In-situ Machining the World’s Largest Four-Stroke Diesel Engines

Ø 64 cm bore, 90 cm stroke, 2’150 kW (2’880 hp) power per cylinder: The world’s largest four-stroke engines are very mighty machines indeed!

These powerful engines were built during the late 1990’s, mostly in a 6-cylinder configuration. With a nominal power output of 12’900 kW, they found popular application as single propulsion engines in multi-purpose cargo vessel of about 20’000 DWT size.

During 20 – 25 years of operation until now, these engines have accumulated more than 120’000 running hours each. In terms of number of engine revolutions, this is equivalent to a car driving for 1.8 million kilometers (1 million miles)!

In-situ crankpin polishing
In-situ crankpin polishing

It is therefore hardly surprising, that after that many running hours signs of wear were found on the crankpins of these engines. As is often the case on medium-speed, four-stroke engines, the crankpins were suffering from what is called “cam effect” or “ridge wear”.

Has your four-stroke engine accumulated around 60,000 running hours or more?

Although the crankpins might appear to be in good condition, it is very likely that they suffer from the cam effect (also known as ridge wear) and are in need of machine polishing. If this is not done, then you might face a failure soon!

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Usually, then the cam effect will manifest itself in two ways:

  1. Through uneven wear in horizontal direction, with nearly no wear at the centre of the pin and at the edges, but with easily noticeable wear to the left and right of the oil bore.
  2. The pin is not affected evenly throughout its circumference. The cam effect is usually most pronounced at about 30 – 45 degrees after Bottom Dead Centre (BDC). For this reason it is called “cam effect” – the pin is not perfectly circular anymore.

QuantiServ appeals to owners and operators of medium-speed four-stroke engines to sensitize the crew about the cam effect. We highly recommend that the pins are carefully checked whenever an engine overhaul or bearing replacement is carried out. If any uneven wear patterns are detected, then the pin must be machine-polished to restore its proper geometry before any new bearings are installed and the engine is restarted.

If the cam effect is detected in good time, then machine polishing of the pins is usually sufficient to correct the problem. After machine polishing, the crankshaft will be ready again for several years of continuing operation. Whether standard bearings or undersize bearings will have to be installed after polishing will depend on the actual situation.

If, on the other hand, the cam effect goes undetected for too long, then a crankpin failure is almost inevitable. Such was also the case here on the first engine. Heat treatment and machining was therefore necessary and was swiftly carried out by our Swedish specialists. Having seen the excellent result and now aware of the cam effect, the customer tasked us to machine polish all pins on this engine and on the sister vessels, which is why we eventually polished about 70 pins in quick succession but in different ports.

In-situ heat treatment
In-situ heat treatment (annealing)
Crankpin machining
Crankpin machining
Completed crank pin
Completed crank pin

All work described above was carried out on board by our Swedish in-situ specialists. They were supported by our reconditioning experts that meanwhile worked on those engine components that were removed from the vessel for an intervention ashore. These components were sent to our reconditioning centre in Kruiningen, The Netherlands, where they underwent  thorough overhauling and machining works.

By the time of writing in August 2022, we have overhauled around 70 cylinder heads and have re-bored a similar quantity of big end bearing housings. Machining the big end bearing housings became a necessity due to excessive ovality in the bore.

Newly overhauled cylinder heads in our workshop
Newly overhauled cylinder heads in our workshop
Big end bearing bore machining
Big end bearing bore machining

More Than 1,000 QS50K Pistons Delivered – And Counting!

In 2019, following an extensive research and testing period, we have introduced the first QS50K pistons into the market. It was the beginning of a lasting success story: Ever since, we have produced and delivered more than 1’000 pieces, to many different customers.

These pistons are now installed all around the world, in ocean going vessels and in power plants. They are performing extremely well and achieve time between overhauls (TBO) that hitherto were unthinkable. The earliest QS50K pistons have accumulated well over 30,000 running hours and are still in service!

