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.

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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.

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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.

Thread Repair on the Low-Speed Rotor of a Wind Turbine

A work site with a view

It is not a secret anymore that our thread repair solutions excel in the most demanding applications and environments. It is therefore not surprising that our colleagues from Lock-N-Stitch were recently contacted for assistance in repairing damaged threads in the hub of a wind turbine operating in the American Mid-West. Our specialists quickly engineered a repair solution and brought it to life inside the 4.2 MW turbine’s nacelle, which sits 105 meters (345 feet) above ground.

Three out of 88 bolt holes that connect the rotor hub to the (low speed) rotor shaft had their threads stripped. Our solution was to machine these to over-size and to install Full-TorqueTM thread inserts. Unlike convential thread repair inserts, Full-TorqueTM thread inserts are equipped with the patented spiral-hook thread, which makes them the ideal for any application, where superior strength is required.

The three inserts that the Lock-N-Stitch specialists installed have an M48 x 5 internal thread that is 130 mm deep. They are also counter-sunk to a depth of 25 mm.

Inside view of the nacelle, towards the rotor, with the drive train components (gear box, generator, ...) removed.
Inside view of the nacelle, towards the rotor, with the drive train components (gear box, generator, ...) removed.

Our specialists locked the inserts in place with three bolts, to prevent them from ever rotating during any future loosening of the bolts.

A few days after we completed our work and after the drive train had been installed back, the customer reported that the alignment of our inserts had been found to be perfect.

Read more about Thread Repairs

 

Damaged bolt hole
One of the damaged M48 x 5 mm bolt holes
During drilling
During drilling
CAD drawing of the thread repair insert
2D drawing of the thread repair insert installed in the hub
Enlarging the bore to accomodate a Full-Torque insert
Enlarging the bore to accomodate a Full-Torque insert

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

Crack Repair on an Excavator Counter Weight

To prevent them from toppling over during digging, transporting earth and raising or lowering the bucket, excavators need to be fitted with a counter weight at their back that balances out the forces.

Typically, these counter weights are made of cast iron. Cast iron offers a number of advantages over other materials, such as concrete: Higher density, less fragile than concrete, made by casting so that even complicated shapes are easy to produce.

Even though cast iron is a strong and very long-lasting material, high degrees of wear and tear common in the construction industry do take their toll over time.

A large provider or construction rental equipment contacted QuantiServ about repairing a cracked counter weight on a relatively large, USA-made excavator.

An inspection showed the presence of three individual cracks with a combined length of 750 mm.  Why the counter weight was suffering from cracks is not entirely clear. One or more collisions with an object during tail swing, or latent stresses in the casting might be possible explanations.

It was in any case apparent, that unsuccessful attempts had been made to repair two of the cracks by arc welding. It is very hard to weld cast iron. Most attempts fail, especially if the repair is attempted under site working conditions.

At QuantiServ we always repair cast iron by metal stitching, which is a cold process and which results in a repair that is always as strong as the original part, and often stronger.

The failed welding meant that we had to spend more time and effort during the metal stitching than would normally be required. We estimate that it took about twenty additional working hours to deal with the damage caused by the arc welding.

We charged the customer a total of USD 15’000 for the repair, including traveling and accommodation costs. The retail sales price of a new counter weight was USD 36’850, meaning that the customer’s insurance company saved USD 21’850 by having it repaired rather than replaced.

Restoring All 90 Teeth on a Two-Stroke Engine Flywheel

Being well known for our repair capabilities, we repair damaged two- and four-stroke engine flywheels frequently. In most cases, a few of the flywheel’s teeth are damaged and we quickly restore these by installing a tailor-made repair insert. We usually do this in-situ, either during a port stay or during a docking.

The situation found on an European-owned 2’300 TEU box ship in September 2022 was very different. When the customer contacted us about a damage to the flywheel, we sent our colleagues from QuantiServ Singapore on board for an inspection.

Badly damaged flywheel

During the inspection it very quickly became clear that this was no ordinary case, as all ninety teeth were found severely damaged. An in-situ repair of 90 teeth would take too long and would not be cost-efficient either. As the ship was about to be docked very soon, we suggested to the customer to carry out the repair during the upcoming docking in southern China.

The colleagues from QuantiServ China took over the case. They worked out a very attractive proposal that was immediately accepted by the customer. Our engineers and technicians then started all preparation and planning.

Once the vessel was in the yard, the yard workers uncoupled the intermediate shaft, took the 3.5 ton flywheel off the engine and moved it out of the engine room through a narrow slot that they had cut into the vessel’s hull. The flywheel was then trucked to Shanghai, where the highly-skilled engineers and technicians from QuantiServ China immediately commenced to machine it.

They machined off its toothed rim and then shrunk on a tailor-made ring of forged steel onto the ø 3.2 meter flywheel. And to make sure that the ring stays put for the lifetime of the ship, they also installed a total of 135 large bolts. Once this was completed, new teeth were milled.

Milling new teeth obviously took time, owing to the large size of the flywheel. In fact it took five days and five nights of continuous milling!

After completing a few more processing steps, our Shanghai colleagues sent the flywheel back to the shipyard and to a very happy customer. The shipyard workers then completed this repair assignment, by reinstalling the flywheel to the 72-bore engine and by re-coupling it to the ship’s intermediate shaft.

Severely damaged flywheel prior to repair
Severely damaged flywheel prior to repair
Milling of new teeth
Milling of new teeth
Ready to be delivered back to the shipyard
Ready to be delivered back to the shipyard
Machining on a large vertical lathe
Machining on a large vertical lathe
The newly milled teeth
The newly milled teeth
During re-installation on board
During re-installation on board

Links

The repair of every single tooth on a flywheel as presented above is not something that we do every day. Typically, just a handful of consecutive teeth are damaged. Follow one of the links below to see how we repair these cases in-situ.

Flywheel In-situ Repair on the US East Coast

Another successful flywheel repair assignment completed, in Florida, USA

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Flywheel Teeth Dentistry in Hong Kong

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

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In-situ Flywheel Repair in Mombasa, Kenya

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

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Metal Stitching an Engine Block from 1921 in-situ!

1921 Duesenberg Model A

We do a lot of in-situ work. We routinely carry out machining and metal stitching work, among others, on components that are too large to be moved to a workshop or where dismantling work is too time consuming or costly. But repairing a an antique car engine block, in the chassis, in a museum, is still quite special. Even for us.

The engine in question is an in-line, eight cylinder one with a bore of 72 mm and a stroke of 125 mm (2.875″ x 5″). With a swept volume of 4’256 cc, or 260 cubic inches, this early Duesenberg Model A engine is capable of producing up to 88 hp (66 kW) of power.

Repair in progress. The engine remained in the chassis, only the cylinder head was removed.
Repair in progress. The engine remained in the chassis, only the cylinder head was removed.

We got the opportunity to work on this engine as cracks had began to show at the corners of the engine block. The cracks originated from the threaded bores housing the cylinder head studs. They extended towards the outside of the engine block on one side and into the cooling water passage on the other.

The fact that the engine was left inside the chassis made the repair a little more challenging than usual. Our metal stitching expert had to use a mirror for much of the repair work. Without it he could not see, let alone repair the cracks at the rear end of the engine block. In addition to sealing the cracks with stitching pins, our expert also installed Full Torque™ thread inserts at the threaded bores. Unlike conventional thread repair inserts, Full Torque™ inserts do not create spreading forces. They are therefore the perfect solution for cases like this one, where threaded bores close to an edge have to be repaired.

Cracks extending from the cylinder head stud bores to the outside and to the cooling water space
Cracks extending from the cylinder head stud bores to the outside and to the cooling water space
Installation of Castmaster stitching pins.
Installation of Castmaster stitching pins. They are the strongest and most advanced stitching pins on the market today.
Ultrasonic inspection of the casting
Ultrasonic inspection of the casting to determine the wall thickness
Metal stitching in progress. Due to the location of the crack a mirror was used.
Metal stitching in progress. Due to the location of the crack a mirror was used.
The completed repair. Cracks stitched and Full Torque thread inserts installed.
The completed repair. Cracks stitched and Full Torque thread inserts installed.

