Telescopic boom repair and lattice boom repair are fundamentally different processes because the two boom types are built on different structural systems, use different steel grades, and fail in different ways. A telescopic boom is a sealed, multi-section sliding assembly, while a lattice boom is an open, modular framework of connected steel tubes and chords. Understanding that distinction determines everything from how damage is assessed to how the repair is executed and certified.
Which types of damage affect telescopic and lattice booms differently?
Telescopic and lattice booms are vulnerable to different damage patterns because of how they are built and how they carry load. Telescopic booms concentrate stress in specific zones along the inner and outer sections, making them prone to cracking and deformation in high-tension areas. Lattice booms, by contrast, distribute load across a network of members, so damage tends to appear as bent or fractured individual tubes, chord failures, or compromised node connections.
On a telescopic boom, the most common damage types include:
- Cracks in high-stress zones near the heel and tip sections where bending forces are greatest
- Dents and deformation in the boom skin caused by side-loading or contact damage
- Wear and scoring on sliding surfaces where sections telescope past one another
- Corrosion in areas where moisture becomes trapped between sections
Lattice booms present a different damage profile. Because the structure is open and modular, individual members can be inspected visually with relative ease, but impact damage to a single chord or diagonal can compromise the load path of the entire section. Buckled or bent tubes, cracked weld connections at nodes, and fatigue cracks along heavily loaded chords are the most frequent findings. The open geometry also makes lattice booms more susceptible to damage during transport and assembly on site.
How does the repair process differ between telescopic and lattice booms?
The repair process for a telescopic boom is more geometrically constrained and technically demanding than that for a lattice boom. Telescopic boom repair requires precise dimensional control because the repaired section must slide within tolerances of fractions of a millimetre. Lattice boom repair is more modular, allowing individual members or sections to be replaced or re-welded with greater flexibility, often at the client’s location.
For a telescopic boom repair, the process typically involves:
- Detailed inspection and dimensional measurement of the damaged section
- Preparation of a Welding Procedure Specification (WPS) and a formal Repair Plan
- Controlled workshop conditions to maintain the correct pre-heat and inter-pass temperatures required by the steel grade
- Welding by certified specialists using procedures approved for high-grade steels
- Post-weld inspection including 100% visual inspection and 100% Magnetic Particle Inspection (MPI) on all new welds
- Ultrasonic or X-ray testing by a third-party Notified Body where required
For a lattice boom repair, the process follows the same quality standards but benefits from greater accessibility. Individual damaged members can often be cut out and replaced, or cracked welds can be ground back and re-welded at the node. Because the structure is open, MPI and visual inspection are easier to perform across the full repair area. Lattice boom repairs can frequently be carried out at the client’s location anywhere in the world, or brought into a workshop, whichever is the more practical and economical option.
Why is repairing high-grade steel booms so technically demanding?
Repairing high-grade steel booms is technically demanding because the steels used in modern crane booms, particularly those rated at 960 and 1100 N/mm², behave very differently from ordinary structural steel during welding. These ultra-high-strength steels are sensitive to heat input, cooling rates, and hydrogen content. An incorrect welding procedure does not just produce a weak weld, it can introduce hydrogen-induced cracking or heat-affected zone embrittlement that may not be visible immediately but leads to catastrophic failure under load.
Several factors make this work genuinely specialist in nature:
- Material strength classification: Steels above 690 N/mm² require purpose-written welding procedures that are tested and approved specifically for that material grade. Generic welding procedures are not acceptable.
- Temperature control: Pre-heating, inter-pass temperature limits, and controlled post-weld cooling must all be maintained within tight parameters throughout the repair.
- Consumable selection: Filler materials must match the mechanical properties of the parent steel. Using the wrong consumable reduces the strength of the repaired zone below the design requirement.
- Welder qualification: Technicians must hold welding qualifications specific to the material grade and joint configuration being repaired.
- Non-destructive testing: Because visual inspection alone cannot confirm weld quality in high-strength steel, MPI and ultrasonic testing are mandatory quality steps, not optional extras.
The scarcity of companies capable of performing this work correctly is significant. Across Europe, only a handful of specialists have the approved procedures, qualified personnel, and controlled workshop environments needed to repair 960 and 1100 grade telescopic booms to a standard that restores the original structural value.
Does a repaired boom retain its CE certification and load ratings?
