This process is trusted in industries like,

• Marine engines and crankcases
• Power plants and turbine casings
• Pump and compressor housings
• Heavy industrial machinery

Why Not Welding?

Welding large cast components often causes:

• Heat distortion
• Loss of strength due to metallurgical changes
• Crack expansion or new cracks
• Metal stitching avoids heat damage and preserves the original material strength.

How Keys & Locks Work in Metal Stitching

The core of Metal stitching involves installing metal keys (locks) and stitching pins into the crack

Step-by-Step Explanation:

Step 1: Drilling and Stop-Holing

• Small holes are drilled at both ends of the crack.
• This prevents the crack from spreading during the repair.

Step 2: Installing “Locks” (Metal Keys)

• A series of overlapping slots are machined along the length of the crack.
• Technicians insert precision-engineered metal locks (keys) into the slots

Purpose of Keys/Locks:

• They mechanically pull both sides of the crack tightly together.
• They distribute load and stress evenly across the repaired area.
• The locks exceed the strength of the original casting and restore structural integrity

Step 3: Installing Stitching Pins

• Holes are drilled perpendicular to the crack.
• Technicians screw stitching pins into the holes to fill and seal the crack,

Purpose of Stitching Pins:

• They hold the metal in compression.

• They make the repair pressure-tight, preventing leaks of oil, coolant, or gas.

Step 4: Surface Finishing

• The repaired area machined flush.
• After finishing, the repair hides the crack and restores the component to OEM tolerances.

Advantages of Using Keys & Locks in Metal Stitching:

Where This Method Is Used

Metal stitching with keys and locks is commonly used for:

• Cracked diesel engine blocks
• Turbine and pump casings
• Compressor housings
• Marine engine frames and bedplates
• Generator casings

Whether the crack is small or several feet long, the stitching process scales to the size and location of the damage.

Metal stitching using precision metal keys and stitching locks is a reliable, proven, and cost-effective cold repair technique. Unlike welding, it involves zero heat—meaning no distortion, no stress, and no change in material properties. This method restores the structural integrity of cracked cast components and saves industries from huge downtime, dismantling, and replacement costs.

And when it comes to execution, RA Power Solutions is one of the leading global experts in metal stitching and metal locking. With four decades of experience and thousands of successful repairs, we specialize in restoring engine blocks, turbine casings, cylinder liners, compressor housings, and other critical equipment right at the site — anywhere in the world.

For more information on metal stitching repair of engine block cracks, metal stitching crack repair, engine block crack repair, and Crack in Cylinder Liner, please email us at rajshahani@rapowersolutions.com or info@rapowersolutions.com, or call us at +91 9582647131 or +91 9810012383.

FAQs:

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In case of cracks in cylinder liners, pistons, or cylinder heads in heavy-duty engines, compressors, or turbines there is no need to reject them as now it is possible to repair the crack by a cold process called metal lock and metal stitching. This is a proven procedure of crack repair which has been followed for over 45 years.

We Undertake Crack Repair of the Following Components and Equipment

• Components Manufactured out of Cast Iron, Cast Steel, etc.
• Cylinder Liners, Cylinder Blocks, and Components Have Higher Hardness.
• Piston Manufactured Out of Aluminium
• Bronze Components

RA Power Solutions regularly undertakes repair of main engine components, which develop multiple cracks at different locations and lengths.

The following components were damaged and successfully repaired by the Metal Locking/Metal Stitching process

• In the case of a main engine, Cylinder liners developed multiple cracks from the outer diameter. The cylinder Liner length and inner diameter were 1500 MM and 600 MM respectively. We measured the cracks from 15 mm to 150 mm. RA Power Solutions Pvt Ltd repaired them successfully using the metal locking and metal stitching process. The repairs perform satisfactorily. The photographs below show the team carrying out the work.
• The engine block of the main engine also developed cracks in different locations. These cracks were repaired on board the vessel by Metal Locking and Metal Stitching Process. RA Power Solutions has more than 45 Years of experience in the repair of cracks, developed in the casting of heavy components.

For more information on metal stitching repair of engine block crack, engine block crack repair and Crack in Cylinder Liner please email us at rajshahani@rapowersolutions.com, or info@rapowersolutions.com, or call us at +91 9582647131 or +91 9810012383.

FAQs:

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The crack repair developed in high-casting components is executed onsite without dismantling the main equipment. RA Power Solutions has developed special alloy keys and locks that have almost ten times more strength than the original casting. Now it is possible to repair the cracks that develop in large, heavy-duty cylinder liners. The cracks repaired are mainly in the non-operational area of the cylinder liners. The repair of cracks in large cylinder liners has become popular, as in most cases, it is not possible to arrange the replacement of the cracked liners with new ones.

