Thornton Bank roll-up operation, UK
ALE has the roll-up of the Thornton Bank jacket, weighing 775t, using the AK912 and TC2800-1.
ALE rigged the AK912 main lift with a 71m maxi boom and a 300t maxi lift ballast. The TC2800-1 catcher crane was rigged with a 48m main boom and 300t superlift.
The jacket, which measured 37m long, 23m wide and 23m high, was built in a horizontal position on 3m high stools. It was designed to be rolled-up to a vertical position using two lattice boom cranes and two specially designed pivot saddles, which were fitted to the jacket pile sleeves.
The AK912’s first lift was 522t at an 18m radius, -0 degrees; it hoisted the jacket and rotated it 50 degrees, where it had a 136.5t, 31m radius.
The TC2800-1 crane was then attached to the jacket’s catcher trunnions. The shackles and slings of the tackle, which was specifically designed to suit the lifting points on the jacket, ensured that the maximum headroom was available for the main lift crane.
Once attached, the AK912 started to hoist and boom to take the jacket to 71 degrees. The weight of the jacket was then transferred to the catcher crane from the AK912’s pivot point.
The TC2800-1 completed the operation by positioning the jacket onto additional grillages, at a weight of 354t, at a 14.8m radius.