Bluff gantry crane commissioned

Jun 18, 2003
Author: P&S


The Bluff Mechanical Appliance (BMA), which has been a feature of the Durban port since the early 1900s, recently completed the upgrading of a 30.5 tonne container crane which has been adapted for use with loading coal.

BMA is part of the Bidvest investment holding company, and specialises in the export (and import) of sized coal parcels from Durban, which for a variety of reasons cannot be handled at Richards Bay.

Currently the BMA handles about 2 million tonnes of exports each year, which may sound insignificant compared with the 60 plus million tonnes handled at Richards Bay, although by most standards is nothing to laugh at. A number of acknowledged coal ports throughout the world handle even less than this sort of volume.

What makes the BMA even more significant is that for many years it has operated with equipment dating back to the early part of the last century. This was kept running by onsite engineers and has been gradually upgraded or replaced with other cargo handling appliances acquired second hand from elsewhere and refurbished.

The average ship size handled by the BMA is 40 000 tonnes with the largest single uplift having been 52 000 tons. At the other end of the scale the BMA regularly handles small parcels of specialised coat of less than 1 000 tonnes.

The BMA features some of the more integrated facilities in the port combining vessel, rail and terminal information, which is updated daily and published on their website www.bulkterminals.co.za

In line with the terminalís re-engineering philosophy, a 30.5 tonne Demag ship-to-shore container crane was purchased from the port of Durban for its scrap value. The crane was designed in1978 and had an all-up machine mass of 450 tonne, but BMA felt it still had value provided it was refurbished.

The first task was to relocate the crane to the BMA, 3km distant, which proved to be no easy task given the constricted access to the Bluff terminal and would require a full dismantling on site before moving it across either by road or on the floating crane. All the electrical equipment was discarded as it was DC whereas BMA is on an AC system. After breaking down to manageable sizes the portís 260-tonne floating crane was utilised with the aid of land-based hydraulic jib cranes. The final section of 200 tons was in fact too large to fit on the deck of the crane and had to be transported across the bay while suspended at the end of the craneís hook.

The first phase of the refurbishment was a thorough inspection and replacement of any sections badly corroded or irreparable. Other specialist companies were brought in to do an evaluation of the machine and to undertake computer simulations based on different load cases. Although the machine had a design capacity under headblock of 30.5 tonnes, modification has increased this to 55 tonnes.

This was made possible because when the machine was designed 25 years ago less sophisticated design tools were available plus the design was selected to minimise costs. There were also some technical requirements imposed on the supplier by the previous owner. Structural changes were made to render the alterations safe and effective including modifying the front rail bogies from single to double rail configuration and a strengthening of the legs.

After shot blasting the machine has been coated with five layers of paint applied to a minimum DFT of 600 microns. Other small components, walkways, stair treads were hot dipped galvanised prior to painting.

With the motors refurbished and re-equipped and an AC electrical system installed, new brakes fitted and new gearboxes fitted, the giant machine was re-assembled over a period of ten days and commissioned for service in February this year. The total refurbishment took 18 months and cost R12 million, a fraction of the cost of a new crane.

The machine is at present operating at an average cycle time of a container lift every 2 to 3 minutes.

During the course of refurbishing this crane a second identical crane became available and has been acquired for strategic purposes. A discharge hopper was designed to be incorporated into the machine. This hopper has a heaped capacity of 115 cu m with a 7m x 7m opening suitable for a 20 cu m hydraulic grab. The hopper is supported off the main portal structure and is able to travel out of the way to the back of the machine when not required.

In addition a rotating container spreader with the ability of lifting a 20-tonne open top container which can be rotated through 180 degrees to empty the contents into the ships hold. This device is designed for the loading of bulk materials up to a density of 1,100 kg/cu m.

The container crane in its present state has the ability to handle four different loading or unloading scenarios by changing the spreader configuration under the headblock in a short space of time.


SOME BACKGROUND

The BMA has four berths and handles over 2 million tonnes per year. 90 % of the ships calling at the terminal are tramp vessels on a voyage charter. The remaining ships are on a time-charter and call at regular intervals. All vessels are required to give a 14-day nomination period in order to qualify and any vessel substitution constitutes a new nomination. Operating Rules and Regulations, which govern the criteria for the berthing and seniority of vessels, are available from the company. The telephone number is 27 31 466 1960, email is bmacoal@icon.co.za Email is the companyís preferred method of communication. See also the website at www.bulkterminals.co.za

Berth 1: 145.8m Draught 8.8m CD
Berth 2: 183.5m Draught 10.3m CD
Berth 3: 183.5m Draught 8.8m CD
Berth 4: 220.2m Draught 10.3m CD

Tides: Spring Rise is 1.8m, Neap Rise is 0.5m

RAIL NETWORK

The Bluff Mechanical Appliance (BMA) has the largest private rail siding in the Port of Durban. This siding (called Wests, with a siding number 651958) is connected to the main line and all incoming trains are brought directly from the mines into the exchange yard.

South Africa has an extensive rail network, currently operated by Spoornet. Rail traffic to and from the BMA is regulated jointly by BMA Operations Planning and Spoornet Central Planning office in Johannesburg.

Trains are scheduled to arrive using a priority permit system that regulates the sequence and flow of traffic. Trains are categorised into two main groups, vacuum brake trains and air brake trains. Vacuum brake trains utilise up to 40 wagons per train, each holding around 35 tonnes of coal while air brake trains consist of 50 wagons, each holding around 48 tonnes.

Careful planning and just in time wagon management is aimed for to achieve the terminalís competitive productivity.

Distances from the BMA to the South African mines range from 300km to over 900km. However traffic from the Copper Belt in Zambia is also routinely offloaded at the terminal.


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