Document Title:PIPELINE BUOYANCY CONTROL ANALYSISCOPI Doc No.: C-84524-PS-KK1-CAL-ST-3K-0020
Originator:
IKPT - KELSRICOPI Group Owner:
UO - Engineering - OEEArea:
PipelineLocation:
StationSystem:
Onshore Infield Flowline / PipelineDocument Type:
CalculationDiscipline / Subdiscipline:PipelineOld COPI Document No.:-
0AIFC24-Nov-11Issued for CommentSuharmadiM. Fechrizal / Leo K.Pramono Arief Pujito / Adam WahyudiNR
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TABLE OF CONTENTS
Page41INTRODUCTION
41.1General
41.2Definitions
42SCOPE
43REFERENCES
44FORMULA
45DATA
45.1General
55.2Functional Parameters
55.3Design Parameter for Soil
55.4Design Parameter for Saddle Weight
66RESULT
67ATTACHMENT PIPELINE BUOYANCY CONTROL ANALYSIS CALCULATION
1 INTRODUCTION
1.1 General
This document cover detailed design of Pipeline for ConocoPhillips (Grissik) Ltd. Engineering, Procurement, and Construction (EPC) Pipeline for LTRO Project EPC PROJECT at GRISSIK, SOUTH SUMATRA, INDONESIA.1.2 Definitions
Within the contents of this calculation report:COMPANY means ConocoPhillips (Grissik) Ltd.CONTRACTOR means IKPT-KELSRI who is specifying/purchasing the equipment, materials and services for and on behalf of the COMPANY.SUBCONTRACTOR means the party which supplies services to perform the duties or the works specified by the CONTRACTOR / COMPANY.
2 SCOPE
This document covers the calculation for pipeline buoyancy control analysis calculation for:a) Pipeline NPS 6 inch carbon steel API 5L X42
b) Pipeline NPS 12 inch carbon steel API 5L X52 NACE MR-0175to ensure negative buoyancy in swampy areas.
3 REFERENCES
1. ASME 31.8 Gas Transmission and Distribution Piping Systems
2. API 5L Specification for Line Pipe3. B-84524-RW-PP0-BOD-ST-00-0001 Project Basis of Design
4. B-84524-LT-CC0-DRT-ST-C1-0001 Letang Tengah Station Soil Investigation for LTRO Project Plant Assessment
4 FORMULAThe attached calculation sheet shows the calculation method.
The case assumes the dimensions of a saddle weight which would be required to hold the pipe down in swampy areas in addition to weight of linepipe. The saddle weight dimensions have been chosen to give a negative buoyancy to the system.5 DATA
5.1 GeneralThe calculation considers buoyancy of the pipe in a buoyant fluid medium and in areas having a high water table and little or no soil cohesion.When the unit weight of the pipeline is lower than the unit uplift force when buried in the soil, the pipeline will float. Adding concrete coating or weight to the pipeline will increase the unit weight and ensure that the pipeline will stay buried in the soil.An empty pipe has been assumed for the purpose of the calculation.
Table below shows the design considered in the pipeline buoyancy control analysis calculations.
DESIGN FACTOR
DescriptionPipeline
Design Factor/Usage Factor
(Table 841.114A, ASME B31.8)NPS 6 : 0.6 (class 2)
NPS 12 :0.72 (class 1 div. 2)
Longitudinal Joint Factor1.0 (for API 5L) (Table 841.115A, ASME B31.8)
Safety Factor1.2
5.2 Functional ParametersFunctional parameters considered in pipeline buoyancy control analysis are as per tables belowa) For NPS 6 Raw Gas from Letang Tengah Well to Letang Tengah StationTABLE 5.2.1 PIPELINE FUNCTIONAL PARAMETERS
DescriptionPipeline
Nominal Pipeline Diameter, inch6
Design Pressure, psig1350 max
Design Temperature, oF60 / 200
Minimum Pipe Wall Thickness, inch0.562
Specified Minimum Yield Strength, Psi42000
Density, lbs/ft3490.063
Corrosion CoatingThree Layer Polypropylene
Corrosion Coating Density, lb/ft356.229 (ASTM D 792)
Corrosion Coating Thickness, inch0.090
b) For NPS 12 Dehydrated Gas Trunkline from Rawa Station to Grissik (Pipeline Section)TABLE 5.2.2 PIPELINE FUNCTIONAL PARAMETERS
DescriptionPipeline
Nominal Pipeline Diameter, inch12
Design Pressure, psig1350 max
Design Temperature, oF150
Minimum Pipe Wall Thickness, inch0.250
Specified Minimum Yield Strength, Psi52000
Density, lbs/ft3490.063
Corrosion CoatingThree Layer Polyethylene
Corrosion Coating Density, lb/ft358.683 (ASTM D 792)
Corrosion Coating Thickness, inch0.110
5.3 Design Parameter for SoilA typical soils density of 94.87 lb/ft3 has been assumed for swampy area.
5.4 Design Parameter for Saddle WeightDensity of concrete 149.828 lbs/ft3 is used6 RESULTThe result of calculation pipeline buoyancy control analysis is shown belowPIPELINE BUOYANCY CONTROL ANALYSIS RESULT
Pipe MaterialWall Thickness
(in)Buoyancy per Joint Pipe
(lb)Result
6 API 5L X420.562-842.67No Need Buoyancy Control
12 API 5L X520.250868.37Need Buoyancy Control
Thus, based on saddle weight calculation for 12 pipeline, each 12 m pipe joint equipped with 3 saddle weight can be stably sunk down in the fluid soil of swampy area.
The saddle weights should be designed with a centre of gravity as low as possible so that they are stable on the pipe and not inclined to topple off.
Reinforcing in the saddle weights should be connected to the lifting lugs so that there is no possibility of the lugs breaking loose during lifting and the weight falling on the pipe.
A proper soft rubber shall be installed between pipe and saddle weight to avoid damage of pipes external coating.
7 ATTACHMENT PIPELINE BUOYANCY CONTROL ANALYSIS CALCULATIONConocoPhillips (Grissik) Ltd.