The following figures show screen captures of the dialog boxes that are displayed when the user clicks various buttons on the main screen. The results in Figure 2 for clay are provided with the caution that the clay calculations have not yet been fully tested. The weight required for an L10 pipe (that limits the lateral displacement to 10 pipe diameters) is predicted to be just 633 lbf/ft. In this case the pipe weight required for a stable pipe is 1294 lbf/ft, almost exactly the same as in the E305 results. Figure 2 -STA BOTSTAB Input and Second Results for Submarine Pipeline On-Bottom Stabilityįigure 2 shows the results for the same input data, but using the generalized method from F109, and for the case of a sand sea bed. A friction coefficient is also given and the sea bed has been selected to be medium sand. Lift, drag and inertia force coefficients have been specified in accordance with recommendations inĮ305.
AĬurrent velocity of 1 knot has been specified, perpendicular to the pipe at an elevation of 16.4 feet above the sea bed.
No wave spreading has been specified and the wave direction is 0 degrees, which is perpendicular to the pipe. A JONSWAP spectrum is used with gamma = 3.3 and Tp = 13 seconds. The significant wave height is 32.8įeet and the water depth is 108 feet. Hence the program warns that the pipe is not stable in this analysis. In the figure above, the predicted weight for a stable pipe is 1269 lbf/ft, or 1888 kgf/m. STA BOTSTAB Input and First Results for Submarine Pipeline On-Bottom Stability STA has implemented parts of the Generalized Lateral Stability Analysis method from F109 and incorporated them into STA BOTSTAB2. In 2007 DNV introduced “Recommended Practice DNV-RP-F109, ON-BOTTOM STABILITY DESIGN OF SUBMARINE PIPELINES” which replaces E306. The pipe weight required for an absolutely stable pipe is given by STA BOTSTAB. STA BOTSTAB has contains curve-fit equations and interpolation methods that remove the need for constantly looking up information in RP-E306. STA BOTSTAB – On-Bottom Stability of Submarine Pipelines