Atmos International senior simulation consultant John Anderton sat down with The Australian Pipeliner to discuss the benefits of Atmos SIM Offline, with a focus on a case study where Atmos SIM was used to manage and model risks on an Australian customer’s water pipeline network.
Pipelines remain the safest means of transporting any fluid, with Australia continuing to invest billions in the expansion of new and existing infrastructure for industries ranging from oil and gas to water.
However, making any change to an existing pipeline network can present risks, such as surge scenarios or damage to the pipeline integrity, but pipeline simulation software like Atmos SIM is able to provide support.
According to Anderton, the following case study is a great example when it comes to managing and modelling risks during planned maintenance of critical water pipeline systems.
The challenge
A pipeline network responsible for providing a critical supply of raw water to a nearby major Australian city encountered some deterioration in the painted lining protection within one of their balance tanks.
Repairs to the protective coating meant that the balance tank had to be isolated for at least four weeks with no guarantee of an alternative balance tank becoming available.
This presented a risk to the continued supply of raw water to surrounding residential areas, so a directly coupled repair was investigated.
The raw system was close coupled, meaning low lift pump sets pumped raw water directly from the reservoir system to the suction of the high lift pumps and then pumped water to the raw water tanks at the filtration plant.
Configuration changes to the pipeline network had many impacts. For example, the high lift pump station suction header would be affected by the induced pressure surge and the increased number of pumps operating.
Without modelling the entire pipeline system, operators would be unable to determine if process control changes or mechanical measures would be adequate to ensure the pipeline operated within the lowest (LAOP) and maximum (MAOP) allowable operating pressure.
The solution
Modelling of the complete pipeline network became crucial for operators to be able to map out planned and unplanned scenarios and command the system to perform the correct action.
Using Atmos SIM Offline, the network’s two pumping stations and the existing large mainline raw water transfer system with the balance tank were modelled and tuned to real-time data.
To reflect the normal operation of the system, the modal elements of the pipeline were tuned and verified to minimise model error.
Modified system scenario modelling
To verify how the pipeline system would cope with the proposed process and mechanical protection changes, the following conditions were changed in the model:
- The balance tank was removed.
- A pressure sustaining valve and 40 meters of pipeline length were added at the pump station.
- Discharge pressure relief valves were added.
Real versus model pump start (left) and real versus model pump stop (right).
Atmos SIM Offline’s output was able to provide confirmation that operating the low lift pump rising main with the intermediate balance tank would not result in the propagation of damaging surge pressures exceeding either LAOP or MAOP of the pipeline or its pump stations.
The simulation software was also able to confirm that, in the event of an instant uncontrolled emergency shut-down of the stations’ pumps, surge pressures would not be exceeded.
Atmos SIM Offline also warned that in case of the failure to install the pressure sustaining valve, there would be an increased risk of all low lift and high lift pumps simultaneously tripping. All recommendations made by Atmos’ simulation software were validated.
Atmos SIM Offline
Atmos SIM Offline works independently of any real pipeline control systems and is the ideal tool for single-phase flow assurance and design, equipment sizing and locating, operational tuning, capacity planning and training.
During tuning operations, the tuning assistant automates the tuning process by calculating specified parameters to achieve the correct hydraulic behavior.
This ensures the model’s accuracy without the need for intensive tuning performed by the user. The configured model may also be used for online hydraulic simulations if required.
Atmos SIM Offline has the following benefits:
- Can be used for oil, gas, water, multi-product, ethylene and chemical pipelines.
- Extensive equipment libraries within the software.
- Drag and drop onto the canvas to build your pipelines.
- Set-points and boundary conditions for each device/object are saved for each scenario.
- Multiple control modes.
- Configurable alarms where safe operating conditions are breached.
- Tuning assistant automates model tuning.
To learn more about Atmos SIM Offline and where it fits within the full Atmos Simulation Suite, click here.
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