Rebuilding the piston ring grooves
Rebuilding the piston ring grooves

Benefits of the QS50K technology

With the introduction of the QS50K coating technology, QuantiServ has redefined the piston reconditioning process. This proprietary technology was developed by QuantiServ and offers the following important advantages:

    • Extremely durable, wear resistant coating, resulting in very long life-time / time between overhauls (TBO)
    • Fully automated process carried out by a robot, resulting in a top-quality product due to the robot’s very high accuracy, repeatability and consistency.
    • Faster than chromium plating, therefore shorter turnaround times
    • Less heat input into the piston, eliminating any residual stresses that over time could develop into cracks
    • Environmentally sound, non-toxic process

Availability

We offer the QS50K technology for any engine brand and for any cylinder bore above ø 48 cm. The QS50K pistons that we have delivered so far covered the bore range, from ø 48 cm to ø 98 cm. They were destined for engines manufactured by the big three OEMs, in an approximately 45%/45%/10% ratio.

At this moment, our recon centres in Kruiningen (The Netherlands) and Suzhou (China) are equipped with the required machinery to offer this product. Our large recon centre in Singapore will follow very soon.

24,000 Hour Ring Groove Life Time. Guaranteed!

The quality of our QS50K coated ring grooves is so good that we now offer a 24,000 hour* warranty on fully reconditioned, QS50K coated two-stroke pistons!

Contact us for details

*pro-rata, 24,000 running hours or three years after delivery, whichever comes first

To give maximum flexibility to our customers, we offer three different ways of working to chose from:

  1. Reconditioning on exchange. The customer gets a newly reconditioned component delivered from one of our four reconditioning centres. Once he has installed the component into his engine, he returns his old part to us.
  2. Reconditioning of the customer’s own part. The customer sends the component to be reconditioned to a QuantiServ reconditioning centre, where it undergoes professional reconditioning after which it is returned to the customer.
  3. Straight sale. The customer purchases a reconditioned piston from us, without returning an old one.

We can apply the QS50K coating to pistons that are undergoing full or partial reconditioning.

Full reconditioning

The entire top surface and ring groove area is first machined off and then rebuilt by robotic MIG or SAW welding. Thereafter, the piston undergoes final machining before the QS50K coating is applied to the ring grooves. The last step is grinding of the ring grooves, which completes the full reconditioning process.

If it is requested by the customer, then we can coat the top of the piston by a protective layer of Inconel. This can be a good solution for engines that suffer from excessive hot corrosion at the piston top.

Partial reconditioning

If only the ring grooves are worn and if a piston is in otherwise good condition, then partial reconditioning is possible. A precondition is, however, that none of the ring grooves has worn so much that not only the chromium layer but the steel substrate itself has worn. In this case, partial reconditioning is not possible and full reconditioning is the only remedy.

During partial reconditioning, any remaining chromium is removed before the QS50K layer is applied to the ring grooves. All mating surfaces will be skimmed, to remove any signs of fretting corrosion and if there are small internal cracks, then these will be repaired too.

 

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Our reconditioning centres

We operate four reconditioning centres that are strategically located along major shipping routes: Singapore, Kruiningen (The Netherlands), Suzhou (China), Dubai. Each of the four centres carries a large inventory, so it can offer components on exchange in addition to reconditioning the customer’s own part. Both ways of working are available, it is entirely the customer’s choice.

Our reconditioning centres are the most modern ones within our industry. Welding and QS50K coating is typically performed by robots and machining is done on numerically controlled (NC) machines.

QuantiServ Reconditioning Centres
We operate four reconditioning centres globally.

This enables us to provide consistently high quality and short turn-around times at attractive prices.

 

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QuantiServ Suzhou Workshop
The QuantiServ reconditioning workshop in Suzhou, China. The others are in Singapore, Dubai and Kruiningen (The Netherlands).

“Reconditioning” Must Mean More Than to “Put Into Good Shape Again”

Component reconditioning is very popular

Component reconditioning has many advantages. This is especially true in case of large, heavy components:

  • Reconditioning usually represents a cost saving of 50 – 70% compared to replacement
  • Reconditioning a component nearly always takes up significantly less time than fabricating a new one
  • Long lead times or supply chain crunches are less of an issue, as supply chains are shorter and simpler
  • No new part might be available when one is needed. To reduce risk and stock keeping costs, OEMs manufacture and sell spare parts for ever shorter time periods only.
  • Reconditioning results in a smaller carbon footprint than replacement

Given these advantages, it is hardly surprising that component reconditioning has been widely used for many years in industries such as marine and power generation, where components are large and where equipment life is long.

But, what does reconditioning actually mean?

Dictionaries and thesauri usually equate the word “reconditioning” with “to put into working order again” or “to put back in shape”. Proposed synonyms are: To fix, mend, patch, renovate, repair and revamp.

