This article describes the hardware and software tools available to the process industries for managing a company’s assets and resources. It will cover the different parts of a process industry network to identify the assets, their capabilities and what type of information can be obtained. This information is vital to maintenance, operations and engineering personnel to make sure the company’s assets are up-to-date and operational.
What are the company’s assets?
In a typical process industry, there are three layers of a network. Starting from the lower level to the upper level, the lowest level is the field instrumentation network. The field network consists of the instrumentation, which includes sensors, transmitters and network diagnostics instruments. The network connections include junction boxes and cables.
Monitoring thousands of instruments will require plant asset/resource management software, which will be accessed from the maintenance shop and a server located in a server room. The clients can be either thick or thin clients located in the second or third layer of the network structure. It is also possible to have a web client to access via internet or intranet (fourth layer). Below are a few examples of the different assets available and the type of data/diagnostics that can be obtained from them.
Field network instruments can communicate via HART, Foundation Fieldbus, wireless or other network topology. Most of these instruments are known as smart instruments. They are embedded with a self-diagnostics feature capable of communicating if anything is wrong. Common issues could include sensor failure, overheating, maintenance requests, calibration requests and more.
Actuators such as valve positioners will have self-diagnostics, which can conduct stroke testing to provide a wealth of information about the health of the valve, e.g., if the valve is having any friction, stiction, slippage, overheating or any type of internal error. The information is then presented on graphic screens consisting of charts (signature curves), tables, dial gauges, level gauge bars and text messages. The asset/resource management software will be able to extrapolate the information from the instrument upon request, or it can send alarms or alerts to maintenance personnel to take action. Some of these actions can also be scheduled and stored in a historical events database for later analysis.
Temperature transmitters can provide many diagnostic details about the sensor and the internal electronics of the transmitter. Sensor diagnostics could include temperature range validation issues, drifts, sensor breakage, degradation of the sensor over time, calibration issues and zero tuning.
Pressure and flow instruments can provide diagnostics such as overheating, calibration issues, plugged or blocked line diagnostics, over-range, sensor failure and internal electronics failure.
Asset/resource management in Foundation Fieldbus networks
The Foundation Fieldbus network topology consists of instruments connected in the star architecture, which consists of the main trunk line connected to the junction box and individual lines (spurs) connecting the transmitters to the junction box. A diagnostics module, which is a device tapped into this network, is capable of monitoring the condition of the network and relaying that information back to the maintenance personnel. The information includes the signal strength of each instrument (node), types of noise and their present level, termination issues, coupling issues and signal range. A diagnostic module can typically integrate into an asset/resource management software program supplied by the manufacturer. This program communicates with the diagnostics module and collects the information from the field, presenting it in charts, graphs and gauges. Some programs also include an oscilloscope to monitor the condition of the signal.
Several diagnostics modules are available on the market. When selecting one, consider the following questions:
- Is the module considered an instrument in the network?
- How easy is it to set up?
- What kind of diagnostics will be provided?
How easy is it to navigate the graphical user interface (GUI)? (See Figure 1.)
Asset/resource management in HART networks
A HART network, on the other hand, uses two wires for communications. Each instrument has its own communication link to a controller. HART is widely used in the industry for its legacy capability.
For example, most of the safety valves connected to a safety instrumented system (SIS) implement the HART technology, and they have to be proof-tested at regular intervals for validation purposes by applying a "partial stroke test" (PST). PST verifies that the valve is capable of moving when it is in demand and that it maintains the safety integrity level (SIL) of a safety instrumented function (SIF). (See Figure 2.)
An asset/resource management system can collect a wealth of information from the HART instruments. That information can be stored in a database for operators, maintenance personnel and engineers (both process and safety engineers) to access.
Continuous use of the instruments in the field will cause them to become off-calibrated, so calibration is needed at periodical intervals. An asset/resource management software program can generate a calibration request by entering the calibration parameters, and then downloading or uploading data into or from a calibrator. It can also generate a calibration certificate and document the data for future reference. The asset/process management can be interfaced to the company’s CRM or ASP system, so the corporate management will have access to real-time information.
