African Fusion’s Peter Middleton visits Hydra Arc’s Sky Hill engineering, fabrication and machining facilities in Secunda and talks to engineering manager Ewan Huisamen and Gert Swanepoel, the superintendent of the state-of the-art machine shop now being finalised in Bay 4 of the facility.

From its roots as a supplier of specialised welders into the local petrochemical industry in Secunda, Hydra Arc has grown into a leading South African provider to South and southern Africa’s petrochemical, power, mining and minerals processing industries. Services offered include: plant refinery maintenance and specialist turnaround contracts; the fabrication of heavy equipment, modular plant, pressure vessels and water tanks; and turnkey onsite construction services and repairs.

TOS Varnsdorf Tandem millThe centrepiece of the new bay is a tandem horizontal boring mill from TOS Varnsdorf, the first tandem machine of this size in the world.

In addition, in spite of current lean times with respect to new investments in plant development, which is particularly acute in the heavy fabrication sector, Hydra Arc is currently undertaking a massive expansion to its Sky Hill facility to position the company as the ‘can-do’ destination for local and regional work that can currently only be accommodated overseas.

“From a machining perspective, we know of several cases where large components had to be sent to China for machining after being fabricated here,” Huisamen tells African Fusion, adding that the lack of large machining capacity also results in whole fabrication contracts being awarded overseas – in spite of the huge associated transportation costs.

The Sky Hill Heavy Engineering facility was opened in October 2009 to service the growing need for replacement and new plant components. Notable completed projects include five 446 ton, 59 meter propylene bullets manufactured in 2013 and heat treated as a single piece in the company’s purpose-built 66 meter furnace; and the fabrication of 24 interconnectable plant modules for Sasol’s Coal Tar Filtration East (CTFE) project, several of which have mass of over 400 tons.

“We have pioneered the local fabrication of a new approach to plant design and construction, an approach that strives to maximise the amount of factory-based fabrication and minimise onsite construction time,” explains Huisamen. “We were able to complete the fabrication of all five bullets, under factory conditions, in a little over six months,” he claims, “a task that has historically taken up to several years to complete if undertaken onsite,” he points out.

With a length of 500 m and a 23 m width, the near-complete Bay 4 of Sky Hill features a hook height raised to 19 m and a total lifting capacity of 1 500 t. Most notably, a state-of-the-art, machine shop is currently being installed to complete the company’s factory-based manufacturing capability for heavy modules and plant equipment.

The centrepiece of the new bay is a tandem horizontal boring mill from TOS Varnsdorf, the first machine of its kind in the world.

This machine consists of two milling stations that travel along opposite ends of a 33 m common rail, allowing two independent machining operations to be completed on the same equipment simultaneously. A floor-level bed 36 m long by 8.0 m wide sits in front of the rail and incorporates two rotary platforms that can handle 60 and 40 t workpieces, respectively.

“Setup times will be halved on very big fabrications, as we have the capacity to machine both ends at the same time. Machining of 33 m in the x-, 5.0 m in the y- and 1.0 m in the z-direction can be accommodated on fabrications of up to 5.0 m high,” says Swanepoel.

“From years of experience on boring mill work, we know the challenges and where the time constraints are. With this machine, along with the work flow and capacities of the supporting machines, we aim to provide a cost-effective and time-saving service that is at or above international quality standards,” Swanepoel explains.

Critical to the modular plant approach is that, once onsite, interconnectivity with other modules is seamless and precise. In spite of jigging and accurate clamping, machine tool tolerances are impossible to achieve through fabrication alone. “This tandem TOS Varnsdorf boring mill allows us to machine heavy plant modules, pressure vessels, columns or heat exchangers to the precise tolerances required. It gives us a capability previously unavailable anywhere in Africa,” Swanepoel says.

In addition to the new Bay 4 and its machine shop, Bays 1 to 3 at Sky Hill are also being extended to the full 500 m length. “We have to move our heat-treatment furnace to accommodate the expansion and, in the process, we intend to upsize it to 15×15×80 m,” Huisamen reveals.

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Peter Middleton
Phone: (011) 622 4770
Fax: (011) 615 6108

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Phone: (011) 622 4770
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