Pipe pigging
| There are basically three reasons to pig a pipeline:
To batch or separate dissimilar products;
For displacement purposes;
For internal inspection.
Pigging
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Pigging
Functions
a Pipe Geometry Measurement
a Internal Inspection
a Coating of internal bore
a Corrosion inhibition
a Improving Flow Efficiency
Pipe pigging
The pigs which are used to accomplish these tasks can be divided into
three categories:
Utility Pigs
which are used to perform functions such as cleaning, separating, or
dewatering.
Inline inspection Pigs
which provide information on the condition of the line, as well as the
extent and location of any problems.
Gel Pigs
which are used in conjunction with conventional pigs to optimize pipeline
dewatering, cleaning, and drying tasks.
Pipe pigging
The type of pig to be used and its optimum configuration for a particular task in
a particular pipeline should be determined based upon several criteria, which
include:
The purpose
Ñ Type, location, and volume of the substance to be removed or displaced
in conventional pigging applications,
Ñ Type of information to be gathered from an intelligent pig run,
Ñ Objectives and goals for the pig run.
The line contents
Ñ The contents of the line while pigging,
Ñ Available vs. required driving pressure,
Ñ Velocity of the pig.
Characteristics of the pipeline
Ñ The minimum and maximum internal line sizes,
Ñ Maximum distance pig must travel,
Ñ Minimum bend radius, and bend angles,
Ñ Additional features such as valve types, branch connections, and the
elevation profile.
Types of pigs
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„ ! Pipe pigging
^ ^ ! " | " Types of conventional pigs
Cleaning Pigs
Cleans the pipeline by removing solid or semi solid deposits or
debris.
Examples - Mandrel pigs, foam pigs, solid cast pigs, spheres etc.
Sealing Pigs
Provides a good seal in order to sweep liquids or acts as an
interface between two dissimilar products in the same pipeline
Examples - Mandrel pigs, foam pigs, solid cast pigs, spheres
Pipe pigging
UTILITY PIGS
ͻ Mandrel pigs
which have a central body tube, or mandrel, and various components which
can be assembled onto the mandrel to configure a pig for a specific duty;
ͻ Foam pigs
which are molded from polyurethane foam with various configurations of
solid polyurethane strips and/or abrasive materials permanently bonded to
them;
ͻ Solid cast pigs
which are moulded in one piece, usually from polyurethane, and;
ͻ Spherical pigs or spheres
which are of either a solid composition or inflated to their optimum diameter
with glycol and/or water.
Mandrill pig
Scraper mandrill pigs
Solid Cast pig
Solid cast pigs
Pipe pigging
GEOMETRY PIGS
A geometry / caliper pig is a configuration pig designed to
record conditions, such as
Ñ dents
Ñ wrinkles
Ñ ovality
Ñ bend radius
Ñ angle
Occasionally indications of significant internal corrosion is
recorded by making measurements of the inside surface of
the pipe.
Foam pigs
Magnetic Flux leakage pig
6e-waxing pig
Ultrasonic corrosion
detection tool
„ " # $ " % $ ! $
# Types of intelligent pigging
M Photographic inspection Pigs
M Crack 6etection Pigs
M Wax 6eposition 6etection Pigs
M Leak 6etection Pigs
M Product Sampling Pigs
M Sampling Pig
Pipe pigging
# # # | $ " " % ! # # " i
6iameter / geometry measurements;
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Photographic inspection;
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Curvature monitoring;
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Crack detection;
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Pipeline profile;
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Wax deposition measurement;
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Temperature / pressure recording;
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Leak detection;
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Bend measurement;
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Product sampling, and;
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Metal-loss / corrosion detection;
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Mapping.
Multi-channel
caliper pig
Geometric inspection
tool
Magnetic flux detection
pig
6ual diameter caliper
Types of intelligent pigging
Geometry Pigs
(eg.-Kaliper Pig, Electronic Gauging Pig, Cal Pig, Geo Control Pig,
6eformation survey tool)
Curvature Monitoring Pigs
(eg.Gyrosystem, Inertial geometry Pig)
Pressure & Temperature Recording Pigs
Types of intelligent pigging
Bend measurement Pigs
(eg. Bend Locator)
Metal Loss Corrosion 6etection Pigs
Magnetic Flux Pigs (eg. Linalog, Magnescan,Corrocontrol
Corrosion detection system, Pipeline corrosion surveyor)
UltrasonicPigs
(eg Ultrascan, Microprobe, RPITT, Flow sonic)
Ultrasonic crack detection tool
Pipe pigging
PLUGS
A plug is a specialist pig that can be used to isolate a section of pipeline at
pressure while some remedial work is undertaken.
The plugs can withstand pressures up to 200 bars typically.
The plug works by gripping into the line pipe and then having a separate
sealing system.
Lower pressure techniques include High Friction pigs, which provide a barrier
for de- pressurised systems.
High pressure plug pig
Pipe pigging
GEL PIGS
Gel pigs are a series of gelled liquid systems which have been developed for
use in pipeline operations, either during initial commissioning, or as a part of
a continuing maintenance program.
Most pipeline gels are water-based, but a range of chemicals, solvents, and
even acids can be gelled. Some chemicals can be gelled as the bulk liquid and
others only diluted in a carrier.
Gelled diesel is commonly used as a carrier of corrosion inhibitor in gas lines.
There are four main types of gel that are used in pipeline applications:
Ñ Batching, or separator gel
Ñ 6ebris pickup gel
Ñ Hydrocarbon gel
Ñ 6ehydrating gel
Gel pig
Pipe pigging
GEL PIGS
As a liquid, although highly viscous, the gel can be pumped through any line
which will accept liquids.
Gel pigs can be used alone (in liquid lines), in place of batching pigs, or in
conjunction with various types of conventional pigs.
When used with conventional pigs, gelled pigs can improve overall
performance while almost eliminating the risk of sticking a pig.
Gel pigs do not wear out in service like conventional pigs.
They can, however, be susceptible to dilution and gas cutting.
Care must be taken, therefore, when designing a pig train that incorporates
gel pigs to minimize fluid bypass of the pigs, and to place a conventional pig at
the back of the train when displacing with gas.
Pipe pigging
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Product separation
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Condensate removal from gas lines
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6ebris removal
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Inhibitor and biocide laydown
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Line filling/hydrotesting
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Special chemical treatment
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6ewatering and drying
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Removal of stuck pigs
Specially formulated gels have also been used to seal valves during
hydrostatic testing. Gels have been developed with a controlled gellation
time and a controlled viscosity for temporary pipeline isolation purposes.
Pipe pigging
PIG TRAPS/LAUNCHERS/RECEIVERS
Pig traps are used for inserting pigs into a pipeline then launching, receiving,
and finally removing them without flow interruption.
Pig traps are not generally proprietary products and are usually made to a
specification drawn up by the user. However, pig trap closures are proprietary
products and form a critically important part of a pigging system.
Safety is a major consideration in the selection of a closure.
All closures must have a built-in safety lock which prevents them being opened
while the trap is pressurised.
6ebris being received in pig receiver
Pig receiver & launcher arrangement
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