Journal of Pipeline Systems Engineering and Practice

Intermittent operation of water networks is prevalent in many developing countries. It is a practical method to continue operation of water distribution networks (WDNs) during unexpected water shortages. Implementation of intermittent water supply compels consumers to withstand periods of interrupted water supply. Intermittent operation increases operating and maintenance costs attributable to the damage of pipes and valves caused by water pressure fluctuations. This paper considers consumers’ welfare and system depreciation simultaneously in a multiobjective optimization model for intermittent water supply in WDNs. The objectives of the optimization model are the improvement of water supply resiliency and the maximization of the mechanical reliability of WDNs. The optimization model is solved by means of the honey-bee mating optimization (HBMO) algorithm linked to WDN hydraulic simulator software. The model’s performance is tested with several shortage scenarios in two different WDNs. The calculated results show the optimization model’s capacity to determine optimal values of water supply resiliency, and demonstrate that consumers’ welfare may conflict with the objective of mechanical reliability, giving rise to an optimization possibility tradeoff frontier.

Failure due to corrosion has become one of the major problems in maintaining pipeline integrity. Smart pigs have been used for decades to assess the in situ condition of steel pipe serving the oil and gas industries. The assessment techniques used are generally described in standards prepared by American Petroleum Institute (API) and American Society for Testing and Materials (ASTM). These standards are viewed by some in the industry as being conservative, resulting in premature repair or replacement of pipelines. Therefore, pipeline operators need better, more reliable condition assessment tools, not only to assure safe operations, but also to optimize maintenance costs. That is to repair or replace only the pipe sections that need the remediation. Recently, an alternative condition assessment method was developed using finite element (FE) analyses that were validated through actual pipe burst tests results. In this paper, the burst test procedure and results of testing a 250-mm (10-in.) nominal diameter API X52 pipe sections are presented. The experiments consisted of an exhumed pipe section with internal corrosion and additional sections with simulated corrosion defects. Details of the pipe and corrosion geometry, material properties, and the conditions surrounding each failure location were recorded.

This paper proposes a general method for estimating pullback force applied on polyethylene (PE) pipes during horizontal directional drilling (HDD) installations based on adapting the Capstan equation to a PE pipe negotiating a curved bore. Compared to current standards, this method can be implemented in any installation regardless of the bore geometry, such as ground surface grade or number of segments composing the bore path. To verify the proposed method, pullback data collected from an HDD installation project is compared to forces estimated by the proposed method as well as standard methods. This paper demonstrates the proposed method’s ability in estimating a more-accurate pullback load.

Water shortages are caused by hydrological droughts and by the disruption of the operation of water distribution networks (WDNs). The water pressure and residual chlorine concentration are examples of quantitative and qualitative indexes, respectively, of a WDN’s performance. This work considers quality and quantity variables simultaneously in the operation of WDNs under water shortages. An optimization model is developed to find the optimum water allocation schedule in WDNs. The objectives of the optimization model are maximizing the number of node-times in which the chlorine concentration is in the allowable range, and maximizing the number of supply nodes under desirable pressure. These objectives satisfy the principle of justice in water distribution under water shortage. The optimization model was solved for a real WDN under different scenarios using the honey-bee mating optimization (HBMO) algorithm linked to a hydraulic simulator. The performance of the developed model was compared to an operation rule based on standard operation policy (SOP) that allocates water among consumers based on constant priority of water supply. The results show that water-shortage operation affects water quality and decreases the chlorine concentration below the allowable minimum in the network, and that applying a water allocation schedule obtained with the developed optimization model minimizes this effect so that this allocation schedule maintains residual chlorine concentration mostly within the allowable range throughout the network. The optimized operation of the WDN satisfies consumer demands fairly under desired pressure while reservoir and hydraulic constraints are satisfied.

Pipelines are primarily instrumental for the transportation and distribution of bulk products from one part of a country to another as well as removing finished products from refineries to terminals and depots. Petroleum products, which are of high and rising value, are becoming a ready and lucrative target for pilferers attempting to tap pipelines. Any pilferage or sabotage of the pipeline leads to serious implications in the distribution of petroleum and petroleum products as well as causes a major risk to people and the environment. In India, a four-pronged security approach comprised of physical, technological, construction, and legislative measures has been in use to check pilferage. Despite the best efforts of oil and gas companies in recent years, incidents of illegal tapping could not be stopped completely. This paper presents a rational and systematic method for security management of cross-country pipelines. It is a risk-based approach that uses an analytic hierarchy process (AHP) model to determine the probability of pilferage in different sections of pipeline. This model has been applied on a 122-km-long section of a 243-km-long operating cross-country multiproduct petroleum pipeline. The method is helpful in identifying pipeline sections having higher probability of pilferage attempts and thus helps in prioritizing security arrangements.

By optimizing the sizing of air vessels, not only is the damage from water hammer prevented, but also the cost of water hammer protection systems is minimized. This paper presents a numerical simulation of an air vessel in a long-distance transfer main system against water hammer resulting from sudden pump stoppage. An optimal design of air vessel parameters is obtained using sequential quadratic programming (SQP) in this case. Three types of connection configuration (between the air vessel and the main pipeline) are tested in the case study, including a vertical cylindrical vessel with a bypass line (configuration 1), a vertical cylindrical vessel with a bypass line equipped with a throttle valve (configuration 2), and a horizontal cylindrical vessel with separated inflow and outflow lines (configuration 3). The variations of optimal volume of the air vessel, $V_T$, are plotted as a function of the allowable maximum pressure head, $H_{\max }^{*}$, with the diameter of the bypass line, $d_b$, or the throttle valve opening angle, $\theta$, respectively. Demonstrating with a case study, this simulation shows that the SQP method was well suited for the optimal design of air vessel parameters in long-distance water-supply transmission pipelines. For configurations 1, 2, and 3, it is beneficial for the optimal design of the air vessel to decrease the $d_b$ value and the $\theta$ value properly. In addition, by plotting the variations of $V_T$ as a function of $H_{\max }^{*}$ with different $d_b$ values or $\theta$ values, it is helpful for the designer to determine the optimal selection of the connecting configuration.