Very Extensive Crankshaft and Block Repair on a Passenger Ferry

Overview

QuantiServ recently completed a large-scale repair assignment on a passenger ferry. The ferry was built in the year 2000 and is equipped with four 12-cylinder, 46-bore main engines, with a nominal power output of 12.6 MW each.

In early 2024, two of these engines required extensive repairs, having each accumulated over 120,000 running hours and having suffered a recent failure.

QuantiServ was contracted to carry out the repair of both engines. As additional defects were found during the repair, the work turned into a sizeable project that took almost four months to complete.

Remarkably, our in-situ machining specialists from Sweden carried out all work during sailing, ensuring there was no off-hire time, demonstrating our commitment to efficiency and operational continuity.

One of the two crankshafts was removed from the engine and underwent repair on the vessel's car deck.
One of the two crankshafts was removed from the engine and underwent repair on the vessel's car deck.

Damage

The following damages were found. They were all addressed by our specialists during the repair.

Engine Number 1

  • Crankpin bearing failure
  • As a consequence: Multiple cracks, excessive surface hardness of 600 – 680 HB

Engine Number 2

  • Failure of four crankpin bearings
  • Crankshaft bent
  • Failure of one adjacent main bearing
  •  A collapsed main bearing saddle, as a consequence of the heat generated
  • Poor fitting of another bearing saddle
  • Severe cam effect on all other crankpins
Multitude of cracks in the crankpin journal
After cutting off some material from the crankpin, a multitude of cracks became visible. They were caused by the rapid temperature raise and fall during the bearing failure.
In-process hardness measurement during machining. The areas with increased hardness are easily visible.
In-process hardness measurement during machining. The dramatic temperature changes resulted in changes in the local microstructure that are easily visible.
Surface hardness of up to 680 HB following the failure. The acceptable limit is 300 HB.
Due to excessive heat generated by the failed bearing, the surface hardness had increased to 600 - 680 HB. The acceptable upper limit is 300 HB.

Detailed Work Performed

All repair works was done during sailing, which means that the vessel remained in operation througout.

Engine Number 1

Crankshaft Repairs:

  • Heat Treatment and Machining: One crankpin was machined to an undersize of -3.00 mm.
  • Polishing: Two main bearings were polished to ensure smooth operation.

Engine Number 2

Due to damage found on the engine block, the crankshaft was removed so that line boring on the block could be carried out. Heat treatment and in-situ machining on the crankshaft was carried out on the vessel’s car deck.

Crankshaft Repairs:

  • Heat Treatment: Four crankpins and one main journal underwent heat treatment.
  • Machining: The treated components were machined to undersize diameters ranging from -2.00 to -5.00 mm, depending on their condition.
  • Straightening: The crankshaft, found bent with a run-out of 1.50 mm, required peening (in-situ straightening).
  • Polishing: All main journals and crankpins, exhibiting strong indications of the “cam effect,” were polished.

Engine Block Repairs:

  • Bearing Saddle Realignment: The overheating of one main bearing caused misalignment, necessitating the replacement of the bearing cap and subsequent line boring.
  • Bearing Cap Adjustment: Another main bearing cap showing a gap with the cylinder block was corrected.

Additional Improvements

In addition to the primary repair tasks, QuantiServ addressed machining work previously carried out by another company on some of the crankpins. The fillets were not nicely cut, and the radius around the oil hole needed improvement. Our specialists refined these areas, ensuring optimal performance and longevity of the crankshafts.

Summary Table of Work Done

 

Engine Work done
# 1 Heat treatment and machining to -3.00 mm undersize of one crankpin
Polishing of two main bearings
# 2 Removal of the crankshaft for external heat treatment and in-situ machining
Machining to undersize diameters of -2.00 to -5.00 mm
Peening (in-situ straighening) to correct a bent crankshaft with 1.50 mm run-out
Polishing of all main journals and crankpins
Replacement of a bearing cap and line boring due to misalignment
Adjustment of a main bearing cap gap with the cylinder block
One of totally five crankpins that our specialists machined to under-size
One of totally five crankpins that our specialists machined to under-size
The mirror-like finishing on one of the crankpins.
Impressive, mirror-like finishing after polishing of the crankpins.

Conclusion

This extensive in-situ repair project on a passenger ferry highlights QuantiServ’s expertise and ability to perform critical repairs without interrupting service.

The phenomena known as “cam effect” or “ridge wear” could be identified as reason for the bearing failures and the ensuing, rather extensive and therefore costly, repairs. It is therefore very important that ship owners and operators are sensitive to this issue and regularly check the condition of the crankpins once their engines have surpassed aproximately 60,000 running hours.

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!

Read more

Repair of a Single Flywheel Tooth on a Bulk Carrier in Canada

Our in-situ specialists recently completed yet another in-situ “tooth dentistry” repair. This particular repair assignment was carried out on a ten year old dry-bulk carrier in Canada. It was a small job that was quickly completed as it just involved the replacement of a single broken tooth on the flywheel of the vessel’s 50-bore main engine.

Two of our skilled in-situ specialists from the United States undertook the task. The process began with machining off the damaged tooth, which they did with the help of a portable milling machine. Following this, a prefabricated tooth, prepared in advance and grought along by our team, was accurately installed, ensuring a tight fit and seamless integration with the existing flywheel .

This successful repair underscores QuantiServ’s ability to provide efficient and reliable in-situ solutions, big and small.

View of the single broken tooth
The completed repair
The completed repair
Removal of the damaged tooth by in-situ milling
Removal of the damaged tooth by in-situ milling
Engine ready to be started up again
The engine is ready to be started up again

Links

Read more about our flywheel repairs – from changing just a few teeth to replacing them all!

