The heave characteristics of the T-2 tanker, C1-M-AV1 ship, and 

 FORDS platform were determined by multiplying the response amplitude 

 operators for heave motion in long-crested seas by the Neumann spectrum. 

 Results of this analysis were combined with the force analysis of the pipe 

 string. Typical resulting curves are given in Figure 6. 



It can be readily seen that for all realistic conditions (sea state 4 or 

 less) the motions of the surface vessels under consideration will not subject 

 the pipe string to dynamic axial forces greater than 25% of the static 

 600-ton load. In fact, indications are that the dynamic forces will amount 

 to less than 5% of the static load more than 90% of the time in most of the 

 oceans of the world. This statement acquires added significance when it is 

 realized that no account was taken of the natural tendencies for the system 

 to dampen out motion. Also, there are some devices, such as bumper subs 

 and shock absorbers, which have been designed to eliminate or greatly 

 reduce the effects of vessel motions on suspended pipe strings. The 

 incorporation of these devices into the system would unquestionably make 

 the problem of dynamic loading either insignificant or very easily solved. 



Pipe Handling Equipment. The equipment necessary to assemble 

 and lower a pipe string for a heavy-lift operation would be very similar to 

 the standard equipment found at any oil well. A thorough assessment of 

 the required items of equipment and the capacities of these units can be 

 found in Appendix B. 



There is substantial evidence to indicate that a considerable portion 

 of the hoisting equipment currently in use is readily adaptable for lifting 

 loads of up to 500 tons in offshore construction. Standard derricks, crown 

 blocks, traveling blocks, tool joints, and draw works will successfully lift a 

 500-ton load. Limited extensions of current technologies will provide 

 items of equipment which will permit hoisting loads of up to 600 tons, the 

 arbitrary maximum for this project. 



Conclusions. It can be stated with confidence that a pipe string of 

 the size discussed previously will satisfactorily support a load of up to 

 600 tons to a depth of 6,000 feet. It is worth stressing that much of the 

 ocean industry is thinking along these lines. The heavy-lift systems under 

 consideration are actually follow-on versions of systems presently in use. 

 Of course, this is the soundest and most economical method of design; new 

 systems are being evolved from the old, rather than basing new designs on 

 heretofore untried concepts. Mobile offshore drilling rigs are serving as 

 baseline designs for heavy-lift systems of the type under consideration. 



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