UNIQUE APPROACH TO HOLDING BACK 'WALKING' PIPELINES WITH THICK THERMAL INSULATION IN DEEPWATERS

Kristen Andrew Foshaug, Chief Technology Officer

E : kaf@connectorsubsea.com | W : www.connectorsubsea.com

Agenda

Company Overview:

▪ About us

▪ Products and services

Case study – “UNIQUE APPROACH TO HOLDING BACK

'WALKING' PIPELINES WITH THICK THERMAL INSULATION IN

DEEPWATERS”

▪ Background

▪ Animation

Questions and answers

About Us

Who are we

▪ Offices in Norway, UK, Croatia, Bosnia, Brazil

▪ 85+ dedicated employees

▪ Complete Deepwater Tie-In and Pipeline Repair Solutions since 2000

▪ MORGRIP Mechanical Pipeline Connectors since 1987

▪ Remote Subsea Pipeline Welding since 1995, key partner to Equinor

EPRS

▪ Global Deepwater Emergency Pipeline Repair Club

Our Experience

▪ 3200+ MORGRIP Graphite Sealing Connectors supplied

▪ Extensive experience in Deepwater repair including:

▪ World First Deepwater Pipeline Repair

▪ World First Deepwater Riser Repair

▪ World First Remote Welded Tie-in & Repair

Products & Services

Diver-Assisted Repair

▪Range of MORGRIP Connectors and Clamps to suit all applications

▪Supporting equipment to ensure successful installation

Remote & Deepwater

Repair

Remote MORGRIP Pipeline connectors & clamps, complete

with all installation equipment & tooling

Bespoke Solutions

▪CRA Pipeline Repair

▪Pipe-in-pipe Repair

▪Elbow Clamps

▪Conductor Repair

▪Hydraulic Leak Repair

▪Holdback Clamps

Rental suite –Tie-in & Repair

▪Pipe Lift & Handling

▪Coating & Weld seam Removal

▪Cutting and End prep

▪Connector & Clamp installation frames

▪Riser Cleaning & Inspection Tool

Fully Remote Subsea Welding Systems

▪Worlds only field-proven system for remote welding for Pipeline tie-in and Repair

Emergency Pipeline Repair Systems &

Club

▪EPRS Club

▪Equipment Maintenance & Storage

▪Personnel

▪Contingency

▪Procedures

▪Preparedness

Subsea Distribution Portfolio

▪Couplers

▪Connectors

▪MQC

▪Ball Valves

▪Flying Leads

FIELD-PROVEN TRACK RECORD IN ALL BUSINESS AREAS

UNIQUE APPROACH TO HOLDING BACK 'WALKING' PIPELINES WITH THICK THERMAL INSULATION IN DEEPWATERS

Engineering Challenges & Technical Solutions

20” production flowline

63mm thermal insulation

800+m water depth

High external pressure – risk of local buckling

10 degree slope

Repair with clamp, tether system and anchors

140t load capacity

280t load test

The installation campaign was completed successfully in December 2020

Background

Two main clamp concepts considered

Grip onto steel Grip onto thermal insulation

Pro

Tried and tested method for gripping of pipelines

Con

Cold spot, scale/wax formation, corrosion

Deepwater coating removal

Pro

No intervention to pipeline

Quick installation time

Con

Coating creep

Coating response (ratcheting, thermal cycles)

Tack record for permanent works?

Creep compensationAlternatives considered

Radial creep compensationCompensation on bolt flanges

Inefficient gripping – long clamp

Challenging subsea installation

Large compensation needed

Compensation only in one direction

Potential fatigue issues for bolts

High degree of coating confinement

Radial activation, fast and simple installation

Short clamp – minimum dredging

Radial gripping and spring compensation

Pressure to the activation cylinder - plunger pulled axially, forcing gripping sleeve to move

radially inwards due to the wedged interface between these two parts.

High contact pressure – hardened parts.

The springs remain uncompressed when the clamp is closed and locked and the compression

only starts once the plunger is stroked axially and the gripping segment is in contact with the

pipeline coating.

Position pins will indicate the position of the plungers indicating if the gripping system is activated

or not.

Full scale prototype testing

Main purpose of prototype testingValidate concept of radial compensation

Investigate coating behaviour:

• Short term creep investigation – to evaluate re-tensioning gripping system

• Axial and radial creep characteristics with high inner temperature and high

tension

• Temperature cycling at high load

• Load cycling for ratcheting behaviour• Load test (280t)

• Load test at simulated maximum creep

Full scale prototype testing

Simplified prototype clamp

Full scale prototype testing

Test set-up

Full scale prototype testing

Instrumentation – gripping force and creep

Full scale prototype testing

Instrumentation – gripping force and axial creep

Full scale prototype testing - pictures

Full scale prototype testing - results

Activation as expected, even in

circumference and either side of clampInitial creep is less than expected, limited

benefit of re-applying gripping force

Full scale prototype testing - results

Spring compression and coating creep at high load and high temperature

Full scale prototype testing - results

Coating expansion and contraction during temperature cycles

Full scale prototype testing - results

Spring compression and coating creep at high load and high temperature

Full scale prototype testing - conclusions

Conclusions

Proof of concept in full scale

Radial creep (5.5%) within design parameters when extrapolated to lifetime of pipeline/field

Thermal expansion and contraction larger than anticipated

Upgrades needed for permanent clamp

HISC protection of disc springs

Method for precise load control to avoid local buckling of pipeline during shut down

In-service inspection ability to confirm gripping is still active

HISC protection of springsAlternatives considered

Fully sealed clampElectrical isolation of springs

• Corrosion of disc springs

• CRA springs?

• Very expensive springs

• Inefficient springs

Sealed spring pockets

• Various options for sealing technology

• Displacing of seawater to inert fluid

• Compensator needed to avoid hydraulic lock for coating creep

• Compensator system can be implemented to achieve:

• Precise load control

• In service inspection of gripping load

• In service inspection forintegrity of HISC protection

• Pre-filled topside. No subseaoperations needed during oras a part of installation

Sealed spring pockets

Compensators

Compensators

Pre-charged topside After activation subsea

FAT complete for two clamps

Animation

As-installed

Kristen Andrew Foshaug

Chief Technology Officer Connector Subsea Solutions

E : kaf@connectorsubsea.com | W : www.connectorsubsea.com

Thank youfor your time!