SAVCOR Art was recently commissioned to carry out remedial works on a chimney stack at Loy Yang Power station. With safety being of paramount importance, and a critical time frame that imposed a challenging deadline, Savcor called upon the expertise and resources of the vertical access solution provider, Alimak Hek. The solution was the Hek MSM Super Mast climber, and the project was the tallest in the world for Alimak Hek, with a working height of 250m. The project called for eight Hek MSM’s of 8.67m length, positioned at 45 degree intervals around the entire circumference. Due to the tapered incline of the chimney stack, only four climbers could be erected at one time, with the erection and dismantle programming critical to ensure optimal productivity.

George Barbour, national product manager notes some of the technical challenges that were faced and overcome:

Special brackets had to be designed, fabricated and fitted on the underside of each platform to support the 250m trailing cables which weighed in excess of 300 kg each.

The trailing cables had to be hard wired into switch boxes fixed to the chimney face at the halfway point to avoid voltage drop.

Standard cable trolleys had to be re-designed and fitted to prevent the trailing cables from being tangled around the mast during the regular periods of high winds.

A 30m high steel structure supporting a horizontal conveyor belt allowed only enough space between the structure and the stack face for the mast to pass through, which meant double deck platforms had to be installed, one below the conveyor so workers could access the façade from ground level up to 30m in height and the second was installed above the conveyor allowing access to the remaining full height of the chimney.

As the platform edges had to be profiled to suit the contoured shape of the chimney façade, and to keep and even distance at both ends of the working deck, the rigging team also had to overcome the natural effect of gravity which causes the mast to want to corkscrew during the erection process.

The project was completed on time, under budget and without a single LTI (lost time injury). The demand for Mastclimbers is growing at an exponential rate as more and more providers of specialised remedial works embrace the concept of rack and pinion work platforms and the benefits when compared to scaffolding and swing stages.

Alimak Hek also provide a cost calculation program which demonstrates the savings available when using this type of vertical access equipment.

Source: Construction Contractor