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Condition Monitoring: The benefits of blending sensor-based and site visit analysis

RJW Intelligent Engineering Solutions > Articles > Condition Monitoring: The benefits of blending sensor-based and site visit analysis
11condition monitoring

Shutting the barn door after the horse has bolted is a phrase that could certainly be applied to repairing equipment which has failed due to poor maintenance. 

The numbers are staggering. Machine downtime costs British manufacturers more than £180bn a year and is responsible for 3% of all working days lost annually in the manufacturing sector. More than half – 53% – of this downtime is due to hidden internal faults. 

The best way to avoid unplanned downtime is through condition maintenance and dealing with issues before they are able to develop into something larger and potentially much more difficult and costly to repair. 

Our Reliability Manager, Tim Wilkinson, has been working in this area for decades.

“Being able to spot issues before they develop into something bigger is absolutely vital. In the past, companies may have accepted downtime as just par for the course, but with the technology and methods available today, that simply no longer has to be the case.”

Condition monitoring 

When it comes to preventative, proactive maintenance, the term most will be familiar with is condition monitoring (CM). Like its name suggests, it involves the monitoring of conditions in machinery, from temperature and vibration to voltage and lubricant levels and many other factors too. 

By carrying out CM, engineers and other skilled experts are better able to spot changes which could provide a vital clue that a piece of equipment could be on its way to developing problems. 

There are two main ways to carry out condition monitoring, in person and remotely. 

Site visits  

Condition monitoring has traditionally been carried out via site visits, with trained staff examining equipment for any signs of problems and recommending actions designed to tackle them before it leads to downtime. This tried and trusted method involves feet on the ground, with expert eyes able to inspect things up close and make informed analyses.  

These walk arounds can take place any number of times depending on need and budget, but the ISO recommends they take place monthly. Visual Assessment is a skilled, technical engineering task, with clearly defined objectives and reporting, not, as some people seem to think, ‘a bit of a walk around’!

The challenge though is that site visits can only be carried out every so often because it can lead to the slowdown or even shutdown of production while equipment is being inspected. By its very nature it can be intrusive and interfere with operations. This is obviously less than ideal.  There is also the issue that not all assets are easily accessible due to their location within the plant or considerations of hazardous environments and atmospheres. 

There is also the risk of an issue developing between visits. Problems can occur at any time, completely out of the blue, and if there are unnecessary delays in them being picked up, by the time of the next inspection visit these problems may have developed into something which is far harder and much costlier to repair. 

Smart technology  

The rapid advancement of smart sensors, cloud tech and machine analytics are in the process of revolutionising condition monitoring because they allow it to be undertaken 24-hours-a-day, 365-days-a-year. Equipment can be monitored in real time with no delays between a fault being detected and it being logged and assigned for repair. 

For remote condition monitoring in industrial settings, this industrial internet of things (IIoT) underpins an ecosystem of technology built around three interconnected components. 

These are:

  • Sensors. Once these ‘fit and forget’ sensors are installed they are on duty from the word go, able to take multiple readings from even the most obscure locations on site.
  • Advanced analytics. Where condition monitoring previously required the manual collection of data which had to be pored over by experts, artificial intelligence (AI) and machine learning can crunch vast amounts of data in real time from sensors in multiple locations, then providing diagnostic information at speed.  
  • Cloud technology. The cloud underpins the internet of things which allow the sensors, AI and monitoring to all interact seamlessly. 

The sensors gather the data, analytics turns that data into actionable information, with the cloud connecting it all. By doing so, it allows for constant condition monitoring to be possible in a way that never has been before. 

But that being said, there are occasions where there is no substitution for a human inspection. A trained technician can get a feel for a particular company and its equipment, as well as the nuances and quirks of how things operate. There are also occasions where it is not practical or cost-effective to have sensors deployed to monitor all types of equipment.

Combination of methods

Just because IIoT technology has been developed does not mean the traditional way of keeping a watchful eye on machinery should be discarded. Instead, a combination of both new and traditional methods of condition monitoring has distinct advantages, says Tim Wilkinson, Reliability Manager at RJW.

“At one particular company I worked with, I found that around 70% of faults were only discovered after visual inspections and couldn’t have been caught by a sensor.” He said.   

“That isn’t particularly unusual, because there are situations where automated systems just won’t pick anything up like when something just works its way loose, seals start spinning or lubrication leaks. Or you could have localised temperature changes where there’s a change in temperature but it’s nowhere near the sensor – if it’s not near the sensor, then the sensor is not going to find it!”

He added: “But of course there are lots of occasions where automated sensors give great data, and a major plus of sensors is that you can put them on kit that you can’t get to for a manual inspection, for example in a tank farm or up in the gods where it would need scaffolding to access – so without sensors you wouldn’t get any data on these systems at all.”


The sheer cost in downtime experienced by British industry means maintenance is the best way to avoid both loss of revenue and productivity. 

While remote monitoring is becoming more widely adopted, with technology such as AI and cloud computing making a new generation of systems a viable solution, there remain occasions where experts in the field are required, both practically and in a way that makes better financial sense. 

A combination of both remote and site condition monitoring can cover all the bases, with experts on hand to spot problems, while constant monitoring of specific machines and components – backed up by analytics – helps ensures a watchful eye is kept on their condition right around the clock. 

Tim loves to discuss integrating sensor and manual checks into preventative maintenance systems. Contact one of our account managers and they can set up a call with Tim, or find him on Linkedin at

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