July 2021, Vol. 248, No. 7
Tech Notes
Using RTUs in Monitoring Pipelines in Extreme Conditions
By Matthew Hawkridge, Chief Technology Officer, Ovarro
While oil and gas pipelines are essential to the industry, they are not fail-safe. Structural failures including corrosion, cracks and leaks are common issues that companies must resolve quickly and effectively to minimize downtime and interruptions, along with increasing efficiency.
As well as costly product loss, pipeline leakages can significantly damage wildlife and the natural environment, posing a threat to workers and the population. There is, therefore, a need to monitor the environmental impact of any operations constantly and, above all else, ensure the safety of staff and the public.
The most valuable tool in meeting this new range of key performance indicators (KPIs) is information; the most appropriate device to collect and process this information is the remote terminal unit (RTU).
For decades now, RTUs have been a key component in the data chain from the I/O to the CEO. These devices have a long-standing track record of sitting on remote pipelines, wellheads and offshore platforms collecting, storing and acting upon data, regardless of the surrounding environment.
To date, most RTUs have been used to collect and log operational data and perform local control.
The RTU is a field-mount computer. It collects data locally, acts upon it immediately, reports data to the central SCADA control room and maintains a local historical store as an additional backup.
In remote locations, communications may be slow, intermittent or unreliable. The RTU is the device at the edge – sitting between the control room and the field instruments – that provides a low-latency response to changing site conditions and performs data filtering.
The RTU ensures that only key, critical information is passed via the narrow communications links, minimizing data throughput but maximizing information throughput.
Within the downstream sector, refineries operate 24/7, which means firms need RTU systems that are robust, secure, reliable and flexible enough to be able to manage and monitor extensive pipeline networks. RTUs are integrated with sensors across these sites and provide data to the SCADA system.
Working the other way, RTUs can receive commands from the supervisory system and transmit them to the end devices as well as retaining an ability to act autonomously. RTUs can do this over large and remote pipeline networks by handling the data acquisition portion of SCADA, providing early warning of impending issues, such as a rise in temperature of a holding tank or decreased pressure in a pipe, and avoiding asset failure and potential environmental incidents.
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