RA Power Solutions has saved a number of engines by repairing damaged cylinder liners. Our technicians repair cracks using our metal locking and metal stitching process

We regularly undertake the repair of engine blocks, compressors, and all cast iron, bronze, and aluminum components for the following engine makes:

• Akasaka
• Mitsubishi
• Daihatsu
• Yanmar
• Hanshin
• Kobe Mitsubishi
• Caterpillar
• Wartsila
• Deutz-KHD
• Volvo Penta SKL
• MAK
• Sulzer
• MAN B&W
• SKL
• MTU MAK
• Pielstick

We have been regularly providing metal stitching, metal locking, metal surgery, and repair services in Iraq, Iran, Dubai, Oman, Saudi Arabia, Singapore, Russia, Qatar, Abu Dhabi, Sharjah, Ajman, Umm Al-Quwain, Fujairah, Bahrain, Gambia, Kuwait, Antigua and Barbuda, Belize, Dominica, Dominican Republic, Malaysia, Indonesia, Madagascar, Vietnam, Grenada, Guyana, Haiti, Jamaica, Saint Kitts and Nevis, Saint Lucia, South Korea, Saint Vincent and the Grenadines, Trinidad, and Tobago, etc.

For more details on the repair of engine blocks, metal surgery, Crack Repair Of Cylinder Liners and MAN engine cylinder liners, please email us at rajshahani@rapowersolutions.com, or info@rapowersolutions.com, or call us at +91 9582647131 or +91 9810012383.

FAQs:

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Metal stitching and metal locking is a simple but proven process of repairing cracks in heavy components without following the wielding method, which generates excessive heat.

We observe that heavy components made of cast iron, bronze, cast steel, and aluminium often get damaged due to accidents. When the damaged portion of the casting breaks into pieces, replacement with a new component is usually not possible. A new part is expensive, takes time to manufacture, or belongs to obsolete equipment.

RA Power Solutions has experienced technicians who cut off the damaged portion of the component completely. They make a new casting of cast iron, cast steel, or aluminium as per the original component and bring it to the site. The team assembles the new casting properly and metal stitches it using the best quality metal keys and locks.

The photographs shown in this blog are of MAN main engine model SMIT MAN R666W (Main Engine Port Side) which met with a serious accident. In this case, we have successfully repaired the engine block, cylinder liner, and piston having multiple cracks, lengths measuring from 75 mm to 190 mm.

Advantages of repair of damage casting and crack by metal lock and metal stitching process.

This method of crack repair is the cheapest and can be executed in a short time. Onsite metal stitching repair is undertaken using our in-house trained technicians and consumables. Crack repair and repair of damage casting can be done in any part of the world and on board the vessel as our technicians have valid passports and seaman books. The process of crack repair by metal lock and metal stitching is approved throughout the world including Lloyds.

For more details regardingCrack repair in cast iron, crack repair of aluminium and cast iron repair by metal lock and metal stitching, please email us at rajshahani@rapowersolutions.com, or info@rapowersolutions.com, or call us at +91 9582647131 or +91 9810012383.

FAQs:

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The following are the main observations after the inspection of the cylinder liners and engine block:

The damaged cylinder liners and cylinder block were subjected to a crack detection test by MPI. RA Power Solutions uses a high-intensity Magna Flux torch to detect the cracks. Our technicians are also level three qualified to undertake the MPI test.

The details of the crack observed in the cylinder liners and cylinder block of the MAN main engine are as follows:

• Cylinder Liners: A crack having a length of approximately 150 mm was observed.
• In the case of the engine block, two numbers of cracks were observed.

1. A crack having a length of about 120 mm was observed in the cylinder liner sitting area on a fuel pump side.
2. A crack measuring about 130 mm was observed in the cylinder liner sitting area on the exhaust side.

The hardness of the cylinder liner was observed between 220-250 HB.

Repair undertaken by RA Power Solutions:

In the case of cylinder liners, the crack was repaired from the inside and from the outer diameter as well by a metal lock process. We used special alloy locks and keys to repair the crack.

The two cracks in the engine block liner sitting area were repaired by a metal lock. After repairs, the proper grinding and polishing were done on the crack area to maintain the specified tolerance.

The liners were assembled in the presence of our technicians. The engine was put into operation after the leak test. The performance of the engine after crack repair of cylinder liners and engine block is observed satisfactory.

We have successfully executed hundreds of jobs. These include damaged and cracked cylinder liners, pistons, engine blocks, and major components used in heavy equipment.

