Answer to Quiz No. 11

Case 1 is YES

Refer to page two for reactor R-1 and note that the Tail Load at initial pick in the horizontal is 240 kips . This value is found by the following formula: 60' * 200 ton/ 100' = 120 ton = 240 kips. As the reactor is up ended, the Tail Load gradually decreases in a predictable manner down to 0.0 kips until the lift crane has the full load. As a general rule of thumb for this case, the Tail Load at 85 degrees is still 50 to 70 % of the original Tail Load at initial pick, depending on the location of the center of gravity and the off set of the tail lug from the reactor centerline. Final Up ending between 85 and 90 degrees should be done very slowly so the full load of the reactor is gradually transferred to the lift crane.


Case 2 is NO

Refer to page three, reactor R-2. The reactor in case II acts like an equalizer beam as the lift point, the tail point and the center of gravity are all on the same line. The result is that the Lift Load and the Tail Load for initial pick remain constant through reactor up ending to the point just before it reaches vertical, a tenth or two degrees less than 90 degrees. This is so because the horizontal distances between the center of gravity and the lift and tail points remain in proportion to each other through the up ending. In that last tenth or two of a degree, the full Tail Load is transferred to the lift crane. Therefore, final up ending with Case II should also be done very slowly and smoothly so the full load of the reactor is gradually transferred to the lift crane.


Case 3 is NO

Refer to page four, reactor R-3. During up ending, the Tail Load will gradually increase in a predictable manner until the center of gravity is centered over the tail lug. At this point, the tail device will have the full weight of the reactor. At this point in the up ending, a horizontal force must be applied at the top of the reactor to keep it from rotating out of control over the tail point as up ending continues. Most heavy reactors are tailed by a tailing device like the one shown in the quiz, but are designed so that as the reactor is up ended to about 45 degrees, the tail point is shifted to a location that is above the centerline of the vessel and then the up ending becomes like Case I.

    


    


Maximum Reach Enterprises

Quiz List     

Home Page