0,50 0.75 1.00 



Frequency, u> (rad/sec) 



Figure 4. Heave amplitude spectra for T-2 tanl<er and C1-M-AV1 with 

 20-l<not wind and fully developed sea. 



Material. Aluminum and steel are the two most common materials 

 used for pipe. It is readily apparent from even the most cursory glance at 

 the literature that aluminum pipe is not suitable for lifting heavy loads. 

 While some akiminum drill pipe has been used in the offshore drilling 

 industry, the loads subjected to the pipe have been comparably mild. In 

 addition, while some grades of alummum are possibly suitable for heavy-lift 

 applications, it has been found that readily available aluminum pipe is either 

 not made of the stronger grades or is much too small for the loads in question. 



High-grade steel is recommended for manufacturing pipe used to 

 support heavy loads. Steels of minimum yield strengths in the range of 

 1 10,000 to 150,000 psi are the most suitable for the purposes of this 

 project. Table 3 summarizes the important properties of two steels meeting 

 these requirements. 



17 



