guide to pigging.pdf

7/25/2019 Guide to Pigging.pdf

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PIPELINE ENGINEERING

Applying Science to the Art of Pigging

Welcome to Pipeline Engineering

As the Managing Director and a major shareholder in Pipeline Engineering I

am committed to ensuring that we meet and fulfil the needs of our customers,our employees and our shareholders.

As technology in our industry advances the needs of our customers areconstantly changing. Every pipeline is unique and each pigging system hasto be carefully designed to ensure maximum efficiency and performance andto closely match the needs of our customers

To meet this challenge it is my intention to ensure that Pipeline Engineeringprovide the best and most cost effective pigging system solution. This meansmaking available to our customers the best design, material, construction andservice facilities.

To make this happen and on behalf of Pipeline Engineering I will ensure that:

Our employees are trained to achieve the highest

standards in the industry


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standards in the industry




Since our formation in 1969, we have been supplying pipeline related

products and services to the oil, gas and petrochemical industries throughoutthe world.

By focusing on our users requirements we have acquired a reputation forhigh quality products, reliable deliveries and a real concern for customerneeds. We are considered by many to be Europes leading manufacturer ofpigs, spheres, scraper traps, pressure vessels and assemblies.

OWNERSHIP

Pipeline Engineering is a private limited company registered in England.Following a management buy out in 1997 the Company shareholders are asfollows:

Quester Venture Capital Trust managed by London based Quester CapitalManagement Limited are one of the UK's leading independent venture capitalgroups devoted to providing finance and support to smaller unquoted


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Willy Watson Managing Director of the Company, is an engineering graduateand a Cranfield MBA. He spent 15 years in the multinational BICCengineering group mostly in international marketing and general

management. More recently he has been involved as managing directorturning around smaller engineering businesses. He joined PE in August1996 and has returned the company to profits after a number of difficultyears. Willy Watson holds 26% of the equity.

With a strong balance sheet and shareholders that are actively involved inthe day to day running of the business, our customers, suppliers andemployees can be assured of a total commitment to this business.

COMPANY STRUCTURE

Pipeline Engineering is structured into five departments:

Quality Assurance

Sales and Marketing


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LOCATION

We are located in the North East of England

Airports Teesside (25minutes)Leeds (1 hour)Newcastle (1 hour)

Railway Darlington(15minutes)London Edinburgh Main Line

Road 2 Minutes from A1London Edinburgh Main Trunk RoadEdinburgh

Aberdeen

Pipeline Engineering


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PRODUCT RANGE

Pipeline Engineering offers solutions to various pipeline problems through pig

and pigging related activities. Some of these areas are as follows:

Design and Manufacture of:

Pipeline Pigs and Spheres

Pig Traps

Trap Closure Doors

Pig And Sphere Signallers Pipeline Isolation Systems

Sub-Sea and On-Shore Sphere Flow Tees suitable forthe passage of spheres and all intelligent pig vehicles

Sub-sea and On-Shore Piggable Wye Pieces

Project Management, Engineering and Fabrication of:


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POLYURETHANE

Our sister company - Polyurethane Engineering - possesses vast technical

and practical experience in formulating and processing urethanes.

This means that we can produce urethanes for specific applications; and donot have to rely on standard urethanes which may not be the best for acritical job. Many pigging operations, which may have been impossible usingstandard rubbers and urethanes, have been carried out successfully afterresearch has resulted in the development of a special urethane for thatparticular application.

Physical and chemical characteristics, such as high tear strength, highresilience, low compression set, high flex life, high heat resistance, highsolvent and hydrocarbon resistance, high abrasion resistance and lowhysteresis, have all been achieved through our research and developmentprogrammes and have resulted in products of outstanding quality andperformance.

TRACK RECORD


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FACILITIES

Pipeline Engineering operates from two factories situated on the same

industrial estate, covering a total area of 20,000 square feet.

Manufacturing is organised into three activities:-

A machine shop which incorporates computer controlled CNCmachines

A polyurethane moulding plant with testing and research

laboratory.

A fabrication shop with metal forming, welding (with coded andqualified welders) assembly and pressure test facilities.

Our manufacturing facilities are supported by fully computerised production,administration, finance, sales & marketing. Design facilities are enhanced bythe use of the latest Computer Aided Design systems


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PERSONNEL

Pipeline Engineering currently employs over 80 people, of which 60% are

directly involved in manufacture.

