Page 62 - Pipelines and Risers

Wall-thickness and Material Grade Selection 35

pw = Seawater density
g =Gravity
h,,, = Deepest depth with current pipeline thickness
ht = Tidal amplitude
h, = Storm surge

Pa =34*SMYS*[2) 2.5
(2.26)

where:
Pa = Propagating pressure for the buckle arrestor
tBA = Buckle arrestor wall thickness
DBA = Buckle arrestor outer diameter = D+Z*tsA [m] (2.27)

2.7 Buckle Arrestor Spacing Design

The following equations have been compiled as an approach to optimizing the buckle arrestor
spacing (JPK, 1997):
CBA = cMan+cMan-cLp (2.28)

where:
CBA = Cost per buckle arrestor [e.g. NOK - Norwegian Kroner]
= Assumed manufacturing cost per buckle arrestor, = Zoo00 [NOK]
CM,~~ P~*C~*VBA (2.29)
=
CLP = Cost of pipeline pipe saved by inserting buckle arrestor
1 (2.30)
-
= L, * [2' +2*t,)'-D; *p, *Cs [NOK]
I)
where:
tp = Pipeline thickness [m]
p, = Steel density [kg/m3]
C, = Cost of steel (assumed) = 8 [NOKkg ]
(2.3 1)

where:
VBA = Volume of buckle arrestor steel [m3]
Cp = Cost of pipeline to be repaired, manufacturing assumed to be included in day
rate of lay vessel [NOK]
CP Man = PS*CS*~P (2.32)