PROJECT OVERVIEW
The Challenges
During the structural survey of the LIEBHERR deck crane, plastic deformation of a lug in the jib-column joint was identified. The damaged lug required replacement.
The original steel grade used during manufacturing was not available at the shipyard, while delivery of the specified material would have resulted in significant vessel downtime and additional costs.
An alternative GOST steel grade was therefore considered. The engineering assessment was performed to determine whether steel grade 10HSND, selected based on comparable mechanical properties, could be used instead of the original material.
The jib structure was checked for static strength under the following conditions:
> Maximum outreach — 22 m with 40 t load
> Minimum outreach — 2.1 m with 40 t load
> Bearing stress in the jib-column joint
The calculations were performed in accordance with the requirements of the Russian Register of Shipping
Norway
LIEBHERR Deck Crane
Static Strength
Russian Register of Shipping (RRS)
STRUCTURAL ASSESSMENT
Engineering Verification
Load Cases
> Minimum outreach — 2.1 m with 40 t load
> Bearing stress in the jib-column joint
Design Standard
The calculations were performed in accordance with the requirements of the Russian Register of Shipping (RRS)
Load cases used for static strength verification of the jib structure.
FINITE ELEMENT ANALYSIS
Structural Analysis Results
Static Strength Verification
Finite element analysis was performed to verify the static strength of the crane jib structure and assess the proposed replacement steel grade under the specified load cases.
The analysis confirmed that the jib strength requirements are satisfied when the GOST steel grade 10HSNT is used.
RRS APPROVAL
The calculation was submitted by the Customer to the Russian Register of Shipping (RRS) as technical substantiation. The RRS inspector granted approval.
PROJECT OUTCOME
Engineering Assessment Result
The engineering assessment confirmed the suitability of the proposed replacement steel grade for the damaged jib component. The calculation was submitted as technical substantiation and approved by the Russian Register of Shipping (RRS) inspector.