Links

Metal Stitching

Metal stitching is a very well-established repair method. It is applicable to a wide variety of materials such as cast iron, cast steel and many non-ferrous metals.

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Thread Repair

The repair inserts that we use to repair damaged threads are super strong and do not create spreading forces. They are ideal for high-load applications.

View more

Metal Stitching a Fractured Engine Block from 1913

Pierce Arrow

This post describes the repair of a Pierce Arrow engine block from 1913. The Pierce Arrow was the largest production automotive engine at its time. The swept volume of this 6-cylinder, 48 hp (36 kW), engine amounts to a whopping 13’500 cc (824 cu in)!

This engine is of the T-head engine type, which is essentially an early form of crossflow engine. This design is characterized by two separate camshafts, one on either side of the cylinder. One camshaft operates the inlet valves and the other the exhaust valves. This makes this engine design quite complex and expensive to produce.

The main advantage of the T-head engine design is the fact that it is not at all prone to knocking – a condition where the gasoline vapour in the cylinder ignites too early by itself due to compression, before it is lit by the spark plug. Knocking was a big issue especially during the early decades of the 20th century, when gasoline sold typically had a very low Octane rating. T-head engines were therefore popular until about 1920, when better fuel became widely available. At that time, the disadvantages of the design started to outweigh the advantages.

A large piece had broken off the cast iron engine block and had to be reattached
A large piece had broken off the cast iron engine block and had to be reattached

The in-line 6-cylinder Pierce Arrow cast iron engine block that we received for repair at our workshop at Lock-N-Stitch in California, USA, was severely damaged. A large piece of the casting had been broken off at the block’s front (timing belt) end.

Our metal stitching specialists successfully reattached it. In order to do so, they installed about thirty Castmaster™ stitching pins over a total fracture length of 160 mm, in material with a thickness ranging from 12 – 16 mm. For additional strength, they also installed two high-strength locks perpendicular to the fracture line.

The fracture line passed through a hole for a positioning dowel pin. To repair that, our specialists first closed the hole by installing a solid Full Torque™ plug, before drilling it anew in the exact location.

Badly fractured engine block
The completed repair.
The completed repair.
Close-up of the fracture line
Close-up of the fracture line
Repair completed. Stitching pins, locks and Full Torque insert installed
Repair completed. Stitching pins, locks and Full Torque insert installed

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
Repair finished

Repairing a V12 Flathead Engine Block from 1934

Packard Twelve

We routinely work on museum pieces. In this post we introduce a typical case: The repair of a Packard Twelve engine block from 1934, carried out by our colleagues from Lock-N-Stitch in California.

As the name implies, the Packard Twelve is a 12-cylinder engine. It is a flathead engine, sometimes also called side-valve engine, where the intake and exhaust valves are contained within the engine block rather than within the cylinder heads. Flathead engines were very popular until the 1950s and were built in large numbers by automotive manufacturers. Their advantage is their simplicity, compactness, reliability and low cost as the flathead design obviates a complicated valve train. Such engines therefore need far less components than alternative designs such as, for example, single or double overhead camshaft arrangements.

The main disadvantage of the flathead engine is its relatively low efficiency and power output. The Packard Twelve V12 engine has a displacement of 7300 cc (445 cu in) and a maximum output of 119 kW (160 hp).

Engine block received with cracks in both longitudinal side walls and around the valve seats
Engine block received with cracks in both longitudinal side walls and around the valve seats
Repair finished
Repair finished. We stitched about 200 mm (8 inches) of cracks in this engine block.

Repair of cracks in the side walls of the engine block

When the engine block was delivered to us, it contained eleven cracks of various lengths. Some were small, others rather long. Added together, they amounted to a total length of 200 mm. In addition, the block suffered from corrosion and material loss around the camshaft spaces.

The cast iron block had been “repaired” before by arc welding. This has not been a great success – new, fairly large cracks could be seen extending to the left and right of the weld.