We offer our services across a wide range of countries, including Singapore, Dubai, Bahrain, Bangladesh, the United Arab Emirates (UAE), Indonesia, Gambia, Iraq, Iran, Qatar, Kuwait, Malaysia, Egypt, Nigeria, Mozambique, Saudi Arabia, Oman, Turkmenistan, Jordan, and Kazakhstan.

For more information regarding cylinder liners, engine block crack repair, and crack repair of MAN main engine, please contact us at rajshahani@rapowersolutions.com or info@rapowersolutions.com or call us at +91 9582647131 or +91 9810012383.

FAQs:

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Over time, cast iron heads can develop cracks, warping, or other damage due to overheating, stress, or wear. That’s where our expert team steps in. With over 45 years of experience, RA Power Solutions uses advanced metal stitching (metal locking) techniques to restore structural integrity — without the risks associated with welding.

Cast Iron Cylinder Head Repair

At RA Power Solutions, we fix broken engine parts called cylinder heads. Imagine a cylinder head like a cap on a bottle- it keeps everything inside safe. Sometimes, these cylinder heads, made of strong cast iron, can get damaged. That’s where we come in! Our experts at RA Power Solutions know how to mend and make them strong again. We use special tools and skills to fix the cracks and make the cylinder head work like new. So, if your engine’s cylinder head is not feeling well, bring it to us, and we make it healthy again.

Cast Iron Head Repair

Cast Iron Cylinder Head Repair by RA Power Solutions is a service that helps fix broken or damaged cast iron heads, and engine block liners of engines. If the head of your engine is cracked, chipped, or not working properly, RA Power Solutions can help make it as good as new. They use special techniques and skilled experts to mend the cast iron head, ensuring it works well, and your engine runs smoothly. Trust RA Power Solutions for reliable and effective cast iron head repairs by metal lock and metal stitching process.

Our Repair Process Includes:

• Thorough inspection and crack detection
• Cold repair using metal stitching, preserving original metallurgy
• Surface machining and pressure testing
• Reassembly and testing for performance assurance

For more information on Cast Iron Head Repair, Cylinder Head Repair and cylinder heads please email us at rajshahani@rapowersolutions.com or info@rapowersolutions.com, or call us at +91 9582647131 or +91 9810012383.

FAQs:

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It was reported that due to an accident, the block of the CO2 compressor was badly damaged and required repair.

Action was taken by RA Power Solutions for the repair of CO2 compressor Block:

Considering the seriousness of the accident, a team of three technicians was deputed. On visual inspection, it was observed that the distance piece housing of the CO2 compressor was badly damaged into pieces. Multiple cracks of different profiles and lengths were also observed on the block of the compressor, the photograph is given below.

Action is Taken for the Metal Stitching & Repair of the Compressor Block

• The damaged area was thoroughly cleaned by the use of special chemicals.
• The paint and red oxide were completely removed.
• The MPI of the damaged area was undertaken by a qualified engineer with a high-intensity magnafux torch.
• Multiple cracks measuring in length ranging from 160 mm to 320 mm were observed.
• The large portion measuring about 8 inches by 6 inches was completely damaged, hence it was decided to completely remove the damaged portion and cast a new piece.
• The area of the housing which was not accessible by the MPI equipment. It was subject to dye penetrant test in order to check the cracks.
• The new piece of casting was placed on the main casing and was metal stitched, as can be seen in the photograph below. The photograph of the new casing piece is also given.
• The remaining cracks were repaired by a metal locking process.
• We used L20 locks and Cast Master pins with a length of 25 mm and a diameter of 8 mm for the metal locking process. The casing had serious damage and multiple cracks.

RA Power Solutions is the only company with forty-five years of experience. The Major repair is by metal locking and metal stitching process.

All our technicians have a valid seaman book, and US VISA . They can fly to any destination in the world in a short time.

Globally Business: RA Power Solutions

We have been regularly executing metal stitching, metal locking, metal surgery & repair services in Iraq, Iran, Dubai, Oman, Saudi Arabia, Qatar, Abu Dhabi, Sharjah, Ajman, Umm Al-Quwain, Fujairah, Bahrain, Kuwait, Antigua and Barbuda, Belize, Dominica, Dominican Republic, Malaysia, Indonesia, Madagascar, Vietnam, Grenada, Guyana, Haiti, Jamaica, Saint Kitts and Nevis, Saint Lucia, South Korea, Saint Vincent and the Grenadines, Trinidad, and Tobago, etc.

For more information on engine block stitching, Repair Of Damaged Compressor Block, and turbine casing crack repair on-site, contact us at rajshahani@rapowersolutions.com or info@rapowersolutions.com, or call us at +91 9582647131 or +91 9810012383.

