Pipeline spans are susceptible to vortex induced vibration, slugging, and flow induced vibration leading to accelerated fatigue of the pipeline. This presentation shows an example return on investment of pipeline span monitoring and flow rate optimization through the use of motion monitoring. Utilizing the monitored data, operators are able to calibrate their models and reduce span mitigation costs.

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Pipeline Free Span
Monitoring: ROI
April 2014

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Services Overview
Pipeline Integrity Monitoring
Slugging
• Cyclic stress and inertial
loading cause fatigue
Free Spans
• Potential damage from
VIV, FIV and slugging
• Increasing flow rates
causing enhanced fatigue
FIV

3. Free Spans

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Pipeline Span Monitoring
• Span- unsupported areas of subsea pipeline
• Two types of span that can cause integrity concerns:
– Free spans
– Pipeline sleepers
• Potential fatigue damage from VIV, FIV and slugging
Introduction
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Soil
Onset of scour Tunnel erosion Lee-wake erosion Equilibrium stage

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Pipeline Free Spans
Reducing Operational Costs: Example
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2*|FFT|ofx-acc.
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frequency [Hz]
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LOGGER NO. T14 - PERIOD NO. 1737
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frequency [Hz]
• Client spends approximately $500K per year on
mitigation costs of pipeline spans for a single
pipeline
• Current model suggests mitigation measures
must be taken on any unsupported span over
20 ft.
• Monitoring chosen to measure VIV response
and current data to calibrate model.
• Little to no evidence of VIV was found to be
present in either the cross-flow or in-line
direction increasing acceptable span length to
35 ft.
Typical VIV Spectrum
Monitored Data

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Typical system layout
Pipeline Span Monitoring
Current Meter
ROV Deployable Motion
Logger

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Estimated Cost Savings
Pipeline Span Monitoring
$120,000
Campaign
Costs
$130,000
1st Year
Savings
$250,000
2nd Year
Savings
$0 $100,000 $200,000 $300,000 $400,000 $500,000
No Monitoring
(1 Year)
With Monitoring
(1 Year)
$130,000
$500,000
Cost Savings
Campaign
Costs
Mitigation
Costs
Mitigation
Costs
$250,000 $120,000

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Pipeline Free Span Monitoring
Summary
• Pipeline free spans can experience
accelerated fatigue due to VIV
• Pipeline operators are spending
millions of dollars mitigating span
issues with sand bags, grouting, etc.
• Span monitoring provides data to
reduce conservatism in design and
reduce mitigation costs by extending
critical span length and reducing risk

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Pulse Structural Monitoring
Paul Chittenden
M: +1 713 422 2674
Paul.Chittenden@pulse-monitoring.com
www.pulse-monitoring.com
www.pulse-monitoring.com
Thank you!