Pigging Test






PIGGING
Integrity management of
subsea pipelines

EXPECTATION
§ Understand the types of pigs available
§ Understand requirements to make a pipeline
piggable
§ Understand the requirements about the
suitability of a pig to be launched
§ Understand the launching method

AGENDA 1 – PIGGING
§ Types of pigs
§ Piggability of pipeline
§ Pig suitability
§ Launching and receiving

JOBS DONE BY PIGS
§ Cleaning wax and solids
§ Sweeping out liquids
§ Corrosion inhibition
§ Proving bore is clear
§ Inspection
Pig designed for very fine
cleaning of aviation fuel line
Note use of sailcloth disks
between wire bristles

SPHERES
§ Solid (smaller diameters) or inflated
§ Sweeping liquids from lines
§ Spreads inhibitor onto wall circumference
§ Automatic launch for frequent basis

Pictures courtesy PII Kershaw
FOAM PIGS
§ Polyurethane foam body
§ Usually polyurethane coated
§ May have ribs or brush bands
§ Seal using axial compression

FOAM PIGS
§ Sweeping liquids from lines
§ Scale and rust removal
§ First stage cleaning prior to brush pigs
§ Negotiate tight bends, dents, restrictions, etc.
§ Flexible but not very durable
§ Heavy duty versions up to 400 km
(250 miles) durability
§ If stuck, can sometimes be broken up with
increased pressure

MODULAR PIGS
§ Metal structure
§ Polymer sealing discs
§ Cup
§ Bi-di
§ Typical utility pigs used for
operational pigging
§ Batching
§ Cleaning
§ Gauge pig

BATCH PIGS
§ Sweeping liquids from lines
§ Inhibitor batching
§ Sweeping spheres and pigs
entering from side branches
§ Used with gel pigs
§ Multiphase lines
§ Sand gathered
into gel
§ Removal of stuck pigs

BRUSH PIGS
§ Removal of solid
debris and wax
§ Many different designs
available

BYPASS PIGS
§ Pressure bypass pig
§ Cleaning pig for when pipeline expected to be
excessively dirty
Picture courtesy PII Kershaw

SCRAPER PIGS
§ Polyurethane or steel blades or ploughs
§ Wax removal

PIN-WHEEL PIG
§ Steel pins with hardened tips
§ Extra tough
applications
§ Scale removal
§ Hardened wax removal
§ Additional pin wheels
added to increase
aggressiveness of
cleaning programme

AGGRESSIVE CLEANING

MAGNETIC PIG
§ Removes ferrous debris
§ Often specified for cleaning programs ahead of
running an MFL inspection tool

CRAWLER PIG
§ Self-propelled
§ Not reliant on back pressure
§ Travel in either direction
§ Can operate in non-operational
pipelines
§ Tethered
§ Cleaning head and inspection
tools can be attached

BULLDOZER PIGS
§ High number of seals allows high differential
pressure and high driving force

GEL PIG
§ Uses
§ Pre-commission of barred tees and unpiggable lines
§ Separator or batching
§ Debris pick-up or condensate removal
§ Biocide laydown or corrosion inhibition
§ Dehydrating, dewatering or drying
§ Paraffin solvent
§ Isolation or stuck pig removal
PPSA gel
Drive
fluid
Separator
gel
Debris
gel
Debris
gel
Debris
gel
Separator
gel
Linefill
Flow direction

GEL PIGS
§ Structure
§ Water, hydrocarbon or chemical mixtures as base
§ Pseudo plastic, cohesive, self-healing and shear thinning
§ Disposal
§ Chemical breaker to destroy visco-elastic structure

DUAL DIAMETER PIGS
Slotted disc pig
Paddle pig
Varipig™

TYPES OF PIGS – SUMMARY
§ Sphere pigs are used for sweeping liquids out of
wet gas pipelines
§ Foam pigs used for range of tasks from
batching to cleaning
§ Wide range of cleaning pigs
§ Gel pigs perform specialist functions
§ Development of bi-directional crawler pigs
§ Intelligent pigs discussed in inspection module
Any questions?

