TABLE OF CONTENTS After a pipeline is installed, efficient operation and automatic controls must be provided to maintain safe operation in the face of unexpected upsets. Leak detection and pigging are typically important procedures.
Leaks in the pipelines originate from a variety of causes, which may include material-related damage and physical damage caused by construction in the right of way. Because accidental product discharges cannot be eliminated entirely, one of the most effective methods of reducing the impact of spills is to detect the leak quickly and to act quickly to stop the discharge. Methods used to detect product leaks along the pipeline can be divided into two categories: external and internal leak detection systems (API, 1995a). Externally based methods include traditional procedures such as visual inspection, as well as technologies such as hydrocarbon sensing using fiber optic or dielectric cables (Sandberg et al., 1989). Internally based methods, also known as computational pipeline monitoring (CPM), use instruments to monitor internal pipeline parameters (i.e. flow, pressure, temperature, and fluid properties), which are input continuously into a computer simulation software linked to a supervisory control and data acquisition (SCADA) system that analyzes the information mathematically or statistically. Leaks result in unexpected variations or in a well-defined deviation pattern between simulated and measured values. These patterns can be detected and assessed to determine if a leak is present (API, 1995b). The method of leak detection selected for a pipeline is dependent on a variety of factors, including physical...
