WHY PIG? - Western Regional Gas Conference

Report
WHY PIG?
• Government Regulations
– 192.150 / 195.120
• Decrease Corrosion
• Increase Efficiency
– Decrease Power Costs
• Pre-Inspection Cleaning
• Operational Pigging
• Gauging Line Geometry
INFORMATION TO KNOW
BEFORE PIGGING YOUR LINE
• Pipe Dimensions
– Line Size
– Line ID
• Pigs 1-5 % Larger Than Pipe ID
• 2% Optimal
– Line Length
• Selection Of Pig Material
– Pipe Material
– Internal Coatings
• Selection Of Pig Material
– Wall Thickness
• Line Pipe Grade May Determines Thickness
• Selection of Pig Material
ID
OD
INFORMATION TO KNOW
BEFORE PIGGING YOUR LINE
• Valve Types
– Single Biggest Cause Of Problems
INFORMATION TO KNOW
BEFORE PIGGING YOUR LINE
• Bends
– 1.5 D, 3D, 5D or Greater
– Miter Bends
INFORMATION TO KNOW
BEFORE PIGGING YOUR LINE
• Branched Fittings
– Wyes
– Tees (Barred or not)
• Tees > 50% of main diameter should be barred
• At Least Three Diameters Of Straight Pipe Between Any Two
Fittings
FLOW RATE
Flow Rate
– Most Effective If Ran At Constant Speed
– Pig Velocity > 4ft/sec But <15ft/sec
– In General, the faster the pig travels the less efficient
it becomes in being able to carry material in front of it
Application
Speed (MPH)
New Construction
1-5
On-Stream Gas
2-8
On-Stream Liquids
1-8
ILI Tools
2-7
FLOW RATE
•
•
•
Pigs Are Driven Through The Line By Applying Pressure In The Direction Of
Required Movement. A Pressure Differential Is Created Across The Pig, Resulting In
Movement In The Direction Of The Pressure Drop.
Once The Force Behind The Pig Becomes Greater Than The Opposing Frictional
Force, The Pig Will Move In The Direction Of The Applied Force (Pressure).
Break Out Point : When A Pig Begins To Move
–
Greater Than Pressure Required To Maintain Movement
LAUNCHING & RECEIVING
LAUNCHING & RECEIVING
Pigging Mediums
• Liquid
– Incompressible Liquids Provide Maximum Control
Over Pig Speed As Well As Lubricating Seals
– Ensure Seal Material Is Compatible With Propelling
Liquid
• Gas
– As Gasses Are Compressible, The Amount Of Stored
Energy Behind A Pig Propelled With Gas Is Far Greater
Than That Of A Similar Pig Propelled With Liquid
– Increased Wear On Sealing Discs
TYPES OF PIGS
Pig Uses
• Batching
–Barrier Between Dissimilar Fluids
• Gauging
–Soft Metal Plate
–90%-95% ID
–Confirms Integrity Of The Flow Area
• Cleaning
Pig Uses
• Magnetic
– Lift Ferrous Debris or Trip Pig Signals
• Gel
• ILI
– Mapping, Geometry Measurement, Metal Loss
CATAGORIES OF PIGS
• Foam
– Negotiate Short
Radius Bends
– Various Densities
• 2-5 LB , 5-8 LB, 8-10 LB
– Reduce In Diameter
Up To 35%
– Numerous Options
• Uses
–
–
–
–
Drying
Wiping
Cleaning
Proving
CATAGORIES OF PIGS
• Solid Cast Urethane
– Hollow Shaft Can Handle 20% Reduction In Pipe ID
– Can Maneuver In Less Than 1.5D Radius Bends
– Advantages: Non Brittle, Elastomeric Memory, Abrasion Resistant
– Disadvantages: Break Down In Higher Temps, Dissolves In Certain Chemicals
• Uses
– Sealing
– Batching
– Cleaning
CATAGORIES OF PIGS
• Solid Cast Urethane
– Types Of Polyurethanes
• Castable Elastomers: Prepolymer And A Curator
– MDI (Methylenebisdiphenyl)
» More Expensive But More Durable
– TDI (Tolylenediisocyanate)
» Better Compression And Holds Up In Higher Temperature
• Durometer
– Measured By Shore Durometer or Rockwell Test
– The Higher The Durometer The Harder The Urethane And The Better
The Scraping Capability. The Softer The Durometer The Better The
Sealing Capability.
