Other key factors in offshore construction are the weather window which defines periods of relatively light weather during which continuous construction or other offshore activity can take place. Safety is another key construction parameter, the main hazard obviously being a fall into the sea from which speedy recovery in cold waters is essential.
The main types of vessels used for pipe laying are the "Derrick Barge (DB)", the "Pipelay Barge (LB)" and the "Derrick/Lay Barge (DLB)" combination. Diving Bells in offshore construction are mainly used in water depths greater that 120ft, less than that, the divers use a metal basket driven from an "A" frame from the deck. The basket is lowered to the water level, then the divers enter the water from it to a maximum of 120ft. Bells can go to 1500ft, but are normally used at 400 to 800ft.
Cold Temperatures Will Delay New Concrete for Transit Center until Spring (Posted 2013-11-06 00:14:37) ; Coounty Officials Miss the "Weather Window" for Pouring New Two- Inch Layer of Concrete
Nov 06, 2013; A new two-inch layer of concrete needed to repair cracks on the second and third levels of the troubled Silver Spring Transit...