Mega Jack rises

ALE has completed its first project using the heavy lift Mega Jack hydraulic jacking tower system. Three 1,500 tonne roof sections for a new stockpile building were jacked up for a mining company in Argentina 4,000 metres above sea level.

Challenges on the high altitude project included high winds, temperatures ranging from -30 to +20 centigrade and air pressure as low as 0.6 bar. It was also in an earthquake area.

The method used to construct the roof was also a first. Due to the altitude and harsh weather it was decided that the girders would be preassembled at lower altitude and transported to the installation site. ALE used the Mega Jack system to raise the roof in three sections, each weighing 1,500 tonnes.

ALE used four towers of the Mega Jack System, with a total capacity of 20,000 tonnes, and ten 90 tonne capacity hydraulic skid shoes. With possible wind speeds of up to 150 km/h ALE took additional precautions by installing a guy wire system consisting of four 200 tonne capacity strand jacks at each end of the building to withstand high winds.

The three roof sections were positioned above the ground on temporary stands. The skid systems were at each end of the building to enable the side sections of the roof to be skidded inwards while the main inner section was lifted 18 m to its final position by the Mega Jack. Once complete the three sections created an A-frame shaped building.

Ronald Hoefmans, ALE group technical director, said, “This project shows not only the capabilities and reliability of our equipment but also that of our highly trained personnel on site who overcame extreme conditions to ensure the project was a success. We are also pleased that the Mega Jack has completed its first project and as such has illustrated its versatility in conditions and also market sectors.”

Mega Jack was launched in 2011 to meet demand from the offshore industry, primarily for the jacking of oil and gas platform modules and other large structures. It is designed to lift up to 60,000 tonnes to a height of 50 m. ALE engineers designed and built it at the UK-based company’s research and development facility in Breda, the Netherlands.

Each jacking tower has a jacking capacity of 5,200 tonnes and each tower consists of four jacking bases that contain an hydraulic jack with a stroke of 1,250 mm. With the starter beams in position above the jacking bases and the jacks fully retracted, the system is ready to make its first stroke. In this position the starter height is just below 3.5 m. After that two of four integral feed-in systems automatically insert the first set of jacking beams through the temporary supports.

Once in place, the jacks extend and raise the beams above the temporary supports, which rotate to hold the load while aligning their open sides with the other two feed-in systems, ready to repeat the process.

The number of towers can be adapted and increased according to the size, weight and balance of the structure, opening up new possibilities for an offshore sector increasingly under pressure to build ever bigger rigs, ALE said.

Basic tower footprints consist of 2.5 x 2.5 m, 2.5 x 5 m and 5 x 5 m jacking base centre distances, allowing tailor made solutions for each client. By combining jacking bases in different configurations, jacking points with 5,000, 10,000 and 15,000 tonne capacities can be created.