3rd party in RTG crane height increase from 18 to 21 meters. Performed RTG structural analysis (fatigue, buckling and static strength), checked the crane stability, design and drawings of the additional leg sections, exhausting pipe section, additional tie beam (BS 2573).

LIEBHERR Deck Crane

During Deck crane structural survey the plastic deformation of a lug of jib-column joint was found. It was to be replaced with a new one.

However, the grade that was used during manufacturing was absent at the ship yard and the delivery time was significant and could lead to the extra costs for vessel idleness.

It was decided to use GOST steel grade, so the question was whether it was possible to use the closest (according to mechanical properties) steel grade 10HSND instead of the original steel grade.

To find this out, static strength of the jib structure was checked for following cases:

• maximum outreach– 22 m with 40 t load;
• minimum outreach– 2.1 m with 40 t load;

Bearing stress in the jib-column join. Calculation was performed in accordance with the requirements of the Russian Register of Shipping (RRS).

CONCLUSIONS

The Structural Analysis has proved that the crane jib strength will be satisfied if the GOST grade 10HSNT is used.

The Customer included the calculation as a substantiation into the documents submitted to the RRS. The inspector granted approval.
This helped in:

1. To save time, which otherwise would have been necessary for delivery of foreign grade steel to Ukraine.
2. To save money, which otherwise would have been necessary to purchase and delivery of foreign grade steel to Ukraine and for the vessel idleness