On every crosshead engine, the condition of the piston rods has a very big impact on the engine’s system oil consumption. If the rods’ surfaces are too severely worn out or scratched, then the stuffing box rings are not able to seal properly anymore and oil carry-over is the inevitable result.
Further problems can be contamination of the system oil with carbon and scrape-down particles from the cylinder liner, as well as an elevated crankcase pressure, which in turn can lead to system oil being pushed out of the crankcase at the flywheel seal.
All piston rods that we recondition undergo a very meticulous quality check before they are delivered to the customer. This includes a dimensional check, hardness measurements, surface roughness measurements and non-destructive crack detection.
QuantiServ discourages metal spraying or chromium plating on piston rods. Both processes are risky – poor bonding adhesion and latent cracks are common – so we are not offering them. Instead, we weld the piston rods over their entire surface with a special welding material. This ensures a high surface hardness, making the piston rod very wear resistant and ensuring a long life time. At the same time, welding ensures a very strong molecular bond between the rod and the hard surface coating.