This implies that the goal of the reconditioning process is to put the component back into the state it was before it got worn or damaged.

At QuantiServ, we are convinced that we should do much more than to put a component back into its original, unworn condition. We set the bar much higher for ourselves. After all, we are one of the largest reconditioning companies in our industry and we have in-house research and development resources, that enable us to continuously push  the technology envelope. Noblesse oblige, as the French proverb goes.

We believe that whenever a machinery component undergoes reconditioning at one of our four reconditioning centres, we are presented with an opportunity to not just put the part back to its original condition, but to improve on it. We habitually apply new technologies, modern materials and advanced processes to improve component design, leading to a better performance and extended Time Between Overhaul (TBO).

This sets us apart from all the low-cost reconditioning companies. These companies return to their customers components that – in the best of cases – perform as good as when they were new, but never better. Unfortunately, by so doing, these companies forego customer value by providing sub-optimal service.

There are many good examples of how we have lived up to our high standards and have engineered, manufactured and delivered to our customers improved components that have subsequently shown superior performance. An illustrative example comes from a power plant in the Caribbean, that suffered from very short TBOs. Pistons on these 90-bore engines had to be pulled every 3’000 running hours, to replace piston rings, pistons and, sometimes, even cylinder liners. To solve the problem of such unacceptably short maintenance intervals and component life-times, we have thoroughly analyzed and then redesigned some components of this 90-bore, two-stroke engines. Specifically, we have altered the number of piston rings, have coated the piston ring grooves with our QS50K material and have applied a coating to the piston skirts.

The result of these modification is that the TBO could be increased from 3’000 hours to 18’000 hours!

Three piston rings instead of five

In internal combustion engines, piston rings seal the combustion chamber. While the piston rings’ purpose is unambiguous, it is less clear how many piston rings are required, to get the job done effectively. Historically, four or five piston rings per cylinder were deemed necessary on low-speed, two-stroke diesel engines. Simulations and field experience collected by us in recent years has shown that on many engine types, pistons with only three or four piston rings perform better than those with five. “Less is more”, when it comes to piston ring tribology.

Anti-friction coated piston skirts

A well performing forced piston cooling system is essential, especially on engines that operate on heavy fuel oil (HFO) to maintain a relatively low and stable core temperature. If the piston temperature rises above a critical threshold, then galling, scuffing or seizing will occur due to thermal expansion and breakdown of the oil film between the piston and cylinder liner.

The performance racing industry has been using coated pistons for some time already for this very reason. These so-called anti-friction coatings, that are applied to the piston skirts, are essentially dry film lubricants with a very low friction coefficient. This results in low friction forces and a reduction of parasitic drag, while also decreasing heat saturation in the piston skirt and core.

A 90-bore two-stroke engine piston with three piston ring grooves (instead of five) and with an anti-friction piston skirt
A 90-bore two-stroke engine piston with three piston ring grooves (instead of five) and anti-friction piston skirt

Anti-friction coatings offer the following benefits:

  • They act as a thermal barrier coating and reduce metal-to-metal contact
  • They increase component life time and TBO due to a lower wear rate
  • Reduced friction (a parasitic loss) results in a lower fuel consumption
  • They support oil film formation and therefore reduce the risk of galling, scuffing and seizing, particularly under challenging operating conditions such a running-in, high load operation and load changes

QS50K pistons

An excellent example of us improving engine component design is the development of our QS50K pistons. From a few years ago, many customers reported excessive wear in the piston ring grooves. The customers informed us that pistons with chromium plated ring grooves, which has been the industry standard for decades, would only last for a few thousand running hours. As reported this applied, in equal measure, to new as well as to reconditioned pistons and to many different engine types.

Our engineering and development colleagues started to investigate. They eventually developed an entirely new process of coating the piston ring grooves. They replaced the chromium in the ring grooves with a very advanced, proprietary material formula which has been proven to easily last for 20’000 hours and more. The successful development and market introduction of the patented QS50K coating process is a good example of how QuantiServ developed a solution to problems reported to us by our customers.

Since its introduction, more than one thousand QS50K pistons have entered service. The earliest ones have meanwhile accumulated well beyond 30’000 running hours!

