Page 199 - Pipelines and Risers

172 Chapter I I

Lateral deflection

3500 3700 3900 41 00 4300 4500 4700 4900
KP (m)

Figure 11.5 Lateral flowline configuration as function of time.
The resulting equivalent stress distribution after t= 0 second, t= 0.3 seconds and t=9 seconds
are presented in Figure 11.6. Figure 11.6a shows the stress distribution in the flowline prior to
trawl impact. The highest equivalent stress of 385 MPa has occurred in the buckled section
and approximately 315 MPa at the hit point. In Figure 11.6b, there is a peak in the equivalent
stress of about 395 MPa at the hit point after 0.9 seconds, which reduces to about 320 MPa
after the passage of the board.
Equivalent stress at t= Osee

290 -
270 -

11.6a