design of subsea pipe lines by apdl and macro programming etc. and ansys software also

2. TEAM MEMBERS
ARUN N R 1RL10ME017
MANJUNATH L 1RL10ME041
NIRANJAN J M 1RL10ME051
PRASHANTH KUMAR S 1RL10ME057
CARRIED OUT AT
R & D Centre,
Department of Mechanical Engineering,
RLJIT, Doddaballapur.
UNDER THE GUIDENCE OF
Mr. Harish Kumar N S
Assistant professor
Department of Mechanical Engg.
RLJIT.

3. CONTENTS:
1.Abstract
2.Introduction
3. Methodology
4. Modelling & Analysis
5. Analytical solutions
6.Summary
7.Refrences

4. ABSTRACT:
 The aim of our project is modelling and analysis of
subsea pipeline using Ansys Parametric Design
Language (APDL).
 It includes the analysis of seabed and pipeline for
different pressure, temperature and load cases.
 The modelling of seabed and pipeline is done by
using surface elements and pipe elements in
ANSYS.
 The whole problem can be written as MACRO file
and can be run many times for parametric study
and compare results with solution obtained by
analytical method.

5. INTRODUCTION:
 Most of us know that the hot and cold water we see in
our houses.
 Also most of us will have seen the plastic pipes laid
under our streets and roads to locally distribute water
or natural gas.
 But most of people do not know is that there are
hundreds of thousands of kilometers of very large
‘pipelines’ crossing our nation and transmitting huge
quantities of crude oil, oil products and gas.
 Most of pipelines are Underground or Undersea water.

6. PIPELINE:
 Pipeline is defined as a system of pipes used to
convey media from one location to another.
 The engineering discipline of piping design studies
the best and most efficient way of transporting the
medium to where it is needed.
 Liquids and gases are transported in pipelines and
any chemically stable substance can be sent
through a pipeline.
 NEED OF PIPELINES: Safer, High reliability,
Environmental friendly, Least energy requirement,
Lowest maintenance cost,Negligible loss of
product in transit

7. TYPES OF PIPELINES:
onshore offshore
OFFSHORE PIPELINES:
 Offshore pipeline transporting a variety of
commodities ranging from oil, natural gas &
petroleum products etc.

8.  Their use as expanded with time because they are
more energy efficient than competing means of
transportation.
 They require significant initial investment, they
have a life span of up to 50 years and require
relatively minor maintenance
 Oil and gas pipelines are usually the longest, often
crossing countries.
 A complete pipeline design includes pipeline
sizing (diameter and wall thickness) and material
grade selection based on analyses of stress,
hydrodynamic stability, span, thermal insulation,
corrosion and stability coating, and riser
specification.

9. SEABED:
 The Seabed (Seafloor/Ocean floor) is the bottom
of the ocean.
 Seabed is a soil like structure under the sea
normally the seabed has two types
 1.Soft seabed
 2.Hard seabed
 The seafloor is an extreme environment; pressure
is high temperature is low.
 Natural resources are mainly available under
seabed which is drilled and that can be extracted
and supplied through pipelines.

10. METHODOLOGY:
1. Start
2. Problem definition
3. Objective
4. Selection of material
5. Modeling of pipeline and seabed by ansys APDL
6. Analysis of pipeline by ansys APDL
7. Ansys results
8. Comparision of ansys results with analytical
solutions.

11. ANSYS:
 ANSYS is a complete FEA software package used by
engineers world wide in virtually all fields of
engineering: structural, thermal, electrical etc..,
 APDL stands for Ansys Parametric Design Language, a
scripting language that we can use to automate
common tasks or even build our model in terms of
parameters (variables).
 Finite element analysis:
 The finite element method (FEM) is a numerical
technique for obtaining approximate solution for wide
variety of engineering problems
 Phases of FEA:
 1. pre-processing 2. solution 3. post-processing

12. COMMANDS USED:
 FINI – Display the program and it is normally exits in pre-processor
 /CLEAR- This command reads the database and if there any change
this intersects and again reads from initial.
 /PREP7-used to initiate the model creation preprocessor. And it
enters the general input data to create the job.
 ESIZE- Specifies the default number of line divisions
 ENDIV- This command takes the automatic size of the element.
 R - Defines the element real constants
 MP- Defines a linear material property as a constant or a function
of temperature.
 ET- Defines a local element type from the element library.
 K- defines keypoint
 DOF- Adds degrees of freedom to the current DOF set.
 *ENDDO -Ends a do-loop and starts the looping action
 ALLSEL- Selects all entities with a single command

13.  TB- Activates a data table for nonlinear material
properties or special element input.
 SFE-specifies surface loads on elements
 LESIZE- Specifies the divisions and spacing ratio on
unmeshed lines.
 MSHKEY- Specifies whether free meshing or mapped
meshing should be used to mesh a model.
 AMESH- Generates nodes and area elements within
areas.
 MAT- Sets the element material attribute pointer.
 ESURF- Generates elements overlaid on the free
faces of existing selected elements.
 /SOLU -Enters the solution processor .