Restoring All 90 Teeth on a large Flywheel

Our colleagues from QuantiServ China successfully restored all teeth on a flywheel

View more

Flywheel In-situ Repair on the US East Coast

Another successful flywheel repair assignment completed, in Florida, USA

View more

Flywheel Teeth Dentistry in Hong Kong

In-situ repair of a large 96-bore engine flywheel at Hong Kong anchorage

View more

In-situ Flywheel Repair in Mombasa, Kenya

In-situ Flywheel Repair on a 3’400 TEU Container Vessel in Mombasa, Kenya

View more

Customer Feedback: “Good Quality, Reasonable Cost, Finish on Time”

Excerpt from an email from the attending Superintendent of the customer to his office, after completion of the work:

"Reasonable costs, where no any additional surcharges were implemented after repair completion / Invoiced amount is corresponding to offer / Not too big amount compared with other vendors, who suggest this type of repair service / Works complete in time (as per the offer) / Good job quality"

Project Overview

QuantiServ recently undertook a challenging and comprehensive repair project on a 46-bore main engine installed on a 12,000 DWT container vessel. The ten-year-old vessel had sustained significant damage to both the crankshaft and engine block. Our team of three highly skilled specialists carried out the repair work in the Caribbean, ensuring the engine was restored to optimal condition and performance.

The entire repair took eight weeks, from start to finish.

Inspection and Proposal

Upon arrival, our team conducted a thorough inspection of the damaged engine components. The inspection revealed extensive damage, necessitating a detailed and precise repair plan. We promptly submitted a comprehensive repair proposal to the vessel’s owner and the classification society. Once the proposal received approval, we commenced the repair work, which included several critical tasks to address the damage.

Whenever we face larger damages, we usually use a 3D scanner to scan the components to be repaired. The highly detailed and accurate geometrical data thus acquired offers numerous advantages. Not only does it accelerate the repair process because it eliminates time consuming manual measurements, it also helps to create very detailed and precise repair castings.

Simulation to show how the repair inserts will fit together
Simulation to show how the repair inserts will fit together

Engine Block Repair

Damage Sustained:
  • Crankcase door damage on both starboard (SB) and port side (PS)
  • Cam floors damaged on both sides
  • Various additional cracks in the crankcase

Our metal stitching repairs are permanent repairs. So much so that we grant up to 5 years of warranty on them.

Read more

Repair Details:
  • Total length of cracks/junctions stitched: approximately 6 meters
  • Number of stitching pins installed: Approximately 1’000 pieces
  • Number of tailor-made repair inserts installed: 8 (with the larger inserts casted in a classification-approved foundry and shipped to the vessel prior to commencement of the on-site repair)
  • Pre-fabricated sleeve installed in the lower cylinder liner guide
  • In-situ line boring and installation of sleeves in two camshaft pockets that were found out of line due to the accident

Our specialists meticulously stitched the cracks and installed the necessary inserts, ensuring the structural integrity of the engine block was fully restored. The use of about 1’000 Castmaster C3 stitching pins and eight custom-cast inserts highlights the extent and complexity required for this repair.

Damage around the crankcase door
Damage around the crankcase door
Dressing up one of the repair inserts
Dressing up one of the repair inserts
One of the repair inserts
Visual simulation how one of the repair inserts is to be fitted into the block
Removal of cracked and deformed material
Removal of cracked and deformed material
Stitching-in one of the repair inserts (left)
Stitching-in one of the repair inserts (left)
Metal stitching is physically very demanding and is often performed in tight spaces
Metal stitching is physically very demanding and is often performed in tight spaces
Preparing the engine block to receive repair inserts
Preparing the engine block to receive repair inserts
During stitching in place one of the smaller repair inserts
During stitching in place one of the smaller repair inserts
The completed repair
The almost completed repair, prior to drilling of some minor holes and painting

Crankshaft Repair

Damage Sustained:
  • Extensive mechanical damage to one crank pin
  • Connecting rod, big end bearing housing thrown out of the engine block
  • Both counter weights thrown out of the engine block, studs sheared off
  • Deep indents in the crankpin surface
  • Long cracks, easily visible by naked eye
Badly damaged crankpin
Badly damaged crankpin and crankwebs
Extensive impact marks
Extensive impact marks on the crankpin
Repair Details:
  • Damaged crankpin machined to undersize
  • Landing surfaces of counterweights milled
  • Counterweight fastening bolt stubs removed

The crankshaft repair involved machining one crankpin to an undersize diameter and installing a pre-fabricated sleeve in the lower liner guide. These steps were crucial in restoring the crankshaft’s functionality and ensuring the engine’s smooth operation.

Blueing check of the completed crank pin
Blueing check of the completed crank pin
Counterweight landing surface restored
Counterweight landing surface restored
Installation of new studs, after removal of the broken stubs.
Installation of new studs, after removal of the broken stubs

Customer Feedback

The customer expressed immense satisfaction with the repair results. The attending superintendent conveyed his positive feedback to his management, highlighting the professionalism and expertise demonstrated by the QuantiServ team. He recommended QuantiServ for future repairs on the company’s vessels, underscoring the trust and confidence our services have earned.

At QuantiServ, we pride ourselves on delivering high-quality, reliable repair services that meet and exceed our customers’ expectations. This project is a testament to our commitment to excellence, precision, and customer satisfaction. We look forward to continuing to provide top-tier repair solutions for the maritime industry.

Follow these links for more information about our in-situ and metal stitching services.

Five In-Situ Machining Jobs on Large Two-Stroke Engines in Three Months

At QuantiServ, we are dedicated to providing exceptional in-situ machining services to the maritime industry.

Over the past three months, our team has successfully completed five significant crankpin machining assignments on large two-stroke marine main engines. These projects, carried out on four different engine types built by the two market-leading OEMs, highlight our versatility and expertise.

