Keep Your Pipeline Network in Sight

In some cases, a disruption can also be caused by specific operational activity, like pumping. Pressure transients, also known as water hammer, are relatively common yet severe pressure fluctuations in pressurized water systems. One way to mitigate the severity of pressure transients is to change the way pumps start and stop, as well as when, where and how valves are opened and closed.

For many years, pressure monitoring has been used to detect hydraulic transients, but the data can often be overwhelming. Water utilities may struggle to know how to use the information to prevent pipe bursts and similar problems. Fortunately, intelligent pipeline monitoring is helping to close that gap by combining high-resolution pressure data with advanced analytics.

With additional context from geographic information systems (GIS) or other network data, intelligent pipeline monitoring can help utilities educate their operators and customers on how to calm their distribution systems to reduce problems and extend the life of assets.

Oh, The Pressure!

In a pressurized water system, a sudden change in flow equates to steep changes in pressure that can propagate throughout the network. If pumps start or stop too abruptly, or when pumps fail either due to mechanical problems or power outages, transients can result from the drastic shift in water flow. Aggressive valve operations can also trigger a pressure transient.

Many utilities also recognize a relationship between customer behavior and pressure transients. Commercial or industrial users, as well as wastewater treatment plants, can cause transients by quickly operating pumps or valves when they utilize significant volumes of water for their own operations. For the most part, these customers are completely unaware of how their behavior impacts the broader system—and how these activities may increase risk to their own operations.

Finding the Needle in the Haystack

Knowing the types of behaviors that can cause pressure transients is one thing, but pinpointing the exact source within the distribution system can be challenging. Historically, pressure transients and water hammer events were located manually by crunching numbers or generating transient models based on reams of data generated by pressure loggers.

Today’s intelligent monitoring systems perform these calculations automatically. To ensure accuracy, however, the monitoring system must have several key features:

1. High-resolution data.

   Different pressure loggers take samples at different rates—and sample rates of high-resolution pressure sensors for monitoring water systems vary widely across the market, ranging between 1 sample per second and 256 samples per second. For advanced transient analytics, a resolution of at least 100 samples per second (100 Hz) is typically required to detect the most severe pressure transients, which can occur within milliseconds. This generates a picture of pressure changes down to 1/100th of a second and provides useful information about the shape of the pressure waves. Some intelligent monitoring systems can use this shape information to classify the transients based on wave shapes commonly caused by specific operational changes, such as pump or valve operations, pipe breaks, etc. It is important to note that sample rate frequency affects power consumption and data transmission or storage requirements, so these considerations must be taken into account by users.

2. High clock accuracy.
   

   To maintain their ability to accurately timestamp pressure changes, intelligent monitoring devices must constantly check against either a cellular connection or GPS signal. By ensuring that all the devices are synchronized to the same time scale, the system can perform time-of-travel analysis between different devices that are picking up the same event. The result is the ability to locate the source of a hydraulic transient.

3. Integrated system data.
   

   Pressure moves differently in pipes of specific sizes and materials. Knowing whether an event occurred in a 12-inch PVC pipe compared to a 10-inch stainless steel pipe makes it easier to track down the exact source. GIS data and operational data (such as pump run times) can typically be uploaded into an intelligent monitoring system’s software platform to improve the accuracy of analytical results.

Although not required, having access to the SCADA system or other operational data systems can be very beneficial. It allows an intelligent monitoring system to cross-reference pressure data with other system data to determine the most likely culprit of a transient. If the event can be traced back to a pump station, for example, the utility can investigate the identified pump’s operations to determine why it is not performing optimally. Was there an emergency pump stop? Is surge equipment not working as expected? Did a valve fail?

Reducing Stress in Systems and Operators

Intelligent monitoring provides two major benefits to a water utility. The first is an immediate operational improvement. With the ability to see where pressure is changing and why, operators can take immediate steps to calm the system and manage their assets most efficiently.

The second is that it proactively prevents future impacts such as pipe bursts. As transients are reduced and system assets are managed more optimally, the system becomes less stressed, which in turn reduces the number and severity of repairs. In the long run, this extends the life of assets, saves money and allows resources to be prioritized for the most critical tasks.

Next-level pipeline monitoring supports an effective approach to managing and maintaining a distribution system. When water operators understand transient activity in their systems, they can identify where investments should be made in terms of equipment upgrades or operational improvements. By prioritizing projects that will provide the biggest value, water utilities can allocate precious funds where it makes the most sense.