• MDI : 70A-85A Range
• TDI : 50A-90A Range
CATAGORIES OF PIGS
Steel Mandrel Pig
• Most Aggressive Pigs
• Most Versitile
– Discs
• Sealing: < 1 Inch (High Sealing Low Scraping)
• Scraping: >1Inch (High Scraping Low Sealing)
• Slotted: Multi-Diameter Lines
– Cups
• Scraper: Maximum Scraping - Reduce 15-20% Of Diameter
• Conical: Maximum Sealing – Reduce 30-35% Of Diameter
– Brushes
• Mounted To Ensure Full 360° Wall Coverage
• Size Of Bristle Has An Effect On The Size Of Anomaly It Can Clean
Brushes
• Flat Wire: Remove dirt, scale and large debris. Doesn’t clean pits well.
• Round Wire Brush: Ideal for pits. Easily handle thickness changes and
1.5D bends.
• Pencil Brush: Best for rust and loose debris. Rigid and doesn’t handle
tight bends well.
• Wire Wheel Brush: Used for smaller diameters and not aggressive.
• Scrub Brush: Total wire foam pig. Good for finishing and polishing.
SOLUBLE PIGS
• Uses
– Proving
• Options
–
–
–
–
–
Length
Size
Shape
Water Soluble
Oil Soluble
• Advantages
• Cannot Get Stuck
• No Cut Outs
PIGGING SPHERES
• USES
– Liquid Removal
• OPTIONS
– Coatings
– Brushes
• Advantages
• Automated Launching
PIG SIZING
• Pig Lengths
– Bullet Shaped
• 2 Times Nominal Diameter
– Sealing Length: 1.5 Times Nominal Diameter
– Double Dish & Light Density Swab
• 1.5 Times Nominal Diameter
– Solid Cast
• Approximately 1.5 Times Nominal Diameter
– Steel Mandrel
• 3” Longer Than Nominal Diameter (Small Pigs)
• 6” Longer Than Nominal Diameter (Larger Pigs)
WHAT IS CLEAN?
• There Is No Industry Cleanliness Standard
• Remove Contaminates A Layer At A Time
– Combination Of Pigs And Cleaning Solution
Dual Diameter Pigging
• Not to be confused with Multi-Diameter
• Solutions
– Butterfly or Petal Discs
– Paddle Pig
– Wheel or Spring Suspension
• Tend to see higher wear in the smaller
diameter line
Cleaning With Solvents
• Ran in conjunction with pigs to aid in cleaning the
line.
– Designed to breakdown, suspend solids, and reduce
surface tension to enhance cleaning programs
• Solvents are designed for:
–
–
–
–
Penetrating solids
Suspending large volumes of solids in fluid columns
Getting deep into pits
Coat solids to keep them from sticking to each other
• Solids come out in a slurry
PRE-RUN INSPECTION
• Pig must be in good condition
• Measure the sealing surface to ensure it is
oversized
• Inspect the sealing surface for defects
• Unrestrained diameter of the brushes must be
measured to ensure contact with the pipe
– Also inspect brushes for corrosion or breakage so they
don’t fall apart in the line or damage fittings
• Documentation of these practices pre and post
run can help maximize pig usage and decrease
costly mistakes
PROGRESSIVE PIGGING
• Run Bare Foam Pig To Determine True Pipe Opening
– Continue To Run Bare Foam Pigs Until They Come Out Clean
• Run A Foam Criss Cross Coated Pig Just Larger Than The True Pipe Opening
– Run A Bare Foam Pig Behind It To Improve Seal and Continue Criss Cross Pigs
Travel
– Continue This Set Up Until A Criss Cross Pig Comes Out Re-Usable
• Increase Pig Size ( ¼ ” to ½”) Until Full ID Attained
• Run Two Full Size Pigs (Criss Cross or Wire Brush)
– Run A Swab Pig Behind It To Clear The Line
• Flush Line
*Ideal Pig Speed 200-300 Feet A Minute
PIGGING APPLICATIONS
Sand Buildup
Method 1
–
–
–
–
Run a large amount of light density swabs
Used when increased pigging volumes are not available
It is very time consuming and not strong enough to push through the entire line
Propelling medium may deposit more sand than pig removes
Method 2
–
–
–
–
–
Using foam or steel pigs with bypass jets
The bypass jets allow the propelling medium to bypass the pig creating turbulent flow keeping the
sand suspended
The bypass jets reduce the pig's speed by as much as 30%.