Yes, a professionally repaired boom can retain its CE certification and original load ratings, provided the repair is carried out by a qualified specialist using approved procedures and verified through proper non-destructive testing. The key requirement is that the repair restores the boom to a condition equivalent to the original, and that this is documented and independently verified where the certification authority requires it.
This outcome depends on several conditions being met. The repair must follow a documented Welding Procedure Specification that has been validated for the specific steel grade. All welds must pass 100% MPI, and ultrasonic or X-ray testing must be completed when required by the Notified Body overseeing the certification. The repair documentation then forms part of the crane’s technical file, demonstrating to inspectors and clients that the boom has been restored to its rated capacity.
For crane operators and fleet managers, this is a critical commercial point. A repaired boom that retains its CE marking and load ratings can return to full operational use without restriction. There is no requirement to downgrade the crane’s rated capacity or impose additional operational limits, provided the repair has been executed and documented correctly.
When should a crane operator repair a boom rather than replace it?
A crane operator should repair a boom rather than replace it in most cases where the structural damage is localised and the boom material has not been compromised beyond what a qualified repair can restore. Repair is almost always faster and significantly less expensive than sourcing a new boom section from the original manufacturer, particularly for high-grade steel booms where OEM lead times can run to months and costs are substantial.
Repair is the preferred route when:
- The damage is confined to a specific zone rather than distributed across the full boom length
- The boom steel grade is 960 or 1100 N/mm², where replacement parts carry very long lead times and high costs
- The crane is a critical asset and downtime must be minimised
- The boom is no longer in production and replacement parts are unavailable from the manufacturer
- The overall condition of the boom outside the damaged area is structurally sound
Replacement becomes the more appropriate choice when damage is extensive across multiple sections, when the boom has reached the end of its fatigue life, or when the cost of repair approaches or exceeds the value of a replacement. A qualified specialist will assess this honestly after inspection, because a reputable repair company will only commit to work they can guarantee meets the original specification.
What should you look for in a qualified crane boom repair specialist?
A qualified crane boom repair specialist should hold approved welding procedures for the specific steel grades they work on, employ certified welders, and be capable of performing and documenting non-destructive testing to the standard required for CE certification. Beyond technical credentials, look for a company with a documented track record of repairing the boom type and steel grade relevant to your equipment.
The key qualifications and capabilities to verify include:
- Approved Welding Procedure Specifications (WPS) for high-grade steels, including 960 and 1100 N/mm² grades if applicable to your fleet
- Certified welding personnel with qualifications specific to the material and joint types involved in boom repair
- In-house non-destructive testing capability, including MPI as a minimum, with access to ultrasonic and radiographic testing
- Quality management certification, such as ISO 9001, confirming that repair processes are documented and consistently applied
- Experience with the specific boom manufacturer and model, since boom geometry and steel specifications vary significantly between manufacturers
- Ability to provide a written repair plan and full documentation for the crane’s technical file
- A guarantee on completed repairs, demonstrating confidence in the quality of the work delivered
For operators with offshore or internationally deployed cranes, the ability to mobilise repair technicians to remote locations is an additional requirement. Not all specialists can deploy globally at short notice, and for offshore platforms or international job sites, this capability can be the difference between a short repair window and a prolonged outage.
How Rusch Cranes approaches telescopic and lattice boom repair
Rusch Cranes is one of only three companies in Europe approved to repair telescopic booms made from 960 and 1100 grade high-strength steel, with more than 27 years of specialist experience in both telescopic and lattice boom repair. Their approach covers every technical requirement outlined above, from initial inspection and WPS preparation through to post-repair non-destructive testing and CE certification. Key elements of their service include:
- A rigorous pre-repair process covering material strength verification, Welding Procedure Specification, and a formal Repair Plan before any welding begins
- 100% visual inspection and 100% MPI on all new welds, with third-party ultrasonic or X-ray testing available through a Notified Body when required
- Repairs carried out in their workshop in Medemblik, Netherlands, or on-site at the client’s location anywhere in the world for lattice boom work
- CE certification validity maintained after repair, with a 1-year guarantee on all completed work
- Global deployment capability for international and offshore projects, with technicians available around the clock
If you are dealing with a damaged crane boom and need to understand whether repair is viable for your specific equipment, contact Rusch Cranes directly to discuss your situation and receive a professional assessment.
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