Project Highlights

  • North America: We performed extensive crankpin machining on a container vessel, ensuring the engine’s optimal performance and reliability. Almost simultenously, we also worked on a bulk carrier, deliverig high-quality crankshaft machining services that meet the stringent standards of the maritime industry.
  • The Caribbean: Our team tackled a challenging crankpin machining job on an oil tanker, restoring the crankshaft to its full operational capacity in less than two weeks.
  • North Asia: On a Ro-Ro ship, we executed a complex crankpin machining task, demonstrating our ability to handle diverse vessel types with ease.
  • South East Asia: Another successful project involved a gas tanker, where our team ensured the engine’s reliability and efficiency through crankpin machining and other repair works.
One of the crankpins undergoing repair
One of the crankpins undergoing repair

In all these cases, we worked on crankpins from Ø 600 to 900 mm and machined off anywhere from 4 mm to 10 mm, due to excessive hardness and cracks following a bearing failure. Typically the repair work involves machining and then machine polishing of the cylindrical crankpin surface and of the fillets1. On some of these vessels our specialists worked in a single-shift modus, while on others they worked around the clock in two shifts. It always depends on the customer’s wishes and on her operational requirements.

*The fillets are the radial undercuts at the transition of the crankpin to the crank web.

One of the crankpins prior to repair
One of the crankpins prior to repair
After machining and polishing
The same crankpin after machining and polishing

Comprehensive Services

In addition to the crankpin machining work, we also provided a range of related services, including:

  • Planning: Remotely assisting the customer to find the best repair solution  and to make arrangements before the vessel even reaches the location where the repair is to be carried out.
  • Sourcing of Under-Size Bearings: : Ensuring the availability of tailor-made bearings, with short lead time. Under-size bearings have a thicker white metal layer and are usually not available off-the-shelf. They have to be produced on a case-by-case basis. Some of these bearings we produce in-house, others we source from specialized manufacturers.
  • Reconditioning of Engine Components: Extending the life and performance of critical engine parts in one of our four reconditioning centres.
  • Other Repair Works: Addressing various repair needs not related to the crankshaft, ensuring comprehensive engine maintenance.

Commitment to Excellence

Each of these projects underscores our dedication to providing reliable and efficient in-situ machining services. Our ability to mobilize almost instanteneously and to perform these tasks on-site in a 24/7 manner, saves our clients valuable time and limits loss of income. Whether it’s a container vessel, tanker, Ro-Ro ship, bulk carrier, or gas tanker, QuantiServ is equipped to handle the unique challenges of each job with precision and professionalism.

We look forward to continuing our tradition of excellence and supporting the maritime industry with our specialized in-situ machining services.

Crankpin machining whereby the cutting tool moves in a continous orbital path around the crankpin, resulting in uniform material removal
Crankpin machining whereby the cutting tool moves in a continous orbital path around the crankpin, resulting in uniform material removal
Blueing test to verify that the bearing shell makes full and even contact with the crank pin.
Final blueing test to verify that no high spots are present and that the bearing shell makes full and even contact with the crankpin

Note: All photos in this post originate from the five projects, they are not depicting the same project.

Line Boring of a Locomotive’s Diesel Engine Block

Our in-situ machining specialists recently carried out line boring of the main bearing pockets on a 20-cylinder, two-stroke engine. The engine is installed in an American-built diesel-electric locomotive and operates in Scandinavia.

Line boring became necessary due to the seizure of three main bearings. We performed the repair work in our workshop in Gothenburg, Sweden.

We routinely carry out line boring on all kinds of diesel and gas engines, mostly on main bearing and camshaft bearing pockets, or to install sleeves to stop water leaking along the cylinder liners into the oil sump.

This particular job stands out due to the innovative design of the engine. And not only is the design innovative, it was very successful too. Between 1965 and 1983, almost 29’000 such engines were built!

Engine particulars:

  • 20-cylinder V-engine
  • 2’900 kW (3’950 hp) output
  • 230 mm bore, 250 mm stroke
  • 900 – 950 rpm nominal speed
Line boring of the main bearing pockets
Line boring of the main bearing pockets

Innovative engine design

In a nutshell: This engine is very compact, very powerful and it runs at a rather high speed for this size of engine: 900 – 950 rpm. This results in a rather remarkable maximum piston speed of just over 12 m/S at mid-stroke1. Because of its high power and compact packaging, this engine has a high power to weight ratio. This is achieved through innovative design features that are worth looking at. Here we look at three of them.

1) 45 degree angle between A- and B-bank

V-engines are a common configuration for internal combustion engines. In a V-engine, the cylinders are arranged in two banks, which form a “V” shape when viewed from the front of the engine. The angle between these two banks is known as the “V-angle” and can vary significantly between different engines.

Most V-engines have a V-angle of 90 degrees. However, this engine type uses a V-angle of only 45 degrees. This design choice can have several implications for the engine’s performance and characteristics.

A 45-degree V-angle results in a more compact engine design compared to a 90-degree V-angle. This can be particularly beneficial in applications where space comes at a premium, such as in high-performance sports cars, in motorcycles or, you guessed it, in railway locomotives.

However, a smaller V-angle can also result in increased mechanical stress and vibration, as the forces generated by the pistons are not evenly distributed across the engine block. This can lead to increased wear and tear on the engine components, and may require additional mechanisms to counteract the imbalance.

In terms of performance, a 45-degree V-angle can potentially offer improved balance and smoother operation compared to a 90-degree V-angle. This is because the smaller angle allows for better primary balance and reduces vibrations.

In conclusion, while a 45-degree V-angle can offer some advantages in terms of compactness and potentially smoother operation, it also presents challenges in terms of increased mechanical stress and complexity of manufacture. As with any engineering decision, the choice between a 45-degree and 90-degree V-angle will depend on the specific requirements of the application.