14. PROBLEM DEFINITION:
Some of the below parameters are given by the flow
assurance engineers engineer depending on offshore field and
using all the below parameters we have to design the pipeline
for different load cases through analysis.
pipe internal pressure pi =30 Mpa
content density ρf =2300 kg/m3
steel density(pipe) ρP =7850 kg/m3
water depth WD = 1200 in m
outer dia of pipe Do = 0.2731 in m (10.75 inch)
pipeline length L = 6Km
Thickness of pipe T=18.3mm

15. ASSUMPTIONS:
 The pipeline is straight
 Seabed is perfectly flat
 The seabed has plane surface with no
thickness
 Pipelines are made from steel API X-65(steel
grade) with inner diameter typically from 4 to
48 inches (100 to 1,220 mm).

16. OBJECTIVE:
 The objective of our project is to design of
safer pipeline through analysis.
 To Optimise the pipeline design by FEA
 It is cheaper compare to experimental method
 Run for different parameter

17. SELECTION OF MATERIAL:
 PIPELINE material used is Steel API X-65,It is most
useful for pipe fitting applications because it
ensures strong seals and it has excellent
weldability
 Material properties
Yield strength = 448-600MPa
Tensile strength = 531 -758MPa
Young modulus = 206842.7MPa
Passions ratio = 0.3
 COMPOSITION OF X-65
CARBON 0.10%,
SILICON 0.35%
SULPHUR 0.005%
IRON 1.5%

18. ELEMENTS USED:
 CONTA177 Is used to represent contact and sliding
between 3D surface segments and deformable line
segment, defined by this element.
 TARGE170 Is used to represent various 3D target
surfaces for the associated contact elements.
 PIPE16 Is a uni axial element with tension,
compression, torsion, and bending capabilities
 The element has six DOF at two nodes translation in
the nodal x, y, & z directions and rotations about nodal
x, y, & z axes. This element based on 3D beam element
includes standard pipe geometry.

19. MODEL GENERATION:

20. PIPE (CONTACT ELEMENT)
SEABED(TARGET ELEMENT)

21. • Given parameters
Pipe internal pressure pi =30 Mpa
Content density ρc =2300 kg/m3
Steel density(pipe) ρs =7850 kg/m3
Water depth WD = 1200 in m
Outer dia of pipe Do = 0.2731 in m (10.75 inch)
Pipeline length L = 6Km
Thickness of pipe T=18.3mm

22. ANALYTICAL CALCULATION:
1. Outer Diameter Do =273.1 mm
2. Inside diameter
Di =D0-2×T =273.1-2×18.33
Di = 236.5 mm
3. External pressure
P0 = ρW*G*WH = 1030×9810×1200
P0 = 12.121 Mpa
4. Empty pipe buoyancy per unit length= =

23. • Empty pipe buoyancy per unit length
• Empty pipe mass in water per unit length

24. • Empty pipe weight in water:
• Flooded water weight in pipe:

25. • content filled pipe weight in water:
• Hoop stress:

26. • Radial stress:
• Axial stress:

27. Results and discussions
Since the above stress obtained is less than the maximum allowable stress hence the
design is safe
FEA results Analytical results Material properties
Hoop stress Yield strength =
448-600MPa
Tensile strength =
531 -758MPa
Young modulus =
206842.7MPa
Passions ratio = 0.3
95.1Mpa 95.111 Mpa
Radial stress
-12.1Mpa -12.121Mpa
Axial stress
-2.66E+8 pa -2.069E+8 pa
Von mises stress
321 Mpa

28. Stresses in Mpa
-3.00E+08
-2.00E+08
-1.00E+08
0.00E+00
1.00E+08
2.00E+08
3.00E+08
4.00E+08
ENUM
147
294
441
588
735
882
1029
1176
1323
1470
1617
1764
1911
2058
2205
2352
2499
2646
2793
2940
3087
3234
3381
3528
3675
3822
3969
4116
4263
4410
4557
4704
4851
4998
5145
5292
5439
5586
5733
5880
VMXSTREi
AXILSTRi
BENDSTRi
HOOPSTRi

29. Forces in KN
-4.50E+06
-4.00E+06
-3.50E+06
-3.00E+06
-2.50E+06
-2.00E+06
-1.50E+06
-1.00E+06
-5.00E+05
0.00E+00
1
144
287
430
573
716
859
1002
1145
1288
1431
1574
1717
1860
2003
2146
2289
2432
2575
2718
2861
3004
3147
3290
3433
3576
3719
3862
4005
4148
4291
4434
4577
4720
4863
5006
5149
5292
5435
5578
5721
5864
FORX
FORX

30. Moments in KN-m
0.00E+00
2.00E+01
4.00E+01
6.00E+01
8.00E+01
1.00E+02
1.20E+02
1.40E+02
1.60E+02
1
144
287
430
573
716
859
1002
1145
1288
1431
1574
1717
1860
2003
2146
2289
2432
2575
2718
2861
3004
3147
3290
3433
3576
3719
3862
4005
4148
4291
4434
4577
4720
4863
5006
5149
5292
5435
5578
5721
5864
MOMZ
MOMZ

31. conclusion

32. REFERENCE:
• Yong Bai, “pipelines and risers”.
• Elsevier Ocean Engineering book series vol 3
• Boyun Guo, Shanhong song, Jacob Chacko, Ali Ghalambor. “offshore
pipelines”. 2005
• http//www.offshore-technology/books/
• Offshore, subsea, Ansys Wikipedia