Key people you may wish to contact are:-

Managing Director Willy Watson

Works Manager Geoff Nathan

Financial Controller Jo Benn

Product Quality Manager John Spraggon

Projects Department Manager Kevin Wilson

Sales Office Manager (Internal) Fred Feenan

Export Sales Manager (Middle East) Nigel Baxter

Export Sales Manager (South-East Asia) Jason Tuer

Contracts Manager John Fisher


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TECHNOLOGY

Pipeline Engineering is a market leader in the design and development of

pipeline pigging equipment being responsible for several industry firsts.These have been achieved in association with our customers or as adevelopment in our own right. Notable amongst these developments are thefollowing:

The first inflatable single-moulding pipeline sphere for generalmeter prover use, thereby overcoming the risk of splitting

Hyperbaric spheres for use in sub-sea completions, in co-operation with Shell Expro and Comex Diving Company

Patented composite pig cups to provide good sealing withadequate support for large, heavy pigs travelling longdistances

Patented low maintenance, magnetically actuated pig andsphere detector

S b i d h d t t


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PROJECT ENGINEERING

Whilst being known world-wide for supplying a complete range of pigging

products, we also have a department integral within our BS EN ISO9001:1994 Quality network to provide a specialised product tailoring service.

Following 29 years of experience in the pipeline and pigging industry we havean enormous amount of experience to draw upon when confronted withspecial problems and needs. These highly qualified engineers workingtogether with experienced field personnel ensure a precise and practicalsolution to even the most demanding of requirements. This means clients

can be sure that multi product packages can be designed, manufactured,tested, commissioned and certified from a single source.

Our customers are closely involved in this process being constantly informedof the progress on their individual job.

This is made possible in part by the use of sophisticated computerisedsystems in the following areas

V l d i


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QUALITY CONTROL

Regular monitoring of materials and manufacturing output ensures that all of

our standard products are manufactured to the highest. This ensures thatoperators can use our products over and over again and still be sure thatthey will give excellent performance.

We have introduced a Quality Assurance system to monitor and controlmaterials, welding standards, assembly, testing and documentation. Thisprogramme more than satisfies the requirements of the industries it serves.

QUALITY ASSURANCE

High quality standards and continued product reliability have resulted inaward of the following recognised quality certificates:

BS EN ISO 9001:1994

Part I (ISO 9001) incorporates specification fordesign/development, production and servicing.


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Design and Application Manual

PIPELINE PIGS & PIGGING

CONTENTS - SECTION 1.0

1.1 Tools and Techniques

1.1.1 Description (What are Pigs?)

1.1.2 Function (What do pigs do?)

1.1.3 Description of Pigging Functions

1.1.4 Method (How do pigs work?)

1.1.5 Selection (How do I choose a pig?)

1 2 Pi li D i F t


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TOOLS AND TECHNIQUES

1.1.1 DESCRIPTION (What are Pigs?)

1.1.1.1 OVERVIEW

Pipeline Engineerings formidable reputation is based on the high specification andquality of its pigs, traps and related equipment which have been used to maintain

pipelines world-wide for many years.

But, what is a pig. The name refers to a mechanical device that can be inserted intoa pipeline and used to carry out pre-defined tasks (depending upon its construction)at critical points, or along the full length of the pipeline.

Pigs are driven by pressurising the pipeline behind them or, in most cases, insertingthem into the existing product flow, using specialised laundering equipment.

Whilst the potential applications for pigs are limited only by the imagination of thespecifier and the manufacturer, most tasks have now been defined and accepteddesign characteristics are used by all the major suppliers.

Pigs and spheres must be suitably equipped to carry out a function or task. Thesetasks are given names (cleaning, gauging, separation, drying, etc.) but the demandsof any individual task may require very different qualities from the pig depending uponthe stage in the development of the pipeline (pipeline development stage) at which

th i i t b d ( t ti i i i i i i t )


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There are two types of pigs at the highest level:

1. In-line inspection tools (Intelligent Pigs)2. Utility pigs

1. In-Line Inspection Tools (I.L.I)

Because of the complexity of these pigs (which make extensive use of on-board

electronics, they fall outside the scope of this manual.

2. Utility Pigs

Utility pigs include all categories except intelligent pigs. They can be divided into 5sub-groups based on their construction characteristics:

1. Metal bodied pigs (often referred to as mandrel pigs) sealing componentsaxially mounted on a tubular or solid metal body.

2. Solid cast pigs single piece polyurethane casting usually dumb-bell shaped3. Foam pigs moulded polyurethane foam, usually in 3 densities: soft; medium;

hard.4. Spheres manufactured from cast polyurethane and various rubbers according

to task5. Special pigs construction is similar to metal bodied pigs.

