Tie-in Analysis GuidelineNomenclature

Abbreviation

TH Termination HeadEF End-fittingROV Remotely Operated Underwater Vehicles

1 Introduction

1.1 Scope

The aim of this report is to provide the guidance to an engineer to:

Identify the input data needed for tie-in analysis in ORCAFLEX Give basic tie-in simulation with ORCAFLEX Familiarize with ORCAFLEX output Present Tie-in Analysis in the Report

1.2 Reference

[1] Orcaflex version 9.7c, Orcina Limited

[2] Det Norske Veritas, “DNV-RP-H103 – Modelling and Analysis Operations”, April 2009

[3] Det Norske Veritas, “DNV-RP-F105 – Free-spanning Pipelines”, February 2006

[4] Det Norske Veritas, “DNV-OS-H101 – Marine Operation, General”, October 2011

1.3 Acknowledgement

Contributions of these following engineers are highly acknowledged (list based on alphabet):

Bjørn Frodesen --Flex RTS Tie-in System, Relocation, Goliat Project Dewintha Kania -Flex ROVCON, UTIS Tie-in System, Relocation, Gullfaks Sør IOR

Project Lars Heimdal - Flex RTS Tie-in System, Goliat Steinar Tveit Trygve Veslum Spool, Flex ROVCON, HCCS

2 Tie-in System

2.1 What is Tie-in?Tie-in is the operation where the tie-in product (such as rigid pipe, flexible pipe, umbilical, cable, etc) will be connected to the fix/movable structures’ part on the seabed (such as hub on the template, riser-base, etc) with some system. The tie-in definition is presented on Figure 2-1 below.

Figure 2-1 Tie-in Definition

Figure 2-2 Principal of Tie-in

Straight Line from Hub

Tie-in Poduct

Tie-in StructureHub

Tie-in System

2.2 Type of Tie-in System

2.2.1 Diver Tie-inDiver tie-in is basically tie-in using hyperbaric welding, done by diver with the special chamber. This diver tie-in doesn’t need the analysis and the scope is not included in this guideline.

2.2.2 Diver-less Tie-in for RigidThis Rigid tie-in can be

2.2.3 Diver-less Tie-in for Umbilical

There are two types of diver-less tie-in, it is separated based on how the operate:1. Diverless on seabed tie-in means the TH will be wet stored on the target box in front of the

hub and the winch from the system docked on the hub is connected to the TH and start to pull-in.

2. Diverless on Vessel tie-in means that the TH will be over-boarded straightly from the vessel to the porch / hub.

2.2.3.1 Diver-less (TH is On Seabed Tie-in)

Figure 2-3 ROVCON / ICARUS Figure 2-4 UTIS

2.2.3.2 Diver-less (TH is On Vessel Tie-in)

Figure 2-5

2.2.4 J-Tube Pull-in

Figure 2-6

2.2.5 Tie-in System Provider

There are many tie-in system used, TNOR’s track record is tabulated below:

Tie-in System Provider TNOR’s Track RecordICARUS GE Åsgard Gas Transfer, 2010

Yme 2006

RTS (Remote Tie-in System) Aker Solutions Oselvar, 2011 Kristin Riser Replacement,

2010 Kristin Replacement, 2008 Vilje, 2006 Fram Øst, 2006 Kristin Marine Operations,

2004

HCS (Horizontal Connection System)

Aker Solutions Brynhild 2013 Åsgard Subsea

Compression 2013 - 2014

UTIS FMC Technology Åsgard Repair, 2007 Åsgard Subsea, 2003 Sigyn, 2002

ROVCON FMC Technology Ekofisk 2009 Gjøa 2009 Rev Øst 2009 Fram øst 2006

STABCON FMC TechnologyVECON Mk2 FMC Technology

Tie-in System Provider TNOR’s Track RecordPSS 16 Ula/Blane, 2010

Gjøa (HCCS), 2009 Snøhvit, 2005

2.3 Limiting Criteria for Diver-less Tie-in System

Tie-in Structure Tie-in Tool Tie-in Product Additional Tie-in Check

Limiting Criteria:

Hub Loads Limitation: Force: Fx, Fy, Fz, Moment; Mx, My,

Mz Visual evaluation

wrt. clearance of TH before entering tool’s funnel.

Limiting Criteria:

Tool’s Capacity includes: Tool’s winch tension

during pull-in (Pull-in winch load)

Tool winch’s declination and azimuth before and during tie-in

Stroking force and moment

Limiting Criteria:

For Flexible lines, Umbilicals and Cables:

Bend Moment MBR Maximum Tension Minimum Tension

(compression) TH’s max bend

moment TH angles before and

during tie-inIn Bending Restrictor:

Bending Moment MBR

For Rigid lines and Spools: Stress Strain

Limiting Criteria:

Free-span Big-bags/ turning

points’ Contact Force

On Bottom Stability?