Do talk to us if you have a specific problem with your installation. If machine uptime or performance is lower than it should be, if components wear out too fast, or if they fail prematurely. It is quite possible that we a solution available – perhaps we have already solved a similar problem for another customer. And if we do not have a tried and tested solution ready, then we will be happy to investigate and look for one.

In the case of the Caribbean Power Plant we have also supplied special piston rings that the engine OEM does not have in his portfolio for this engine type. This, in addition to implementing the modifications described above.

 

Our Reconditioning Offering

Sustainability

QuantiServ’s enduring commitment towards resource reduction and sustainability is demonstrated by our membership in the Association for Sustainable Manufacturing (MERA). We proudly carry MERA’s Manufactured Again Certification Mark, which is a recognizable symbol
that represents the quality, value and sustainability of our processes.

Image Gallery

Example of anti-friction coating on 90-bore piston skirts in our reconditioning centre in Kruiningen, in the Netherlands. Once the anti-friction coating is applied, the piston skirts get cured in an oven. As is usually the case, reconditioning of these piston skirts included the replacement of the four bronze bandages.

A 90-bore two-stroke engine piston with three piston ring grooves (instead of five) and with an anti-friction piston skirt

Key Data 2020 – Number of Customers and Orders Increased

We have steadily grown our reach and our customer base during recent years. In 2020, our 356 staff have successfully processed close to 3’000 Reconditioning, In-situ Machining, Metal Stitching, Epoxy Resin or Mobile Team orders from nearly 700 individual customers.

We carried out 70% of these orders in one of our 14 workshops. The remaining 30% of orders we processed on board ships or in customers’ plants.

The customers that we served stem from a wide range of industries. On average, we commenced a new in-situ machining assignment every three hours, anywhere in the world.

Key Data 2020:

QuantiServ Has Been Awarded “Manufactured Again” Certification

If you are a buyer or a procurement officer, then you probably already know about the economic advantages of reconditioning/remanufacturing. However, you might worry about the quality of the work performed and the durability of the reconditioned component. That is why the Remanufacturing Association (MERA) has developed a formal certification program.

Manufactured Again Certification

MERA’s Manufactured Again Certification Program promotes environmental stewardship. It does this by recognizing remanufacturing companies that meet the same quality standards as new manufacturing facilities.

QuantiServ is proud to have achieved certified status and to be a member of the program. The Manufactured Again certification gives our customers piece-of-mind and assurance that we are providing them with a quality product and thus enables them to make better buying decisions.

Read more about our technologically advanced yet economical reconditioning solutions by following the link below.

Reconditioning Solutions

Our Brand-new Case Study Page is now Online!

The new QuantiServ Case Study page is now online. It introduces recent work that we have done for customers coming from a variety of industries ranging from Marine, Mining, Hydro and Thermal Power Plants to Oil & Gas.

The cases are sortable by industry and cover services such as in-situ machining, metal stitching, reconditioning and many more. They each include a short description of the problem that the customer was facing, the solution and include many before/after and in-process pictures.

Case Studies

 

Four-stroke Cylinder Head Valve Seat Bore Repair

Our reconditioning centre in Vancouver has just carried out furnace brazing of 13 pieces of 32-bore four-stroke engine cylinder heads for Canada’s premier ferry operator.

The valve seat bores were seriously damaged by cavitation and corrosion. Machining to over-size was not possible anymore because this had already been done during past overhauls and the maximum diameter had already been reached.

QuantiServ’s unique process starts with the generous removal of any damaged material around the valve seat bores. Thereafter steel sleeves are soldered in in a vacuum oven before finishing off the heads by NC machining of the valve seat bores. Standard-size valve seats can then be installed, followed by pressure testing of each cylinder head.

QuantiServ’s furnace brazing process is applicable to four-stroke cylinder heads of any engine type with a cylinder bore diameter of > 200 mm. It is patented word-wide and classification approved (LR / ABS). Classification certificates are available on request.

Condition of the cylinder heads before reconditioning:

 

Condition of the cylinder heads after reconditioning, before installation of the valve seats:

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Reconditioning of Two Large Hydraulic Rams in Singapore

Ram 2

In January 2018 our reconditioning centre in Singapore carried out the overhauling and reconditioning of two large hydraulic rams belonging to a major American offshore company. The rams are part of knuckle boom cranes that are installed on an ultra-deep water drill ship that operates off the coast of Myanmar.

