Manufacturers already look at chronological equipment ageing, but when failures occur the mechanism and root cause must be identified. Corrosion – both internal and external – is the most common mechanism by which containment equipment ages, followed by stress corrosion, fatigue, erosion and high temperatures.
Additional influencing factors include design, construction, service conditions and maintenance.
“Safety should always be the priority when it comes to the combination of ageing equipment and hazardous fluids in particular,” says Chris Haines, industry marketing director at Schneider Electric.
Understandably, due to the delicate nature of hazardous fluids, the equipment used to hold them is subject to stringent regulations, which means that there is no such thing as a quick upgrade.
Safety should always be the priority when it comes to the combination of ageing equipment and hazardous fluids in particular
Chris Haines, industry marketing director at Schneider Electric
“Rigorous testing and safety regulations are responsible for ensuring superior product quality and the avoidance of hazards,” says EU Automation’s marketing director, Jonathan Wilkins.
“Although the need for enhanced regulation is self-evident at times, it stands in the way of the adoption of cutting edge automation equipment and innovative manufacturing practices,” adds Wilkins.
The consequences are that automation equipment tends to be dated, with a heavy reliance on obsolete parts.
“Many industries should take note and learn from the extensive measures implemented specifically onto nuclear programmes,” says Haines.
For assistance, the HSE report RR912 is readily available and contains advice and guidelines, much of which can be adapted for use in general industries.
“In this area,” says Haines, “it is often referred to as an ageing management programme (AMP) and should form part of an company’s overall maintenance and asset management strategy.”
However, the term ‘ageing’ can be a little misleading, because it is not a simple case of identifying chronologically old equipment.
“Critical equipment is that which may suffer some form of degradation with an increasing risk of failure over time,” says Haines.
The HSE defines an ageing asset by describing the following characteristics:
- damage due to degradation that has accumulated and may have become widespread and be accelerating
- design or performance margins that may have eroded to a point where future acceptable performance cannot be assumed
- a different, more quantitative, approach to inspection and non-destructive testing that may be necessary for determining the extent and rate of damage to demonstrate fitness for service
- proactive ageing management and asset care being required through revalidation, major repairs, refurbishment and replacement of key items at various times.
Facility managers can often feel overwhelmed by the daunting task of managing all the equipment and ensuring it is fully operational around the clock.
“Having a risk assessment performed is a good starting point to help qualify what equipment is ageing and what is not,” says Haines.
“Inspections are crucial to identify safety improvements and productivity-enhancing recommendations. “Having the historical data of a machine is also useful as sectors move to a more proactive (rather than reactive) maintenance model.”
From this accumulated information patterns start forming, such as a trending decrease in performance or an increase in downtime and repair activity.
“In general manufacturing, we are beginning to see more implementations of condition monitoring with predictive capabilities,” adds Haines.
Corrosion is one of the greatest problems facing process plant operators and its monitoring and effective management is a neverending battle
Kjell Wold, global business development manager, Emerson
What used to be just the domain of oil and gas or process industries is now a realistic proposition for many as implementation costs decrease while the financial impact of downtime becomes ever greater.
Trends like IIoT (Industrial Internet of Things) has amplified this monitoring ability due to increased connectivity and smart devices with embedded intelligence.
“A good place to start is the all-important topic of maintenance and how it fits into the Industry 4.0,” says industrial automation firm, Omron.
Today’s intelligent power monitoring and control systems can now support migration from time-based maintenance, to condition-based maintenance, where cycles can be based on actual circuit conditions instead of specific time intervals.
Modern automation systems store data for maintenance records that can be analysed and applied as problem prevention. For example, the process influence on equipment of temperature, flow and water content.
“Corrosion is one of the greatest problems facing process plant operators and its monitoring and effective management is a neverending battle,” says Kjell Wold, global business development manager for flow assurance at Emerson Automation Solutions.
Alongside rising maintenance costs, corrosion poses risks to the safety and integrity of the plant if not properly managed.
“Age, original construction specification and processes vary from plant to plant, whilst raw materials, operational temperatures and velocities can also influence equipment and pipework corrosion.
“Within refineries, for example, effective monitoring is essential and a range of intrusive and non-intrusive methods exist.
“A combination of methods will often provide the best overall monitoring programme,” adds Wold.
Intrusive, retractable style probes are commonly used as well as non-intrusive sensors, and wireless devices are making installation much easier, faster and cost effective.
“Over recent years, we have several cases where monitoring data has been actively used to tune opportunity crude programmes.
“We recently solved a critical corrosion problem at a large refinery that could have required a shut down in advance of the next scheduled turnaround.
“A very severe metal loss from one of the reactor inlet pipes was detected and manual inspections revealed three critical points that needed to be monitored to enable production to continue safely.
“Critically, the refinery had an existing WirelessHART network installed, with easy connection to additional Emerson sensors, such as Permasense,” states Wold.
A combination of methods will often provide the best overall monitoring programme
Kjell Wold, global business development manager, Emerson
These devices continuously monitor the pipe wall thickness, providing accurate and timely understanding of corrosion rates, erosion rates and insight into the impact of changes to production.
“For example,” says Wilkins, “a turbine in a nuclear power plant requires considerable support from a number of pumps to ensure the condensate water and cooling water systems are maintained properly.”
Due to the required capacity of these pumps, most are powered by high voltage motors, a number of which are in excess of 20 years old.
Wear and tear
After years of continual stress on the motor, it is understandable that it is going to show signs of wear.
“Purchasing a new motor will require checking compatibility with the rest of the system, not to mention ensuring it fits with stringent industry regulations typified in pharmaceutical and nuclear.
“There’s also the added cost of upgrading other elements of the system that need to be adapted as the result of changing the motor,” adds Wilkins.
By using a combination of data and insights, and relating it to the environment in which the equipment operates, it is possible to proactively assess the mechanism of deterioration.
While recognising that design and construction also play a significant part in the behaviour of equipment in any given environment.