An extensive reference base of successful heavy lifts, an experienced design, rigging and operational crew, the company’s cost effective 50 t, 38 m radius lifting capability, and the ability to mobilise quickly and efficiently were deciding factors in the award of a heavy-lifting contract to South Africa-based mobile crane hire company Johnson Crane Hire.

The company started work on the removal and replacement of a number of components on hard stone processing company Debmarine Namibia’s !Gariep offshore diamond mining vessel in March this year.

While Johnson Crane Hire has supplied several smaller cranes to a variety of diamond producer De Beers Marine’s projects in the past, this is the first time that the company has performed a heavy lift for the organisation.

The scope of work for the project comprised removal and installation, in this specific order, of the 24 t crown; the 45 t lifting guide beam complete assembly; the 42 t compensating guide beam complete assembly, including spout and upper universal; the 42 t stabiliser guide beam, including the lower universal, power swivel, water rotor and elevator; the 22 t gimbal; and two 50 t drill bits; as well as various mining system equipment.

Johnson Crane Hire Heavy Lift Division GM Cornelis Grotius explains that the company is able to leverage its extensive experience with a wide spectrum of clients across the petrochemicals, civil engineering and construction, power, mining and heavy manufacturing sectors.

“Working conditions on a marine vessel heavy lift could be compared to the congested conditions and space constraints experienced on petrochemicals contracts. The emphasis on safe operating conditions, while always a priority for Johnson Crane Hire, is magnified in such environments. Careful planning, reliable equipment and a well-trained and experienced operational team are critical factors in the success of these projects,” Grotius points out.

Upgrade Plan
The !Gariep was acquired by diamond major De Beers in 1998. The vessel was redesigned, re-equipped and then deployed to the Atlantic 1 mining concession area, near the mouth of the Orange river, off the Namibian shoreline.

The !Gariep is now owned, operated and managed by Debmarine Namibia and is registered at the Namibian port of Lüderitz. Scheduled maintenance and upgrading of the Debmarine Namibia vessels are undertaken every three years, when the vessels berth at the Sturrock dry dock, in Cape Town.

De Beers Marine senior mechani- cal engineering officer Eugene Lamont explains that plant and equipment upgrades are undertaken to improve the performance of the vessel and require extensive forward planning. “Once the !Gariep is placed in the dry dock, it is critical that all repairs and upgrades are expedited, to allow for the vessel to return to base as rapidly as possible,” he says.

Lamont adds that the company has started planning the next round of upgrades for the vessel for 2018.

Johnson Crane Hire selected its Liebherr 750 t, all-terrain hydraulic crane for the !Gariep contract, owing to the sheer size and weight of the components to be lifted. The crane was deployed from Johannesburg under its own power and the counterweight and 28 m luffing jib were transported sepa- rately on low-bed trucks to Cape Town.

“We were cognisant at all times of the tight contract period so the team quickly sprang into action to ensure that deadlines were adhered to. “The sometimes excessive winds in the harbour area were an aggravating factor but, due to careful planning and our ability to work in challenging environmental conditions, we were able to [stick to] the project schedule without incident,” says Grotius.

He notes that the team, by working between 10 to 12 hours each day, successfully completed the project within the revised forecast period of 55 days.

Grotius adds that conditions at the Sturrock dry dock were extremely congested, with several marine contractors vying for space to work on the !Gariep at one time. “Proper planning of the lifts and open communication lines with the client and other contractors were paramount to the success of the project. “It was incumbent on the Johnson Crane Hire team to remain adaptable and adept at all times,” he emphasises.