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Buoyancy Calculation

This document provides calculations to determine the buoyancy control for a pipeline. It includes inputs like the pipe diameter, wall thickness, densities of water, pipe material, and coatings. It then calculates the weight of the pipe, coatings, and contents to determine the buoyancy force. It finds the pipe has a specific gravity less than 1.1, requiring counterweights. It also calculates the size and weight of a concrete weight needed every 12 meters to offset buoyancy in a swamp area.

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HerruSetiawan
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608 views2 pages

Buoyancy Calculation

This document provides calculations to determine the buoyancy control for a pipeline. It includes inputs like the pipe diameter, wall thickness, densities of water, pipe material, and coatings. It then calculates the weight of the pipe, coatings, and contents to determine the buoyancy force. It finds the pipe has a specific gravity less than 1.1, requiring counterweights. It also calculates the size and weight of a concrete weight needed every 12 meters to offset buoyancy in a swamp area.

Uploaded by

HerruSetiawan
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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PIPELINE BUOYANCY CONTROL CALCULATION

1 INPUT

Pipa Data
Outside Diameter OD : 168.3 mm
CS Wall Thickness t : 7.11 mm
Corrosion Allowance tca : 0.0625 in
-3
Water Density ρw : 1000 kg.m
-3
Content Density (gas) ρf : 35.61 kg.m
Pipe length L : 12 m
-3
CS Density ρst : 7850 kg.m
Coating Thickness (3LPE) t3lpe : 3.0 m
-3
Coating Density (3LPE) ρ3lpe : 950 kg.m
-3
Concrete Density ϒconc : 2400 kg.m

2 CALCULATION
2.1 Weight of pipeline
Cross section area steel
= − −2 −
4
2
As : 0.0028 m
Weight of steel = .
Ws : 22.1692 kg/m

Cross section area - internal


= −2 −
4
2
Ai : 0.0194 m

Weight of pipe content = .


Wi : 0.6916 kg/m

3LPE coating insulation


= +2 −
4
2
A in : 0.0016 m

Weight of coating insulation = .


W ins : 1.5337 kg/m

Total weight = + +
: 24.3946 kg/m

Buoyancy Force on Pipe, BF


= +2 .
4
BF = 23.8608 kg/m

Pipe Submerged Weight Wsm = Wpipe - BF = 0.53 kg/m

Specific Grafity +
=

SG = 1.022

Check for pipe floatation with allowable 1.1 SG


Check Float = " Counter Weight Required!!!" if SG ≤ 1.1
" Counter Weight Not Required!!!" otherwise

Check Float = Counter Weight Required!!!


2.2 Concrete Weight Calculation

a = 150 mm
b = 188.3 mm
c = 100 mm
d = 150 mm
e = 150 mm
f = 94.15 mm
g = 300 mm
h = 150 mm
Figure 1. Typical Concrete Weight

Cross section area of concrete weight


.
= . + + − − .ℎ − .
2 8
2
Acw = 0.081 m

Volume of concrete weight

Vcw = A cw . C
3
Vcw = 0.008 m

Weight of concrete weight

Wcw = V cw . ϒconc
Wcw = 19.32 kg

Buoyant force due to fluid displaced by concrete weight

Bcw = V cw . ρw
Bcw = 8.050 kg

Effective set on weight Buoyancy force each pipe joint

Weff = W cw - Bcw BS = (BF . L) - (W pipe . L)


Weff = 11.271 kg BS = -6.405 kg

Hence concrete weight required for each pipe joint 12 m (T)

T = 0.57 ≈ 1.00

Each length (12 m) of line pipe shall be installed with additional 1 concrete weight to laid down the
pipeline in swamp area

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