Equipment inspection and monitoring are important activities for safe operation and productivity in the oil and gas industry. Remote corrosion monitoring systems enable companies to collect accurate corrosion measurement data from remote field sites by detecting possible problems in advance. Timely corrosion rate data helps organizations to accurately forecast when pipelines or other plant equipment will need to be repaired or replaced. (Learn more in An Intro to Pipeline Corrosion.)
What is Remote Corrosion Monitoring?
In its simplest form, remote systems collect data from remote monitoring units at remote field sites and then deliver the information to computers in the office. The systems can be configured to trigger automatic alarms when dangerous or destructive upset conditions are detected. This allows personnel to respond and act quickly before further damage occurs.
A typical remote corrosion monitoring system consists of various sensors, a power supply, a data acquisition system and a cellular network for data transfer. Systems sometimes use electrochemical multi-probe instruments with data collection capabilities. These instruments are capable of measuring and recording many key parameters that contribute to corrosion.
The remote systems are permanently attached at the point where corrosion is anticipated, where they provide reliable and repeatable corrosion test results on demand. Some fully integrated systems have automatic alarms, data analysis, data management and reporting capabilities. These systems employ a variety of techniques depending on the application. For example, ultrasound tests can be used to monitor oil and gas pipelines.
In remote locations without access to the electrical power grid, solar panels and cellular networks provide a data communication link back to a control center.
Why Use Remote Corrosion Monitoring?
Operations in sensitive industries such as oil and gas production require plenty of equipment and maintenance. (Discover the 6 Corrosive Components Found in Crude Oil.) Remote corrosion monitoring is particularly well suited for hard-to-access locations on pipelines or in oil and gas facilities. The complex nature of their processes, coupled with remote and inaccessible locations due to distance, hostile environments, height or severe operating conditions, provide challenges to maintenance personnel.
Such challenges may require shutting down the industrial plant, or at least removing insulation covers or erecting temporary scaffolding. Furthermore, monitoring corrosion manually can sometimes lead to misinterpreting the results especially when a series of measurements are taken in slightly different positions of the metal over time. As such, manual corrosion monitoring may produce misleading data, adversely affect productivity, and be inconvenient or impractical in some locations.
The problems associated with manual measurements can be overcome by using a remote corrosion monitoring system, which guarantees repeatable and reliable results. In addition, the systems generate high-quality data in a format that is easy to interpret without the need of a specialist. The remote systems can be configured to collect corrosion data continuously or at set intervals.
Some fully integrated remote systems include a web-based view of the corrosion data collected in real-time. These systems may have a graphical view of conditions along a pipeline or within a plant. The data is analyzed by corrosion management experts, who then send an alert when measurements exceed critical levels. (For more on these powerful internet of things systems, read IoT for Corrosion Monitoring in the Oil and Gas Industry.)
In addition to problem detection, the remote systems can analyze the overall health of a pipeline or plant and provide periodic reports.
Requirements for Remote Monitoring Systems
The main considerations when selecting a remote corrosion monitoring system are:
- Power: Since many of these sites lack access to electrical utilities, the system should have the option to use portable power supplies such as batteries charged from solar energy or other methods. Thermoelectric generators are another option. Even when utilities are available, it may be prudent to add a backup power source in case of outages.
- Equipment interface options: A system that can connect to multiple interfaces is recommended. This should have a configurable reporting schedule to meet the company's requirements.
- Human interface: A web-based interface to view the data from desktops or mobile devices—with the ability to send timely alerts by text message, email or phone—is desirable.
- Communication options: Look for compatibility with several communication modes such as satellite and cellular messaging, or even using the pipeline itself as the data transmission path. The data collected from the remote monitoring must be reliable and accurate, and the data transmission must also be reliable for future data analysis.
- Reports and data integration: Systems should provide customized reports so that the raw data can be converted into useful information. The ability to load the data into the enterprise's computer system can be very useful and will allow the production, maintenance and accounting departments to understand what is happening at remote sites.
- Global Positioning System: A global positioning system (GPS), which reports precise position and time, can be beneficial.
- Hardware Miniaturization: Sensors may be located in cramped locations.