TDP tension How many

buoyancies needed

Pull-back rigging and winches for contingency

Vessel’s crane deployment needed, weather limitation for AHC and rigging load should be determined

2.3.1 Limiting Criteria for Tie-in Product

2.3.1.1 Rigid SpoolsStandards where appropriate:

Upheaval Buckling - DNV-RP-F110 On Bottom Stability Design of Submarine Pipelines - DNV-RP-F109 Free-spanning - DNV-RP-F105

2.3.1.2 Flexible Pipe, Umbilical, Cable On Bottom Stability Design of Submarine Pipelines -- DNV-RP-F109 Upheaval Buckling - DNV-RP-F110

2.3.2 Limiting Criteria for Tie-in Tool

ROVCON angle relative to pull-in ropes

2.3.3 Limiting Criteria for Tie-in Structure

ROVCON and inboard/outboard hub axis system

2.3.4 Tie-in’s Supports’ Limiting Criteria

2.3.4.1 Free-spanThe after tie-in route will create the free-span, especially when the line is crossing berms. The allowable free-span should be checked (DNV-RP-F109).

2.3.4.2 Big-bags’ Contact Force

3 Tie-in Analysis

3.1 Modelling in Orcaflex

Input Data What to use in

ORCAFLEX?

Settingnecessary

Input Data Specific

Required Output

Comment

Environment DataSeabed profile GeneralCurrent GeneralWaveOn Field LayoutNeighboring Spools

Drawing Coordinate Shape

NoneIf the clash check is needed, set the stuffs in elastic solid, otherwise can be set as drawing just for info.

Existing Sleeper/ rock-berm

Elastic Solid/ drawing

Coordinate Shape

None

Existing Mattresses

Elastic Solid/ drawing

Coordinate Shape

None

GRP Covers Elastic Solid/ drawing

Coordinate Shape

None

Neighboring Flow-line Arrangement

Drawing Coordinate Shape

None

PLET Drawing Coordinate Shape

None

Neighboring Structure’s slope, edges,etc

Drawing Coordinate Shape

None

Tie-in StructureTemplate, Manifold, XT, Riser-base Structure

Drawing None

Hub or

Drawing Coordinate Shape Inclination Hub Height

from seabed

None The hub loads is extracted from the Flowline’s end. The hub here as a

Input Data What to use in

ORCAFLEX?

Settingnecessary

Input Data Specific

Required Output

Comment

visualization to check that the flowline really connect hub’s coordinate

Tie-in ProductFlow-line (Pipe, Umbilical, Cable)

Prescribed Line for umbilical and pipe resting on seabed.

Catenary for umbilical hanging from vessel.

For each Segments of the line (TH, EF, Umbilical, Flex pipe, Cable), have an input data such as:- OD- Submerged weight- EA, EI, GI- MBR- Max, min Tension- BR section length and properties- Seabed’s Friction factors

- Hub Loads- Tie-in angles- MBR on flexible lines

- MBR and bend moment at BRs

- Free-span

Spool OD- Submerged weight- EA, EI, GI- MBR- Max, min Tension- BR section length and properties- Seabed’s Friction factors

- Hub loads- Stresses for rigid spools

Tie-in ToolROVCON Vessel - Loads during

tie-inUTIS

Tie-in SupportTarget Box Drawing

Input Data What to use in

ORCAFLEX?

Settingnecessary

Input Data Specific

Required Output

Comment

Back Tension Winch with history and constant tension at the end.

Buoyancy As an attachment on the line data

Big-bags Elastic solid shape

3.1.1 Field Layout

3.1.1.1 Environment InputData needed for environment input can be found in Met-ocean Report, including sea-water temperature, seabed friction coefficient, soil stiffness, sea-bed contour, survey, etc. There is no current and no wave for analyzing tie-in.

3.1.1.2 Existing Seabed on Tie-in Area

3.1.1.3 Existing Nearby Structures and Constraints

Figure 3-7

Template

Concrete Mattress

GRP Cover PLET

Spools

Spools

Concrete Mattresses

3.1.2 Tie-in Products

3.1.2.1 Rigid Pipe

3.1.2.2 Flexible Pipe /Umbilical

Questions before modelling Line in Orcaflex: Does it installed empty, water-filled, etc? Does the line Mono-bore or Multi-bore Does the line consists of many segments?

For modelling tie-in with TH on seabed, the tie-in route is more important than TH arrangement, this can lead to simplified line’s segment as line type, as described on Figure below:

Figure 3-8

Figure 3-9

Figure 3-10

For modelling tie-in with TH will dock straightly to the porch from the vessel, the TH arrangement should be modelled as 6D buoy to catch the behavior of the head during docking.

