Transcript Slide 1

Pipeline Engineering - PE
Developments in Mechanical
Production Cleaning of Pipelines
Robin Brinham
PPSA Aberdeen Nov. 14th
Agenda
• Why Pig a pipeline?
• Production Cleaning Process
– Data Gathering
– Phase 1 Proving Piggability
– Phase 2 Progressive Cleaning
• Factors Affecting Cleaning Tool Design
• Designing the Right Cleaning Tool
• Case Studies
• Conclusion
Why Pig A Pipeline?
Pigging is an operation to remove debris or
unwanted deposit build up in a pipeline
Build up of deposit can:
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restrict fluid flow/increase pressure
damage pumps
prevent chemicals accessing pipe wall
encourage corrosion
prevent assessment of pipeline integrity
Wax removed from a 14”
line using a dual module
tool
Planned pigging program is essential to overcome the above
Production Cleaning
Process
• Data Gathering
• Develop Pigging Program/Design
the Tool
• Implement the Production
Cleaning Program
– Phase 1, prove piggability
– Phase 2, progressive cleaning
Solid Works based pig design
(computer modelling can be used
to help confirm tool can traverse the line)
Data Gathering
Effective Production Cleaning depends critically on
gathering the appropriate data
• Nature/quantity of debris
• Handling eg NORM, black powder etc
• Line Conditions:
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temperature
pressure
flow rates
product chemistry
• Line Features/Geometry
• Bends, ‘Y’s’, ‘T’s’, valves, id changes,
• Pigging History
Heat damaged PU cup
Progressive Cleaning
Phase 1
For infrequently pigged lines it
can be critical to prove
piggability.
Low density followed by higher density
foams of increased diameter
• Risk of wax candle (esp. <12”)
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• Once plugged d/p may harden
wax consistency
• Consider the use of chemical additives
for wax dispersion prior to cleaning
Foams of different diameter and coating
Progressive Cleaning
Phase 2
Progressively increasing the
“aggressiveness” of the tool
minimises the risk of blockage
• Tool design will generally consist of a metal body
with discs and/or cups attached or both
• In the final stages they may have studs, pins,
scraper blades or metal plates attached
• The removal of highly abrasive deposits e.g.
black powder or sand particularly in gas lines often
involves the use of pick up gels
• Pingers/Transmitters are often used to help
confirm tool location
• The art is to remove enough but not too much of
the debris during any one pigging run
Studded Cups
Factors Affecting
Cleaning Tool Design
Out of the many factors affecting pig design
three are especially critical:
• Pipe Size
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Effectiveness of attachments eg brushes in small ID’s
Higher frictional resistance on the PU for small ID tools
Weight stress for larger ID tools (friction, compression
set/static stress..)
• Pipe Length
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Additional friction wear and possible heat build up
• Bend Radius
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Pig length, body tube diameter, sealing length
56” tools, 54% weight saving
using Aluminium.
Factors Affecting
Cleaning Tool Design
Other factors include:
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Medium used to propel tool
ID changes
Valves, Y’s, T’s etc
Subsea or Cross Country
• extra sub sea features eg
manifolds, pigging loops etc
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Pig Trap Design
Dual diameter, unbarred “T’s”…
Designing The Right
Cleaning Tool
Each pipeline is different, use of ‘standard’
tool designs does not guarantee success
In many cases a bespoke approach is
required:
• Gather the data
• Design the tool
• Build the prototype
• Test Loop trial
• Finalise Tool design
• Client witnessed trial
The overall objective to maximise tool
effectiveness and to minimise risk
Equal ‘Y’ test loop
arrangement with
5D back to back
bends
What’s New?
Many recent developments
are incremental:
• Towing module for brushes etc
• Annular cleaning heads
• Brush redesigns
• A new innovation is the Automatic
Multiple Pig Launching System
(AMPL) whereby depressurising the
launcher will arm the next cleaning
tool ready for launch
AMPL pigs in launch cassette
Waxy Crude Oil
Large trunk line with heavy wax deposits
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Cleaning to be affected along
considerable length and at elevated
temperature
Substantial sand inclusion
Tool needed to be robust with careful
choice of PU grade
Cleaning tool after receipt, low flow,
check valves..
Mineral Extraction
Minerals (Zn/Pb) extracted from powdered ore
then residue mixed with cement and piped
underground for mine roof support
• 4.5km, 8” line used intermittently
• Residue paste settled/set restricting line
• Used progressive macerating pigs to remove hard sludge
(5” to 6.5” in 0.5” increments).
• Sludge removed in sections (too much to remove all at
once)
• Complete removal of all sludge achieved
Metal ‘cutters’ to break up sludge
Sludge layer breaking up
Conclusions
• To effectively clean lines it is essential to gather the requisite
information
• Using a ‘standard’ pig will frequently give unsatisfactory
results (every line different)
• The potential cost of inadequate pipeline cleaning can be
very high