We’ve recently been sent 3 ABB VTC 254 turbochargers to overhaul.
The operator reported that the heatshields on some of them had cracked previously, and its happened again.
After investigating, we found the root cause of the damage: The way some of the heatshields had been fixed.*
The fixing methods used were different on the three units – some were fixed with bolts and locking tab washers and others with drilled setscrew and stainless locking wire.
The locking wire design is not shown in the manufacturer’s manual, so must be a modification from the prime mover’s request, or this turbocharger is used on an engine using different fuel.
To prevent these overhauled turbos from suffering the same cracked heatshields, as part of the overhaul we’ve replaced the heatshields where required and fixed them with drilled setscrews, serrated washers and stainless locking wire.
These fixings should perform more effectively providing a longer, more reliable operating life for the turbochargers.
*Due to the extreme heat generated by the exhaust gas on a spun steel shield, these shields have been known to crack and break causing extensive damage to the turbocharger meaning great expense and unplanned downtime.