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The Power in

Electrical Safety

Integrity Management in Subsea Systems

Subsea Expo 2016

2BENDER > Presentation Theme

A big idea,

which still drives us to this day.

Walther Bender‘s vision over 70

years ago: comprehensive

protection against the dangers of

electrical current.


Bender Group – Offshore Experience and Project Scope

Bender Americas

• Chevron Bigfoot

• Shell Olympus

• BP/Hess – Tubular Bells

• Many more projects on a global level

• Extensive experience monitoring subsea umbilicals

4BENDER > Presentation Theme 4

What is “Asset Integrity Management”?

• The ability of an asset to perform its

required function effectively and efficiently

whilst protecting health, safety and the

environment.

• The means of ensuring that the people,

systems, processes, and resources that

deliver integrity are in place, in use and

will perform when required over the whole

lifecycle of the asset.

• The challenge to management is to

ensure that the integrity of engineered

systems – for instance, offshore

structures, ships, pipelines and process

systems – is maintained throughout the

anticipated service life.

Bureau Veritas, Asset Integrity Management


Risks Associated with Poor Integrity Management

• Loss of Life and Injury to Personnel

• Environmental Damage

• NPT – System Downtime and Production

Losses

*Non-Productive Time accounts for substantial losses in

output and revenue in the global offshore industry. NPT is

estimated to cost upwards of $400-$500 million USD

annually. Drilling Rigs and Automation, 2015


What is Insulation Monitoring (Offshore and Subsea)?

• Monitoring topside, hull, and subsea networks

for unintentional current leakage and loss of

resistance to ground.

• This term typically refers to unearthed or

“floating” electrical systems, such as would be

encountered on subsea umbilicals.


Insulation Monitoring as Integrity Management

• Allows for the detection and prediction

of decreasing insulation resistance in

offshore and subsea assets.

• Advanced techniques allow for the

location of fault conditions, which

facilitates corrective maintenance.

• Trending of ohmic values over a set

period of time enables operators to

determine activities that contribute to

hazardous conditions and equipment

failures.


Consequences of Poor Insulation Monitoring

• Failure of critical electrical components and systems.

• Unexpected NPT and loss of production revenues.

• A “blind spot” in determining umbilical damage, as well

as contributing factors.

• Failure of electrical systems that protect personnel and

provide environmental protection (including BOP, Hull

electrical distribution networks, and topside equipment*).

*Equipment such as blow-out

preventers (BOPs) and top drives can account

for 51% - 75% of all equipment related NPT.- Jeff Swain, Chevron Rig Systems


Potential Causes of Low IR – “Tin Whiskers”

• Tin whiskers pose a serious reliability risk to

electronic assemblies.

• Stable short circuits in low voltage, high

impedance circuits.

• Whiskers or parts of whiskers may break loose

and bridge isolated conductors.

• Many sudden failures and intermittent problems

are associated with tin whiskers because of their

ability to short closely spaced electronic circuits.


Potential Causes of Low IR – Abrasion and Device Failure


Potential Causes of Low IR - Water and Electrical “Trees”

• “Treeing” is an electrical pre-

breakdown phenomenon in solid

insulation.

• A damaging process due to

partial discharges and

progresses through the stressed

dielectric insulation, in a path

resembling the branches of a

tree.

• Treeing of solid high-voltage

cable insulation is a common

breakdown mechanism and

source of electrical faults in

subsea umbilical cables.

Water trees begin as a microscopic

region near a defect. They then grow

under the continued presence of a high

electrical field and water. Water trees

may eventually grow to the point where

they bridge the outer isolative layer to

the center high voltage conductor,

leading to complete electrical failure at

that point.


Passive Resistance Monitoring Technique


Passive Resistance Monitoring Technique

Limitations/Deficiencies:

• Inability to detect a symmetrical ground fault, as opposed to faults on a single phase.

• Lack of predictive capability in determining the potential for equipment failure.

• No indication of the severity of a fault condition in terms of insulation resistance.


Active Insulation Resistance Measurement

• Typically involves the injection of

low-level pulse current into an

electrical system.

• If a ground fault occurs, the

measuring circuit is closed and a

small measuring current will flow.

• Return of the measuring pulse is

evaluated to determine system

insulation resistance levels.

• Proactive approach to resistance

measurement in topside and subsea

electrical systems.

Measuring current is proportional to the

insulation resistance (the magnitude of the

ground fault), and is evaluated by the detector.


Active Measurement of Insulation Resistance - Benefits

• Detection of symmetrical and

asymmetrical ground faults.

• Indication of fault severity as

expressed via a resistive value.

• Allows for trending of drops in

insulation resistance, as well as the

comparison of such events against

offshore and subsea operational

activities, in order to determine

precipitating factors

• Can provide early-warning to

facilitate preventative and corrective

maintenance actions by operators


Importance of “real-world” data and trending

• Best practice and due-diligence dictate the

replacement of components whose

structural and functional integrity are high

risk.

• A lack of recorded data means equipment

failure can take place without preparation

on the part of the operator.

• Measurement trending allows for the

operator to identify hazardous practices

and take corrective action, while benefiting

from advance warning in planning NPT for

maintenance procedures.

• A true understanding of electrical isolation

values is VITAL to integrity management.


Additional Electrical Integrity Management Techniques

• Power Quality Management – including

analysis of Frequency, Phase Sequence,

Under/Over-Voltage, Under/Over-Current,

Power Factor, Harmonics, and L/G Voltage

Imbalance.

• Fixed and portable ground fault location

systems.

• Offline monitoring of critical electrical

systems (including fire pump motors)

• System integrity evaluations by qualified

consultants and subsea experts.

• Standardized procedures for the utilization of

ground fault data when coordinating field

replacement of critical equipment.


What does the future hold for subsea fault monitoring?

• Fault detection and location on subsea

“trees” and electrical network installed

below the waterline.

• More accurate fault location

capabilities, beyond the feeder level.

• Remote data-logging and assistance

via VPN.

• Fault location on active umbilicals via

the use of Spread Spectrum TDR

Technology.


Questions and Comments?


The presentation, its content, pictures and drawings are protected by copyright law. Duplication, translation, microfilming and transfer into any electronic systems, especially for commercial purposes is not allowed and subject to approval by the issuer. We do not assume any responsibilty and liabilty forfaulty or missing content. All data is based on manufacturers‘ information. All logos and product descriptions are registerered trademarks of therespective manufacturer.

Bender Inc.

420 Eagleview Blvd.

Exton, PA 19341

www.bender.org

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