Abstract
The IR drop test span is a specialized cathodic protection test station that is very effective in determining magnitude and direction of DC current flowing on a buried structure. The test span can provide the CP technician with critical information pertaining to current distribution, interference current detection, excessive current loss, and current mapping on protected pipeline structures.
The data derived from an IR drop test span is most useful when compiled over a period of time. The technician can use that data to identify trends, changes, and to develop a concise overall profile of the current flow on the structure in the area of the test station. This type of profile is essential for detection of interference and inadequate protection in areas where multiple pipelines and other sources of interference share congested pipeline right of ways. It is also valuable to measure additional parameters at the site (AC interference, AC and DC density, instant-off voltage potentials) in order to create an accurate assessment of the cathodic protection on the structure at the test site. Typical methods of deriving measurements at IR drop test spans are periodic measurements using a hand-held volt meter, or the use of data-logging devices. Periodic measurements require a long period of time in order to acquire a significant amount of data and are labor intensive. Data-logging provides a significant amount of data in a shorter period of time, but are subject to limitations regarding the parameters that can be measured.
This paper is a case study on the adaptation of remote monitoring equipment to provide continuous data recording of multiple pipeline current and voltage parameters at IR drop test spans. Several sites in congested pipeline corridors were used to demonstrate the effectiveness of using remote monitor equipment with data-logging capabilities to record the data, transmit the data to the technician, and to provide notification of significant changes measured in any of the monitored parameters.
This method of data acquisition and analysis offers several advantages over typical methods. The technician is provided with time-stamped measurements of multiple parameters affecting the performance of the cathodic protection system. Data is continually recorded and stored in device memory, but can be transmitted on demand to the technician’s computer. The technician can receive instant notification of any sudden significant (user defined) changes to any monitored parameter. The ability to use an interactive web interface for the display and use of the data makes graphing, comparing, and profiling data from multiple locations very simple to accomplish. These advances allow the technician to gather more data, faster, and in a more organized manner. This facilitates the use of this data in evaluating, designing, and measuring the ongoing performance of cathodic protection systems.
This case study provides information regarding how cutting edge technologies incorporated in current generation monitoring systems can be applied to specific tasks beyond the scope of basic rectifier and test point monitoring tasks. Through incorporation of advances in telemetry, electronics design, and data interface capabilities, remote monitor systems have evolved into multi-application tools for evaluation, benchmarking, and detailed CP system performance monitors.
