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Pipes or pumps? The use of cost-benefit analysis in investment decision-making for public water infrastructure
Published in Airong Chen, Xin Ruan, Dan M. Frangopol, Life-Cycle Civil Engineering: Innovation, Theory and Practice, 2021
Subnetworks are designed in hydraulically separated ring or grid configurations that are connected via remotely controlled internetwork valves, which can be opened to supplement supply during high-demand situations. In the event of failure or maintenance work, regularly placed isolation valves allow for effective isolation of the affected network section and mitigate service interruption. In addition, redundancy is built into the network at multiple levels. Generally, large water distribution networks are designed so that network components and even entire facilities can be taken offline for maintenance for extended periods during low-demand months (i.e. winter). Subnetworks may be equipped with parallel water mains and critical public infrastructure (e.g. hospitals) may have multiple service lines connected to different water mains to improve service reliability.
Occupational Health and Safety
Published in Terry Jacobs, Andrew A. Signore, Good Design Practices for GMP Pharmaceutical Facilities, 2016
All energy isolation devices must be readily accessible (e.g., located at ground level near equipment controls) with adequate clearance to accept the application of lockout devices. The design of the facility electrical and piping systems should be such that the application of any one energy isolation device will result in the minimal interruption of service to other equipment or processes. It is particularly important to provide an adequate number of isolation valves in pressurized liquid, gas, and chemical lines to help eliminate the need for hot tapping during maintenance activities. It is also important to plan for the ongoing maintenance of equipment and systems, including the changing of in-line filters and the removal and maintenance of inline pumps. In these cases, the types of appropriate isolation devices, such as isolation valves or flanges, must be installed to limit the potential hazards associated with line breaking. Electrical equipment that is equipped with capacitors or otherwise has the ability to store or build up an electrical charge must have the capability to be easily grounded and the charge dissipated. Equipment with suspended parts, moving mechanical parts, and springs must have the capability to be physically restrained.
Unsteady release model of natural gas transmission station considering effects of safety interlocking system
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
For natural gas transmission station (NGTS), release parameters are important basic parameters for quantitatively predicting natural gas (NG) dispersion range and assessing the consequences of release accident. The release process includes both steady and unsteady release periods. Many researches have been carried out on steady release process and release model of pressure vessels such as gas pipeline and storage tanks. The research results have been widely used in hazard assessment (Bariha, Mishra, and Srivastava 2016; Casal 2008; Crowl and Louvar 2007; Ebrahimi-Moghadam, Farzaneh-Gord, and Deymi-Dashtebayaz 2016; Khan, Rathnayaka, and Ahmed 2015; Moloudi and Esfahani 2014; Witlox, Maria, and Mike et al. 2018). Automatic isolation is performed by activating emergency shut-down valves (ESDVs) once gas release is detected. These isolation valves divide the process system into small units and block them separately (Mahgerefteh, Sundara, and Brown et al. 2016; Montiel, Vı́lchez, and Casal et al. 1998). Then the initial steady release becomes unsteady and lasts till the release ends absolutely. In such accident scenarios of unsteady release, if the conventional steady release models are used for release hazard assessment, it will obviously overestimate the assessment results and lead to unreliable decision-making (Beychok 1997; Woodward and Mudan 1991).
A novel device for pressure-based leakage characterisation in water distribution pipes
Published in Urban Water Journal, 2022
Craig T. Tanyanyiwa, Jakobus E. van Zyl
Due to the ongoing drought in the region, the input pressure had been dropped to an average of 30 metres as a water demand management and leakage control strategy. It was thus required that the tests conducted on the pipes not exceed this average pressure to avoid creating new leaks in the system. One of the early findings from the field tests was that some of the isolation valves were faulty such that the pipe section could not be isolated. This led to the researchers selecting only dead-end pipes, where only one valve had to be functional for the assessments (Figure 14).