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Metal Stitching for Cast Iron Block Repair

Goltens’ Cast Iron Repair Minimizes Cost and Downtime

On-site Metal Stitching is often the only reasonable method to repair cast iron cracks and salvage what is otherwise a condemned component or major piece of machinery. Traditional welding methods are not effective for repairing cast iron and other cast metals and in many cases can result in more damage to the piece being welded.

Metal stitching to repair cast metal damage has a variety of benefits:

  • It provides a permanent crack repair without the introduction of heat associated with welding.
  • It can be performed on-site avoiding the high costs associated with disassembly and transport.
  • The repaired area is restored to its original strength with a watertight and gas tight repair.
  • On-site machining and milling restores the surface of the repaired area to original dimensions

The applications for the process are many and cover a broad range:

  • Cracked Engine Block Repairs (sidewalls, liner bores)
  • Damaged Engine Bedplate repairs
  • Steam turbine repairs
  • Repairing damage to heavy industrial machinery
  • Metal crack repairs for mining equipment and large earth moving machinery
  • Damaged pump casings, gear boxes and gears

How to repair cast iron?  This is how the metal stitching process works.

1. The image shows damage to a MaK 12M282 diesel engine block resulting from a connecting rod failure. Without metal stitching to repair the cast metal damage, the block would be condemned.

2. After performing extensive crack tests to ensure that all damage is captured, the damaged area is cropped out of the engine block leaving a clean surface to metal stitch a replacement piece into place.

3. A replacement cast iron insert section matching the original casting is then shaped to the exact dimensions of the cropped section of the block in preparation for repairing the block.

4. This cast metal insert is then fit into the hole in the damaged engine block, checking for fit and grinding the insert as necessary to unsure the mating surfaces have perfect contact before beginning stitching.

5. Once the insert is fit, holes for the metal stitching pins are drilled and tapped along the mated seam between the block and the insert.

6. Stitching pins are then screwed into place along the entire seam between the engine block and the cast metal insert. The stitching pins draw metal on both sides of the seam together when they are tightened.

7. Once the seam is completely stitched, the heads of the stitching pins are removed in preparation for insertion of the locks.

8. Prior to lock insertion, the surface of the stitched seam is machined using portable machining tools and stress relieved and checked to ensure that there are no cracks or irregularities.

9. Using a drilling template, a precision hole pattern matching the dimensions of the metal locks are made at various points along the stitched seam.

10. Locks are then driven into the hole patterns along the seam drawing the repaired seam even closer together.

11. Once the locks are installed along the seam, the surface is machined clean and the repair is checked to ensure it is crack free resulting in a watertight and gas tight repair using a dye penetrant or other NDT method.

FAQs


What is metal stitching, and when do marine and industrial operators need it?
Metal stitching is a cold, mechanical repair method that permanently rejoins cracked or broken cast metal without welding or heat, restoring the component to its original strength as a watertight, gas-tight repair. Operators turn to it when a large, expensive casting cracks and the alternatives are unattractive.  Welding cast iron risks making the damage worse, while replacement means long casting lead times, increased replacement cost and extended downtime. For examples of metal stitching repairs performed for marine, power generation and marine take a look at representative metal stitching case studies. Metal stitching is frequently the only practical way to salvage a component that would otherwise be condemned.

How does Goltens' metal stitching process work on large engine and machinery castings?
Goltens begins with crack testing to map the full extent of the damage before any work starts, then drills and taps a hole pattern along the fracture and threads in stitching pins that draw both sides of the crack together. Metal locks are then driven across the seam to pull it tighter still, the surface is machined flush, and the finished repair is verified crack-free by dye penetrant or another NDT method. Where a section has broken away entirely, a matched cast insert is fabricated to the exact dimensions of the cropped area and stitched into place and on-site machining returns the repaired surface to its original dimensions.

Can a cracked engine block or bedplate be repaired without removing the engine?
Yes. Because metal stitching is a cold process, Goltens performs it in place — a cracked main engine block, sidewall, liner bore, or bedplate can be repaired without pulling the engine or moving the vessel to a specialist yard. That is a decisive advantage at sea and in port, where removing an engine is often impossible without major disassembly and interruption and every day out of service is off-hire. Goltens combines the metal stitching with in-place machining, including line boring, laser alignment, and other specialty services as required so the full repair is completed on board by Goltens.

Why is metal stitching preferred over welding for cast iron in marine and power generation equipment?
For cast iron engine and machinery components, metal stitching is generally the better repair because it introduces no heat into a material that reacts badly to it. With its extremely high carbon content, welding cast iron risks fresh cracks, distortion, and residual stress that can reopen under the thermal and vibration loads of a running engine or generator set (a serious liability on a diesel, dual-fuel, or gas engine). Metal stitching instead delivers a permanent, watertight and gas-tight joint restored to the casting’s original strength, without the heat-affected zone that undermines a welded cast iron repair.

What components does Goltens repair with metal stitching across marine, offshore, and power generation?
Goltens repairs cracked and broken cast components throughout heavy engine and industrial equipment: engine block sidewalls and liner bores, engine bedplates, steam and gas turbine casings, as well as pump casings, compressor casings, gear boxes, and other machinery. It has salvaged severely damaged assets others had written off — including HP and LP compressor casings and large marine diesel blocks. When a repair needs more than the stitching, Goltens draws on adjacent in-situ services such as crankshaft machining and repair and engine parts reconditioning.

Is metal stitching more cost-effective than replacing a cracked engine block or casing?
In most repairable cases, metal stitching is significantly more cost-effective than replacement, because it salvages a component that would otherwise be scrapped and avoids the price and long lead time of a new casting. For marine and power generation operators the larger saving is often downtime where an in-place repair keeps the asset where it is and gets it back online without a removal-and-transport cycle. Because every crack differs in size, location, material, and accessibility, Goltens quotes each job after inspection — you can start that with a service request.

What makes Goltens different from other metal stitching providers?
Goltens pairs metal stitching service with its complete in-place machining and large engine service capability and decades of heavy marine, offshore, and power generation experience.  Goltens provides a single team that is capable of performing the entire repair rather than handing the job across multiple vendors. Its work is proven on demanding assets, including a Wärtsilä 18V32LN engine block, a MaK 12M282 diesel block wrecked by a connecting-rod failure, and badly damaged HP and LP compressor casings, all documented in the metal stitching case studies. Goltens is built for operators who need a repair done where the equipment is — a service request reaches the right one.

Case Studies

Case Study

Engine Block Repair – Metal Stitching Wartsila 18V32LN

 Case Study

Is a repair even possible?

 Case Study

Goltens Metal Stitching repairs salvage engine block

 Case Study

Metal Stitching Salvages Badly Damaged HP And LP Compressor Casings
All Metal Stitching Case Studies

Let Goltens Solve Your Challenge

Goltens is the right partner for ship owners and power plant operators all over the world. Response to all service enquiries typically falls within 12 hours.

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