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There are thousands of miles of long-distance product transport pipelines on the planet Earth. They serve for transportation of crude oil, petroleum-based products or gas. There is no manner of protecting the product lines against accidental or intentional loss of integrity; what can only be done is to minimize the damage caused as soon as possible.

As the density of long-distance transport pipelines network becomes ever greater, the risk of breakdowns/accidents of these lines grows. In most cases the damage is caused by natural forces; such as cracks of pipelines during surface erosion, during landslides, or corrosion effects may be the culprit. Human factors may be the causes in other instances (thefts of products, sabotage actions or operators’ faults). The ill effects are, nevertheless, always immense. Soil can be contaminated, drinking water sources may be destroyed and fires may also result.  The extent of damage is usually so great that the potential risks are addressed in multiple international agreements; such as Kyoto Protocol.

What is of utmost importance during detection of leaks from pipelines? First, it is the trust in information that it informs on actual leak. Then, exact location of the defect is also of great importance. And, of course, the speed, as with the volumes of material pouring out to the field each second, the time must be expressed in terms of millions of currency units rather than in minutes.

The Leak Detection Systems (LDS) is a worldwide unique technology, which serves for detection of even tiny cracks immediately after their emergence. The system is exact, reliable and fast. The PAS company has for several years been protecting miles of pipelines of major product transporters against the ill effects of environmental disasters.

Key features:

• The system detects leaks of gaseous or liquid media.
• It operates both in static and dynamic mode.
• It responds to apertures as small as 1/100 of the internal diameter of the product line.
• Alarm is triggered after a few minutes.
• The accuracy of location of leak is less than 50 meters.
• The system relies on pressure measurement only.
• Remote control modules can be adopted (SCADA functionality).

Technical Description

The system is based on the energy conservation law. Disruption of energetic balance in a closed system (pipeline) evokes characteristic change of pressure. This negative pressure wave then propagates in the pipeline in both directions from the place of leak (method according to API 1130). Pressure measurements take place at several points on the pipeline concurrently. The distances between measurement points are ten to thirty kilometers. The data measured by pressure transmitter are relayed from the measurement points to the central point, where the location of the leak is calculated. The two level algorithm used (first level at the measurement stations, the second level in the centre) filters reliably the natural changes in pressure, caused for instance by temperature fluctuations during the day or due to pumps operation.

Pressure in the pipeline drops at the moment of leakage for about 10 kPa.

The Structure of the System

The system consists of several measurement stations and one central station. Typically, the distance between individual measurement stations is ten to thirty kilometers, whilst whenever branches from the pipeline occur, a measurement station is also installed at the branching point. Each measurement station can accommodate several pressure measurements, which is used for example during monitoring of condition of parallel lines.

The measurement station is essentially a switchboard equipped with programmable controller (PLC) as well as with other equipment serving for energizing, communication, heating and transmitter settings. The measurement stations are typically installed in existing buildings or structures near the pipeline, where electricity is available for supplying of the station. The cabinet dimensions are just 600 x 600 x 210 mm.

The picture on the right shows separate power supply cabinet with batteries. This cabinet is to be installed where external 24VDC supply is not available. Batteries enable full functionality (incl. heating) of a measurement station for at least 48 hours.

Central part

The central station consists of central PLC and industrial server, which can be connected to several operator workstations. The communication usually uses a radio network or an optical cable. System can be easily integrated into existing SCADA via OPC technology.

In case of a leak, the central station program identifies the expected location of the leak, including tolerance (scatter of results of individual iterations). Afterwards, relevant alarm is displayed on the screen. At the same time all the information is printed and saved in the computer. Then, as the established routine and actual needs may be, alarm SMS’s are dispatched to relevant mobile telephones, as well as e-mail messages including a map showing the affected sector of the pipeline. It is also possible to send automatically fax messages with relevant data for the intervention team etc. On the operator’s screen the leak is displayed as a flag in the technology scheme, the relevant pipeline section is highlighted in color on the map and acoustic signal is initiated.