Pipe and Pipe Handling 
The pipeline from the surface platform to the seafloor would probably 
consist of oilwell tubular goods, either "tubing" or "drill pipe," 
depending on specific availability. Oilwell pipe is furnished in 30-foot 
lengths with threaded joints; pipe is manufactured in various sizes and 
material grades to American Petroleum Institute standards for size, 
shape, joint configuration, and tensile, burst and collapse strength. 
For the proposed concreting system, pipe in the 3-1/2 to 5-in. size 
range will likely provide the desired combination of flow capacity and 
friction head loss. Flush joints of constant internal diameter will be 
used in order to minimize disturbance to flow. 
The pipe handling system consists of a conventional oilwell mast, 
drawworks, other hoisting and joint make-up equipment and power supply. 
If a floating drill ship or barge is chosen as the platform, this equip- 
ment will already be in place. If a special barge is outfitted, then a 
portable rig would be rented and installed on the barge. Either a 
workover rig or a small drilling rig with a 250,000-1lb hook capacity is 
adequate to support a submerged weight of up to 10,000 ft of 3- to 4-in. 
ID pipe filled with concrete, as shown in Table 2. The pipe handling 
system may need to have some modifications such as provision of lateral 
guides on the mast for the traveling block. 
The pipe will be stored horizontally in stacks on the deck. As an 
example, 4-1/2 in. tubing in 30-ft lengths stacked in several layers 
requires about 150 feet of deck space for each 1,000 feet of pipe, which 
has a total weight of about 14,000 pounds and thus a deck loading of 90 
pounds per square foot. Some rigs can handle 60-ft doubles (two 30-ft 
lengths already joined) or 90-ft triples. The longer stands permit 
faster placing and retrieving of pipe. For example, both the Glomar 
Challenger and the CALDRILL can deploy about 14 stands per hour. The 
Challenger, using 90-ft lengths, requires about 4 hours to place 5,000 
ft of pipe; the CALDRILL, using 30-ft lengths, needs about 12 hours. 
However, longer stands require longer clear deck space for storage and 
extra mast height with its additional weight and increased operational 
difficulties on a rolling and heaving platform. 
Pipeline of the type that is normally used for pumping concrete on 
land is not suitable for a long vertical line: it lacks tensile strength 
and suitable joints; no practical deployment system exists. 
Flexible pipe (hose) is often used for pumping concrete. However, 
hose is more subject to blockage than "slickline"--rigid steel pipe--and 
is otherwise less suitable for vertical transport of concrete. Also, 
reinforced hose with adequate tensile and burst strengths is considerably 
more expensive for two reasons: (1) it costs more per lineal foot than 
steel pipe, and (2) it is not readily available off-the-shelf in long 
lengths and likely would need to be specifically manufactured along with 
its deployment system, thus incurring substantial capital investment. 
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