cycle time (frequency), the maximum penetration of liquid into the inlet section, and the pressure in each line. The solutions of multiple sections are compared to the case of a single line/riser case.

Case Study: Successful Application of a Novel Gas Lift Valve in Low Pressure Wells in Fuling Shale Gas Field

The Fuling shale gas field is facing a rapid gas production decline due to heavy liquid loading issues. Given the condition that most wells are located at remote areas in the mountains, the traditional gas lift methods that require either fixed compressor or skid-mounted gas lift trucks do not seem feasible and occur high operation costs. A new type of gas lift valve that can be opened or closed at a low valve dome pressure indicates the high sensitivity to low production pressure. Thus, the piping line pressure can be utilized to activate the valve due to its new advantages. In addition, the specially designed structure of the gas lift valve can be activated via pressure increases in the tubing to create a channel between the tubing and annulus. The valve that previously functioned as a dummy valve was then switched to a gas lift valve. Field application results show that all wells were successfully restarted by only utilizing the low piping pressure, and loaded liquid was lifted with gas production at an incremental rate that reached up to 27.4 × 10 kscm/d per well. Fewer slickline operations were conducted to replace the dummy valve. The result of the application shows that the new type of gas lift system has a wide range of application prospect for low pressure wells, especially for shale gas wells.

Corrosion Failure Analysis of CuNi 90/10 on Seawater Fire Protection System

The failure analysis of a seawater fire protection system of oil and gas processing facility was observed in this paper. The fire protection pipe line & hull seawater filter were made of CuNi 90/10. Severe deep pits and fracture were observed at bottom of jockey pump spool pipe and hull seawater filter. Visual observation, scanning electron microscope, energy dispersive spectroscopy, x-ray diffractometry were employed in the present failure analysis. The oxygen exposure on CuNi 90/10 of Seawater Fire Protection system had a significant impact on failure and was exacerbated by the presence of chloride exposure.

Computer Vision Based Path Following for Autonomous Unmanned Aerial Systems in Unburied Pipeline Onshore Inspection

Unmanned Aerial Systems (UAS) are becoming more attractive in diverse applications due to their efficiency in performing tasks with a reduced time execution, covering a larger area, and lowering human risks at harmful tasks. In the context of Oil & Gas (O&G), the scenario is even more attractive for the application of UAS for inspection activities due to the large extension of these facilities and the operational risks involved in the processes. Many authors proposed solutions to detect gas leaks regarding the onshore unburied pipeline structures. However, only a few addressed the navigation and tracking problem for the autonomous navigation of UAS over these structures. Most proposed solutions rely on traditional computer vision strategies for tracking. As a drawback, depending on lighting conditions, the obtained path line may be inaccurate, making a strategy to force the UAS to continue on the path necessary. Therefore, this research describes the potential of an autonomous UAS based on image processing technique and Convolutional Neural Network (CNN) strategy to navigate appropriately in complex unburied pipeline networks contributing to the monitoring procedure of the Oil & Gas Industry structures. A CNN is used to detect the pipe, while image processing techniques such as Canny edge detection and Hough Transform are used to detect the pipe line reference, which is used by a line following algorithm to guide the UAS along the pipe. The framework is assessed by a PX4 flight controller Software-in-The-Loop (SITL) simulations performed with the Robot Operating System (ROS) along with the Gazebo platform to simulate the proposed operational environment and verify the approach’s functionality as a proof of concept. Real tests were also conducted. The results showed that the solution is robust and feasible to deploy in this proposed task, achieving 72% of mean average precision on detecting different types of pipes and 0.0111 m of mean squared error on the path following with a drone 2 m away from a tube.

Experiment and evaluation model of liner design for renewal of deteriorated reinforced concrete pipes utilizing cured-in-place-pipe technology

Cured-In-Place-Pipe (CIPP) is an emerging trenchless rehabilitation technology for repairing urban drainage pipes growing significantly in China. However, overestimated external loads due to a completely deteriorated-pipe assumption may increase conservatism in the CIPP liner structure design. In this study, ring stiffness test machine was employed to quantify the bearing characteristics of pipe-liner system. The concrete and reinforced concrete pipes with an inner diameter of 200 mm, which deteriorated to several states, were renewed with CIPP. Digital Image Correlation (DIC) was employed to reveal the contact characteristics between the host pipe and CIPP liner under external loads and the mechanism of loads transferred from the pipe to the liner. An evaluation model for load-bearing performance of reinforced pipe was established. Parametric studies were carried out including lateral load distribution angle, concentrated load dispersed angle, and lateral interactions. Furthermore, a case study was conducted in conjunction with the indirect design method for buried pipes, and then the improved model was compared with experiment results. An average value of 20 % reduction in CIPP liner thickness was achieved by employing the modified model than the ASTM standard. This study can serve as a database for engineers designing CIPP rehabilitation projects for concrete pipes whose structure has not been completely damaged.