2) Non-offset V-engine block

Some V-engine blocks have cylinders that are not offset (when viewed from above), meaning that the cylinders of both banks are exactly aligned. This design is known as a non-offset V-engine block. One advantage of this design is that it results in a more compact engine, as the cylinders are arranged in a more space-efficient manner.

However, there are also some disadvantages to this design. One potential issue is that it can result in increased mechanical stress and vibration, as the forces generated by the pistons are not evenly distributed across the engine block. This can lead to increased wear and tear on the engine components, and may require additional mechanisms to counteract the imbalance.

Overall, the choice between an offset and non-offset V-engine block will depend on the specific requirements of the application. While a non-offset design can offer some advantages in terms of compactness, it may also have some drawbacks in terms of increased mechanical stress and vibration. It is important for engineers to carefully consider these trade-offs when designing an engine.

3) “Blade and fork” connecting rods

The blade and fork type connecting rod arrangement is a unique way of joining two pistons to a single crankpin. In each pair of engine cylinders, a “fork” rod is divided into two parts at the big end and a “blade” rod is tapered from the opposing cylinder to fit this gap in the fork. This type of connecting rod has long found application on for example V-twin motorcycle engines (by BSA and Harley Davidson, among others) and V12 aircraft engines. The most famous example of a “blade and fork” engine is probably the Rolls Royce Merlin aircraft engine. Close to 200’000 such engines were built over many years. They were installed in many very famous aircrafts, such as the North American P51 Mustang, the Supermarine Spitfire, the Avro Lancaster and the Hawker Hurricane.

The advantage of this arrangement is that it allows both cylinders and rods to be in the same plane, as is required by an non-offset engine block. It also makes the motions of the two pistons identical. In the aircraft world, there were additional reasons for using fork-and-blade rods, rooted in history. Both Allison and Rolls-Royce produced V-12 engines which used knife-and-fork rods.

However, there are also some disadvantages to this arrangement. The underlying physics and manufacturing practice supporting plain journal bearings have improved to the point that big-end bearings no longer require the support of a full-width bearing. This means that side-by-side con-rods can now be used instead of fork-and-blade rods, which are more complex to manufacture.

Overall, the blade and fork type connecting rod arrangement has its advantages in terms of simplifying design and making piston motions identical, but it is more complex to manufacture than side-by-side con-rods. With advances in bearing technology, side-by-side con-rods have become a viable alternative. However, the choice between the two arrangements ultimately depends on the specific requirements of the engine design.

Work performed

The work that we carried out to get this 20-cylinder engine block back into good working condition consisted, broadly, of the following tasks:

  • Laser alignment and dimensional check
  • Hardness check and Magnetic Particle Inspection (MPI) to search for cracks
  • Line boring of the 12 main bearing pockets to remove existing fretting corrosion. We machined all main bearing bores to nominal dimension.
  • Blue fitting of the bearing caps

Read more about line boring

1This is an approximation calculated according to the formula PSmax = 250 x π x 950, where 250 is the piston stroke in millimeters and 950 is the engine speed in revolutions per minute

20-cylinder engine block at workshop
The 20-cylinder, welded engine block in our workshop. Note that the gear train is centrally located.
The block turned on its side with main bearing caps removed.
The block turned on its side, main bearing caps removed
Blueing test of the main bearing cap serration
Blueing test of the main bearing cap serration

Metal Baler Cladding and Machining Work

Cladding and milling work

With this short post, we introduce in-situ machining work that we have done recently on a piece of equipment installed in a metal recycling yard in southern Sweden. The assignment consisted of patch welding (cladding), followed by machining work. It was carried out in our workshop in Gothenburg, Sweden.

After many years of compacting car bodies and other metal components , the equipment in question, a metal baler, was in need of repair and modification work. Some of the surfaces on the baler’s crushing panel had been worn and needed to be restored. Thus, the customer sent the 8 meter long, 0.80 m wide and 15 ton heavy crushing panel (sometimes also called “press bar”) to our workshop for repair.

First, our Swedish colleagues replaced any worn material by arc welding (cladding) work. Thereafter, they milled it. In total, they milled off about 5’800 cm3 (350 cu in) of material along the crushing panel’s length and breadth. A portable, NC-controlled 3D axis milling machine was used for the task. The result was excellent and gives a new lease of life to this heavy duty metal baler.

With this post we conclude our short run of examples of us serving the various life cycle stages in the automotive industry.

The baler at its working location in southern Sweden
The baler at its working location in southern Sweden

Our commitment to the circular economy

QuantiServ is very committed to the circular economy. Our offering includes many modern machining and repair solutions that are applicable to almost all life cycle stages of many capital goods. During the last seven posts in this blog have we looked at how we support the automotive industry, all the way from a car’s manufacturing until the end of its life. The same is true for other industries as well and we are going to introduce some of them in the near future.

QuantiServ strongly focus on reusing, reconditioning and repairing in our own operations whenever possible. And we passionately encourage our customers to do the same. The great majority of the solutions in our offering help our customers to keep their equipment in use and to therefore consume less energy and raw materials. In turn, this generates less waste, pollution and emissions.

MERA membership since 2019

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.

Our numeric controlled milling machine mounted on the 8'000 mm long work piece
Milling machine mounted on the 8 meter long work piece
Milling of the longitudinal side
Milling of the longitudinal side
Milling of the longitudinal side
Milling of the longitudinal side
Press bar about to be shipped back to the customer
Press bar about to be shipped back to the customer

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.

Dynamometer Roller Machining in a Swedish Car Factory

Our in-situ specialists from Gothenburg, Sweden, carried out an in-situ machining assignment in a Swedish car factory.

The four rollers of an end of line (EOL) dynamometer had to be machined. Their surface had been found worn and the customer therefore asked us to undersize them by 1.0 mm, so that they could be plated again by thermal arc spraying.