If adequate volume is not available to propel a pig with bypass jets this method should not be used
This method should not be used is where extreme deposits of 30% or more of sand exist
Method 3
–
–
–
Foam pigs and extreme high-volume propelling medium
• The pigs diameter is equal to the internal pipe diameter, less the largest amount of deposited
sand per a cross-sectional view.
– For example, if we were pigging a 24" pipeline with a buildup of sand of 8", we would
subtract 8" from 24" and use a 16" foam pig
The large volume propelling medium is going to bypass the pig causing turbulence to agitate the
sand and keep it in suspension
Increase pig diameter until nominal internal diameter of pipe is reached
PIGGING APPLICATIONS
Butterfly Valves
• Butterfly valves cannot be pigged. It is not recommended to
attempt pigging through a butterfly valve. If one is willing to
attempt to pig a butterfly valve, they must accept full responsibility
for any problems.
*It is highly recommended to seek the aid of someone experienced
with this type of special application pigging and to use a pressure
recorder with 0 to150 psi and one-hour rotation capability. This should
be mounted on the launching end of the line.
PIGGING APPLICATIONS
Drying Pipelines
• This first run will remove anywhere from 85% to 95% of the water in the
line.
– Most use criss-cross foam pigs because of flexibility, easy handling and low cost
• Run a series of swabs to remove any moisture from the air in the line.
– From this point further the propellant should be dry.
• Brush foam pigs and swabs are now used to begin cleaning and removing
the rust and millscale.
– These pigs are run at speeds of 7 to 10 feet per second and in alternating
groups: first, three brush pigs, and then ten swabs.
– If receiving dust dry pigs, the pipeline is considered at 00 dew point.
– For negative dew points, pigging is continued.
• The last stage of pigging involves running a medium-density bare pig for a
final wipe down and sweep of the line.
PIGGING PROBLEMS
• Over Cleaning
– Pigging To Bare Metal Invites Oxidation
– A Few Mils of Build Up Prevents Oxidation And Minimally Affects Flow
When To Stop Pigging
1.
2.
3.
4.
5.
Monitor pressure drops when readings essentially level out.
Time pig runs, if the volume is consistent pigging should stop when
cleaning time has leveled out.
When the number of seconds of receiving effluent is the same during
subsequent pig runs, pigging should be stopped.
Wirebrush pig runs should be limited to two or three.
By running swabs nearing the end of pigging operation, they will both
sweep the line of loose buildup as well as gauge the line’s cleanliness.
When a swab is retrieved in good condition, pigging should stop.
STUCK PIGS
STUCK PIGS
STUCK PIGS
STUCK PIGS
STUCK PIGS
STUCK PIGS
STUCK PIGS
STUCK PIGS
STUCK PIGS
STUCK PIGS
STUCK PIGS
STUCK PIGS
STUCK PIGS
STUCK PIGS
STUCK PIGS
WHAT IS PIG TRACKING
• Pig Tracking refers to monitoring the passage
of a pig as it moves past prescribed and
monitored points along the pipeline.
• Pig Locating refers to pinpointing a pig that
has become stuck or lost in a given pipeline or
pipe manifold system on land or at sea.
TYPES OF TRACKERS
Unfortunately, carbon steel pipe acts as an ideal electromagnetic shield, which limits the possible methods of transmitting a signal through
the pipe wall to a sensor. The common methods used to sense the passage of a pig or attempt to locate it are:
•
Mechanical:
–
have several drawbacks.
