25 March 2008
The custom designed, fabricated and certified lifting slings and rigging used to lift and place on a barge the special dual and quad Pipe In a Pipe (PIP) was an integral part of the overall shipping process. The special deepwater pipe was built for placement 7,000 feet down on the floor of the Green Canyon Sector in the Gulf of Mexico.
Before this could be done the pipe sections had to make a short but critical move from a land stockpile out to the ocean going barge for transport the 150-plus miles offshore.
The 275 ton capacity Liebherr LR 1200 SX lattice crawler crane with 154 foot main boom was rigged with two wire rope and spreader bar con. gurations, one for each length and weight of pipe. The basic pipe length was 40 feet. The dual sections were 82 feet and the quad sections were 165 feet long when they had been welded together.
The lift of each pipe began with the Liebherr's five-part main lifting line and a 220,500 pound. ve-sheave hook block. These are factory standards. The engineering drawings for the slings were done by Toby Dugas Engineering of Loreauville, LA. The spacer bar for the PIP double joints was 37 feet 10 inches long and fabricated from 3 inch diameter pipe. For the quad lift pipe sections slight modi. cations were made using a 100 foot long by 24 inch closed pipe with four lifting lugs for even lifting capability. This was analyzed and certi. ed.
A structural analysis with 2:1 safety factor was made by SRC Engineering of Lafayette, LA, prior to any lifts. In each case, a written report and drawings were submitted to the Bayou Companies, leaving nothing to chance.