Advantages of Remote Corrosion Monitoring
The benefits of remote monitoring systems include:
- Time and cost savings through higher productivity and reliability
- The ability to obtain and utilize corrosion rate data from hazardous locations, remote locations or otherwise inaccessible areas
- A flexible means to monitor corrosion in environmentally sensitive applications
- Data collection at locations lacking access to utility power
- A possible solution where corrosion monitoring has previously been performed manually
- Anytime, anywhere access using desktops or mobile devices
Typical Remote Corrosion Monitoring Locations
The following locations are exceptionally good candidates for remote monitoring:
Pipelines in production plants are often in hostile environments, possibly subjected to extreme climates, terrorist activity or other conditions that make it difficult to monitor the installation with traditional techniques. The system configuration and data-transmission methods may vary depending on the nature of the environment. For example, a monitoring system for a desert environment might be put in an enclosure that maintains a stable temperature and then buried in the sand.
Inaccessible Plant Sites
This includes equipment covered with insulation, at great heights, or buried pipelines where manual monitoring is difficult or costly.
When corrosion is detected in areas not previously monitored, it is a common practice to repair the defect and then add a continuous monitoring system to periodically test the area and relay the results to a maintenance department.
Automatic systems allow for monitoring without the need for inspection personnel to be in the hazardous location. In addition, it eliminates the need to take equipment out of service and strip the insulation every time an inspection is needed.
Remote Corrosion Monitoring Case Studies
The following two examples are typical remote corrosion monitoring scenarios.
Remote Monitoring of Pipework
A typical remote corrosion monitoring system is used by BP Exploration Colombia for their pipework in a hostile environment.
The system consists of a series of daisy-chained sensors connected by a high-temperature coaxial cable. The sensor and cable assembly is then fully encapsulated in the pipeline's coating material. The coaxial cable is plugged into a battery-powered data logger connected to a transmission modem.
The corrosion monitoring and data transmission system is buried with the pipework to protect it against water and mechanical damage.
A modem transmits data to the control center via the pipeline’s metal structure.
An internal battery, which provides power to the system, is usually recharged by a current that it draws from a cathodic protection system. The battery recharges between transmissions.
To activate the system, a start-up signal from the control facility is usually sent to the remote monitoring system. This triggers the data logger, which begins interrogating every sensor in the chain, in turn.
The system collects measurements including the local thickness, cathodic protection potential and temperature. Each data transmission contains the sensor identification number and the time of inspection.
The information is collected, processed by a data logger, and then transmitted by the modem to the control facility where it is accessed by any Internet-connected computer.
Remote Monitoring of Jetty Pipelines
The jetty pipelines at oil terminals and refineries often suffer from internal corrosion leading to leaks that spill oil into the water. As a result, the jetty operations must be suspended to repair the leak. In addition, there are associated spill clean-up costs, reputation damage and strict scrutiny from environmental regulators.
A permanently mounted ultrasound thickness monitoring system or other suitable monitoring system provides a way to measure and report on the corrosion rates without the need for physical access to perform the measurements.
A typical arrangement uses a permanently mounting ultrasound wall-thickness monitoring system to assess the pipeline's integrity. This provides a means to detect the wall losses and corrosion rate.
By spreading battery-operated, wireless sensors uniformly along the pipeline, it is possible to pinpoint high-risk locations. The sensors measure the wall thickness and transmit the information to the jetty control room located several miles away.
Integral magnets and a straining strap are used to permanently affix the wireless sensors to the pipe. Since the wireless system does not require cables either for a power supply or for data communication, the installation of the entire system takes only a few hours.
The sensor data is fed to a control computer in real time and stored in a database, which is accessible anywhere on the company’s network.
Widespread Use of Remote Corrosion Monitoring
Remote corrosion monitoring is used in a wide range of applications including pipelines, processing plants, process vessels, tank farms and aircraft. In particular, it enables oil and gas companies to attain a high level of equipment availability, dependability and profitability in inaccessible locations. By using suitable and well-designed systems, companies can receive timely information and notification of important events without dispatching technicians to the sites.
A remote system with satellite or cellular communications gives companies cost-effective visibility into their equipment regardless of its location. The captured data provides useful information about the equipment's status to support timely remedial action. This maximizes the useful life of the pipeline, and improves the safety of the employees, general public and the environment.