As they always so on cast iron parts on which someone has already been attempting a repair by welding, our specialists cut out all material in the vicinity of the weld, in the so-called heat affected zone. This is our standard operating procedure. Whenever cast iron is welded at, the heat from welding burns out the carbon, which constitutes between 2% and 4% of the cast iron. Once the carbon is burnt, the cast iron becomes hard and brittle, looses its structural integrity and becomes worthless.

To replace the cut out material on both longitudinal sides of the block, our specialists installed repair patches made of cast iron. They stitched them firmly in place with Castmaster™ stitching pins. Similar pins of various lengths and diameters were also used to repair the cracks found in various locations on the block, in material ranging from 3 – 10 mm thick. Some of these cracks are visible in the pictures below.

Our specialists also installed five Full Torque™ thread inserts to repair thread holes damaged by corrosion and erosion.

The engine block had been arc welded in the past. As expected, this did not solve the problem but led to further cracks extending left and right.
The engine block has been arc welded in the past. As expected, this did not solve the problem but led to further cracks extending to the left and right of the weld.
Crack extending leftward from the weld, serious corrosion at the edge of the sealing surface.
Crack extending leftward from the weld, serious corrosion at the edge of the sealing surface.
We removed the material that has previously been welded and installed a repair patch.
We removed the material that has previously been welded and installed a repair patch.
Crack extending rightward from the weld. Again, serious corrosion at the sealing surface.
Crack extending rightward from the weld. Again, serious corrosion at the camshaft cover sealing surface.
Installation of stitching pins to seal the crack
Installation of stitching pins to seal the crack
Skimming of cylinder head landing surfaces
Skimming of cylinder head landing surfaces
Left longitudinal side wall completed
Left longitudinal side wall completed
Right longitudinal side wall completed
Right longitudinal side wall completed

Repair of cracks around the valve pockets

A thorough magnetic particle inspection (MPI) of the block revealed hairline cracks between some of the valve seat and cylinder liner bores. We permanently repaired these cracks by installing small size stitching pins.

After completion of the repair, we took the opportunity to skim all cylinder head gasket mating surfaces, on the engine block as well as on the two cylinder heads.

Crack between valve seat and cylinder bore clearly visible during Magnetic Particle Inspection (MPI)
Crack between valve seat and cylinder bore clearly visible during Magnetic Particle Inspection (MPI)
Cracks between valve seat and cylinder bores successfully repaired
Cracks between valve seat and cylinder bores successfully repaired
Another crack
Another crack, seen here under Ultraviolet (UV) light during MPI

Tractor Engine: Stitching Repair in the Combustion Chamber

Ford 1710

This post is about a small metal stitching repair that we carried out on the cylinder head of a Ford 1710 tractor built in 1984.

The cylinder head of this 3-cylinder, 1’400 cc (85 cu in), 84 mm bore and 84 mm stroke engine suffered from a crack close to one of the fuel injectors. The crack led to cooling water leaking into the combustion chamber. The cylinder head had been repaired before, by metal stitching, but not by us.

3-cylinder, 26 hp (19.4 kW), Ford 1710 tractor cylinder head
3-cylinder, 26 hp (19.4 kW), Ford 1710 tractor cylinder head

To permanently repair it, we carried out the following work on the cylinder head of this 19.4 kW (26 hp) engine:

  • Dismantling
  • Visual and Magnetic Particle Inspection (MPI)
  • Metal stitching of two cracks
  • Milling of the landing surface
  • Reassembly
  • Pressure testing

Metal stitching cracks inside various engines’ combustion chambers is something that we routinely do with excellent results. Our repairs are well able to withstand the challenging environment of up to 200 bars (2’900 psi) pressure and 350° C temperature that exists there. This time, the repair will last (unlike the earlier one, not done by us).

Magnetic Particle Inspection (MPI) reveals two cracks, extending from the earlier repair into the valve seat bores
Magnetic Particle Inspection (MPI) reveals two cracks, extending from the earlier repair into the valve seat bores
Cracks repaired, valve seat rings reinstalled
Cracks repaired, valve seat rings reinstalled
After skimming of the landing surface
After pressure testing and skimming of the landing surface
The reassembled cylinder head prior to return to the customer
The reassembled cylinder head prior to returning it to its owner

Metal Stitching and Line Boring on a Japanese Auxiliary Engine Block

In late 2021, a Greek owner of a 4250 TEU container vessel approached us for the repair of an auxiliary engine. The 26-bore, japanese-made engine had suffered from a so-called “side kick” – the connecting rod had smashed a hole in the engine block, above cylinder #2.

