Large Reconditioning Order in China Successfully Completed

Our colleagues working at our reconditioning centre in Suzhou, China, have completed what most likely will be their single largest order of the year 2022.

The work came from an european-owned, 6600 TEU boxship docked in a shipyard in Zhoushan, China. Many components of the 19-year-old, 12 cylinder, 96 cm bore main engine were in need of reconditioning and/or overhauling. Of course our colleagues in Suzhou were more than happy to comply.

The components arrived at our workshop on 30 July 2022 and were returned to the vessel in two batches, on 28 August 2022 and 01 September 2022 respectively. Thus, the work took just took 32 days, from start to finish.

During this time, we reconditioned the following components:

  • 15 pistons: Full reconditioning including coating of the piston ring grooves with the QS50K material
  • 13 piston rods: Reconditioning of the running surface, skimming of the landing surfaces
  • 9 piston skirts: Renewal of the rubbing bandages and skimming of the landing surfaces
  • 12 stuffing boxes:  Overhaul and modification of the housings (upgrade)

The work included dismantling, reassembling and pressure testing where required

This case neatly demonstrates that our reconditioning centres have sufficiently many skilled workers and machining capacity at their disposal to handle even the largest reconditioning orders with ease.

Piston assembly
Assembly of the stuffing boxes
Robotic welding of pistons
Robotic welding of pistons
Piston rod reassembling
Piston rod reassembling
Six of the piston assemblies ready for delivery

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).

15’000 TEU Container Ship Intermediate Shaft In-situ Machining

Our colleagues from QuantiServ Shanghai have just completed an intermediate shaft repair assignment on a 15’000 TEU container ship.

While underway to a southern Chinese port, the almost new vessel had suffered a breakdown to one of its line shaft bearings. Running steel to steel as a consequence of the bearing failure, the intermediate shaft got severely damaged.

QuantiServ Shanghai got contacted while the vessel was on tow to one of Chinas largest shipyards in the greater Shanghai area.

Our experts immediately got to work and presented to the shipowner and shipyard a repair plan and schedule, before the vessel even reached the shipyard. The plan included the re-design of the line shaft bearing, the design and fabrication of special in-situ machining tools and the execution of the work in three shifts, around the clock. All stake holders agreed to the plan.

Once the tools had been fabricated, our technicians performed the following work on board the vessel, while alongside in the shipyard. Some of the tasks had to be carried out multiple times, for example laser alignment checks before, during and after machining.

  • Laser alignment checks and alignment calculation
  • Dimensional and hardness measurements, non-destructive crack testing
  • Removal of cracks, shaft journal area machining to under-size, then polishing
  • Shaft alignment adjustment
  • Bearing load jack-up tests

Our six technicians performed the work in two shifts, around the clock. The entire repair took just seven days to complete to the full satisfaction and appreciation of the shipowner, shipyard, classification society and shaft line bearing OEM.

 

Key data of the installation:

  • Intermediate shaft total length: ~ 39 m
  • Shaft diameter: 790 mm
  • Shaft journal length: 1’200 mm
  • Max continuous engine power transmitted through shaft: ~ 53’000 kW
Intermediate shaft in-situ machining
In-situ machining (cutting)
Measuring of the diameter
Measuring of the diameter
In-situ polishing
In-situ machine polishing

Line Boring Work on Large Hydraulic Forming Press

Last month, our colleagues from QuantiServ Shanghai completed an in-situ repair assignment on two large hydraulic forming presses. The two presses, that have a capacity of 2,000 tons each, are installed in a factory in Northern China. They are used to manufacture automobile chassis parts for BMW and Mercedes Benz, among others.

The situation on both presses was almost identical. Specifically, it was the gearbox sections at the upper ends of the press that were in need of repair. A total of six bearing housings (2 x 3 each) were found to be worn. Their diameters, concentricity and coaxiality were all out of tolerance.

Large hydraulic forming press
One of the two 2,000 ton hydraulic forming presses that we worked on

To bring the bearing housings back into specification, our in-situ specialists line bored them. Thereafter, they installed specially manufactured bushes. Non-destructive crack testing and multiple laser alignment checks prior, during and after the repair completed the work.

To minimize expensive down-time, the work was carried out around the clock, 24/7, to the full satisfaction of the customer.

Installing the boring bar
Installing the boring bar
Laser alignment check in progress
Laser alignment check in progress
During line boring
During line boring
Coaxiality calculation
Coaxiality calculation

Metal Stitching Repair of Two-stroke Engine Bedplates

This post introduces metal stitching as an attractive solution to repair cracks in two-stroke engine bed plates.

Background

The term “metal stiching” is most commonly associated with the repair of cast iron parts, as an alternative to welding, to which cast iron does not lend itself easily. Due to its brittle nature, cast iron tends to fail again rapidly after welding, unless the welding takes place at very elevated and uniform temperatures. These conditions are hard, if not impossible, to achieve in most workshops, let alone at site.