AGENDA 2 – PIGGING
§ Types of pigs
§ Piggability of pipeline
§ Pig suitability
§ Launching and receiving

PIGGABILITY
§ Piggable now?
§ Has pig launchers and receivers?
§ Operationally pigged?
§ Sphere and/or pig launchers?
§ Potentially piggable?
§ No pig traps installed
§ Pipeline satisfy minimum bend radii and other requirements
§ Unpiggable
§ Subsea
§ No easy provision for tie-in of trap
§ Too small diameter
§ > 4 in for an intelligent pig

PIGGABLE NOW
§ Launchers and receivers
installed
§ Serviceable?
§ Small traps used for
commissioning?
§ Potential issues
§ Are traps long enough to
handle intelligent pigs?
§ Are pig signallers
functioning

POTENTIALLY PIGGABLE
§ No launcher/receiver
§ Pipeline satisfies minimum requirements
§ Minimum bend radii
§ 3 D
§ Minimum bore
§ Change in pipeline ID
§ Bore restrictions, e.g. Valves
§ Branch connections
§ Sphere or barred tees
§ Internal surface material
§ HDPE liners or flexibles

POTENTIALLY PIGGABLE
§ Other factors to consider
§ Does pipeline have double isolation at the ends?
§ If not may need to plug the riser to enable new valves to be
installed
§ Is there sufficient space and access to enable the
use of an intelligent pig?

PIGGING LOOPS
§ No subsea pig traps
§ May need DSV
§ Requires dual production flowlines
§ May be able to use injection water as driving medium
§ Now more common
§ FPSO operations
§ Deepwater fields
§ BP King

BI-DIRECTIONAL PIGGING
§ Some pigs are designed to be
bi-directional
§ Tethered pigs allow pig to be
retrieved
§ Return back to launcher
§ Difficult if many bends
§ Development of self powered
tools

PIGGABILITY OF PIPELINE –
SUMMARY
§ Not all pipelines have pigging facilities installed
§ Most pipelines are potentially piggable
§ Satisfy minimum bend radii
§ Pigged during commissioning
§ Some pipelines considered unpiggable
§ Subsea
§ Too small diameter
Any questions?

AGENDA 3 – PIGGING
§ Types of pigs
§ Piggability of pipeline
§ Pig suitability
§ Launching and receiving

PIG SUITABILITY
§ Is pig suitable for passing down line?
§ Risk of stuck pig
§ Does not fulfil function
§ Issues
§ Maintaining seal
§ Bore compatibility
§ Tee and wye passing
§ Minimum seal length
§ Structural integrity
§ Fatigue of welds
§ Coupling failures

PIG SUITABILITY
§ Issues (continued)
§ Geometry compatibility
§ Minimum bend radii
§ Passage of restriction
§ Dent
§ Check valve
§ Weight and size restrictions
§ More an issue for large pigs
§ Maximum temperature
§ Seals
§ instrumentation

INSTRUMENTED PIGS
§ ATEX compliance
§ Method of activating tool
§ Battery life
§ Pressure or time activated
switch
§ Max. temperature
capability
§ Electronics
§ Batteries

TRANSPONDERS
§ Should be fitted if risk of stuck pig
§ P/L not pigged before
§ Inspection tool
§ 3 main types
§ Acoustic pingers
§ Electromagnetic
§ Radioisotopes
§ Need to consider attenuation of signal
§ e.g. burial depth

PIG SUITABILITY – SUMMARY
§ The suitability of a type of pig to pass down the
pipeline should be assessed
§ Consideration should be given to:
§ Ability of the seals to perform
§ Ability to pass restrictions
§ Ability to perform at temperatures above 65 °C
(149 °F)
§ ATEX requirements (if Europe)
Any questions?