As the vessel was about to call Singapore, QuantiServ Singapore arranged for one of its metal stitching specialists to go on board to conduct a comprehensive damage assessment.

As is nowadays almost always the case, our specialist deemed the engine block damage to be repairable. We engineered a repair proposal, consisting of metal stitching and in-situ machining to be carried out in our workshop in Singapore. The customer gladly accepted our repair proposal due to the obvious time and cost savings compared to replacing the engine block. He made arrangements for the 12-year old engine block to be sent to our Singapore workshop for repair.

The block arrived at our workshop in March 2022 and was immediately attended to. The repair work carried out included the following main steps:

  • We arranged for a tailor-made cast iron repair patch to be cast in a certified partner foundry. The repair patch was then stitched in place using Castmaster™ stitching pins and matching locks. This provides for a permanent, very strong repair.
  • As the damage extended into the lower cylinder liner bore, a repair sleeve was installed there. The repair sleeve guarantees a good fit with the cylinder liner o-rings, preventing water leaks.
  • The ovality of seven out of nine main bearing pockets was found to be excessive. This finding was independent of the accident but needed attention too. We corrected the ovality with in-situ line boring.
  • All eight cylinder liner landing surfaces in the engine block were machined to clear them from corrosion and cavitation damage.

A Magnetic Particle Inspection (MPI) was carried out on the completed repair to the satisfaction of the customer and attending class surveyor.

From start to finish, the repair work took approximately four weeks to complete, well in time for the engine block to be sent back to the vessel during her next routine call to Singapore.

Engine block damage at cylinder number 2
Damaged engine block
Installation of stitching pins
Installation of stitching pins
Machining of the cylinder liner landing surface
Machining of the cylinder liner landing surface
Engine block debris
Engine block debris
Repair patch installed
Repair patch installed
Cylinder liner landing surface after machining
Cylinder liner landing surface after machining
Newly casted repair patch
Newly casted repair patch
MPI inspection after stitching
MPI inspection after stitching
Another job well done
After completion. Another repair job well done!

More metal stitching information

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.

 

The Benefits of a Global Footprint: Connecting Rod Repair “On the Fly”

If your ships operate globally, then you benefit from relying on a service partner that has a truly global footprint. This post neatly exemplifies this fact.

The subject is an American-owned, 9’000 TEU container ship with an 82-bore main engine. The vessel experiences a crosshead bearing failure while crossing the Atlantic. We repaired it “on the fly” with a minimum of down-time:

  1. During the last days of 2020, the vessel experiences a severe crosshead bearing failure close to Bermuda island. The crosshead pin and connecting rod are found severely damaged and are in need of repair or replacement. Our experts assess the situation and give remote assistance to the crew during removal of the connecting rod from the engine. Once that is done, the vessel continues its journey towards Europe with one cylinder cut out.
  2. On 15 January 2021, the vessel arrives in Algeciras. The damaged connecting rod gets offloaded and is transported by truck to our workshop in Genoa.
  3. It arrives at our works on 18 January and at once undergoes repairing. After completion of the repair, we ship the connecting rod by air freight from Milan, via Doha, to Singapore. It arrives in Singapore in the morning of 05 February 2021.
  4. Our technicians in Singapore assist the crew to reinstall it. After a short and successful trial run, the ship continues its journey towards the South China Sea.

QuantiServ operates out of 15 locations that are strategically placed along major shipping routes or close to important ports. Wherever your ships go, we are never far away.

Severely damaged crosshead bearing bore
Severely damaged crosshead bearing bore
Close-up of the damaged area
Close-up of the damaged area
While sailing with one cylinder cut out
While sailing with one cylinder cut out
After initial cleaning
After initial cleaning
Remachining of the bore
Remachining of the bore in Genoa
Crosshead bearing bore after machining
Crosshead bearing bore after machining
Corrosion protected and ready for dispatch
Corrosion protected and ready for dispatch
Connecting Rod ready for dispatch
Connecting Rod ready for dispatch

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.

