Table 3. High-Grade Pipe Steels 

 (Source; FORDS Study, Table XI-8, Volume I) 



Steel Grade 



Properties 



P-110 



Minimum Yield Strength 



11 0,000 psi 





Minimum Tensile Strength 



1 25,000 psi 





Average Elongation in 2 Inches 



15% 



V-150 



Minimum Yield Strength 



150,000 psi 





Yield Strength Maximum 



171,000 psi 





Average Elongation in 2 Inches 



19% 



Pipes over 13 inches in diameter have been manufactured using 

 P-1 10 and V-150 steels (Reference 7, p. S-45). Table 4 presents some 

 relevant design parameters for a suitable range of pipe diameters. These 

 pipes are off-the-shelf items and come in lengths of about 50 feet. 



Couplings. Table 5 illustrates how the strengths of typical pipe 

 joints compare with the strength of the pipe. It can be seen that the joints 

 are at least 90% efficient and in two cases are actually stronger than the 

 pipe. The joints are of the "shrink grip" variety, which is very similar to 

 the standard plumbing coupling used in home water systems. 



Design. Assuming a safety factor of two for static loading and 

 limiting attention to the severest case of a 600-ton load at 6,000 feet, it can 

 be shown that of the different pipes listed in Table 4, only the last three of 

 V-150 grade steel will meet the requirements. These are 10-3/4-inch OD 

 weighing 71.1, 76.0, and 81 .0 pounds per foot, respectively. 



It is obvious that at lesser depths and/or with lesser loads the static 

 safety factor would increase. 



The combined static force of the pipe string and load is necessary but 

 not sufficient for a realistic design analysis of the pipe system. There are 

 two types of dynamic loading that must be considered in a complete 

 investigation: (1 ) loads incurred during sudden stops and (2) loads imposed 

 on the pipe due to ship motion. 