We frequently perform this kind of work on rams large and small, often for offshore and construction companies.

The work included chemical stripping of the worn chromium layers, followed by new plating with an underlay of nickel and top-layer of chromium. We also honed the barrel, changed all seals and carried out various NDT tests on the rod and barrel.

All work was carried out in-house and was completed within 14 days.

At QuantiServ Singapore we are able to carry out galvanic nickel and hard-chrome plating and grinding of up to 6,000 mm length and 800 mm diameter.

Update April 2018:

The customer was very satisfied with the two rams that we overhauled for him in January 2018. In March he sent us another two similar ones belonging to the same ship. We have just finished the work on them, which means that we have now reconditioned all four units that are installed on this drill ship.

Reconditioning of Fourteen 96-bore Cylinder Covers

In November 2017, our Reconditioning Centre in Shanghai carried out reconditioning of fourteen cylinder covers for a major European ship owner. These covers came from one of the world’s largest container ships, equipped with a 14-cylinder, 96-bore main engine.

All fourteen cylinder covers and all fourteen exhaust valves were reconditioned within a period of less than one month, while the vessel was undergoing steel work at a shipyard in Qingdao.

This was the third vessel out of a series of similar vessels for the same customer. QuantiServ carried out the reconditioning work for all these vessels.

Significant Reconditioning and Field Service Job in Shanghai

In September our Reconditioning Centre in Shanghai carried out a a major reconditioning and field service order for an Iranian-owned tanker that was docked in a Chinese shipyard. This example shoes well the breadth of QuantiServ’s offering.

The following components were reconditioned:

  • 8 piston rods
  • 7 piston crowns
  • 7 cylinder covers
  • 6 exhaust valves
  • 7 crosshead pins
  • plus a number of smaller, related components

We also sourced for the customer a couple of new crosshead and crankpin bearings while we re-babbitted others, such as for example guide shoes.

QuantiServ engineers also carried out the overhaul work on board, supervised the oil flushing and attended the seatrial after the docking. We also replaced the stern tube shaft seals and in-situ polished some of the crankpin journals.

All the work was completed in 32 days.

QuantiServ at the Norshipping 2017 Exhibition in Oslo

Our participation at the recently held Norshipping 2017 exhibition in Oslo, Norway, was very successful. We displayed our exciting metal stitching, in-situ machining and reconditioning solutions. These solutions created quite a lot of customer interest and led to many interesting discussions. It was also nice to meet many existing customers again and to know some new ones too.

Our next stop will be the Philmarine 2017 exhibition, which will be held from 12 – 14 July 2017 at the SMX Convention Center in Manila. We will be at booth 111/118. Come and visit us there.

QuantiServ at the Sea Asia 2017 Exhibition in Singapore

Sea Asia Exhibition 4Our participation at the recently held Sea Asia 2017 in Singapore was a big success. We displayed our metal stitching and in-situ machining solutions, as well as the refurbishment of four-stroke cylinder covers by furnace brazing, which we are particularly proud of. These solutions created quite a lot of customer interest and led to many interesting discussions.

Our next stop will be the Norshipping Exhibition in Oslo, 30 May – 02 June 2017, where we will be at booth D 05-34. Come and visit us there.

Crank pin machining mock-up

Crank pin in-situ machining mock-up

Furnace brazed 32-bore 4-stroke cylinder cover

Furnace brazed 32-bore 4-stroke cylinder cover

Fully reconditioned 35-bore 2-stroke cylinder cover

Fully reconditioned 35-bore 2-stroke cylinder cover

No job too small – if it solves the customer’s problem

No job too small – if is solves the customer’s problem

A ship’s crew received a new cylinder liner in a mid-eastern port. Unfortunately, while lifting it onto the vessel, a sling came lose and the liner crashed hard on to the deck. Luckily no one was injured, but it caused a piece of cast iron at the circumference to be chipped off, rendering the liner unusable.

Instead of scrapping the liner, the Superintendent contacted QuantiServ and sent us pictures. After we confirmed that we could salvage the liner, he shipped it to our workshop in the Netherlands.

repair-mill

There our skilled machinists milled off a section of the liner and confirmed that there were no further cracks in the material. They then produced on a CNC milling machine a new piece that perfectly resembled the size and shape of the missing material. This they locked in place with glue and screws, thus saving a liner that otherwise would had to be scrapped.