Alatas Service: Field Service
Alatas was tasked with the sheave overhaul and repair the EH36 top steel sheaves column structure after it had collapsed after an accident.
After we assessed the GA of the vessel, we found the adjacent crane could not reach the repair location where it’d be required to perform the lifting of the damaged steel bracket sheaves and the newly fabricated 3-ton replacement.
Cutting Costs of Overhauls
To perform these repairs at anchorage usually requires a floating crane which can cost S$38,000 per day in Singapore.
Designing and fabricating an A-frame davit to be mounted at the top of the column to carry out the lifting activities proved to be a cost-effective alternative solution for our client. The fabrication cost for the A-Frame davit amounted to only S$900.
Engineering the Solution for Repairs
Delivering this money-saving option for our client, we opted for a highly technical process that took all of the skills of our Field Technicians; combining construction methods, skilled trades and a competent understanding of a variety of tools and equipment.
Job Scope of Sheave Overhaul
- Supply of 5 new EH36 steel plate sheaves from Alatas Equipment stock
- Plates cut, shaped and bent as per Alatas repair procedure
- Sheet work approved by NKK Surveyor before installing at the top of the column
Safety and Certification
EH36 is high-strength steel but requires a more complicated welding process and specific weld rods are needed. At Alatas we have specialist expertise such as our ABS-certified welders who were ready to perform the welding work right away.
Quality-control inspections and ultrasonic testing (NDT) was undertaken by the NKK surveyor. The sheaves and pins shafts were were also MPI inspected (NDT) ensure there was no other defect after the accident.
With steel repairs and a satisfactory function test, we used our certified load test equipment to perform the overload test in the presence of the NKK surveyor.
A final ultrasonic test (NDT) was carried out on the welded areas then the job was completed after the confirmation that there was do damage after load testing.