Dynamometer rollers look deceptively small as only a small part of them is visible. They in fact each have a diameter of 1’500 mm and they are 900 mm wide.

Our specialists used one of our NC-controlled, mobile milling machines fitted with a lathe cutting tool for the task. This arrangement worked very well and led to a great result.

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!

Read more

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

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

Crankpin Grinding in 18 Hours, Between Christmas and New Year

True to our credo of “whenever, wherever”, our in-situ machining specialists in Singapore completed a repair assignment during the final days of 2021 in just 18 hours.

At 22:00 on 29 December 2021, at a time when most people traditionally enjoy seasonal festivities and spend time with their loved ones, they boarded the ship with just a few hours notice. The vessel, a German-owned 4200 TEU box ship had arrived in Singapore 9.5 hours earlier and was now waiting for them on anchorage. Once our specialists were on board, the vessel proceeded to the terminal while our colleagues immediately went to work on one of the three Japanese-made auxiliary engines. This engine had suffered a crankpin failure on one of its units.

The engine is equipped with a hardened crankshaft. This means that the crankpin could not be machined but had to be ground. Through the night, our two specialists ground the pin from 260.00 mm to 259.50 mm so that the first undersize bearing can be fitted.

In-situ crankpin grinding
In-situ crankpin grinding

At regular intervals during and after the grinding and subsequent polishing work, our two in-situ specialists verified the dimensional accuracy and the hardness of the pin. The final hardness was measured to be 625 HB, which is a very good value. And for final verification, our specialists also checked the contact area on the completed pin. For this, they used a specially manufactured template and engineering blue.

Our specialists completed their work and disembarked from the vessel at 16:00 on 30 December 2021. It took them just 18 hours to repair the crankshaft!

Fifty minutes later, after the completion of cargo operations, the vessel left Singapore for China. The ship crew will install the new – 0.50 mm undersize bearing shells once they arrive on board and will then restart the engine.

Verifying the contact area on the completed crankpin
Verifying the contact area on the completed crankpin
Surface roughness measurement on the completed crankpin
Final surface roughness measurement

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

Stern Tube Machining: Two Case Studies and a Time-Lapse Video

Within the marine industry, in-situ machining of stern tube bearing pockets or of bearings themselves belong to a group of line-boring assignments that we carry out very frequently. In this post we would like to introduce two recent cases, one performed in Las Palmas, Canary Islands, and the other in Singapore.

Case 1: Machining of stern tube forward and after bearing pockets in Singapore

Damage to the stern tube bearings is found during the routine dry docking of a vessel in a shipyard in Singapore. Upon this discovery, the ship owner turns to us for advice. As this is evidently an unplanned and serious case, our specialists mobilize very quickly and carry out an initial laser check of the pockets’ alignments and geometries. The check reveals that the bearing pockets are misaligned and that the ovality that is measured is excessive.

The customer concurs that line boring presents itself as the best remedy. Again, our machining specialists mobilize quickly and rectify the poor alingment and ovality. Both the forward and after bearing pockets are machined. Working around this clock, this is acomplished in just five days.

We arrange two new bearings to be made in Spain on an urgent basis. Once they are delivered, we supervise their installation at the shipyard in Singapore. A final laser alignment check confirms that the alignment is correct now. We also carry out a load test of the entire shaft line and attend the sea trial, which goes smoothly.

Case 2: Machining of stern tube after bearing pocket in Las Palmas, Canary Island

A Norwegian ship owner decides to upgrade the stern tube bearings and seal assembly on a 20-year old ship to a newer, improved design. The upgrade means that the after bearing pockets has to be machined to accomodate the new bearing bush and seals.

Our work scope is as follows:

  • Measure stern tube diameter using a micrometer
  • Find the existing center line through laser measurement
  • Set up the CLB80 line boring machine inside the stern tube and align it with the help of lasers
  • Machine the stern tube according to drawings
  • Final measurement of the stern tube using a micrometer and laser measurement equipment

As is usually the case with stern tube bearing bushes, three different inner diameters (Ø525, Ø524 and Ø523 mm) have to be machined. The  total lenght of the of the stepped area is 935 mm. Two QuantiServ specialists from Gothenburg, Sweden, complete the work in two weeks.

They use our new CLB80 line boring machine that we designed and built ourselves. This machine is capable to very accurately bore holes with Ø140 – 600 mm that are up to 10,000 mm long. Its flange facing capability ranges from Ø90 – 700 mm.

Here is a time-lapse video of the line boring work performed in Las Palmas. The laser alignment and measurement works taking place before and after the line boring are omitted from the video to keep it short.

 

Comprehensive Repairs: We Succeed Where Others Fail

Example of a Comprehensive Crankshaft Repair Assignment, Started and Then Abandoned by a Competitor

During the last days of 2020, our in-situ repair specialists out of Gothenburg, Sweden, repaired a damaged crankpin on a Korean-made four-stroke engine. The engine has a 32 cm bore and a 40 cm stroke and is installed on a 5 year old, 9’200 TEU container vessel.

When contacted by the ship owner, we proposed to carry out an inspection on board. The shipowner agreed, whereafter our specialist from QuantiServ Panama carried out a thorough inspection in Panama. To our disappointment, the ship owner then awarded the repair work to another company. Their technicians machined the pin to – 0.80 mm undersize and then gave up and disembarked from the vessel.

Finding himself in a tight spot, the customer came back to us and asked us if we could continue the repair that was abandoned by the other company. We took the opportunity to demonstrate that we succeed where others fail. Two in-situ specialists from QuantiServ Sweden joined the vessel and successfully carried out the repair work while  underway from Lima, Peru to Manzanillo, Mexico. They solved the problems as follows:

Issue Action taken Result
Damaged surface and cracks Machining Crankpin under-sized to – 3.00 mm
Excessive hardness Heat treatment (Annealing) Hardness Reduced from 620 HB to 255 HB
Bent crankshaft Peening Run-out reduced from 0.27 mm to 0.03 mm

The customer was very happy with the skills and performance of our specialists. He therefore kept them on board for subsequent reassembly and overhaul works and he also asked us to supervise an  overhaul of a similar engine installed on a sister vessel.

