JOB NO.
DOC. NO.
REV.
A DATE:
SHEET : 1
OF 8
PREP’D BY CHK’D BY APP’D BY
PIPELINE ENGINEERING
WALL THICKNESS and BUCKLING CALCULATION CHECK
JOB PERTAMINA – PETROCHINA EAST JAVA. J AVA.
REV
DATE A
PAGES
DESCRIPTION ALL
ISSUED FOR REVIEW
PREP’D
CHK’D
APP’D
COMPANY
JOB PERTAMINA-PETROCHINA EAST JAVA
TABLE OF CONTENT Cover ...............................................................................................................................1. Table of Content.............................................................................................................2. 1. Scope....................................................................................................................3. 1.1 1.2
2. 3.
References ...........................................................................................................3. Pipeline Design Parameters ................................................................................4 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8
4.
Project Description ................................................... ........................................................... ................3 Objectives ....................................................... ........................................................... ..........................3
List Of Primary Coordinate Of The Pipeline Route................................................... ..........................4 Pipeline Design Life ........................................................... ........................................................... ......4 Pipeline Design Factors ...................................................... ........................................................... ......4 Exposure Condition ............................................................ ........................................................... ......4 Environmental Data ............................................................ ........................................................... ......4 Seawater Properties................................................... ........................................................... ................4 Functional Parameters............................................... ........................................................... ................5 Material Properties................................ ........................................................... ....................................5
Design Requirements...........................................................................................5 4.1
Wall Thickness Calculation .......................................................... ....................................................... 5 4.1.1 General ........................................................ ........................................................... ............... 5 4.1.2 Hoop Stress............................................................ ........................................................... ..... 6 4.1.3 Buckle Propagation ......................................................... ...................................................... 5 4.1.4 Buckle Initiation .................................................... ........................................................... ..... 7 4.1.5 Pipe Collapse................................................................... ...................................................... 7 4.1.6 Summary ..................................................... ........................................................... ............... 8
Attachment Attachment 2 Wall Thickness Calculation Spreadsheet
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JOB PERTAMINA-PETROCHINA EAST JAVA
1. Scope 1.1
Project Description
Recently JOB Pertamina –Petrochina East Java has been operating 10” diameter subsea pipeline extending from palang station located at Tuban seaside, to FSO Cinta Natomas located at Java Sea 22 km northern of Tuban. The pipeline has now been operated at maximum flow capacity of 60.000 BOPD, whereas the production forecast snows that the increase of the production will be continue until 2011. Many alternative solutions have been studied, the additional pipeline installation will be the best option. Therefore, Company intend to have additional 10” diameter subsea pipeline 22 km long from Palang to Station FSO Cinta Natomas. The proposed pipeline can be started from offshore initiation point and onshore point then goes pararel with existing 10” diameter pipeline. The proposed pipeline will pass inter tidal crossing at palang then goest further northern to sea using the existing ROW. The engineering scope of work based on EPCI contract. The SOW will be divided into the following: • Pipeline Engineering Design and Installation • New PLEM design, Fabrication and Installation • SPM Piping Modification 1.2
Objectives
This report covers pipeline wall thickness calculation check of the new 10” diameter pipeline. The wall thickness criteria are hoop stress, collapse, initiation buckling, and propagation buckling analysis. The Analysis is carried out for installation and operation loading condition. 2. References
A. ASME B31.4 B. API RP 1111, Design, Construction, Operation and Maintenance of Offshore Hydrocarbon nd Pipelines, 2 Edition 1993. C. API 5L, Specification for Line Pipe, 2000 Edition. D. DNV OS F101, Rules for Submarine Pipeline System, 2000 Edition. E. DNV 1981, Rules for Submarine Pipeline System.
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JOB PERTAMINA-PETROCHINA EAST JAVA
3. Pipeline Design Parameters 3.1
List of Primary Coordinate of The Pipeline Route
The list of primary coordinates of the pipeline route is given in table 3.1.1. Table 3.1.1 Primary Coordinate of The Pipeline Route Location Latitude Longitude SPM and PLEM
3.2
6° 40' 15" S
112° 09' 33" E
Northing
Easting
9 263 279.5 N
712 152.0 E
Pipeline Design Life
The design life for the pipeline system is 20 years [Ref. H]. 3.3
Pipeline Design Factors
Design factors used for the analysis of the pipeline are shown in table 3.3.1. Table 3.3.1 Design Factor [Ref. A]. Description Wall Thickness Design Factor
3.4
Zone 1
Zone 2
0.72