It is less commonly known that metal stitching is also an increasingly often used process for the repair of steel parts, where welding actually would be possible. There are good reasons for chosing stitching over welding, even in steel.

First and foremost, metal stitching is a cold process and thus does not lead to deformation or latent heat-induced stresses in the part being repaired. Post-repair (in-situ) machining to correct these deformations is therefore rarely required.

Second, as we have shown through independent labaratory testing, a metal stitched junction that has been made by a qualified operator using Lock-N-Stitch tools and stitching components, exhibits a tensile and fatigue strength that is equal to, or better, than that of a welded junction.

During the last few years, QuantiServ have gained extensive experience in applying the metal stitching process to crack repairs in two-stroke engine bedplates and columns. Two instructive cases are discussed below, both involving container ships with 96-bore engines.

On the first vessel, the stitching was carried out in stages, during successive port stays. On the second, the repair was carried out during a regularly scheduled dry docking in China.

Case 1: Bed Plate Metal Stitching During Successive Port Stays

In the course of a crank case inspection, a 800 mm long crack was found in the main engine bedplate on board a 15,500 TEU container vessel in 2019. Contacted by the ship owner, we carried out an assessment. It revealed that the crack would propagate quickly if the engine, a 14-cylinder, 96-bore one, would continue to operate at, or near, its nominal speed.

We proposed to the customer to carry out the repair while the ship remained in service. As the thirteen year old vessel was engaged in a “high-rate/less-time” trade, the customer of course jumped at the opportunity to get the crack repaired without any vessel off-hire. Following a review of the vessel’s trading pattern, we decided to carry out the repair during successive port stays during the vessel’s Northern European loop.

Our specialists commenced their work as soon as the vessel was alongside in port and did not stop anymore until the engine had to be restarted. They then rested during the short voyage to the next port, where they continued in the same manner.

While working, our specialists discovered that the crack in fact was about 300 mm longer than had previously been reported by the crew. This meant that the time in Europe was insufficient to repair the crack in its entirety.

Our specialists revisited the vessel a few months later, again in Europe, to repair the previously unreported section of the crack. All in all, it took seven port stays of a few hours each to repair the bedplate.

Attendance Voyage Number of port stays
First Antwerp – London 4
Second Bremerhaven – Antwerp 3

In total, we repaired on this bed plate over 800 mm of crack in steel plates with thickness ranging from 18 – 50 mm, without a single day of off-hire or otherwise interfering into the vessel schedule.

To repair this bed plate, metal stitching was chosen over welding because it has the following advantages:

  • The vessel stayed in operation throughout the repair. The stitching was done in stages during port stays, a few centimeters at a time. With welding, this would not have been possible. The vessel would have had to be taken out of operation for around three weeks.
  • Lower costs, compared to welding. A competitor proposed to carry out repair by welding in 20 days. We repaired it by stitching in 12 days. Less time spent means less costs.
  • For metal stitching, a hot work permit is not normally required. Such a permit would be very difficult to get in container terminals, meaning that welding would not have been possible from a safety point of view.
Crack runs from the girder side plate down into the oil sump
The crack runs from girder side plate down into the oil sump
Metal stitching repair in progress
Crack without the sealing compound that was temporarily applied
View of the crack without the sealing compound that was temporarily applied
The completed repair, prior to cleaning and painting
The completed repair, prior to cleaning and painting

Case 2: Bedplate Stitching During Dry Docking

The second case discussed here concerns an 8-year old, 13,000 TEU container vessel with a 12-cylinder, 96-bore main engine. The crack discovered on this engine was quite similar to the one described above.

Since the crack was discovered shortly before the vessel was scheduled to undergo a routine dry docking, it was decided to repair it during the docking period in China in 2020.

The crack extended over a length of 750 mm in steel plates with thickness ranging from 18 – 50 mm. Repairing it took our specialists eight days, working in single shifts.

Crack runs from girder side plate down to oil sump
The crack runs from the girder side plate down into the oil sump
Stitching of the crack in progress
Metal stitching of the crack in progress
The completed repair prior to repainting
The completed repair prior to repainting

The first two-stroke diesel engine that we have metal stitched has meanwhile accumulated 77,000 hours. We repaired a 600 mm long crack in the gear column (A-frame), in 2006. The repair is still in perfect condition today.

04 January 2021

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The two repairs presented above were carried out using stitching components from the American company Lock-N-Stitch. We would like to stress that we have labaratory-tested other products available in the market and that we have found their strength to be insufficient for demanding applications like these.

Read more about metal stitching

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.

It’s All in a Month’s Work for QuantiServ’s In-situ Machining Crew!

On board various ships and oil rigs, in power plants and in factories: Far from being idle during the holiday season, during the month of July our in-situ specialists were maintaining and repairing our customers’ equipment in 26 different countries, across four continents. No other in-situ machining company has such global reach and completes more projects than QuantiServ. Wherever the location, whatever the damage – it’s all in a month’s work for us!

Explore the interactive map below and discover what services our in-situ engineers have been providing to our customers during the month of July 2017.