AGENDA 4 – PIGGING
§ Types of pigs
§ Piggability of pipeline
§ Pig suitability
§ Launching and receiving

RISK ASSESSMENT
§ Launcher/receiving procedures in place
§ Handling of pigs to and from traps
§ Simultaneous ops
§ Shut down of well
§ Other health hazards
§ Purging of H2S
§ Effect of contaminants
§ Effect of magnets on
heart pacemakers

SAFETY ISSUES
§ Must not be able to open pig trap whilst trap is
pressurised
§ Must be depressurised before opening
§ Purging may be required
§ Valve and door closure interlock
§ Average 1 death per year due to pig trap
accident

SAFETY ISSUES
§ Pig signallers
§ Valves – fully open or fully closed?
§ Seal explosive decompression – use non-
permeable elastomers
§ Interlock
§ Closure mechanism – hand operated
§ Corrosion – seal housing

PIG LAUNCHER

SPHERE LAUNCHER
§ Automatic launching from
unmanned platform
§ ‘Magazine’ of spheres
§ Launch pins, flaps or launch
valve to allow 1 sphere at a
time
§ Significant incline on barrel

Vent valve D
and gauge
Mainline trap
valves B
Trap
kicker
valve C
Mainline
bypass
valve A
Door
Launch
tray
Flow
Flow
Balance line
valve
PIG LAUNCHER
Pig
1. Trap vented and purged
2. Door opened, pig inserted, door closed
Pig signaller

Vent valve D
and gauge
Trap
kicker
valve C
Mainline
bypass
valve A
Door
Launch
tray
Flow
Flow
Balance line
valve
PIG LAUNCHER
Pig
1. Trap vented and purged
2. Door opened, pig inserted, door closed
3. Valves C and B opened, A closed
4. Pig leaves trap
5. Pig passes signaller and moves into pipeline
Pig signaller
Mainline trap
valves B

Vent valve D
and gauge
Trap
kicker
valve C
Mainline
bypass
valve A
Door
Launch
tray
Flow
Flow
Balance line
valve
PIG LAUNCHER
1. Trap vented and purged
2. Door opened, pig inserted, door closed
3. Valves C and B opened, A closed
4. Pig leaves trap
5. Pig passes signaller and moves into pipeline
6. Valve A opened, B and C closed
Pig signaller
Mainline trap
valves B

RECEIVER
Pipeline
Pig trap barrel
Bypass
line
Pig signaller
Trap isolation
valves
Drain
Vent
Closure
Balance line

PIG SIGNALLERS
§ Intrusive
§ Mechanical
§ Often non functioning
§ Non-intrusive
§ Acoustic
§ Liquid lines only
§ Electromagnetic
§ Pigs fitted with strong magnets
§ Risk of pig held up at by-pass
tee or main valve

PIG HOLD-UP
§ Damage to sealing disc
§ Possibly due to
the pig being held
up at the bypass
tee before the
receiver
§ Pig signallers
could identify if
hold up is taking place

ROSEN – VIDEO

ROSEN – VIDEO

EFFECT OF SPEED
§ Pigs operate best at certain speeds
§ Cleaning
§ Minimum speed to efficiently pick up debris
§ Minimum speed to enable use of bypass
§ Inspection
§ MFL tools have minimum and maximum speed limits
§ Typically 1 m/s to 5 m/s but lower speeds may be acceptable
§ UT tools
§ Typically 0 m/s – 3 m/s
§ Low pressure gas lines problematic
§ Stick-slip behaviour

SPEED CONTROL
§ Applicable to gas pipelines
§ Some pigs have active speed control
§ By-pass
§ Larger pig sizes only
§ Otherwise rely on process control
§ Not always successful

LAUNCHING AND RECEIVING –
SUMMARY
§ Pigs are launched and received using pig traps
§ Limited interruption to operation
§ Sphere launchers can hold multiple spheres
§ Risks can be high
§ Strict accordance to operating procedures
required
Any questions?

PIGGING – SUMMARY
§ There are wide range of pigs available to do
different jobs
§ Need to consider whether a pipeline is suitable
to be pigged
§ Need to consider that the design of pig is
suitable for use in the pipeline
§ Reviewed the launching a receiving operations
and considered safety issues
Any questions?

PIGGING
Integrity management of
subsea pipelines
Thank you for listening
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