•
•
•
•
•
•
•
invasive into the line, which makes them a potential environmental and safety hazard.
subject to contamination by materials in the pipe, which can prevent them from operating correctly.
subject to mechanical wear and damage, which will prevent them from operating properly.
–
Intrusive Pig Signals
Radioactive:
–
two main drawbacks.
–
the radioactive nature of the transmitting device itself makes people extremely skittish in regards to using it.
–
the transmitting distance is very limited which makes it primarily usable only when the “outside-the-pipe” sensor is directly attached
to the pipe.
Acoustic:
–
systems generate an audible signal, which can be picked up by external sensors, but only when there is sufficient acoustic coupling
between the transmitter and the wall of the pipe.
–
This usually limits their use to lines filled with liquid, and as you might expect lines which do not operate in a high noise environment
such as sub-sea lines.
–
Geophones
Magnetic:
–
Magnet equipped pigs operate well for tracking.
–
They are not of any use in locating a stuck pig as it is practically impossible to locate them when they are not in motion.
–
Non Intrusive Pig Signals
Electromagnetic:
–
Utilize an electromagnetic transmitter, which is attached to, embedded in, or travels with the pipeline pig, and a receiver/wand that
will pick up the signal from those transmitters at a distance allowing for significant ground cover.
–
This signal is a low frequency signal that operates in the magnetic range of the electromagnetic spectrum, which allows the signal to
penetrate the steel pipe wall to transmit a given distance through the ground.
PINPOINTING A STUCK PIG
• Pinpointing the location of the transmitter located in a stuck pig is a
relatively simple operation.
– Move to the last leapfrogging location where you know the pig passed. At this point hold
the wand horizontally and begin to slowly walk the line listening for the steady pulsing
beep of the transmitter.
• Please note that you must be sure where the pipe is when you are attempting to walk the line.
• Lateral distance from the center of the pipe will greatly decrease the possibility of picking up
the signal.
– Upon picking up the signal, continue walking towards the transmitter while watching the
analog sweep meter.
– When the meter movement begins to decrease, move backward until you see the
approximate maximum signal strength.
– Turn the wand vertical over the pipe.
– Slowly move the wand over the approximate area of maximum signal strength.
• The signal strength will increase and then fall to zero as well as the audible signal will disappear
(in other words “NULL”) and then start to rise again.
– Move the wand back and forth until you center over the “NULL”.
– You should now be standing directly over the transmitter.
REMOVING STUCK PIGS
• Type 1:
– Loss Of Seal →Propelling Medium Bypassing Pig
•
•
•
•
Excessive Wear On A long Pig Run
Dual Diameter Line
Abrasive Line Conditions
Torn Pig Due To Partially Closed Valves Or Debris
• Options:
1.
Increase Pigging Volume
•
2.
Remove Pressure & Volume
•
3.
Wait 15 Min For Pig To Regain Shape
Run A Line-Size Swab
•
4.
2LB Density Pig Will Try To Bypass Stuck Pig & Reseal 1st Pig
Reverse Flow Direction
•
5.
Amount Not Bypassing May Be Enough To Propel The Pig
Send Pig Back A Few Feet Then Send The Original Direction (Bidirectional
Only)
Cut Out
REMOVING STUCK PIGS
• Type 2:
– Obstructed
• Excessive Debris Build-Up
• Partially Closed Valves
• Tools, Animals, Etc.
– Options:
1.
Increase Pigging Pressure
– Increased Force To Push The Obstruction
2.
Increase / Decrease Pigging Pressure
– Quick On-&-Off Fashion (Kick In The Rear)
– Works Well In Small ID Fittings, Tight Bend Ells & Valves
3.
Remove Pressure & Volume
– Wait 15 Min For Pig To Regain Shape
4.
Reverse Flow Direction
– Send Pig Back A Few Feet Then Send The Original Direction (Bidirectional
Only)
5.
Cut Out
Any Questions Or Comments?
• Any Further Information Or Assistance Can Be
Provided.
– Just Contact Us By Email Or Phone.
• The Pigging Guide CD-ROM Has Pigs Available
As Well As Technical Information.
– Anything Not Seen In The Catalog Can Be Made

similar documents