AGENDA
•What is needed to keep aging pipelines
healthy
•Cleaning pig types used
•Inspection technologies
•Data Quality and reporting
Internal Maintenance and Monitoring
programs
Continous treatment with biocide and corrosion
inhibitor
Monitoring with coupons and probes.
Product Sampling
Control of BS&W.
Batch treatment with chemicals
Regular cleaning pig programs.
Types of cleaning pigs used at Ekofisk
Foam pig for light
cleaning, stuck pigs, and
verification of pigability.
BI-DI for removal of wax,
biofilm, scale build up.
Types of cleaning pigs used at Ekofisk
Pit-Boss – more aggressive
cleaning, hard wax, more
scale
Pencil brush pig.
Cleaning pig Interval
• Weekly
• Bi-Weekly
• Monthly
• Yearly
• Extra cleaning prior to internal inspection
Regular Internal Inspections
• Base case is internal inspection every 5th year
• Inspection results are used to optimize program
(risk based)
• Intervals from every 3rd month to every 10th
year
Use of different technologies for internal
inspections.
• Every 5th year – MFL
• Gasslines – MFL
• Three Phase lines – MFL
• When features above 70%wt loss – UT
• Water Injection lines - UT
• Pipelines of extreme importance / significant risk
UT alternating with MFL
Dual inspections/alternating years
MFL – Magnetic Flux Leakage
Spec: 10% +/- on measurement accuracy, 85%
confidence level
Qualitative analysis
Can be used in almost all piggable lines
Excellent automatic screening system, handles huge
amount of data, no threshold
Speed range from 0.4 – 4m/s
Superior on small pittings
MFL – Magnetic Flux Leakage
Less efficient on thick wall pipes
Speed limitations
Gas pipelines with low pressure causes problems
Difficulties with channeling corrosion
UT- Ultrasound Pig
Spec: +/- 0.2mm on measurement accuracy, 95%
confidence level
Direct measurements/analysis
Good quality on data in thick walled pipelines
No problems with findings
under extra sleeves
Speed range from
0.1 – 4.5m/s
Superior on
channeling
corrosion
Combined wt and crack detection
pig
Crawler, Tethered tool.
Same spec as UT pig.
Ultimate choice for unpiggable pipelines.
lack of launchers/receivers
Dual diameter pipelines with large difference in
dia.
Restrictions in pipeline
Requires – liquid filled lines
Limitation on length of tether/wire
Quality of inspection data
• Data quality is dependent on equipment,
cleaning and speed
• MFL – needs less cleaning than UT.
Tolerates some level of wax and scale
Flow between 0.4m/s and 4.0m/s
• UT needs pristine clean pipeline
No gas bubbles
Scale < 1mm
Experience wax problems well before MFL.
Analysis
• Automatic analysis not enough – needs manual sizing in
addition
•Only manual sizing reduces the number of reported features
due to time/cost
•Vendor needs a strong analysis team with lots of experience.
•Need good basis in verifications of findings (dig-ups& pull
through)
•No good with good analysis and poor reporting.
Reporting.
• Standard reporting:
> 10% wt, automatic sizing / threshold of 10%, 10 features pr km.
• Copsas require ALL defects to be reported – on a best endavour basis
•Requests runcom reports for all lines.
• Manual sizing of the most serious ML from last run, and any new
significant ML (deep, ERF, rapid growth)
• No requirement of number of defects to be reported for runcom
• Decision based on pipeline, defects, growth etc.
Conclusion
•MFL first choice for untroubled pipelines/low level
corrosion
•Gas and multiphase pipelines
•Pipelines with pitting corrosion
•UT first choice for pipelines with deep corrosion
•With channeling corrosion
•Un-piggable pipelines
•For pipelines of extreme importance/very high corrosion
rate
•DUAL INSPECTIONS