Earlier engineering surveys had found that the plate could break up when it lifted, if it were not supported properly. “The last thing we would have wanted to do is lift up the air grid with the Transi-Lift and have parts fall off,” says Nooter rigging engineer Marcus Hackstadt.
A total of 64 ropes descend from the crane to points on the plate air grid
The air plate is supported by four concentric circles of 16in diameter pipe. It rests inside a cone. Nooter considered lifting grate and cone together, but the combined load would be top-heavy, and the grate blocked access to rigging points on the surface of the cone.
Instead, Nooter used Lampson’s custom-made round spreader to sling 64 wire ropes around the support pipes underneath the plate: 40 on the outside plate ring and 24 on the inside rings.
The air plate being lifted is part of a unit that regenerates a catalyst
The plate is part of a regenerator, which blows hot air on a catalyst so that it can be reused. As part of the work, a new plate and regenerator head were fitted. The regenerator, a reactor and connecting pipes make up a fluidised catalytic cracking unit (FCCU), which helps turn crude oil into gasoline. Nooter was the primary contractor on the project, which also included installation of a new reactor head, new regenerator head, new catalyst and other lines, and internal equipment in a fractionator. The work took place in February and March.
The 3t capacity chain hoist is included in the rigging
Nooter installed a chain hoist in each load line to lift the entire load off its supports. “We were prepared so that if we had an individual hoist that was spongy we could either move the attachment to a more solid area of the plate grid, or else install reinforcing,” Hackstadt says. Nooter designed the entire lift plan. Industrial Hoist Services supplied all of the 3t capacity 10ft Kito and Nitchi chain hoists. Each hoist on this job carried a load of about 2.3t.
The plate rises
“Multipoint shell rigging lifts are relatively routine in our business,” Hackstadt says. Nooter specialises in FCCU refinery turnarounds. “It involves taking the slack out of the rigging with a relatively light load and then going around and actually putting your hand on the line and shaking it, to get a feel for what slings are tighter than the others. It is a lot like tuning a string instrument like a guitar or piano. The hoists made adjustment easy. We normally use large turnbuckles in multi-point lifts which are turned by heavy so-called cheater bars. When we lifted the 1,600,000 lb (725.6t) regenerator head we used 32 three-inch (70mm) diameter, two-foot-long turnbuckles.”
The Transi-lift, with special circular spreader bar, raises the plate
“Using the load cell on the Transi-Lift we could tell when we had the entire weight of the air grid. It was like having all 64 chain hoists in a load test fixture at the same time. We went all around the edge of the air grid to see where the plate was free. We could also get under the air grid and see daylight at the vertical support pipes.
“We pulled up on the chain hoists and used the crane load cell to know when we should be floating in order to determine if we were hung up on something, and to know when it would be safe to get in under the air grid and cut off the supporting columns.
The Lampson LTL-2600 Transi-Lift was equipped with 420ft (128m)of main boom and 190ft (58m)of mast with 42 parts of 1.5in diameter (38mm) load line. Both the load and boom lines measured 20,000ft (6,100m). “We used 4,400,000 lbs (1,995t) of counterweight for all the lifts except for the new regenerator head, for which we used 5,800,000 lbs (2,630t),” Hackstadt says.
The Transi-lift, with special circular spreader bar, raises the plate The Transi-lift, with special circular spreader bar, raises the plate The air plate being lifted is part of a unit that regenerates a catalyst Nooter hooks up the plate The 3t capacity chain hoist is included in the rigging The 3t capacity chain hoist is included in the rigging A total of 64 ropes descend from the crane to points on the plate air grid A total of 64 ropes descend from the crane to points on the plate air grid The plate rises The plate rises