Specialised categories are allocated according to function (the task, or type of work

th t th i ill b i d t f ) Alth h f ti f d t


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Solid cast pigs are constructed entirely from polyurethane whilst spheres can be madfrom several types of elastometric material:

Polyurethanes

Rubbers: Neoprene; Nitrile; Silicon; Viton Seals

There are 3 types of detachable seal:

Discs Standard Cups

Conical Cups

Seals made from polyurethane are specified for most pigging functions it possessesexcellent physical characteristics which can be formulated for specific applications.However, there are good reasons for specifying some rubbers, which are given later.

Careful formulation of urethanes allows characteristics such as harness, tearstrength, abrasion resistance, hydrocarbon and hydrolysis resistance, flex life andcompression set to be modified.

There are 2 types of polyurethane:

Ethers (Good hydrolysis resistance; high resilience; low compression set).

Esters (Better physical properties than ethers).


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The pig body is manufactured from steel tube in pigs 8 and above and a steel bar inpigs below 8. Other materials, including aluminium and polyurethane, are also used.Flanges are welded to the body at both ends of the pig for seals and spacers; studsand pads are provided for attachment of fittings.

These pigs incorporate discs, standard cups and conical cups, manufacturedprimarily from polyurethane, although discs can also be supplied in several types ofrubber, as previously described. The quantity and type of seal depends upon the

pigging function and operating conditions.

Metal-bodies pigs allow the greatest range of fittings to be attached. This rangecovers fittings of all types and includes brushes, scrapers, plough blades, transmittedhousings, gauging plates, magnets and many other types necessary for specifictasks.

Solid Cast Pigs

These pigs are made from a single polyurethane casting. Therefore, the sealingelements are not interchangeable or replaceable. All seals are disc-type andcomprise 4 sealing and 2 support discs. They are designed, primarily, for small-borepipelines of approximately 2 to 12 nominal diameter.

The one-piece construction method limits the choice of fittings. However, brushes,gauging plates and magnets (for tracking and location purposes) can be fitted to thistype of pig.


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Spheres

The spherical elastomeric body of a sphere forms a single-line seal in the pipe.Therefore, there are no independent sealing elements to consider. Spheres do notaccept fittings (with the exception of some spheres which have magnets cast intothem for tracking and location purposes).

There are 2 types of sphere (with typical uses given):

Solid automated pigging programmes; batching; condensate removal

Inflatable meter proving; batching; condensate removal

Once the type has been decided, the characteristics of the pig are dependent uponthe formulation of the material from which the spheres are constructed. This willinfluence properties such as sealing efficiency, rate of wear, operating temperaturelimits and chemical resistance.

Inflatable spheres have a removable valve and are usually filled with water or awater/glycol mixture. Meter proving spheres are produced in hardnesses of 65-70Shore A while, for most other operational purposes, spheres tend to be specified withhardnesses of approximately 65 75 Shore A.

Special Pigs

Special pigs define those pigs usually metal-bodies which have to be significantly


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1.1.2 FUNCTION (What Do Pigs Do?)

1.1.2.1 OVERVIEW

Pigs must first be selected to carry out a specific function (task). This results in a pigwhich can generally be described by its function type. e.g cleaning pig, gauging pig,de-watering pig (section 1.4.0 explains this principle in more detail). For now, thescope of pigging functions is set out as follows:

1.1.2.2 PIGGING FUNCTIONS

As a result of the experience gained in pigging operations world-wide, most functionsare now pre-defined and can be found somewhere within the following list:

Debris removal

Cleaning

Gauging Filling

De-watering

Drying

Separation (batching)

Condensate removal

Meter proving

Product displacement

P d t i


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1.1.2.3 PIPELINE DEVELOPMENT STAGE

Pigging function depends upon the stage in the operational life of a pipeline at whichthe pig must carry out its task. Most stages in the development of a pipeline can befound in the following list:

Construction

Pre-commissioning (including hydrostatic testing)

Commissioning On-line operations

Inspection

Maintenance and repair

Renovation and rehabilitation

Decommissioning

Some pre-defined functions can take place at several stages in the development of

the pipeline. However, pigs designed to carry out tasks at one stage of pipelinedevelopment may not possess features that are suitable to enable them to carry outthe same task at other stages. This is due to a combination of the following factors:

Pigging distance

Frictional resistance of the materials in contact

Lubrication

Pigging speeds


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Compressed air operations impose several conditions on the pig no lubrication isavailable and pigging occurs in a series of high speed excursions between localisedrestrictions. The pig stops and the pressure builds until there is sufficient energy tolaunch the pig past the obstacle. As the pig moves forward rapidly, the pressure isdissipated until the pig reaches the next restriction, causing the process to berepeated.

