Precision planning is crucial for rigging
02 August 2019
Modulift’s Harshal Kulkarni discusses the importance of precise rigging calculations when using spreader bars and other lifting devices.
As the demand to lift heavier and more complex objects increases, it becomes more important than ever to precision plan in advance.
I have a great passion for chess which I’ve played since I was a child. It keeps my mind sharp as I plan my next move and formulate a strategy. The middle game is my favorite part. As an engineer, I’ve specialized in integral lifting analysis – the science of calculating correctly how to design a safe lifting process. This requires a similar approach – careful planning and a robust strategy.
To provide an accurate analysis of a lift, it requires the customer to provide their design and it’s then integrated with a lifting design model, which produces a combined computer analysis. For heavy lifting, which includes items weighing more than 100 tons, these calculations are even more crucial. Fortunately, we have the technology and the skills in our team to perform this analysis to a very high standard.
I’ve worked extensively in the oil and gas industry, typically lifting fired heaters – critical pieces of equipment that heat gases or liquids as part of the refining process. These are complex, expensive and relatively fragile items and, as you can imagine, there’s a lot that can go wrong when craning these sorts of things onto oil platforms in the middle of an ocean.
Equally, heavy lifts can be tricky on land too. In 2014, while working in my previous job for Nass Corporation, I was asked by the Electric and Water Authority in Bahrain to assemble an elevated service reservoir – this is basically an above ground water tower. It was designed by Pittsburgh Tank and Tower Group in Kentucky. As you can imagine in Bahrain, water is a very precious commodity, so there is a great demand for water storage.
At the top of the tower to support the water tank there is a metal knuckle plate. These plates are 2.5 inches thick and once fully assembled weigh 120 tons. Previously, no one had been able to lift them in one piece, so the individual sections were usually lifted to 135 feet and then welded together onsite at the top of the tower – a very tricky and time-consuming operation.
If I could find a way for the knuckle plate to be fully assembled in the factory and then safely lifted into position in one piece, we could save a lot of time and money. But it had never been done before and there’s always a reason for that. So my team first studied the previous lift plan, and then we had a design review meeting to look at improving the process. We asked why the knuckle plate hadn’t been lifted in one go, undertook a full risk analysis and then set about overcoming the problems.
First, we needed the right crane – we chose a mobile crane with a 500-ton capacity and then adapted the boom. We needed a telescopic boom that could cope with a 135-foot high lift. The tower was in the middle of a busy water station and the ground was soft, so we had to sit the crane on firm foundations. This was solved by using concrete thrust blocks as a base. These are usually used to stabilize pipes but worked just as well for the crane.
On the day of the lift it was a bit nerve wracking. The knuckle plate was transported to site, four slings were attached and slowly but steadily 120 tons was lifted 135 feet up and then placed carefully on the top of the tower. We all held our breath. It worked perfectly. You always learn from experience.
We had achieved the assembly of the water station in Juffair in just one week, when previously a similar operation would have taken two months. My team then went on to build four additional water towers across Bahrain. I enjoy working out how to tackle these complex heavy lifts – it can be challenging but really rewarding when everything goes to plan.
At Modulift, we have a great deal of professional talent. Sue Spencer, who founded the company in 2002, and the rest of our engineering team help our clients with lift planning and engineering. Modulift has five U.S. distributors that cover the whole of the states and one that covers Canada.
Modulift supplies spreader beams for lifting, lifting beams, spreader frames and other below-the-hook lifting equipment. As specialist lifting engineers operating in a niche market, we concentrate on the provision of off-the-shelf and custom lifting products. We provide lifting analysis to help customers get the calculations right in the planning stage.
In chess, there is the opening, the middle game and the end game. The middle game is the bit where you work out what you want to achieve. The end game is where you consolidate your strategy, but achieving checkmate in the middle game means there is no need for the end game. That’s the way I like to play. Plan well and have a good strategy and you can complete the task safely and ahead of schedule.