Propeller Shaft Line Work on New ULCS

After we have in an earlier post looked at some recent two-stroke main engine crankshaft repair assignments that we have carried out on ships in operation, we now move the focus further towards the after end of the ship.

In this post we look at how we routinely support new building shipyards with shaft line alignment and machining work.

Read more about our recent two-stroke crankshaft work assignments

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Shaft Line Work for VLCS in China: Recent Success Stories

At QuantiServ, we routinely perform essential alignment and machining work on behalf of shipyards in China on new vessels under construction. We do this for a wide range of vessels.

In this post we look at some of the very largest vessels that we work on, namely Very Large Container Ships (VLCS). These are vessels with a capacity to simultaneously carry up to 24’000 standard, 20-foot shipping containers. Typically, these ships are 400 meters long, about 62 meters wide and have a draught of about 16 meters when fully loaded.

These colossal vessels typically feature shaft lines that span between 80 to 100 meters in length, with shaft diameters ranging from 900 mm to over 1000 mm. These impressive dimensions are imperative due to the massive power of these ships’ main engines, which can reach up to 60,000 kW. This is equivalent to the power of 600 average-sized cars.1

Case 1: Stern Tube Bearing Failure Recovery

In one notable project, we assisted a shipyard and shipowner after a stern tube bearing failure on a recently delivered VLCS. While underway, the ship’s stern tube bearing suddenly overheated, reaching temperatures of well over 200 ℃, leading to the complete destruction of the bearing bush. The sudden heat increase also led to cracks in the propeller shaft.

Obviously, this critical issue required prompt action to prevent extensive downtime. Our team efficiently assisted the shipyard to replace the bearing bushes and machined the shaft in-situ to remove the cracks in its surface. Our ability to machine the shaft in-situ eliminated the need to withdraw it, which would have been a time consuming and risky operation. This approach thus not only saved valuable time and therefore minimized operational losses. It also reduced the risk of anything going wrong during the delicate propeller and shaft removal and reinstallation work and  ensured that the vessel could return to service swiftly.

After completion of our work, the shaft bearing temperature was recorded at just 32 ℃, no more than 13 ℃ Celsius above the surrounding sea water temperature, which is an excellent result!

Shaft alignment check by laser
Shaft alignment check by laser

Case 2: Construction Phase Alignment and Line-Boring

During the construction of another VLCS, our laser alignment checks revealed that the newly delivered and installed stern tube suffered from ovality and incorrect slope, posing a significant threat to the vessel’s long-term, safe performance. Once our team brought this information to the attention of the shipyard and proposed to line bore the stern tube, the shipyard, classification society and shipowner quickly agreed to our solution.

By employing precise in-situ line boring techniques, we corrected these issues, ensuring that the ship’s shaft line  will perform optimally for many years to come. This intervention during the ship’s build phase highlights our commitment to quality and foresight.

Case 3: Long-standing cooperation

QuantiServ has long been a trusted partner for shipyards worldwide. We are often involved from the early stages of new-building projects, providing technical expertise and precision machining services. For example in China we have ongoing agreements with several major shipyards, whereby we carry out laser alignment and inspection services for entire series of vessels.

During the summer of 2024, we for example completed shaft alignment services for the sixth and final delivery in a series of large, LNG-fueled ships built for a major container shipping line. All six ships are now in operation and are performing very well.

Demonstrating Expertise Across the Industry

All three cases were undertaken in China on some of the worlds’ very largest and newest ships, that will be owned and operated by three of the world’s largest container shipping lines. They involved different shipyards and different classification societies. This diverse customer base underscores the broad acceptance and trust in QuantiServ’s expertise and know-how within the maritime industry.

The three ships highlighted in this post are all either LNG-powered or are able to operate on more than one fuel. As such, they contribute to the decarbonisation of the marine industry, which is a goal that QuantiServ very much supports. Furthermore, QuantiServ is proud to contribute to the reliability and efficiency of these magnificent vessels, ensuring they meet the highest standards of operational performance and safety.

A severely damaged stern tube bearing bush
A severely damaged stern tube bearing bush
Machining the outer circumference of a stern tube bearing bush
Machining the outer circumference of a stern tube bearing bush
Stern tube line boring
Stern tube line boring
Delicate, ctitical work creates a lot of attention
Delicate, ctitical work always creates a lot of attention
Calibrating the outside diameter of the bearing bush
Calibrating the outside diameter of the bearing bush at our workshop in Shanghai
Inspection of a large stern tube bush at the shipyard
Inspection of a large stern tube bush at the shipyard

1 In 2018, the most recent year for which data are available, the average car in the European Union was fitted with an engine that was able to produce 98 kW of power.

“Manufactured Again”-Certification Renewed

Our reconditioning centres in Dubai, Kruiningen, Singapore and Suzhou have been Manufactured Again certified since 2018. This prestigious mark represents the quality, value, and sustainability of our reconditioning (remanufacturing) processes and has just been renewed for another year.

Let’s delve into how this renewal benefits both our customers and our commitment to sustainability:

  1. Quality Assurance: The Manufactured Again Certification ensures that our reconditioned products meet rigorous quality standards. By adhering to stringent processes and standards, we guarantee consistent excellence in our reconditioned goods.
  2. Value Proposition: Reconditioned products offer exceptional value. They combine like-new quality with reduced production costs, resulting in better prices for our customers. By choosing our certified products, customers make an economically savvy choice without compromising on quality.
  3. Environmental Impact: Sustainability lies at the heart of our journey. Reconditioning conserves embodied energy and reduces waste. For instance, reconditioning one large piston consumes about six times less resources than producing a new one! Our commitment to reconditioning and sustainability aligns with global efforts to reduce environmental impact.
  4. Customer-Centric Approach: By holding the Manufactured Again Certification, we demonstrate our dedication to customer satisfaction. Customers can trust that our reconditioned components are not only eco-friendly but also reliable and high-performing.

In summary, our renewed certification reinforces QuantiServ’s position as a responsible service provider, creating value for customers while simultaneously advancing our sustainability goals. Together, we’re driving positive change — one reconditioned component at a time.

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Webinar from the Swedish Club: Dealing with Crankshaft Damage

According to statistics compiled by the Swedish Club, crankshaft damage is the most expensive class of engine damage, with an average claim cost of 1.2 million USD.

In a webinar held on 26 October 2022, a panel of experts from the Swedish Club and from QuantiServ explored the common causes and types of damage to internal combustion engine crankshafts. They also explored different repair options and what can be done to prevent damages from occurring in the first place.

Panelists:

  • Henrik Karle, Technical Manager, The Swedish Club
  • Peter Stålberg, Senior Technical Advisor, The Swedish Club
  • Johannes Roberts, Manager, QuantiServ Sweden
This webinar was brought to you by The Swedish Club in collaboration with QuantiServ Sweden. It was broadcasted live via zoom on 26 October 2022.
Special thanks to the Swedish Club for making it possible. Previous webinars from the Club’s Loss Prevention series can be found here.

“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