1.1.3.2 CLEANING

The specification of cleaning pigs depends upon the pipeline development stage atwhich cleaning is required usually at one of the following:

Pre-commissioning

On-line operations

Inspection

Renovation and rehabilitation

Decommissioning

Cleaning at each stage imposes a different set of demands on the pig. This could,but would not automatically, require variations in pig design. There are 2 mainrequirements for cleaning irrespective of the type of pig.

1. Pigs must be fitted with cleaning devices brushes (circular or spring mounted;scrapers; ploughs.

2 B t b i t d d th i d i ti l th b h


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1.1.3.3 GAUGING

Gauging is commonly carried out at the following stages:

Construction

Maintenance and repair

Decommissioning

It is necessary for 2 reasons:

To check that there are no unintended intrusions into the Pipeline Engineering

To confirm that the ovality of the pipeline is within acceptable limits (tolerances)

Metal-bodied pigs (uni-directional or bi-directional) are fitted with a circular aluminiumgauging plate (steel plates can also be used), which is usually machines to 95% ofthe smallest internal pipeline diameter. Foam pigs can also be adapted to accept

gauging plates but they are not often used for this purpose.

At the construction stage, gauging operations are usually conducted with compressedair. As with all other operations using compressed air as the pigging medium, it isextremely dangerous and less effective.

1.1.3.4 FILLING

Filli i i d t t th f ll i t


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1.1.3.5 DE-WATERING

After hydrostatic testing the water must be removed from the pipeline prior to dryingand subsequent commissioning. This is done by a series of pigs pushed through thepipeline using compressed air.

The same qualities are required for de-watering as for filling the most importantcharacteristic again being the ability to maintain an effective seal in order to minimise

leakage. All relevant pipeline design factors should be considered.

Soft foam pigs (swabs) are often run after de-watering to swab away any waterremaining on the pipe walls, or which has accumulated at low points in the pipeline.

1.1.3.6 DRYING

In on-shore pipelines, foam swabs are pigged with extremely dry compressed air (-

90F atmospheric dew point temperature). Together with pigs and the air pick up theremaining water leaving behind a dry pipeline. However, it takes more than oneswab to do this and is, of course, dependent on the length of the pipeline. Severalhundred swabs may be required to fully dry a pipeline.

After the pipeline is dry, brush pigs must be run to remove the rust, mill scale and anydeposits that have settled out from the hydrostatic test. Again, several hundredswabs may be required to remove the material loosened by the brush pigs. Theseswabs will then be run until the air reaches a specified dewpoint.


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1.1.3.9 METER PROVING

Meter proving describes the procedure for calibrating flow meters (e.g turbine andpositive displacement meters) in which pigs are used to batch a known volume ofproduct through the meter. This volume is then compared against the volumeindicated by the meter.

Early meter provers were simply a measured mile of pipe in which batching pigs

were used to push the product through the meter in one direction only. When thepigs had completed the task they were transported back to the launcher to be usedagain. To save on transportation and handling costs, bi-directional pigs began to beused as these pigs could be returned simply by reversing the flow of the pipeline.

The next development saw spheres used in a continuous pipeline loop with aninterchange valve closing the top from the bottom. These interchange valvessubsequently proved to be inadequate and bi-directional meter provers became

standard.

In their simplest forms, meter provers consist of an internally coated pipe containingan inflatable sphere. Electrical pig signallers and a scraper trap (for launching andreceiving spheres) are installed at each end of the pipe. The volume of productcontained in the pipe between the detectors is accurately calibrated against certifiedcolumetric tanks and the meter to be proved s connected in series with the meterprover system.


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1.1.3.11 PRODUCT DISPLACEMENT

The same qualities are required for displacement as for filling and de-watering duties.Product displacement is carried out whenever the pipeline contents have to beevacuated, particularly at the decommissioning stage.

1.1.3.12 PRODUCT CONVERSION

This involves sterilising the pipeline prior to running other products which maybecome contaminated. Pigs used for this purpose require similar quantities to pigs

used for filling and de-watering duties.

1.1.3.13 GEL PIGGING

This technique does not involve utility pigs. A jelly-like substance is either injecteddirectly into the pipeline or moulded into cylindrical pigs. The jelly picks up andholds within it deposits found in the pipeline. It is bio-degradable and can be brokenup under pressure.

1.1.3.14 COATING APPLICATION

There are 2 pigging phases involved in the application of in situ pipeline coatings:

1 Cleaning2 Coating application

1. Cleaning


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1.1.4 METHOD (How Do Pigs Work?)

1.1.4.1 PROPULSION METHODS

Pigs travel through the pipeline under pressure from the pigging medium beingpumped behind them. This medium takes on of two forms:

1 Gas2 Liquid

Whatever the medium is gas or liquid has a dramatic effect on operational piggingcharacteristics, especially in terms of the pigs velocity profile.

