Most of the oil and gas pipelines around the world are between 30 to 100 years old.
While pipeline networks are the most economic and safest mode of transportation for oil, gases and other fluid products, the chance of corrosion and leaks gets higher as the subsea structures get older and older.
In fact, the frequency of leaks reported in recent years is almost more than twice of the rate it used to be. Due to local and international environmental policies, many countries now have standards in place for leak detection and consequent pollution of the environment.
Some of these regulations mandate all hazardous liquid pipelines such as oil and gas to have a leak detection system in place.
The primary purpose of leak detection systems (LDS) is to help pipeline controllers to detect and localize leaks. LDS provide alarms and display other related data to the pipeline controllers to assist decision-making. Pipeline leak detection systems can also enhance productivity and system reliability thanks to reduced downtime and inspection time.
Pipeline leak detection is used to determine if and in some cases where a leak has occurred in systems which contain liquids and gases. Methods of detection include hydrostatic testing, infrared and laser technology after pipeline erection and leak detection during service.
One of the most commonly deployed pipeline leak detection processes is the sound wave propagation and acoustic method. This works because escaping liquids create an acoustic signal as they pass through a hole in the pipe. Acoustic sensors affixed to the outside of the pipeline create a baseline acoustic “fingerprint” of the line from the internal noise of the pipeline in its undamaged state.
When a leak occurs, a resulting low frequency acoustic signal is detected and analyzed. Deviations from the baseline “fingerprint” signal an alarm.
Another pipeline detection method is the deployment of ground geo-phones with a filter arrangement. This method is very useful to pinpoint a leak while saving excavation costs. The water jet in the soil hits the inner wall of soil or concrete. This creates a feeble noise. This noise will decay while coming up on the surface. But the maximum sound can be picked up only over the leakage position.
Amplifiers and filter helps to get clear noise. Some types of gases entered into the pipeline will create a range of sounds when leaving the pipe.
Then there’s the vapor-sensing tube leak detection method that involves the installation of a tube along the entire length of the pipeline. This tube — in cable form — is highly permeable to the substances to be detected in the particular application. If a leak occurs, the substances to be measured come into contact with the tube in the form of vapor, gas or dissolved in water.
In the event of a leak, some of the leaking substance diffuses into the tube. After a certain period of time, the inside of the tube produces an accurate image of the substances surrounding the tube. In order to analyze the concentration distribution present in the sensor tube, a pump pushes the column of air in the tube past a detection unit at a constant speed. The detector unit at the end of the sensor tube is equipped with gas sensors. Every increase in gas concentration results in a pronounced “leak peak.”
Want to know more about pipeline leak detection? Tonex offers Pipeline Leak Detection, Theft and Illegal Tapping Training Bootcamp, a 5-day course that covers Leak Detection System (LDS), Leak Detection methods, Supervisory Control and Data Acquisition (SCADA), pipeline theft, illegal taping and safety.
For more information, questions, comments, contact us.