why pig?

WHY PIG?

• Government Regulations– 192.150 / 195.120

• Decrease Corrosion• Increase Efficiency– Decrease Power Costs

• Pre-Inspection Cleaning• Operational Pigging• Gauging Line Geometry

• 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

INFORMATION TO KNOW BEFORE PIGGING YOUR LINE

ID

OD

• Valve Types– Single Biggest Cause Of Problems


• Bends– 1.5 D, 3D, 5D or Greater– Miter Bends


• 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– 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

FLOW RATE

Application Speed (MPH)

New Construction 1-5

On-Stream Gas 2-8

On-Stream Liquids 1-8

ILI Tools 2-7

• 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

FLOW RATE

LAUNCHING & RECEIVING

• 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

Pigging Mediums

TYPES OF PIGS

• 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

Pig Uses

• Foam– Negotiate Short

Radius Bends– Various Densities• 2-5 LB , 5-8 LB, 8-10 LB

– Reduce In Diameter Up To 35%

– Numerous Options

CATAGORIES OF PIGS

• Uses– Drying – Wiping– Cleaning– Proving

• 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

CATAGORIES OF PIGS

• Uses– Sealing– Batching– Cleaning

• 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

CATAGORIES OF PIGS

• 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.

Brushes

• Uses– Proving

• Options– Length– Size– Shape – Water Soluble– Oil Soluble

SOLUBLE PIGS

• Advantages• Cannot Get Stuck

• No Cut Outs

• USES– Liquid Removal

• OPTIONS– Coatings– Brushes

PIGGING SPHERES

• Advantages• Automated Launching

http://www.pigsunlimited.com/standard.aspx?elid=101&plk=279




• 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)

PIG SIZING

• There Is No Industry Cleanliness Standard

• Remove Contaminates A Layer At A Time– Combination Of Pigs And Cleaning Solution

WHAT IS CLEAN?

• 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

Dual Diameter Pigging

• 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

Cleaning With Solvents

• 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

PRE-RUN INSPECTION

• 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

PROGRESSIVE PIGGING

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.


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.


• Over Cleaning– Pigging To Bare Metal Invites Oxidation– A Few Mils of Build Up Prevents Oxidation And Minimally Affects Flow

When To Stop Pigging1. Monitor pressure drops when readings essentially level out.2. Time pig runs, if the volume is consistent pigging should stop when cleaning time

has leveled out.3. When the number of seconds of receiving effluent is the same during subsequent

pig runs, pigging should be stopped.4. Wirebrush pig runs should be limited to two or three.5. 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.

PIGGING PROBLEMS

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 TRACKERSUnfortunately, 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.

• 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

• Amount Not Bypassing May Be Enough To Propel The Pig

2. Remove Pressure & Volume• Wait 15 Min For Pig To Regain Shape

3. Run A Line-Size Swab• 2LB Density Pig Will Try To Bypass Stuck Pig & Reseal 1st Pig

4. Reverse Flow Direction• Send Pig Back A Few Feet Then Send The Original Direction (Bidirectional Only)

5. 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

REMOVING STUCK PIGS

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

why pig?

Documents

pig usage

defectsunrestrained

main diameter

nominal diameter small

total wire foam pig

line bends1

round wire brush

wire wheel brush