Irrespective of the type of pigging medium, pig velocity has a profound effect onpigging efficiency. Pigs are designed to work most efficiently within a limited velocityrange which may be difficult to achieve, depending upon the pigging medium or otherfactors, such as the ability to regulate existing product flow rates.

1.1.4.2 PIGGING WITH A GAS

A stationary pig requires increased pressure to start it moving. Once this pressure isreached, the pig moves forward very quickly as the pressure begins to decreasebehind it. Eventually the pig comes into contact with an obstruction, such as a weldbead, the pressure is insufficient to keep it moving forward and the pig stops. Thecycle then begins again.


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The differential pressure contributes to the efficiency of pigging operations in the

following ways:

It improves sealing efficiency by forcing the seals against the pipe wall, makingthem act like non-return valves.

It is used as by-pass in cleaning operations

1.1.4.4 BENEFITS OF BY-PASS

By-Pass is the controlled flow of pigging medium, gas or liquid, through and/or pastthe pig. It has two effects:

It reduces the pressure (P1) behind the pig and hence the differential pressure(delta P) across the pig variations in the differential pressure effects the speedof the pig. The pig slows down as the differential pressure decreases.

It provides a very necessary jetting action which increases the efficiency of

cleaning pigs by preventing brushes from becoming blocked with looseneddeposits and holding these deposits in suspension in front of the pig rather thanallowing them to form into a solid slug. These slugs are difficult to deal with atthe receiver but, more importantly, may cause the pig to become stuck.

Studies have shown that it is better to drive the pig in the pipe using the front sealsonly, the rear seals act as support. Pluggable by-pass ports are built into the pigbody for this purpose and allow the pressure to flow through the pig body and be


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2. Cleaning

During cleaning operations, especially was removal, the deposits on the pipe wallvery quickly build up in the brush reducing its effectiveness. To prevent thishappening, limited by-pass can be used to create a flow path of pipeline productthrough and around the brushes. This tends to prevent the deposits removed fromthe pipe wall from building up in the brush by holding them in suspension within theproduct flow created by the by-pass.

Pigs are often fitted with jetting nozzles (also known as spider noses) which arepositioned in front of the leading set of seals. The nozzle jets are directed backtowards the leading discs or brushes (depending on the pig type) and again are usedto create a flow of product that is designed to hold in suspension any depositsremoved from the pipe wall.


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1.1.5 SELECTION (How Do I Chose A Pig?)

1.1.5.1 OVERVIEW

There are 3 fundamental questions to ask when selecting the appropriate type of pig:

1. What is the function, of task of, the pig?2. At what state in pipeline development will the task be performed3. Which pipeline design factors are relevant and to what extent will they influence

pig design

This approach will establish:

1. The most suitable type of pig and consequent arrangement of body, seals andfittings

2. The extent of any modifications and additions to the body, seals and fitting ofstandard pigs (resulting in the basis of a design or a special pig).

All pre-defined tasks will be carried our by one of the following 5 types of pig:

1. Metal-bodied pigs2. Solid cast pigs3. Foam pigs4. Spheres5. Special pigs


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The way in which some fittings are mounted will influence the pigging direction. The

following table refers to those fittings which do influence the pigging direction:

Uni-Directional Bi-Directional

Brushes U-spring mounted Circular Cantilever Mounted Arch-spring mounted

Blades U-spring mounted Arch-spring mounted

Cantilever Mounted

Scrapers U-spring mounted Arch-spring mountedCantilever Mounted

Each pig type incorporated very different design characteristics which are examinedin more detail below:

1.1.5.2 METAL-BODIED PIGS

Metal-bodied pigs are divided into 2 groups according to their directional ability withinthe pipeline. This can be selected or, more likely, will be imposed by the operatingconditions;

Uni-directional pigs travel through the pipeline in one direction only

Bi-directional pigs travel through the pipeline in either direction


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Cups

Standard cost effective design

Conical greater flexibility of use

Selection depends on the pipeline design factors detailed in section 2.0.0. However,conical cups do offer one particular advantage over standard cups an increasedability to pass restrictions in the pipeline (up to 20% of minimum pipeline internaldiameter compared to 5% with standard cups).