Figure 3-11

3.1.2.3 Spool

3.1.3 Tie-in Structures

3.1.3.1 Hub’s Declination

Figure 3-12

3.1.3.2 Determining Hub Height

3.2 Tie-in Simulation

3.2.1 Tie-in System Methodology

3.2.1.1 UTIS

3.2.1.2 ROVCON/ ICARUS

3.2.1.3 RTS

3.2.1.4 HCS

3.2.2 Simulation of Base Case

ROVCON / ICARUS HCS UTISStep 1 – Connect the winch from the hub to the TH, start to pull-in

Step 1 – Overboard TH from the vessel

Step 1 – Connect the winch from the hub to the TH, start to pull-in

Step 2 –stop pull-in 500mm away from the hub, Attach the head with vessel, ready for stroking by adjusting the heading, declination and gamma in the time history.

Step 2 – Lowering TH, ready for upending around the porch.

Step 2 - Pull-in TH until it fully enters the funnel. Rotate the funnel to 90 degree.

Step 3 – Stroking done Step 3 – Docking to the porch Step 3 - Hydraulic stroking to the hub. Tie-in completed. UTIS tool recovered.

3.2.3 Sensitivity Study = Load Cases

3.2.3.1 TH position on Target Box

Figure 3-13

3.2.3.2 Seabed’s Soil Friction Coefficient (min, nom, max)

3.2.3.3 Route Over-length (short, nom, far)

3.2.3.4 Hub angle vertical plane (Fy –Fx plane) (min, nom, max)

3.2.3.5 Rock berm height (min, nom, max)

3.2.3.6 Neighbouring Spool’s length (min, nom, max)

Figure 3-14

3.3 Analysis Results

3.3.1 Fulfilling Limiting Criteria

Check Tie-in Structure

Existing Model Arrangement

RUN

Check Tie-in Tool

Check Tie-in Product

OK

Not OK

OK OKExisting/ New Model Arrangement Accepted

Additional Structure:

Support Mattress Needed

Additional Aids: BuoyancyBack TensionBig-bagsWinch from Vessel

Additional Aids: BuoyancyNew Route for Flexible

New Tie-in Arrangement

Created.

Not OK Not OK

Not OK

OK

After Tie-in Route will be input for GRP

cover Design

Arrangement will be an input for making procedure, rigging design, procurement,

etc

OK

3.3.1.1 Tie-in Product and Tie-in Tool Check

Load Case

ROVCON ISU

Pull-in Tension

TH Heading Offset

TH End Declination

Offset

Stroke Force F_L

Max alignment

force horizontal

M_V,

Alignment force

vertical M_T

Max Combined alignment

(M_V, M_T) *)

ISU's MBR

BR’s MBR

Free-Span 1

**)

Free-Span 2

**)

[kN] [deg] [deg] [kN.m] [kN.m] [kN.m] [kN.m] [kN] [m] [m] [m]Limiting Criteria 210 +/-20 +/- 15 660 512 732 475 13 13  39.59 39.59

End-OLC 02 98.34 5.28 4.92 7.54 5.72 246.43 246.50

19.4613.06 21.4 12,4

End PLC 02 96.90 -0.62 10.57 16.78 10.55 204.36 204.63 13.08 18,3 8,8

Utilisation 0,48 0,4 0,6 0,02 0,02 0,3 0,48 - - 0,5 0,3OK / not

OK OK OK OK OK OK OK OK OK OK OK OK

3.3.1.2 Tie-in Tool Check

3.3.1.3 Tie-in Structure Check (Hub Loads)

CasesP-End

F_V F_T F_L M_V M_T M_LLimiting Criteria 60 ±20 50 ±40 200 ±20

Case1 (TH at N, BE soil friction) 43.72 -0.88 11.88 9.67 197.80 0.00Case2 (TH at N, HE soil friction) 44.01 -0.82 13.74 8.73 199.50 0.00

Case3 (TH at NEC, BE soil friction) 43.60 -0.92 11.01 10.32 197.13 0.00Case4 (TH at FEC, BE soil friction) 43.75 -0.84 12.00 9.16 197.95 0.00

Max Value 43.60 -0.82 13.74 10.32 199.50 0.00Utilisation 0.73 0.04 0.27 0.26 1.00 0.00

OK/Not OK OK OK OK OK OK OK

3.3.1.4 Before and After Tie-in Route

Figure 3-15

3.3.1.5 Allowable Free-span

3.3.2 The New arrangement with Additional Installation Aids

Figure 3-16

3.3.2.1 Back Tension

3.3.2.2 Big-bags

3.3.2.3 Buoyancy

3.3.2.4 Mattresses

3.3.2.5 Sliding Skid

3.3.2.6 Winch from Vessel

3.3.3 Present the Findings

3.3.3.1 Quick Tie-in Introduction

3.3.3.2 Summary Modelled in Orcaflex

3.3.3.3 Recommendation / Assessment

3.3.3.4 Sensitivity Analysis Tables

3.3.3.5 Screenshots Drawings

3.3.3.6 Appendixes

4 Worked Examples

4.1 Flexible/ Umbilical Tie-in

4.1.1 ROVCON

4.1.2 UTIS

4.1.3 RTS

4.2 Rigid Pipe/ Spool Tie-in

4.3 Tie-in with Relocation (HCS)

4.4 Worked Tie-in Analysis Report on IPC+