Four-stroke Engine Block Metal Stitching and Crankshaft Machining

Over the years, medium-speed diesel engines have become very popular for a variety of applications, most notably in ship propulsion and in power generation. Accordingly, the number of such engines in service is very large.

Due to their large number and to the relatively high nominal speeds, combined with significant mass inertias, one would from a theoretical stand point expect more fequent and more severe damages on medium-speed, four-stroke diesel engines than on low-speed, two-stroke ones. That this is indeed the case in practice is evidenced be the fact that we are frequently contacted and subsequently repair a few dozen cases of severe engine damage every year.

Here is a typical example, one of many:

A Korean-made auxilliary engine with eight cylinders, 210 mm bore and 320 mm stroke suffered a serious bearing failure on crankpin #1. The engine block and crankshaft both got severely damaged, due to the connecting rod impacting both. The accident happened while the vessel, a Ro-Ro ship, was trading in East Africa.

Her next port of call was in Florida, United States, where our technicians went on board for a thorough inspection. They determined that both the crankshaft and engine block were repairable. As in addition to crankpin #1, which was badly damaged, all other pins were found with corrosion and scratch marks, we suggeted to the customer to offload the engine and to sail a few weeks without it. The customer agreed.

The engine was offloaded in Freeport, Texas, for repair and was delivered back to the vessel 46 days later in the same port. In the meantime, the vessel continued to sail with one engine less. The duration of the voyage, 46 days, was more than sufficient for our specialists to repair the crankshaft and engine block according to our very exacting standards.

Repair of the crankshaft

Due to the damage sustained by the accident, crankpin #1 had to be machined to – 3.00 mm. This was necessary to clear all dent marks. And as the other seven crankpins were suffering from scratches and/or corrosion, it was decided to machine them all to – 0.50 mm.

Repair of the engine block

Repair of engine block before and after

The cavity in the block caused by the accident was fairly substantial. A total volume of about 6’000 cm³ (366 in³) of material was missing and cast iron plates with a thickness of 19 – 51 mm (0.75 – 2 in) had to be repaired.

Our cast iron repair specialists scanned the damage with a 3D scanner. The data thus acquired was then used to fabricate a perfectly-fitting cast iron repair patch. The repair patch was stitched in place with stitching components, chiefly Castmaster stitching pins and locks, that are sold by Lock-N-Stitch.

After the repair was completed, it was hardly visible and the customer was very pleased with the outcome.

Here is a step-by-step description of how the block repair work was carried out:

 

Jaw Crusher In-situ Machining, 700 Meters Underground

In November 2018, our in-situ specialists carried out machining work in one of the world’s most modern underground mines, located in central Sweden. The mine processes about 2.5 million tones of ore annually and produces gold, silver, zinc and lead.

The assignment lasted about a week and consisted of milling, drilling and tapping work on a large jaw crusher located at a depth of 700 meters. There, the ore is crushed before it is hoisted to the surface for further processing.

Our specialists machined the upper section of both the stationary and the moving jaw. On each jaw, they milled off about 26,000 cm3 of steel and then drilled and tapped them so that a newly fabricated section could be bolted on.

QuantiServ’s In-situ Machining Specialists are Very Highly Trained

The last few weeks have been a busy period for our internal trainers at our in-situ training center in Gothenburg, Sweden. Courses were scheduled back to back. In-situ machining colleagues from around the world were undergoing refresher training on a variety of topics: in-situ crankpin machining, in-situ heat treatment (annealing), engine block machining, etc.

At QuantiServ, we very highly value formal training. All our in-situ machining specialists undergo rigorous training and assessment when they first start to work for us. And it does not stop there. As we constantly keep on further developing and improving our tools and processes, we regularly call the in-situ machining specialists that normally are stationed all around the world back to our in-situ training centre in Sweden to equip them with the most updated skills and knowledge.

This was the case with colleagues from Italy and Brazil that joined a training course last month. Even though some of them already work for us for ten years or more, there are always new tricks that they can pick up. A lot of knowledge sharing and networking takes place during these courses too. The trainees meet with our designers and tool developers and provide them with valuable feed-back and experience from the field. This information then flows into the next generation of tools so they become ever better and more efficient. It is highly trained machinists and cutting edge tools that keep QuantiServ at the forefront of the in-situ machining industry.

Crankpin machining training

Crankpin machining training

Crankpin machining training

Crankpin machining training

 

 

 

 

 

 

 

 

In-situ heat treatment training

In-situ heat treatment training

In-situ machining specialists from Italy

In-situ machining specialists from Italy

 

 

 

 

 

 

 

 

Our Brazilian colleagues proudly showing off their renewed certification. Notice the quality of the pin surface.

Our Brazilian colleagues proudly showing off their renewed certification. Notice the quality of the pin surface.

 

 

 

 

 

 

Brand New Light Surface Grinding Tools Now Available for Sale!

We are asked frequently, whether we are selling the in-situ machining tools that we have developed and manufactured and that our specialists use in the field. While such requests are of course flattering and while we appreciate that other companies find our tools appealing and would like to purchase them, we have up to today always politely declined such request. The reason is that we first and foremost see ourselves as a top-notch in-situ machining company and not as a tool manufacturer. Our tools are thus a means to end – the more accurate and efficient they are, the better the result of our machining assignment that our customer comes to enjoy.

Our very newest Light Surface Grinding machine (LSG) has now proven to be so popular, that we have decided to break with tradition and to make it available for sale.