0.5
Exposure Condition
Pipeline installation at water depth more than 13 meters will be exposed to seawater while the remaining portion which is installed at water depth less than 13 m eters will be buried under seabed. Table shown below presents the pipeline exposure condition: 3.5
Environmental Data
The water depth along the pipeline route considers Mean Sea Level (M.S.L.), Highest Astronomical Tide (H.A.T), 1-year storm surge and 100-year storm surge. Table 3.5.1 Water Depth Data Description Water Depth Max. [Ref. K] Min. [Ref. K] Lowest Astronomical Tide (L.A.T.) [Ref. L] Highest Astronomical Tide (H.A.T) [Ref. L] 1 Year Storm Surge [Ref. J] 100 Years Storm Surge [Ref. J]
3.6
Unit
Value
m m m m m m
25 0.0 -1.18 +1.098 4.9 8.5
Unit kg/m3 o C o C m2 /s
Value 1025 28.9 15 9.6E-7
Unit
Value
Sea Water Properties Table 3.6.1 Sea Water Properties [Ref. H] Description Density of Sea Water Max. Sea Floor Temperature Min. Sea Floor Temperature Kinematics Viscosity
3.7
Functional Parameters Table 3.7.1 Functional Parameters [Ref. H] Description
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JOB PERTAMINA-PETROCHINA EAST JAVA
Description Pipeline Size ANSI Flange Class Design Pressure, at 200 oF Hydrotest Pressure Design Temperature Content Density
3.8
Unit Inch # Psig. Psig. o F kg/m3
Value 10.75 600 1350 1688 200 48.944
Unit Psi. kg/m3 MPa 1/ oC -
Value API 5L Gr. X-52 52,000 7850 207000 1.17E-5 0.3
Material Properties Table 3.8.1 Material Properties [Ref. H] Description Material Specified Minimum Yield Strength Steel Density Young Modulus Thermal Expansion Coefficient Poisson Ratio
4. Design Requirements 4.1
Wall Thickness Calculation 4.1.1
General
The nominal wall thickness (tnom) is the sum of the minimum design wall thickness (tmin), a corrosion allowance (tcorr), and a manufacturing tolerance (tfab). t nom = t min + t corr + t fab
The design thickness used will vary depending on the phase, i.e. t = tmin for operating condition, and t = tmin + tcorr for the testing phase. The engineer should take account of the the lifecycle conditions which may cause a wall thickness reduction through the design life of the pipeline. The corrosion allowance is applied to pipelines operating in a corrosive environment, the corrosion allowances may be either internal and/or external. The requirement for the corrosion allowance varies between codes (refer to Section Error! Reference source not found.). The manufacturing tolerance is required to account for the variations in wall thickness that occur during fabrication. These tolerances generally comply with API 5L unless it is expressly specified otherwise. Where the nominal thickness varies from the standard production pipe thicknesses then economics may dictate a thicker section than necessary be used to match the commercially available wall thicknesses. 4.1.2
Hoop Stress
The DnV code includes the external pressure in the hoop stress calculation. It also uses the median diameter, i.e. the average between the Internal and external diameters [Section 5 B211]. Page 5 of 8
JOB PERTAMINA-PETROCHINA EAST JAVA
σ h =
( Pi − Pe )
( D − t ) 2t
where: σh = hoop stress Pi = internal design pressure Pe = external design pressure D = external diameter t = wall thickness DnV approach applies the following limits to the hoop stress [Section 5 C203 & C204]. Yielding Limit State σh ≤ ηsSMYS Ultimte or Bursting Limit State σh ≤ ηuSMTS where: ηs, ηu = load factor
SMYS = minimum specified yield strength SMTS = minimum specified tensile strength Load Factor
Safety Class Low Normal 0.83 0.77 ηs 0.72 0.67 ηu Table 4.1 - Internal Pressure Design Load Factor specified by DnV 96
Pressure Test High 0.77 0.64
0.96 0.84
The DnV code also allows higher load factors to be used when certain criteria are met [section 5 C205]
4.1.3
Buckle Propagation
The DnV approach for external pressure collapse is as follows [Section 5 C306]:
(P
col
(
− Pcr ) Pcol − Ppl 2
2
)= P
col Pcr Ppl U 0
D t
where: Pcr, D, t Pcol = ≤
U0 Ppl
= = =
= As defined above As defined above with the following condition Pcr [Section 5 C310, C311, & C312] 11 . γ R as defined above with 0.5% ≤ U0 ≤ 3% [Section 5 C306 & C800] Plastic collapse pressure 2σ y t D
4.1.4
Buckle Initiation
The minimum wall thickness for buckle initiation is calculated as per API RP 1111 [Ref. B]. The formula used for the calculation is the same with buckle
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JOB PERTAMINA-PETROCHINA EAST JAVA
propagation but with taking the initiating buckle pressure equal to 1.25 times the propagating pressure. 4.1.5
Pipe Collapse
The DnV code has two separate design cases for the combined loading consideration, load-controlled conditions and displacement-controlled conditions. A load -controlled condition is characterised by loads that are independent of displacement, and displacement controlled condition is characterised by displacements that are independent of load. The load-controlled condition check can always be applied as it is more conservative than the displacement-controlled condition. [section 5 C100] The combined loading checks are defined as follows [section 5 C305] Load-Controlled condition: 2
2
γ γ M + γ M Pe E E ,c F C F ,c + ≤1 M c Pc γ R γ R
Displacement-Controlled condition:
γ F γ C ε F ,c + γ E ε E ,c ε M ,c γ ε
0.8
+
Pe ≤1 Pc γ R
where: MF,c ME,c Mc γ F γ E γ C γ R Pe Pc εF,c εE,c εM,c γ ε
4.1.6
= = = = = = = = = = = = =
characteristic functional bending moment characteristic environmental bending moment characteristic limit bending moment [section 5 C307] function load factor environmental load factor condition load factor strength resistance factor characteristic external over pressure characteristic collapse pressure [section 5 C306] characteristic function longitudinal strain characteristic environmental longitudinal strain characteristic buckling strain capacity [section 5 C308] strain capacity resistance factor
Summary
In order to fulfill the requirements, minimum nominal wall thickness will be taken as the following: Page 7 of 8
JOB PERTAMINA-PETROCHINA EAST JAVA
•
Kp. 0.0 to Kp. 22
: 0.5 in wall thickness
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ATTACHMENT Wall Thickness Calculation Spreadsheet