Asset/resource management as housekeeping
Maintenance personnel sometimes need to refer to instrument reference materials such as documents, technical data, specifications, schematic (PID) diagrams and instruction sheets. They might need to know how to install, maintain, replace or operate an instrument, or they might need to reference certain alarm codes and error messages and how to correct them. An asset/resource management system can keep all of this information in the database, and help to associate specific instruments with the correct edition of a document.
In a typical process industry application, there are hundreds or even thousands of instruments. Keeping an accurate inventory is vital for maintenance
personnel, so they have easy access to a transmitter when a replacement is required. Asset/resource management software can maintain accurate inventory and notify the team when a replacement is necessary. Work order software, which can maintain records, generate work orders and notify the right person, can be integrated into the asset/resource management software. All these actions are documented for future reference.
As previously mentioned, instruments have many parameters. Sometimes maintenance personnel can predict an instrument’s operation by comparing the current parameters with parameters stored in the past. An asset/resource management system can place these parameters side by side and highlight any parameter differences. This will enable maintenance personnel to take corrective action and predict the operation of an instrument and when calibration or replacement is forthcoming.
The device replacement process is a critical task for maintenance personnel to perform. The asset/resource management system can handle the message communication between maintenance personnel and operators. Aside from the message communication, the new device may have to be configured with the same operational parameter as the old device. Here again, an asset/resource management system is capable of uploading and downloading the parameters from the old instrument into the new instrument. This operation will help a process engineer replace an instrument faster with little or no impact to the daily operation. If an instrument is a loaner or a temporary device, the asset/resource management system can save the parameters associated with the old device, such as tag information or instrument identification, until the original is returned from a maintenance shop.
With thousands of devices to manage, an arrangement or "hierarchy buildup" of devices is necessary. This will enable maintenance personnel to arrange the instruments in groups based on the instrument type, protocol, site and location. A good and logical structure will enable a maintenance operator to locate a device. Using an advanced search utility makes it easy to search for the specific instrument quickly.
A database is a major part of an asset/resource management software program. The database stores all events, parameter changes and user activities for future retrieval. This feature will require periodic backups.
With thousands of instruments in a typical network, it is crucial for maintenance personnel to have a process to manage alarms and alerts. With asset/resource management software, alarms can be separated into two categories: maintenance and operation. This feature will route maintenance alarms to the maintenance technician and operator alarms to the operators. This will reduce the alarm cluttering on an operator screen. The NAMUR NE 107 standard, which most vendors have implemented, helps categorize the alarms into four or five categories. With the help of mapping tables, maintenance personnel can reassign the alarms to simple, easy-to-identify groups.
Different users have different access levels, for viewing purposes or for making changes. Access rights can also be granted to the instruments or groups of instruments. This will allow different maintenance groups or personnel to manage different parts of a plant.
Some asset/resource management software can be integrated with a plant historian system, which can retrieve long-term data for the purpose of trending and exporting to spreadsheets.
Most recent asset/resource management software programs have implemented options for device commissioning. This will speed up the installation and startup of a plant. Another possible use for the software is to aid the installers for the loop-check.
Asset/resource management software is a worthwhile investment. It helps to organize and manage instruments, users, documents and reports. It simplifies parameter storage and retrieval, as well as manages instrument utilities and alarms. This will make the maintenance personnel’s job easy to manage, while giving them a better understanding of the plant’s assets/resources (see Figure 3).
Ray Azizian is the Lead Product Solution Support – Safety Systems at Phoenix Contact USA. For the past three years, he has supported safety products for failsafe applications. Prior to Phoenix Contact, Azizian worked for nine years as a Technical Support Engineer III at Yokogawa Corporation of America, supporting a wide range of hardware and software products. Azizian is a 1984 graduate from the University of Missouri – Rolla in BSEE and worked on MAIS at the University of Houston – Victoria.