Energy engineers and surveyors have carried out boiler inspections for over 25 years, but there are still instances that can shock them: Such as the boiler showing 180 cracks just two years after purchase, says Mark Ormrod, NDT & Material Testing Manager at British Engineering Services. “Of course, most plants are simply running their boilers in line with manufacturers’ guidelines and there are no unexpected shocks found on inspection. We’ve taken a look at the practical issues underpinning our worst and best findings for industrial boiler maintenance, to highlight how to maximise your boiler lifespan, instead of running it into the ground.”
The 'good'
When visiting a large manufacturing plant in Nottingham for its 5 year NDT test of their John Thompson boiler, one of the firm’s inspectors found that the boiler was still fully functional, despite being manufactured in 1966, so it had far outlived the typical industrial boiler lifespan of 30 years.
“When our Engineer Surveyor looked at the repair history, he could see that it had only required one repair in its lifetime,” Ormond said, pointing out that this has been achieved by running the boiler correctly.
The user carefully monitored that the boiler is slowly warmed up. Moreover, “they run it at optimal efficiency all week, before going onto low fire towards the end of the week in preparation for powering down. This ensures they minimise cyclic / thermal stress on the boiler,” he explained.
The ‘ugly’
At the opposite end of the spectrum is the example of the boiler showing no less than 180 cracks just two years after purchase. The engineer surveyor had discovered evidence of 'cyclic abuse' and so had requested non-destructive testing (NDT) – despite this usually only taking place every five years.
The plant had been running the boiler up to its top temperature as fast as it could to generate steam for a key part of their operations. They would then dump the steam and refill using cold water, which creates a thermal shock to the boiler and then starting the cycle again.
“In the last example, the boiler was not the right choice of equipment for their operations. A steam accumulator with the boiler would have been a much better fit for purpose,” Mr Ormrod commented. “The cyclic abuse was most probably a by-product of changing the ownership of asset integrity management from in-house to less experienced sub-contractors.”