FAQs:

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We undertake the repair of the damaged and cracked engine block by metal stitching and metal locking process, the advantage of which is as follows.

Repair Of Cracked And Damaged Engine Block By Metal Stitching And Metal Lock Process:-

The repair by metal lock and metal stitching technique is a proven method. It is used for repairing damaged engine blocks, turbo casings, cylinder liners, pistons, and other major spares of diesel engines and heavy mechanical equipment.

The area of the crack must be identified and marked. We undertake crack detection by MPI and the dye-penetrant method, depending on the thickness of the casting. When necessary, we perform metal stitching on both sides of the damaged area. We provided that there is sufficient space for the approach of our pneumatic tools.

RA Power Solutions uses high-quality metal keys, metal locks, and consumables. Combined with the expertise of our experienced technicians, this ensures successful repairs through metal stitching and metal locking.

We have been regularly undertaking repair of engine blocks, compressors, turbochargers, and all cast iron, bronze, and aluminium for the following makes of engines:-

• Akasaka
• Mitsubishi
• Daihatsu
• Yanmar
• Hanshin
• Kobe Mitsubishi
• Caterpillar
• Wartsila
• Deutz-KHD
• Volvo Penta SKL
• MAK
• Sulzer
• MAN B&W
• SKL
• MTU MAK
• Pielstick
• MWM MAK

We have been regularly executing the repairs in Argentina, Bahamas, Barbados, Bermuda, Bolivia, Brazil, Canada, Chile, Colombia, Costa Rica, Cuba, Dominican Republic, Ecuador, El Salvador, Guatemala, Guyana, Haiti, Honduras, Jamaica, Mexico, Nicaragua, etc.

Mr. Shahani is a highly experienced business leader with 45 years of rich experience in the field of Power, Heavy, and Shipping industry. He is a Technical Adviser to many shipping and heavy industries across the globe.

Mr. Shahani is one of the most enthusiastic professionals, and he has all the brilliance of an exemplary leader. Mr. Shahani is an extremely effective coach and mentor of teams and is adept at providing leadership in a global, cross-cultural environment.

For more information on metal locking a cracked engine block, cracked engine block repair, repair of damaged engine block, metal stitching technique, or cracked and damaged engine block, contact us at rajshahani@rapowersolutions.com or info@rapowersolutions.com or call us at 9582647131 or 9810012383.

FAQs:

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RA Power Solutions technicians visited the island and undertook the inspection as per the following details:

• Inspection of engine block/entablature of Wartsila engine, model 12V32.
• On a visual inspection by our technicians, it was observed that the engine block developed multiple cracks near the inspection window.
• A piece measuring 590 mm X 360 mm was damaged from the entablature casting and came out.
• Our qualified technicians cleaned the surface area thoroughly, even the paint and the red oxide were removed.
• The MPI was done for crack detection and all the cracks were clearly identified.
• The measurement of broken casting was also taken.

The details of the crack observed are as follows:-

• Multiple cracks having a length ranging from 20 mm to 430 mm were observed.
• The discipline profile of the damaged portion of the Wartsila engine block was given by cutting and grinding the final dimensions which were observed as 660 mm X 396 mm.

Non-availability of Wartsila 12V32 engine block

Diesel engines are in operation all over the world in power plants, ships, heavy engineering industries, etc. The breakdown of the engine happens either due to mishandling, material defects, or poor maintenance of the engine. This results in a major breakdown, which can be devastating.

These types of accidents cause severe damage to the engine component or even injuries to the operator present in the engine room.

The concentrated heat caused by the welding process also results in the expansion and contraction of the casting, developing the stresses in the engine block/entablature.

Prior to the arrival of RA Power technicians on site, the owners of the Diesel power plant explored various possibilities of repair, including repair by welding process. Our technicians explained the difficulty in repairing the engine block, which is manufactured out of cast iron by the welding process. Cast iron contains a high level of carbon, which burns when the repair of casting is undertaken by a welding process.

In some cases, the welding due to the high-temperature process also results in the hardening or rather development of more cracks. We have also experienced that due to stress and contraction, there is a significant loss of the centreline of the main journal housings of the block, which is of great importance.

Repair of Wartsila 12V32 engine block by metal stitching and metal locking process

The repair of engine block and entablature of Wartsila engine model 12V32 was undertaken by metal stitching and metal locking process which is a proven cold repair method of repairing heavy cast iron casting, aluminium casting, Broken Engine Block and steel cast components.

