Automated field calibration for the oil and gas industry
Thursday, 16 November, 2017
Calibration is an essential element of any instrumentation maintenance program — but without the right tools, calibration operations can be time-consuming and error-prone.
Technicians who maintain and troubleshoot process automation systems used in refineries, pipeline custody transfer applications or pumping operations know that there are thousands of sophisticated devices required to perform countless critical operations ceaselessly, accurately and reliably. Those devices require regular inspection, testing, calibration and repair to protect the health and safety of the public. Businesses and governments require highly specific documentation of those maintenance and calibration tasks performed on these critical assets.
Traditional calibration and documentation practices are labour-intensive and in today’s downsized environment there simply aren’t the resources to keep up. However, automated calibration practices are proving a practical alternative because they require smaller teams, while increasing productivity and operational reliability at a lower overall cost.
Increased safety and productivity with reduced costs
Whether you’re installing a new device, changing the settings of an existing device or reinstalling a repaired device, calibration is the only way to ensure that the device meets performance requirements. This is important for:
- Safety: When valves and gauges are not regularly calibrated, they can fail, cause an unsafe condition possibly leading to an explosion and loss of life, and cause great damage to infrastructure.
- Quality: To perform at the highest efficiency and quality, equipment must be well maintained and adjusted.
- Revenue: Calibration of the devices that make custody transfer measurements are necessary to ensure that purchased products, such as petroleum or natural gas, are measured and taxed correctly.
- Compliance: Government regulation and enforcement agencies often require calibration and documentation to verify that devices conform to rules and standards. Poor calibration documentation can put the manufacturer at risk of government fines and loss of production.
- Cost savings: With automated calibration and documentation, a lean team can complete twice as many calibrations in the same amount of time, which lowers the cost per calibration significantly. Regular calibration can also reduce the risk of lost revenue from accidents; if a disaster strikes, good calibration records can support a strong defence against legal action.
In the oil and gas industry, some believe that digital fieldbus devices do not require calibration. This is not true. A fieldbus signal provides diagnostic information; it does not provide information about the accuracy of the device, nor does it verify that the device is reporting the process accurately and precisely.
For example, a fieldbus flow transmitter can report diagnostic information about the transmitter, but it cannot report on the physical condition of the orifice plate across which it is measuring flow. Consequently, even if the electronics are operating perfectly, the flow reading transmitted may be inaccurate. Calibration is required to ensure the flow reading is accurate.
Addressing documentation challenges
Traditionally, documenting a calibration has meant hand writing the results on a clipboard or in a logbook. Pencil-and-paper documentation both produces and perpetuates errors. The data in handwritten records is often illegible or insufficient. And facilities that use a computerised maintenance management system (CMMS) must allot additional time to manually enter the handwritten data into the system, which creates additional opportunities for error.
Another challenge is that many facilities store field data in more than one database. Calibration data entered in the operations database may not be populated into, or accessible by, the maintenance database. These challenges are being addressed by:
- installing more digital instruments and valves
- using interconnected asset management software to help manage documentation
- using handheld documenting process calibrators to automate field calibrations and upload digital documentation to a CMMS
- using route-based calibration.
Doing more with less
Budget cuts and the retirement of experienced workers have been substantially reducing engineering, maintenance and operations staff numbers. Working with a leaner team makes it harder to have a large group of technicians to do rounds and, as a result, calibration rounds often fall by the wayside.
Reductions in team size also mean that experienced team members have less time for mentoring and on-the-job-training. This means that equipment and system-specific knowledge is not being successfully transferred from the individual to the institution and, as older operators and engineers retire, they take this knowledge with them.
Automating calibration and documentation
Companies in the process industries can mitigate losing the benefit of staff experience and knowledge by using multifunction documenting process calibrators and a new generation of handheld pressure calibration tools. Most of these devices feature recording and memory functions so that the technician can log measurements and upload them to a PC for reporting and analysis. Multifunction calibrators consolidate multiple calibration steps and functions into a single handheld device that sources, simulates and measures pressure, temperature and a wide variety of electrical and electronic signals. Likewise, handheld pressure calibrators combine pressure and temperature measurements and in some cases an integrated electric pump, which saves hand-pumping and extra equipment to carry around.
These multifunction tools are instrumental in:
- reducing the number of tools technicians have to carry and learn to use
- making it possible to collect multiple datasets with one tool
- replacing many manual calibration steps with automated procedures
- allowing just one person to perform calibrations in most cases
- limiting the calculated error to a single tool rather than multiple tools
- isolating a device from the process, verifying that it’s depressurised and applying pressure with an electric pump.
Using calibration routes
The biggest savings from using a documenting calibrator come in the route management tool built into the device. The technician can load up a ‘round’ of calibrations that walks the technician consistently through the steps of each procedure. Using a single set of permits and paperwork for an entire route of calibrations for maybe 20 instruments reduces the cost per calibration considerably compared to performing one-off calibrations.
Reducing maintenance costs and risk
Because documenting process calibrators automatically record the as-found and as-left state of each field device in situ, and can be operated by a single technician, route-based documenting calibrators can save as much as 50% of the time and cost of traditional manual, single-device calibration methods. Besides saving maintenance costs, this process can help companies avoid the legal costs and lost revenue from accidents. Good calibration and maintenance practices help reduce the probability of accidents. And, if a disaster strikes, good calibration records can be a part of a facility’s legal defence.
In summary, implementing route-based calibration, paperless documentation and CMMS data management:
- makes it more practical and affordable for companies to perform calibrations more consistently
- reduces risk and liability exposure
- supports knowledge transfer from the individual to the team and to the institution
- helps to increase both productivity and quality.
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