The machine was designed to be as compact and portable as possible. It has an adjustable base, no heavy adapter plates are therefore necessary. Its total weight is 30 kg (66 lbs). This is significantly less than any comparable machine currently on the market and means that it does not have to be sent as cargo to a ship or power plant, but can be brought along as checked-in luggage.

The tool’s main purpose is to quickly and accurately skim the cylinder liner landing surfaces at the top of medium-speed engine blocks. It can be used to machine diameters of 360 – 670 mm, which makes it suitable for engines with a bore size of 260 – 500 mm. Additional accessories to also skim the landing surface on the cylinder liner are also available.

The advantages of the Light Surface Grinder (LSG) are many:

  • High accuracy
  • Fast to set up and easy to use
  • Compact design
  • No adapter plates are necessary as the machine’s base is continuously adjustable
  • A single machine covers the range from ⌀ 360 – 670 mm
  • Total weight = 30 kg (66 lbs)

Contact us for more information, or to order one.

Contact us

 

 

In-situ Straightening (Peening) of a Bent Crankshaft

The pictures below show the straightening and subsequent machining of a bent crankshaft, carried out by our specialists in Singapore. All work was carried out in-situ. The crankshaft was found bent following a crankpin bearing failure.

The crankshaft belongs to a 12-cylinder, 40-bore engine installed on a dredger. A straightness check revealed that its run-out was 0.18 mm, which is far beyond the acceptable threshold.

Our specialists therefore carried out in-situ straightening by peening the shaft. Peening is a cold-process that consists of applying a small force repeatedly to the correct places to bring the shaft back to its original straightness. This took one day and resulted in an improvement of the run-out from 0.18 mm to 0.03 mm.

After straightening, our specialists machined the crankpin to -7.00 under-size and then polished it.

Two-stroke Bedplate Line Boring in Mexico

When a six year old bulk carrier suffered main bearing failures on its Japanese-made main engine, QuantiServ was called in for an initial inspection and for discussions on how to arrange the repair in the fastest and most economical way. The inspection in Veracruz, Mexico, showed that main bearings # 7 and 8 failed and that the crankshaft as well as the main bearing pockets were damaged.

The crankshaft was beyond repair and had to be replaced by a new one. The bed plate, on the other hand, could be recovered by line boring. With the engine frame lifted up, QuantiServ’s in-situ specialists carried out

  • a thorough inspection of the bedplate, including NDT crack detection and hardness measurements
  • laser alignment checks before line boring
  • line boring of main bearing pockets # 7 and 8
  • laser alignment checks after line boring
  • blueing checks

The work was carried out successfully while the vessel was alongside in the shipyard in Mexico.

Be Aware of Cam Effect/Ridge Wear that Affects Four-Stroke Crankshafts!

Whenever a four-stroke engine has accumulated around 60,000 running hours or more, then its crank pins are in all likelihood affected by what is called the “cam effect” or “ridge wear”.

This phenomenon develops over time and manifests itself in an uneven wear pattern that is, with the right tools, easily detectable as a protruding band (“cam”) that goes around the circumference of the crank pin. It usually only develops on engines equipped with grooved bearing shells and its development is a function of time. The more impurities (abrasive particles) the lubricating oil contains, the faster the cam effect develops.

The two major makers of medium-speed diesel engines, MAN Diesel & Turbo and Wärtsilä, have booth issued Service Letters to make their customers aware.

The following pictures are typical and exemplify well how the cam effect develops and what damage it can cause. The pictures were taken during an attendance on a German-owned small tanker, where QuantiServ’s specialists machined one crank pin and polished all the others on the vessel’s single 50/54 main engine. The damage was in fact so severe that in-situ heat treatment (annealing) had to be performed too in order to reduce the crankpin’s hardness, which had increased as a result of the failure.

QuantiServ very much recommends to all owners and operators of medium-speed four-stroke engines to keep a close eye on the condition of the crankpins and to regularly inspect them once they have surpassed around 60,000 running hours. The cost of rectifying the pin geometry in good time pales in comparison to the cost of a repairing a failed crankpin bearing. And fail they will, if no action is taken.

Read more

 

 

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.

Polishing All Main Journals and Crankpins on World’s Largest Engine

QuantiServ in-situ machining specialists from China, Sweden and Singapore joined forces in a shipyard in China to carry out in-situ polishing on one one of the world’s very largest diesel engines. The 14-cylinder, 96-bore engine is installed on a 14,000 TEU container ship.

Our engineers and technicians worked in two shifts, around the clock, seven days a week to machine-polish 17 main journals and 14 crank pins while the vessel was docked in Beihai Shipyard, Qingdao, undergoing steel work. It was one of the most extensive polishing jobs that we have ever carried out. And it was done in record time!

All the necessary dismantling and reassembling work was carried out by us as well. In a case like this it pays off that many of our in-situ personnel are multi-skilled – they don’t only do the machining work, but can conduct any mechanical work as well if required.

In addition, our reconditioning centre in Shanghai also carried out cylinder cover reconditioning for a sister ship, belonging to the same customer, that was docked in the same shipyard a few weeks earlier.

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.

Flywheel Teeth Dentistry on a Container Ship in Hong Kong

 

Our in-situ specialists from QuantiServ Dubai have just completed another flywheel repair. This time it was for a very large European owner, on one of their large container ships with a 12-cylinder, 96-bore engine while on anchorage in Hong Kong. Our specialists machined off two damaged teeth and installed an insert, which they had pre-fabricated at their workshop before boarding the vessel and which they sent on board jointly with the in-situ tools.
The total work took 42 hours – three long days of work – and the result is something that they can be very proud of!