Other Factors

After ensuring that the pig will travel through the pipeline, selection is based on thepigging function, particularly when the function relies on the qualities of the seal (e.g.de-watering, filling, pigging long distances)

Unless operating conditions dictate otherwise, the pig body will be constructed

relative to the diameter and length of the pig. This ratio is as follows and variesbetween pig types it does not include spheres:

Length of pig = nominal pipe diameter x n(The value of n varies between approximately 1.4 2.0 according to pig type)


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1.1.5.4 FOAM PIGS

Foam pigs are initially selected according to pigging functions the following typesare commonly available for the task specified:

Bare swabbing displacement

Fully polyurethane coated displacement

Criss-cross polyurethane coated displacement/light cleaning

Wire brush spiral pattern cleaning

Wire brush fully covered cleaning (long run) Silicon gritted heavy cleaning/scale removal

The characteristics of foam pigs are more closely matched to the task by specifyingthe density of the open cell polyurethane foam:

Soft approximately 2lb/ft3

Medium approximately 5lb/ft3

Hard approximately 8lb/ft3

Hard foam pigs assist aggressive cleaning whilst Soft foam pigs improve swabbingcharacteristics.

Foam pigs are often specified as an alternative to metal-bodies pigs as they haveseveral advantages.


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1.1.5.5. SPHERES

Spheres play a vital role in pigging operation due, particularly, to their shape. Itallows them to be pre-loaded into launcher magazines and used to carry outautomated pigging operations (e.g. batching, condensate removal in untreated gaslines) where the launching facilities are un-manned for long periods.

There are 2 types of sphere:

Solid Inflatable

Solid spheres can be made from various elastomer materials:

Polyurethane

Nitrile rubber

Neoprene rubber

Solid spheres are used for batching and condensate removal from unmannedlaunching stations

Inflatable spheres made from polyurethane are always specified for use in meterprover loops because the sphere can be precisely inflated to give a constant seal asthe sphere wears with use. Meter prover spheres are softer than standard spheres(65-70 Shore A compared to 70 75 Shore A for standard spheres). Making the


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1.1.5.5 SPECIAL PIGS

If standard pigs must be modified to such an extent that they no longer comply withan ideal standard model in order to perform a function, then a special pig must bedesigned.

This usually involves changing the dimensions of a pig relative to the nominal pipelinediameter. The body dimensions may be changed or constructed in two modules(articulated), and the fittings and seals may also be suitably adapted. In some

instances, the dimensions of the pig remain unchanged with modifications beingconfined to altering the specification of the materials used in the construction of thepig.

Pigs designed for one-off tasks (tasks for which there is unlikely to be any furtherdemand) can also be classified as special pigs.


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PIPELINE DESIGN FACTORS

1.2.1 INTERNAL CONDITIONS (What Are Conditions Inside the Pipe?)

This section considers the potential problems posed by factors such as the chemicalcompatibility of the pipeline product with the materials used in the construction of thepig. It also considers the contributory effects of temperature, pressure, flow andpipeline deposits on the pig and its components.

1.2.1.1. PIPELINE PRODUCTS

Most pipelines carry one or more of the products listed below:

Hydrocarbons

Petrochemicals

Chemicals

Water

Food Products Gases

Each of these product groups has an effect on polyurethanes and rubbers to agreater or lesser extent. (Pig body materials are also effected by pipeline product).

The typical effect of chemical incompatibility with polyurethanes and rubber leads toblistering, cracking and chemical breakdown (Material is described as having a


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1.2.1.3 PRESSURE

Pressure does not have a significant effect on the construction of utility pigs whichcontain no sealed units. In-Line (I.L.I) pigs do have sealed units and pipelinepressure has a much more significant effect on this type of equipment.

The general effect of pressure is to move the pig in the pipeline. If this movement issmooth and constant then pigging will be much more efficient. In pipelinestransporting liquids, this characteristic movement is not difficult to achieve. However,

it is much more difficult in gas pipelines or where pigging is being carried out usingcompressed air.

Minimum pressure levels need to be achieved in order to keep pigs moving pastobstacles (typically weld beads) without stopping. IF a pig does stop, pressure willincrease until it is sufficient to launch the pig past the obstacle. Initial acceleration willbe rapid and overall velocity will be high with consequent safety implications, possibledamage to pipelines and fittings and much lower pigging efficiency. These problems

can be relieved by pressurising the pipeline ahead of the pig and venting at thereceiver.

Recommended minimum pigging pressures are often requested but are not easy tosupply as they are a compound of many factors: function, pipeline, condition,deposit, lubricant, seal material and type, liquid or gas pigging.

1.2.1.4 PRODUCT FLOW


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Condensates and water are swabbed our using pigs with seal discs, spheres or foampigs.

Polyurethane ploughs and scrapers are recommended for removing soft and hardwaxes respectively. Scale and mineral deposits often have to be removed usingfoam stud pigs to break up the hard scale initially then followed using cleaning pigsequipped with brushes.