Weldability evaluation of X80 sour line pipe using a combination of thermal simulation and actual girth welding

The weldability studies of API 5LX80 pipes developed for sour service are very recent and limited information about its heat-affected zone (HAZ) properties can be found. This paper presents a comprehensive evaluation of HAZ using both thermal simulation and the production of actual girth weld joints. The test methodology included microstructural analysis, Charpy impact test, hardness (HV10), microhardness (HV0.1), and sulfide stress cracking tests (SCC). The intercritical coarse grain HAZ presented impact toughness reduction from values above 300 J to less than 50 J at 0 °C when heat input is increased above 1.5 kJ/mm. It can be explained by grain coarsening and martensite-austenite (MA) formation as a ‘necklace’ structure at previous austenite grain boundaries. Hardness and microhardness values for both simulated and actual HAZ were below the maximum limit of 250HV usually specified by industry. Specimens submitted to the sulfide stress cracking (SSC) tests did not present any crack demonstrating that the welded joint is appropriate for sour environments. Finally, a maximum heat input of 1.5 kJ/mm is recommended for field welding. For higher heat inputs, a deeper evaluation of HAZ toughness should be done. The results contribute to supporting the application of this material as an alternative for long-distance high-pressure pipelines with H2S.

Torsion-induced failure of a reinforced thermoplastic pipe used in a gas lift system

After servicing for 4.5 years, a reinforced thermoplastic pipe utilized in a gas lift system experienced a burst failure. FTIR, visual inspection, TGA, tensile test, VST, pressure test, DSC, and torsion test were performed to investigate the root cause for the failure. The findings demonstrate that the failed pipe had suffered serious torsion. The torsion led to the significant performance deterioration of reinforced fibers and liner pipe. The liner pipe has multiple torsion morphologies. Tensile test results show that torsion led to the deterioration of the mechanical properties of the liner pipe, especially the modulus (14.7%). There was a 60–80% drop in both elongation at the break and tensile strength of the fibers. Results from the torsion-pressure test illustrate that torsion would lead to a decline in the pipe’s pressure capacity. The operating record indicates that this pipeline was a gas lift pipeline with long-term and high-pressure operations and weekly sweeping operations in winter. The pressure fluctuation was relatively frequent. The pipe failed when the instantaneous pressure exceeded the torsional pipe’s capacity.

Collapse Limit of Thermally Treated Line Pipe Under Combined External Pressure and Bending Deformation

Abstract This study discusses the collapse criteria for thermally treated line pipe and their bending interaction against collapse based on a full-scale test under external pressure with and without bending loading. The critical collapse strain in the pressure bending test was much higher than that estimated by the DNV-ST-F101 standard because it was calculated based on estimating collapse pressures without bending interaction based on specified minimum yield stress (SMYS) of design pipe in the standard. However, the collapse pressures without bending interaction in full-scale test was significantly higher than that of the estimation according to DNV-ST-F101 standard. The effect of the thermal heat cycle simulated anti-corrosion coating heating on line pipe collapse criteria is also discussed based on the change of yield stress of pre-strained and thermally treated material. As the maximum heat cycle temperature increases, the reduction of the compressive yield stress along circumferential direction by the Baushinger effect due to UOE process (U: U-ing, cold forming from a plate; O: O-ing, cold forming from the U shape; E: cold expansion to meet geometric tolerances) becomes small. It is thought that a DNV equation for estimating the critical bending strain to collapse will provide a more accurate estimation of the critical collapse pressure and strain for thermally treated line pipe when the collapse pressure is calculated considering the change of strength parameters due to the tensile pre-strain level and heat cycle temperature.

Effects of large plastic deformation and residual stress on the path independence of J-integral for cracks in ductile materials

Large plastic deformation and residual stress exist in the oil and gas transmission pipelines with mechanical damages that often contain a gouge or crack. Residual stresses can alter the mechanics behavior of the crack, and cause the standard J-integral to become path-dependent and unable to describe the crack driving force.This paper investigated the effects of large plastic deformation and residual stress on the path independence of the J-integral for a crack in ductile materials. The basic conditions required for the path independence of the standard J-integral were first reviewed, and the major factors that affect the path independence were then analyzed. This includes the theory of plasticity, finite strain formulation, and residual stresses. Then, a residual stress modified J-integral was introduced for ensuring the path independence. After that, the elastic–plastic finite element analyses were performed for a notched beam in terms of the incremental plasticity to create residual stresses and to simulate a crack at the notch root subject to three-point bending. The path independence of the standard and modified J-integrals was numerically evaluated for each of the major factors. Results showed that the modified J-integral is path-independent and able to describe the crack driving force for a crack in a residual stress field, but the standard J-integral cannot do so because of its nature of path dependence when residual stresses are present. Thus, the modified J-integral can be used as an appropriate fracture parameter to assess the pipeline integrity for line pipes containing cracks and residual stresses.