Damaged flywheel with two severely damaged teeth

Damaged flywheel with two severely damaged teeth

Removal of the damaged teeth by in-situ milling

Removal of the damaged teeth by in-situ milling

Pre-fabricated insert installed, repair completed

Pre-fabricated insert installed, repair completed

ABC Engineering Pte. Ltd. in Singapore joins QuantiServ

abc-logoWe are very honoured and happy to announce that all personnel from ABC Engineering Pte. Ltd. have decided to join QuantiServ with effect from 1 April 2017. This combination of forces further extends QuantiServ’s offering and geographical reach, particularly in Indonesia.

ABC Engineering is a well known company with excellent reputation that has been providing in-situ crankshaft and engine block repair services to customers in Southeast Asia since the 1970s.

The personnel from ABC Engineering and QuantiServ look forward to continue to serve ABC Engineering’s customers as reliably and to the same exacting standards as they always have.

In-situ machining of lateral surfaces on 20V32 engine block in Bangladesh

Lateral surfaces before and after in-situ machining

Lateral surfaces before and after in-situ machining

In-situ machining of lateral surfaces on a 20V32 engine block in a power plant in Bangladesh

In October 2016, QuantiServ received an urgent request to carry out in-situ machining on a 20-cylinder 32-bore engine block in a power plant in Bangladesh. During the replacement of the crankshaft it was noticed that both lateral surfaces of main bearing cap number 5 showed signs of severe fretting and were in need of machining.

Immediately, in-situ machining equipment was prepared at QuantiServ’s Dubai workshop and was sent to site. Once the equipment had arrived at site, QuantiServ’s engineers from Dubai performed in-situ machining on the engine block to achieve a clean surface that was free from damage. The in-situ machining process was constantly monitored by laser to ensure perfect alignment and adherence to very tight machining tolerances.

The main bearing cap was sent to a local workshop in Bangladesh for machining and installation of compensation plates. This process was supervised by QuantiServ’s engineers. Once the machining was completed, all mating surfaces for the main bearing cap were checked with marker blue to ensure a perfect fit.

Once the work was completed, a final check by laser on the assembled bearing cap showed that both the bore alignment and diameter fully conformed to the engine maker’s specification.

QuantiServ unveils its brand new, centreless facing machine

Months of design and development work came to culmination last week at a dry dock in Marseille, France, when QuantiServ’s new, state-of-of-the art surface facing machine was deployed into the field for the very first time. The machine is designed for in-situ milling and grinding of large, circular surfaces such as those found on large thrusters and well inserts, on slewing rings, hydro turbines, and on blast furnaces. Its first assignment was on the steerable thrusters and well inserts of a cruise ship.

The machine is highly versatile and able to machine surfaces that are vertical, horizontal or inverted. It is ideal to machine circular surfaces between 1500 mm and 5000 mm diameter.

The main advantage of this machine is that it is centreless. The machining head is supported very near to the surface that is to be machined. Thus, the cantilever-effect, which always occurs on traditional facing machines with a central pivot system and that negatively impacts their accuracy, is completely eliminated.

Surfaces that are not circular but rectangular or square shaped, are better suited to X-Y milling and grinding, which QuantiServ also offers.

Getting the machine ready for action at the bottom of the drydock

Getting the machine ready for action at the bottom of the drydock

Metal stitching test piece resists water pressure of 12 bars

Metal stitching test piece resists water pressure of 12 bars

Metal stitching, as long as it is carefully and properly carried out by trained technicians, is tight against gases and liquids. To demonstrate this, QuantiServ has manufactured two cast iron half-shells and has joined them together by metal stitching. The resulting container was successfully pressurized to 12 bars (175 psi) and no leak was observed.

This proves that there is no issue to repair cooling water spaces in for example engine blocks, where the cooling water pressure typically lies around 3 – 4 bars (44 – 58 psi), by metal stitching. In fact we knew this well, because we have done it successfully many times. But that the stitching could easily withstand 12 bars impressed even us.

 

 

In-situ Flywheel Repair on a 3’400 TEU Container Vessel in Mombasa

milling-and-tapping-quantiserv

Milling and tapping, preparation for the teeth inserts to be installed

In-situ Flywheel Repair on a 3’400 TEU Container Vessel in Mombasa, Kenya

QuantiServ received a request from a customer to repair the serration on a main engine flywheel. The vessel called Dubai, where QuantiServ engineers carried out an inspection. They found that five teeth were missing; an isolated one and four in a row.

While the vessel continued her voyage to Africa, our technicians manufactured new teeth and fitted bolts at our workshop in Dubai. They then brought these jointly with the required in-situ machine tools to the vessel, which had meanwhile reached the port of Mombasa in Kenya. There, the machining and installation work was carried out by four engineers in two shifts, around the clock, while the vessel was undergoing cargo operations.

Prefabricated teeth and fitting bolts

Prefabricated teeth and fitting bolts

The work was completed successfully within a tight time window of 72 hours without delaying or otherwise interfering with the vessel’s normal sailing schedule.

The final result, five missing teeth replaced

The final result, five missing teeth replaced

Rudder Stem Housing In-situ Machining on New Type of LNG Carrier

laser-alignment-rudder-stem

Laser alignment of the rudder stem housing

Rudder stem housing in-situ machining on a new type of LNG carrier

QuantiServ have a long-term and good cooperation with many newbuilding and repair shipyards.

Recently QuantiServ were requested to carry out in-situ machining (line boring) of a rudder stem housing on a new type of LNG carrier that is under construction in a Chinese shipyard. Our team were on-board to calibrate the inner diameter of the rudder stem housing and found that the ovality and parallelism were out of limit.

Thereafter, a laser alignment check of the rudder stem housing was done and the corrections to be made were calculated. Finally in-situ line boring of the rudder stem housing was carried out successfully.

In-situ line boring of rudder stem housing

In-situ line boring of the rudder stem housing

A final check showed that the ovality, parallelism, roughness and centre line of the rudder stem housing were all within tolerance. The shipyard was very satisfied with our service and confirmed the final result.