A sustainable alternative to chromium plating
Chromium plating has long been used in industrial applications, including the reconditioning of pistons. However, tightening regulations on hazardous chemicals call for an effective alternative that is safe for both operators and the environment.
Engines are at the heart of industrial processes, and it is the pistons that are the vital and most hard-working components. But after tens of thousands of hours of mechanical wear, contact with corrosive substances, and extremes in pressure and temperature, pistons generally need replacing or reconditioning.
Antoine Vos, Senior Manager for Remanufacturing at QuantiServ, Wärtsilä’s business line that offers repair and overhaul services to companies in the marine and energy sectors, explains:
“Pistons have piston rings that guide them inside their liners and that also seal the pistons from the combustion side to the crankshaft side. These rings turn around, and they are subject to high pressure. They’re exposed to oil, fuel, and a lot of acids as part of the combustion process. All these factors have an effect on the lifetime of the piston rings and the piston ring grooves.”
“In the reconditioning process, the surface treatment of piston ring grooves was – and still is – done by applying chromium plating,” says Vos, who is based at QuantiServ’s reconditioning centre of excellence located in Kruiningen in the Netherlands.
However, Chromium VI, the chemical compound that is typically applied when reconditioning piston ring grooves, has been found to cause negative health effects, including cancer. For this reason, European, as well as global regulations for the industrial use of the compound are tightening, with a ban expected as soon as 2024.
Challenged to find a viable solution, QuantiServ began developing and testing an economical substitute for chromium plating. At the start of 2018, the company introduced QS50K TM, a new technology for the reconditioning of large bore pistons in 2-stroke engines that drastically extends the life of piston ring grooves.
Excellent performance with little to no wear
In extensive field testing, QS50K has shown excellent running behaviour and very low piston wear rates, with no measurable wear in the ring grooves after 15,000 hours. With the tests having successfully undergone an official validation process, QuantiServ now uses the technology as its latest standard.
“We apply QS50K to every system that we recondition, not only for Wärtsilä products but also for other brands,” says Vos. “What we have found is an alternative to chromium plating which, at the same price to the customer, is even better than the original process, so that over their lifetime, the piston ring grooves show little to no wear,” he says.
“Because of the coating’s endurance, the time between overhauls is extended so the piston can be left inside or reused after the piston rings, which have a shorter lifetime, have been changed.”
“We have only satisfied customers,” remarks Vos.
Furthermore, since QS50K is an in-house application, QuantiServ has full control over the entire production process and delivery chain when reconditioning a piston for a customer.
“From receipt of the goods to the delivery back to the customer, or to the vessel, it’s an in-house process. This also reduces production time. The lead time for the customer is now tremendously shorter,” Vos says.
Robotisation and a controlled environment
Perhaps most importantly, the process takes place in a controlled environment, making it safer for operators.
“In January, we will start to build a new customised QS50K application centre – a conditioned booth containing a robotised system. It can easily double the capacity as the existing equipment is overbooked,” says Vos.
QS50K has been commercially available since the beginning of 2018, and has predominantly been used in reconditioning pistons for two-stroke engine power plants. QuantiServ also maintains contracts to apply the technology to customer engines, including Maersk, MSC, CMA CGM, and with other major customers increasingly opting to use the technology.
QuantiServ currently offers the revolutionary solution from its Kruiningen facility. QS50K will soon also be available to customers from the company’s workshops in Asia.
"What we have found is an alternative to chromium plating which, at the same price to the customer, is even better than the original process."
Antoine Vos, Senior Manager, Remanufacturing, QuantiServ