Failure analysis of the leakage in girth weld of bimetal composite pipe

A bimetal mechanically-composite pipe leaked at the entrance of processing station. The failure location was the 6o'clock direction of the girth weld connecting the gathering pipe and pipe in the station. In order to figure out the root cause of the failure, a series of experiments were carried out. The macroscopic analysis and metallographic test results show that the leakage point is located at the 6o'clock direction of the girth weld, the root welding and the base pipe of the bimetallic composite pipe are corroded, resulting in perforation. The end of the bimetallic composite pipe is not seal-welded, the girth weld has misalignment and at 6o'clock, the root weld was concave, and the wall thickness of the root weld and the lining is<1.5 mm. The FeCl3 pitting corrosion test results of the girth weld show that the pitting corrosion resistance of the root weld is lower than that of the liner and pure stainless-steel pipe. The galvanic corrosion test shows that the galvanic corrosion grades of weld-pure material, weld-liner, carbon steel-weld, carbon steel-liner are all severe corrosion, and the galvanic corrosion of carbon steel-weld is the most serious. The root cause of the failure of girth weld puncture leakage: the end of the bimetallic composite pipe is not seal-welded. At 6o’clock, the girth weld has misalignment, and the root weld is concave, resulting in that the thickness connecting the root weld and the liner being small. In the medium environment containing Cl- and CO2, local corrosion occurs, and then the medium enters the base pipe and the liner interlayer, and the galvanic corrosion aggravates the corrosion of the base pipe. To avoid the reoccurrence of such failure, the mitigation measures were proposed.

Chemical composition and weld cooling time effects on heat-affected zone hardness of line pipe steels

In the past few years, the pipeline industry in North America has faced a reported increase of pipeline girth weld failures predominantly in grade X70 pipe welded with cellulosic consumables. Weld strength matching and HAZ softening were two factors believed to have contributed to the concentration of strain during, or soon after, construction which ultimately lead to an overload failure of the girth welds. The work reported in this paper aimed to establish and clarify the correlation between steel chemical composition and the HAZ hardness in typical production girth welds and a range of weld thermal simulations. The first stage was to calibrate the influence of weld cooling rate of both thermal simulations and real welds in steels over a wide range of chemical composition, typical of commercial high strength API pipe. Second, the influence of Pcm, carbon content, Mo content and cooling time in terms of minimum and maximum hardness were investigated. The comparison between simulated HAZ's and real welds showed that thermal simulation produces samples that adequately duplicate the real condition in terms of maximum and minimum hardness and can accurately assess both hardening & softening which occur in different regions of the HAZ. The simulated samples provided increased areas of different HAZ regions in order to more accurately identify the range of hardness values across the HAZ which was then correlated to real weld hardness profiles. It is concluded that ultimate hardness in the HAZ is directly related to steel chemical composition in terms of Pcm and weld cooling rate. It is however apparent that the relative percentage change in hardness from the original parent pipe hardness (also called % HAZ softening), which is important in determining the strain capacity of the weld joint, is principally dependent upon steel processing, especially the degree and severity of thermomechanical processing. This is evident by the fact that same API pipe grades have a wide range in chemical composition and most importantly Pcm, and the response to field welding conditions can be quite different depending on weld heat input, pipe wall thickness and preheat, all of which define the weld cooling rate.

Performance evaluation of deteriorated and rehabilitated corrugated metal pipe culverts using multiphysics simulation

Owing to their high strength to cost ratio, corrugated metal pipes (CMPs) are well accepted among professionals for accommodating water runoff under roadways and railroads. Installed CMPs reach various states of deterioration over their service life resulting in diminishing strength. This can result in a sudden collapse of the CMP and thus, poses a risk of traffic disruption and a threat to public safety. To restore the capacities of aging CMPs, appropriate rehabilitation methods are required after relevant condition assessment techniques are utilized for projecting service life. This paper presents a multiphysics simulation study to assess the structural performance of new, deteriorated, and rehabilitated CMPs in buried conditions. The validity of the developed model was obtained by comparing simulation results with previously conducted full-scale tests. This study investigated performance improvement by two trenchless rehabilitation techniques – cured-in-place-pipe (CIPP) and sliplining with high-density polyethylene (HDPE) liner. The deflections obtained from the simulations under various static surface loads are also compared with values computed using the Modified IOWA equation. The results demonstrate that the deflections obtained by the numerical model offer better agreement with full-scale tested CMP deflections than does the Modified IOWA equation.