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Predictive maintenance using infrared thermography

Growing a successful infrared thermography program involves planning and action, but will quickly become an essential part of a manufacturing plant’s processes, writes Steve Hood.

Growing a successful infrared program involves planning and action. This article shows a variety of steps showing how to develop a thermography program that becomes an essential part of a processing plant’s operations.

The first thing to do is to gain support from management. Management buy-in is essential to the success of establishing an infrared thermography maintenance program. To get support from management you need to communicate the benefits and requirements of your program and outline how thermography performance results will be measured.

You should also practice reading thermographic images, as to get the best results from your thermal imager, you need to become a proficient user. Take time to use it regularly including planning, tracking and documenting results.

Meet regularly with first level managers, line supervisors and other co-workers. The more people who understand the benefits of thermography the greater chance you have at establishing an entrenched infrared program. You need to explain what thermography involves, demonstrate the camera, ask for support and set up a mechanism to request thermography surveys.

Also, you should think about integrating with other predictive maintenance efforts. As data from several technologies can all be used to study the condition of a machine asset, integrate the results from you thermal readings with those from other testing devices. Ideally, these technologies will work from and with the same computerised maintenance management system (CMMS), to access equipment lists and histories, store reports and manage work orders.

Written inspection procedures drive the quality of data collected and ensure inspections are done safely. Ensure you develop these before implementing your program. As a starting point for creating specific inspection procedures, review current industry standards.

Inspection procedures should include details on such things as what personal protective equipment (PPE) must be made available to minimise the risk should an accident should occur. Inspection procedures should also address the conditions required to locate problems and acknowledge other technologies needed to troubleshoot further.

Creating inspection routes

For best use of time and resources, make a list of the equipment to be inspected. Using existing lists of equipment from a CMMS or other inventory, eliminate items that aren’t well suited for infrared measurement and focus on equipment that creates production bottlenecks. If possible, look at history as a guide including where failures have occurred in the past.

The lists may not be up to date, so the first inspection cycle may take more time as equipment is located and lists updated. If thermography is new in the plant, the first few inspection cycles may yield a large number of finds. After about three cycles, re-organise the routes so they are more efficient and add new routes and equipment into the inspection cycle as necessary.

The optimum frequency of inspection will be determined by: the needs of the equipment assets; safety; the criticality of the equipment; and the expense of a failure and the frequency with which problems impact production and/or maintenance. It is also vital to inspect all new equipment both as part of the acceptance process and to establish a baseline.

When repairs or modifications are made to equipment, the CMMS must alert the thermographer to conduct a follow-up inspection.

Conducting inspections

When making your inspections, always use a pre-inspection checklist, which might include:

• making sure the thermal is ready to go

• charging the batteries

• ensuring the system is within calibration by viewing a black body reference or conducting a simple ‘tear duct check’

• clearing the memory of previously recorded data

• uploading past results so they can be compared to new findings if following an inspection route that has been inspected previously

• ensuring any additional equipment acquired is in good working order.

More than one person should conduct routine inspections. The second person will usually locate the exact equipment to be inspected, remove panel covers, take load readings and watch for the safety of the thermographer. When entering an inspection area, take a moment to get oriented, determine an emergency exit strategy and note any potential hazards.

Unless conducting a first-time baseline inspection, only record thermal images when problems or ‘exceptions’ are located. Take time to look at the finding from several different angles and collect any other data that might be useful for analysis, including additional visual images of the component.

When the inspection is complete, meet briefly with the area manager to review the findings. Download any data collected after each route as soon as possible to reduce the risk of accidental erasure. Delete any unnecessary images and process the rest individually while fine-tuning temperature measurements. Enter any supplementary data into the report page along with the visual image of the equipment inspected. As a final task, update the equipment list with any changes, additions or deletions.

Reporting results

The software that comes with thermal imagers can support simple but useful comparisons of asset condition over time. An alarm temperature can be loaded onto an image before it is uploaded into the camera. During the current inspection, both that alarm setting and the previous image can be used to determine the extent of any changes that might have occurred.

The actual report format can vary widely and can be customised to suit your needs. If you can tie the report into the work order generated by the CMMS, findings can be tracked through the equipment’s useful life.

Once the data is correlated with data from other technologies, the actual operating condition of all assets will be known and can be reported in an integrated form. Those assets that are in an alarm stage (red) or an unknown stage (yellow) can then be scheduled for either repair or further monitoring or managed in some other way, such as reducing load, to minimise the risk of failure. Assets in good condition (green) are ready and available to make your plant profitable.

Tracking results

Analysis of data over the long term is very important, so plan on accumulating it in forms that facilitate this process. Tracking can highlight trends that may not be obvious in a day-to-day analysis and help in fine-tuning the program.

Also track increased machine asset availability, production, production quality and the distribution of maintenance dollars and total maintenance costs over time to evaluate the overall success of the program.

[Steve Hood is Fluke Australia’s managing director.]

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