Page 216 - Pipelines and Risers
P. 216
Installation Design 189
pipeline. The horizontal component of the tension (Th) is constant from the point where the
pipeline touches the seabed and up to the stinger tip. The vertical component of this force (T,)
increases from the touch down point on the seabed and up to the stinger, because of the
submerged weight of the suspended part, see Figure 12.8.
X
Figure 12.8 Catenary model.
Shape of the catenary can be expressed as:
xw
t =X(coshI-l) (1 2.2)
w~ Th
where:
X= horizontal distance from touch down point
Z= height above seabed
Th = horizontal force at seabed
ws = submerged weight pr. unit
Curvature is then:
(12.3)
where:
8 = angle to the x-axes
s= arclength
The greatest curvature is at the touch down point:
