Page 63 - Pipelines and Risers

36 Chapter 2

where:
V, =(S+3*h)*[$*[(Di +2*t)2-D?! (2.33)

where:
Vp = Volume of pipe to be repaired [m3]
S = Spacing between buckle arrestors [m]
h = Greatest depth in the section considered [m]
CF 3o*(cLV + CDSV) (2.34)

where:
CF = Fixed cost if repair is needed [NOK]
30 = Assumed time from buckle occurs until repair [Days]
is done and regular pipe laying is started
CLV = Daily rate of lay vessel (assumed) = 1.5*106 [NOK]
C~sv = Daily rate of Diving Support Vessel @SV) (assumed) = 1.25*106 [NOK]
CTOTAL = CBA*X + (CP + CP)*M (2.35)

where:
=
C~TAL Total cost of buckle arrestors, repair pipe and repair [NOK]
M = Assumed probability of risk of a propagating buckle during the laying, can be
between 0 and 1. It is assumed to be 1 for the first 50 km of the first lay season,
after which a probability of 0.05 is assumed until the end of the first lay season.
For the second lay season a probability of 1 is assumed since the relative cost of
delaying the installation of the riser is large.
L
X=- (2.36)
S
where:
X = Number of buckle arrestors for the pipe length considered
L = Pipe length considered [m]

2.8 References
1. ABS (2000), “Guide for Building and Classing Undersea Pipelines and Risers”,
American Bureau of Shipping.
2. ASME B31.1, (1951) “Code for Pressure Piping”, American Society of Mechanical
Engineers.
3. ASME B31.3, (1993) “Chemical plant and petroleum refinery piping”, American Society
of Mechanical Engineers.