Different types of specially designed screws and locks are used in crack and damaged casting repair in the metal stitching and metal locking process. The multiple cracks as per the details mentioned above were repaired by the metal stitching process. The damaged area of the Broken Engine Block was fitted with a new piece of casting and was metal stitched. The engine was put on load after the repairs by metal lock and metal stitching process and performance was observed as satisfactory. This job of repairing of Wartsila engine block/ entablature of 12V32 was executed in the Year 2013 and since then it has been performing satisfactorily. The client has not only saved a considerable amount by avoiding the purchase of a new engine block but also saved on downtime as they are in the business of power generation for the islands based in the Maldives.

RA Power has a dedicated team of experienced technicians headed by an engineer with more than 44 years of experience in the repair of cracks in cast iron, aluminium cast steel, and steel casting by metal stitching and metal locking.

All our technicians have valid CDC and can fly to any destination on short notice. The portable, lightweight pneumatic tools are carried by them as accompanied baggage. We have been regularly executing the repairs in Madagascar, Oman, Qatar, Philippines, Bahrain, Sri Lanka, Bangladesh, Myanmar, Turkey, Nigeria, Greece, Saudi Arabia, UK, Dubai, Malta, Cyprus, Singapore, Malaysia, Colombia, Indonesia, Hong Kong, Spain, Netherlands, Dubai, Portugal, Estonia, Morocco, Belgium, Vietnam, Canada.

This blog is written by Mr. Raj Shahani (Managing Director of RA Power Solutions India Pvt. Ltd.).

Mr. Shahani is one of the most enthusiastic professionals, and he has all the brilliance of an exemplary leader. He is an extremely effective coach and mentor of teams and is adept at providing leadership in a global, cross-cultural environment.

For more information on repair cast iron, cast iron stitching, cast iron engine repair, cast iron crack repair, cold metal stitching, cast iron engine block metal lock, broken engine block, and metal surgery contact us at rajshahani@rapowersolutions.com or info@rapowersolutions.com or call us at +91 9582647131 or +91 9810012383.

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RA Power Solutions undertakes aluminium crack repair by metal stitching, metal locking and metal surgery process which is a cold process of repair of cracks of aluminium components, cast iron components, and cast steel.

Generally, all the heavy components manufactured out of aluminium casting can be repaired by metal stitching, metal locking and metal surgery.

Cracked Aluminium Cylinder Head Repair

It is not possible to undertake repair of cracks & damage to cylinder head, cylinder liner, and components manufactured of aluminium or cast iron by welding process due to the generation of heat.

A few of these are described below:-

• Crack repair of aluminium cast pistons.
• Crack repair of the engine block manufactured out of aluminium alloys.
• Damaged or cracked pump casings, turbocharger casings, and turbine casings can be repaired by the metal locking and stitching process.
• Repair of cylinder liners and cylinder heads manufactured out of cast iron or aluminium.
• Aluminium Piston Crack Repair.

In order to undertake aluminium crack repair or repair of damaged aluminium casting, cast iron or steel casting components.

We follow the procedure given below:-

• Crack detection.
• It is important that prior to starting the process of crack repair, the cracks are properly identified, and the location is marked. The cracks are checked by the following methods.
• Visual Inspection
• Dye penetrant test of cracks in the damaged area.
• Crack detection by MPI using the high-intensity magnaflox torch.
• Pressure Testing

We strongly recommend that in case of red oxide or paint on the surface of a damaged component, it should be thoroughly removed.

• Aluminium Crack Repair by Metal Stitching and Metal Locking process

After the location of the crack or cracks is identified, the cracks are repaired by metal stitching and metal locking process.

We use the following special pins and locks for metal locking:-

• Standard threaded pins – They are straight-thread L-Series pins. They are designed to seal by interference fit after threads. The threaded pins exert spreading pressure for sealing, seat retention, and crack removal.
• Spiral thread hooks for radial drawing force are used, which creates structural integrity, seals leaks, and also prevents crack propagation.

The repair of cracks in aluminium cast components requires special tools and experience as the aluminium casting cuts easier than the cast iron, RA Power Solutions regularly undertakes repair of aluminium cast iron and steel casting components and has executed repairs successfully in countries like Dubai, Greece, Maldives, Malaysia, Singapore, Madagascar, Nigeria, South America, UAE, Germany, Monaco, Qatar, Sri Lanka, Bangladesh, Italy, Spain, Czech Republic, UK, Philippines, Singapore etc.

For more information on Piston Repair by Metal Locking, Turbine casing crack repair on-site, Cracked Aluminium Cylinder Head Repair, and Cylinder liner head repair, contact rajshahani@rapowersolutions.com or info@rapowersolutions.com or call us at +91 9582647131 or +91 9810012383.

FAQs:

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