Rust (corrosion) can be removed using brush-equipped cleaning pigs, possibly withmagnets fitted to pick up the ferrous debris. Foam pigs gritted with silicon carbide

can be used to burnish the pipeline, which will improve frictional losses and which, inturn, lead to increased pipeline output.


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1.2.2 PIPELINE SPECIFICATIONS (What Are the Pipeline Dimensions and

Materials?)

1.2.2.1 PIPELINE LENGTH

It is not the overall pipeline length that is of interest but the maximum piggingdistance the distance between launching and receiving stations. This factorinfluences the wear rate of the seals along with several other factors:

Pipe wall condition Pipe wall lining (if any)

Product compatibility

Seal material

Pigging medium

Presence of lubricant

Pigging speed

Throughout the world, pigging distances range from a few metres to hundreds ofkilometres. Whilst the pig design for the two extremes may possibly involve similarcharacteristics, it is essential that, along with the factors mentioned above, themaximum pigging distance is specified.

1.2.2.2 PIPELINE DIAMETER

Most pipelines have a constant external diameter while their wall thickness changes


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1.2.2.4 PIPELINE MATERIALS

Pipelines are made from many different materials:

Steel, including stainless steel.

Cast iron

Wrought iron

Cement

Reinforced concrete

Plastic

Whilst there are many reasons for selection of the line pipe, compatibility with theproposed product is extremely important. If the product is particularly aggressive, thepipe can be lined (this also improves the flow characteristics of the product in thepipe.

1.2.2.5 INTERNAL LININGS

Linings minimise corrosion of the pipe walls and improve the flow characteristics ofthe product. They can be applied when the pipe is constructed or after it has beenlaid.

There are several types of lining:

Epoxy linings


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1.2.2.8 BUNDLES

Bundles allow several pipes to be laid together. The operational pipelines arecontained within a large conduit that is laid as a single pipeline in the normal manner.Bundled pipelines do not present any problems to utility pigging.

1.2.2.9 RELATIVE POSITION FEATURES

This refers to the minimum distance between any two significant pipeline featuresthat might influence the efficiency of a pig or cause it to become stuck.

These features are as previously listed and are particularly relevant to the positioningof:

Valves

Offtakes (tees and laterals)

Bends

The general rule is that a minimum distance of 3 x pipeline diameters should beallowed between any two features.


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1.2.3 FITTINGS AND EQUIPMENT (What Components Are Fitted to thePipe?)

1.2.3.1 VALVES

Valves present major obstacles to successful pipeline pigging. There are severaltypes:

Ball valves

Gate vales

Check valves Butterfly valves

Plug type valves

Some types cannot be pigged but others can. Certain features can be included in thevalve design to assist pigging. Only those valves which can be pigged are illustrated,with relevant features noted.

There are two types of valve that cannot be pigged:

Butterfly/Plug type

There are three types of valve that can be pigged:

1. Ball valves2. Gate vales


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Possibly the single most important factor applies to all valves, irrespective of type.

They must all be OPEN. Appropriate mechanisms or checking procedures must bein place to ensure that this happens as the consequences of not doing so involvegreat expense.

Valves should always be fully specified as there will usually be some compromisewith regard to the most effective pig design for the function. Specialised componentsmay need to be added to the pig to improve its ability to pass safely through anyvalves.

1.2.3.2 OFFTAKES

All offtakes present a potential hazard to pigging. It is easy for pigs, especiallyspheres, to be diverted into an offtake and become stuck or continue their journeydown the offtake with obvious and expensive implications. Alternatively, if the sizeand relative positioning of offtakes are not offered for consideration at the pig designstage, it is possible that the pig may stall at the offtake as a flowpath opens up forproduct/pressure to bypass the pig. Spheres are particularly vulnerable as theyincorporate a single line seal (the circumference of the sphere I contact with thepipe).

Offtakes are sub-divided into 2 groups:

1. Offtakes which connect to the main pipeline at 90 - Tees2. Offtakes which connect to the main pipeline at other anges Laterals


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Sphere Tees allow product flow into and out of the offtake through slots around the

inner sleeve preventing the sphere from pushing into the offtake.

2. Laterals

Laterals are offtakes that connect to the main pipeline at angles other than 90. Theyare either barred or unbarred although, when designing pipelines for pigging, theyshould always be barred. Laterals present an increased opening when compared toTees. Therefore, pig design must take account of this. Pigs have to be made long

enough to span the opening to prevent stalling.

1.2.3.3 WYES

For the purpose of pigging, wyes join two lines together, both of which must bepigged. The pig emerges from a branch pipeline into the main pipeline (main andbranch do not imply any difference in pipe diameter) where it changes direction bybouncing off the opposite wall of the pipeline into which it has emerged. Theconvergence angle between the two pipelines is between 22 - 30.

