Since childhood, we have seen large pipelines been placed on roadsides and installed underground. The large pipeline we saw and still see today are quite important as they carry different types of liquids from one place to another. Liquids and as well as gases are transported in pipelines. It is near to impossible to transport a large number of liquids or gases without the help of a pipeline.
The long-distance transportation of liquid or gas over a large network of pipes is called ‘pipeline transport.’ The majority of the pipelines that exist in the world are used to carry off transport water, gas, or fuels such as petroleum, oil, and even biofuels. The pipelines can also be used to distribute or carry hot water, sewage, or slurry over short distances. The big pipelines are usually made from steel or high-grade plastic tubes. The installation and maintenance of pipeline infrastructure are quite important as most of the energy resources are transported and distributed through a system of interconnected pipelines. The increasing energy demand would require more development and installation of pipelines to ensure proper transportation and distribution of energy resources.
The pipelines run across the entire countries and bring fuels and other resources to the consumers, which includes government-run power plants, businesses, and homeowners. Many people may not give it a thought but oil and natural gas are used for a variety of purposes such as for heating and cooling. In transportation, nearly every car, bus, and other vehicles require fuel to run. The pipelines are the backbone of energy transportation that ensures that the energy needs are fulfilled, and the country is functioning properly.
The pipelines are quite heavy and require constant checks and maintenance. There is a whole system that monitors the movement of liquid or gas content in the pipeline. Flow analysis is the term used for the safe and successful transfer of liquids, although this terminology is more apt for the oil and gas industry but can also apply to water distribution. The surge analysis is another essential element and refers to the pressure changes in the pipelines. Surge analysis itself is a flow assurance activity and is mostly done on liquid pipelines as the liquid compression is unimportant, and sudden fluctuations in flow velocity can either under or over-pressurized the pipework.
Surge analysis of pipeline can be defined as the sudden pressure changes that occur in the pipeline carrying fluid, and the pressure change is due to a change in flow velocity where the valve is opened or closed quickly. When the valve is closed quickly, then the energy of the liquid going forward in the pipe results in the sudden rise of pressure due to compression upstream of the valve.
An opposing and negative pressure will result instantly in the downstream of the valve, the liquid will still be running; as a result, the liquid column would be separated, and there will be a reverse flow towards the valve if the pressure is high, this may damage both the valve and pipe. The maximum surge pressure occurs when all the pumps are operating at the pumping station stop due to power failure. The point of disturbance results in changing the pressure and velocity, which continues both upstream and downstream at pressure wave propagation velocity.
The impact of pressure surge depends on the piping design and layout. The allowed negative pressures are
- Maximum 0.2 bar for pipes made from plastic and fiberglass reinforced plastic
- Approximately 0.4 bars for welded steel pipes
The pressure surges can cause substantial damage to pipelines, which include cracked pump castings, pipeline leaks, contamination, and also a negative impact on the environment. Surge analysis is necessary to prevent economic damage and ensure correct pressure and flow of liquids in pipelines. The surge protection mechanism will considerably reduce the downtime and delays in power plants, distribution networks, and increase the life expectancy of the pipelines.
Both the flow assurance and surge analysis comprise of different elements and objectives. The phases in which flow assurance and surge analysis are needed are
- Design
The design stage involves the complete design of the pipelines, which includes the size of pipes, flow and pressure conditions, and capacity of the system. The elements can easily be simulated to ensure the proper size and design of the pipes. The modern-day pipes can easily be sized correctly, controlled, and tuned while the system bottlenecks can also be identified. The equipment to suppress surge pressure can also be installed and calibrated. The surge pressures are used when there is a sudden change in the flow of liquid, which usually happens due to sudden opening and closing of the valve or due to shut down or startup during operation.
- Planning
The planning stage determines the way the pipelines will be operated. The normal startup procedures will be defined and also steps for equipment maintenance. The future conditions for the operation will be influenced by the flow, pressure, distribution, and temperature.
- Forecasting
The forecasting stage is linked with the planning stage, which will help to determine future demands such as heating water and gas usage. The forecasting step allows us to manage any future disruption and pressure surges better.
- Operations
The operations stage deals with the numerous problems during transportation of liquids which can be
- Surge-related issues
- Problems with the product quality
- Surge suppression equipment not working
- Incorrect temperature distribution
The pipelines manufacturers and installers have devised certain steps and methods to deal with surge pressure which are
- Ensure that the pipes are of the proper size, the larger the diameter, the slower the fluid will move
- Do not install fast-moving valves. The fast-acting valves are one of the vital factors in surge pressure.
- Control the flow of liquid, and the velocity within the system should not be more than 5 feet
- Removing any air to prevent airlock. Excessive air should not be allowed to accumulate in the system during operations.