See the time line, pictures and additional information

Metal Stitching on Historic Bridge in Washington DC, United States

Our American colleagues have just completed metal stitching repairs on a historic bridge crossing the Chesapeake and Ohio Canal.

The Canal

The Chesapeake and Ohio Canal stretches over a distance of 297 km (184.5 miles) from Cumberland, Maryland, to Georgetown, DC on the US East Coast. It was constructed between 1828 and 1850 by approximately 35’000 labourers, mostly immigrants from Europe. Its purpose was to enable the shipment of coal from the rural but coal rich Allegheny Mountains to the much more densely populated regions and sea ports along the Atlantic coast.

The canal was operated from 1831 until 1924. While originally built for the transportation of coal, it quickly became an important lifeline for communities along its way.

The bridge we assisted restoring. Visible in the foreground is one of the canal's 74 lifting locks
The bridge we assisted restoring. Visible in the foreground is one of the canal's 74 lifting locks

Boats were used to ship agricultural produce and lumber to markets downstreams. They then returned loaded with manufactured goods. These boats typically did not have their own means of propulsion, but were pulled along by mules walking on towpaths located at either side of the canal.

One end of the canal, Cumberland, lies at an altitude 184 m (605 feet) higher than the other end, Georgetown.  This meant that lift locks were needed – in total 74 of them were constructed. One of them is visible in the picture above, in front of the bridge.

In addition to the 74 locks, the canal also featured many other feats of early engineering. There were seven dams, about 240 culverts, a few aqueducts, a tunnel 950 meters (3’120 feet) long and, of course, bridges. A few of these bridges still exist today, such as the one that our metal stitching specialists proudly helped to restore.

Metal Stitching Work Performed

Exposure to the elements for over 150 years took its toll on the bridge structure. Cracks had developed in many of the vertical cast iron columns carrying the bridge deck. In all likelyhood, the cracks that were found were freeze cracks. Freezing temperatures are common in Georgetown from the middle of December until early March. If water enters one of the exposed, hollow columns and gets trapped there, then it very likely freezes during a cold winter night. Over time, the freeze/thaw cycles led to cracks.

All of the cracks ran in vertical direction. They had a cumulative lenght of 7’400 mm (25 feet). Our specialists sealed them with stitching pins and added perpendicular locks for extra strength. They then ground the locks and pins flush and made them blend in well with the weathered surface texture of the antique columns.

For the work to be carried out, a section of the canal had to be drained
For the work to be carried out, a section of the canal had to be drained
The width of the cracks required pins with a large diameter to length ratio
The width of the cracks required pins with a large diameter to length ratio
Installation of stitching pins
Installation of stitching pins: Close to 1'000 were used for this project
In many locations, the cracks were wide open
On some of the columns, the cracks had caused a gap of up to 12 mm
Our specialists stitched over 7 meters of cracks
On this restoration project, our specialists stitched over 7.4 meters (25 feet) of cracks
Once completed, the repair blends in very well
The completed repair blends in very well
Stitching in progress
Metal stitching in progress: Stitching pins installed in an overlapping pattern
Locks were added for extra strength
Metal stitching in progress: Adding of locks, perpendicularly to the crack, for extra strength

Nuclear Power Plant Emergency Diesel Generator Block Repair

The operational requirements for emergency diesel generators (EDG) installed in nuclear power plant are very strict and demanding. In case of an emergency event leading to the loss of off-site power, a nuclear power plant’s EDGs are meant to supply independent, redundant power. From this follows that they have to start reliably and quickly  under any condition and must be able to take on load almost instantaneously, which generally means within about 10 Seconds. This is tested regularly under real-life conditions, according to the prevailing nuclear codes, standards and regulations.

This testing regimen of sudden load changes puts an enourmous thermal loading on most of the EDG’s internal components and on its auxiliary systems. Excessive wear and tear is therefore to be expected and is indeed a small price to pay for ensuring plant safety.

