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STATS GROUPProcess & Pipeline Integrity Solutions

Pressurised Pipeline Repair or Modification

Enabled by Double Block And Bleed Isolation Tools

Dale MillwardDirector – EPRS & Subsea Services

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Reasons for pipeline repair or modification

RISK level - ALARP

Double Block Isolation Tools – Piggable and non Piggable

Repair or Modification Scenarios

• Valve Replacement/Installation

• Pipeline Tie Ins

• Retrospective installation of pigging facilities

• Dead leg Removal

Recent Case Study – pipeline tie in.

Short Animation

Q&A

Presentation

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Valve replacement or installation

Reasons for Repair or Modification

36” ESDV Replacement 36” SSIV Installation

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Making pipelines piggable / Removing unpiggable features


Retrofitting pigging facilities

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Tie-in of new pipeline to existing


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Removal of dead legs - due to accelerated corrosion rates in stagnant piping


Replacement of a damaged section

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Initially, it may be considered that the safest way to repair or modify a pipeline is todepressurise it and remove all hydrocarbon content, prior to doing the work; i.e. It hasa risk level that is As Low as Possible.

However, this may not be the safest method, or the way that has a residual risk levelthat is As Low As Reasonably Practicable (ALARP).

The risks associated with ceasing production, depressurising, hydrocarbon removal,dewatering and starting up again need to be properly assessed.

The following factors should also be assessed:

• Discharge to the environment

• Risks associated with decommissioning and recommissioning work scopes

• Stopping downstream production

• Flow assurance issues

• Out of service time

Following a proper risk assessment it could be decided that depressurising the entirepipeline is not the safest overall way of doing the work– or it does not have residual risk

that is ALARP.

So, what's the safest way ?

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If it turns out that it is not reasonably practicable to depressurise and hydrocarbon freethe pipeline then it may be necessary to break containment while the pipeline ispressurised and contains production inventory;

If the system has insufficient existing methods of isolation, then a temporary, fail safe,pressure capable, isolation tool, complying with industry isolation standards andrecommended practices will be required - typically a double block tool, where bothbarriers are fully proven in situ (in the isolation position).

Double Block Isolation Tool

The next section of this presentation will introduce isolation tools that provide therequired level of isolation and explain how they can be assessed to provide an isolationbarrier that is deemed to reduce the risk to As Low As Reasonably Practicable.

ALARP - Isolation

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Isolation Guidance

Industry isolation guidance specifies:

A proved DBB Isolation exists where the sealing integrity of two separate isolation barriers are proven before the isolation is relied upon.

Each part of the isolation should be proved separately.

BOTH isolation seals must be proven using full isolated pressure in the correct direction.

This level of isolation ensures that no single isolation barrier failure will endanger the worksite.

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Type Approved

Double Block Isolation tools

Tecno Plug™BISEP™ (Branch Installed Self Energised Plug)

DNV·GL TYPE APPROVAL for Pipeline Isolation Plugs

Type Designations BISEP™ and Tecno Plug™

Complying with DNV-OS-F101, DNV-RP-F113 & ASME VIII div. 2

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BISEP™

Proved Double Block Isolation

In Situ Test Sequence

Tecno Plug™

Secondary Seal Integrity Test

Pressure locked in the annulus Pressure behind vented,

Secondary seal tested with: Full differential pressure in correct direction

Page. 11

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Primary Seal Integrity Test

Pipeline pressure in frontAnnulus pressure vented

Primary seal tested with: Full differential pressure in correct direction

BISEP™ Tecno Plug™

Page. 12

Proved Double Block Isolation

In Situ Test Sequence

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Self-energisation feature maintains safe isolation while differential pressure

(above the verified minimum pressure) exists across the tool

The Isolation plug has two separate activation mechanisms – Dual Redundant Activation

The Isolation tool is

• activated and held in place by internal hydraulics

• and it is energised and mechanically locked in by differential pressure

Both separate activation mechanisms need to be removed to unset the plug

Tecno Plug™ Self Energisation

Self Energisation, Failsafe Feature

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In the unlikely the event of control system failure or possibly flat batteries, the PassiveUnset feature ensures the Tecno Plug™ is always recoverable upon job completion.

Passive unset is achieved by raising the tail pressure to equalise with the head pressure.

This de-latches the locked in hydraulic pressure; it is open circuited to return.

Equalising the pressure removes self –energisation force.

Once equalised the plug will then passively unset – without any active control input

NOTES:

• Isolation cannot be unset until the breaking containment operation is completed and the pressure behind the plug is raised to pipeline isolated pressure.

• If the pressure is equalised, the plug will become unset unless it is actively commanded not to unset.

• The passive unset is done in a safe and controlled manner only when the pressure is equalised across the tool.

PASSIVE UNSET

Fail-Safe Unset and Recovery Feature


Scenarios

Valve Replacement

BISEP™ and Tecno Plug™ used together to replace receiver and kicker line valves

without affecting production

Tecno Plug™ Isolation of 36” gas export pipeline for SDV replacement


Pipeline Tie In

24” pipelines tied into existing 36” trunk lines


Removing Un-piggable features

Retrofitting Pigging Facilities


Removing Dead Legs

With the isolation tools installed and tested. Dead legs were removed.

Flange were welded on so new valves could be installed.

Repeated at 12 similar locations


Case Study

Subsea pipeline tie in

Following animation will run through how this was achieved

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