For years, QuantiServ has been supporting nuclear power plant operators and contractors serving them with specialist services throughout the long service life of the plants. We are happy to play a small, but nevertheless important role in ensuring safe and reliable electricity supply from whatever source.

The enclosed pictures show the machining of an impressively large, 20-cylinder engine with a rated output of 4000 kw, a cylinder bore of 240 mm and a stroke of 230 mm. It suffered from a small internal defect, caused by wear and tear, that we successfully remedied in our workshop in The Netherlands in 2020.

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

Read more

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

Flywheel In-situ Repair on the US East Coast

Starting up a handymax bulk carrier’s 48-bore, two-stroke main engine with its turning gear engaged resulted in the turning gear shattered and in damage to 12 consecutive teeth on the flywheel.

The turning gear was damaged beyond repair and had to be replaced. Not only was its housing shattered but the planetary gears were completely destroyed too.

Faced with the costly and unpalatable reality of most likely having to replace the flywheel as well, the ship management company turned to QuantiServ for help. Always liking a challenge when we see one, we engineered and delivered a comprehensive solution that consisted of the following:

  • Inspection on board
  • CAD and FEA modeling to engineer an economical yet structurally very strong solution
  • CNC machining of repair inserts in our workshop
  • In-situ machining of the flywheel on board
  • Stitching the repair inserts in place

Our in-situ machining and metal stitching specialists carried out the work in February 2019, during the vessel’s port stay in Florida, without interfering in her schedule.

QuantiServ carries out a number of gearwheel repair assignments every year, mostly for industrial, marine and mining customers.

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.

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

 

 

Four-stroke Cylinder Head Valve Seat Bore Repair

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

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

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

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

Condition of the cylinder heads before reconditioning:

 

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

Read more

 

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.

Reconditioning of Two Large Hydraulic Rams in Singapore

Ram 2

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

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

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

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

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

Update April 2018:

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

Reconditioning of Fourteen 96-bore Cylinder Covers

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

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

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

Significant Reconditioning and Field Service Job in Shanghai

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

The following components were reconditioned:

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

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

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

All the work was completed in 32 days.

Repair of Externally Damaged Cylinder Liners

Our reconditioning centre in the Netherlands has just completed the repair of yet another externally damaged cylinder liner. We carry out this kind of repair quite frequently.

External damage to a cylinder liner is usually caused by rough handling. Liners are made of cast iron and cast iron is brittle. If a liner is dropped on the floor or is otherwise handled roughly, then material may chip off. Most damages occur in the vicinity of the o-ring grooves, where the material is thin.

If such a liner has to be scraped, then it is obviously a big waste. This is why we frequently repair them. Typically, the repair costs amount to approximately 20% of the replacement costs.

The following pictures show three examples of such repairs on liners of different sizes: An 84-bore liner, a 72-bore one and a 60-bore one.

 

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 Singapore

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.

Metal Stitching of an Engine Block in Tehran, Iran

 

Metal stitching on an auxiliary engine block

Our metal stitching expert traveled to Tehran, Iran, last week to repair a four-stroke main engine block on board a tug boat. It had a crack between the charge air space duct and the cooling water space around one of the cylinder liners, as well as some dents. Cooling water was leaking into the charge air space.

To repair the damage took our expert just one full day of work. The customer was very pleased with the result and was impressed by how fast the repair was being carried out.

Once again it was proved that metal stitching is a quick and reliable solution for cast iron repairs – for jobs big and small!

 

 

Enjoying a cup of tea in the engine room after a job well done

Enjoying a cup of tea in the engine room after a job well done

Metal stitching

A very happy customer

Our very own wharf in Singapore, right next to our workshop.

QuantiServ Singapore’s own wharf again able to accommodate vessels

Maintenance dredging at our own wharf in Singapore has just been completed. We are now again able to accommodate vessels of up to 110 meter length and 5.0 meter draft for repair, right next to our very well equipped 10,000 square meter workshop. It does not get any more convenient and economical than this!

Our very own wharf in Singapore, right next to our workshop.

Our newly dredged, very own wharf in Singapore, right next to our workshop.

 

Lateral surfaces before and after in-situ machining

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.

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