Wyes can be pigged on one direction only and there is therefore no requirement forthe pigs to be bi-directional although disc-type pigs offer the most popular solutions.

There are two types of wye, each of which requires a pig possessing different designcharacteristics:

1. Wyes with parallel bores


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1.2.3.4 DIVERTERS

Diverters are designed to guide pigs from a main pipeline into a branch (lateral) theopposite of wye pigging. The pipeline product is not diverted only the pig.

Most diverters use mechanical methods but some divert pigs by means of magnetswhich attract the metal bodied pigs.

1.2.3.5 BENDS

There are three types of bend:

1. Forged (or factory) bends2. Field bends3. Mitred bends

1. Forged (Factory) Bends

Forged bends are classified according to their bend radius which is expressed interms of diameters or D. Standard sizes are produced as follows:

ID or short radius bend should not be included in a system designed for pigging.However, if they are present, it may be possible to manufacture special pigs tocope.

1D or long radius bend suitable for: spheres, foam pigs, specified metalbodied pigs

3D most utility pigs are suitable


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The minimum bend radius is almost always the first piece of information requested bythe pig manufacturer after establishing the pipeline diameter and pigging function. It

is important that as much relevant information as possible is made available.

1.2.3.6 TRAPS AND PIG HANDLING EQUIPMENT

To some extend, pig design is dependent upon the type of launching and receivingequipment installed. Some systems will only accept their own specially designedpigs and some systems will allow pig design within the limits of the trap dimensions.These systems may be specified in applications where complex industrial pigging

strategies are necessary or where trap size must be restricted because of spacelimitations.

Where there are no such restrictions, the following points should be considered:

Are handling facilities adequate for pig types and weights?

Are the traps sufficiently oversize to allow the pigs to be properlylaunched/received?

Are the traps large enough to meet the requirements of the pigging programme? Do the traps have the necessary characteristics for launching and receiving?

Are the traps suitably equipped for automated pigging programmes?


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Design & Application Manual

HYDROSTATIC TESTERS


2.1 Introduction

2.2 Description and Purpose

2.3 Function

2.4 Construction

2.5 Selection


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HYDROSTATIC TESTERS

INTRODUCTION

1.0 INTRODUCTION

Testing the integrity of joints in pipelinesystems can be a time consumingbusiness. In many instances, testing a

joint just a few millimetres wide around the

circumference of a pipe involves longhours fitting blind flanges and flooding theentire pipe section with a pressurisingmedium (usually water). This liquid - and it

can be a substantial volume - has then tobe disposed of safely when the test hasbeen completed.

Pipeline Engineering have simplified this process. They have developed specialisedequipment which can be used to test most pipeline joints, in a fraction of the timeand at much less cost when compared to the previous method. Moreover, the tools

can be used time and time again, and - in some instances - are suitable for a rangeof internal pipeline diameters.

Fig 1.


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HYDROSTATIC TESTERS

Flange Weld Testers (fig. 3) are designed totest the weld securing a flange onto the end of apipe spool. They can be used for all types of

flanges, including weld neck types, and can beextended for special applications.

Internal Joint Testers provide solutions for a more diverse range of applications.

Primarily, they allow welds tying two lengths of pipe together to be tested (fig. 4a).However, they can also be used to test pipeline fittings such as valves withouthaving to remove them from the pipeline system (fig. 4b). They can even be used toisolate individual branches of a pipeline system for hydro-testing (fig. 4c).

Fig 4a Fig 4b Fig 4c

Fig 3


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HYDROSTATIC TESTERS

1.2 FUNCTION

All testers work by pressurising a contained volume of test medium (usually water)

between two sealing faces and the pipe wall, thus producing a low volume testcavity. FWTs contain the medium between an expandable elastomeric seal, theface of the tester flange and the pipe wall (fig. 5a). IJTs contain the mediumbetween two expandable elastomeric seals and the pipe

wall (fig. 5b).

Fig 5a Fig 5b

The test medium is introduced through a special fill port, irrespective of the type of

tester. This port is also used to pressurise the medium and complete the test. To dothis reliably a separate vent port is provided in order to expel any air within the testcavity.

When an efficient seal has been created in which to contain the test medium, wesay the tester has been energised. How this is done is depends upon the nominal

Fig 5a


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HYDROSTATIC TESTERS

Flange Weld Testers are, by design, quite specific for their intended purpose andany variations are normally confined to extended body lengths, flange specifications

and installation/handling requirements depending upon the installation orientation ofthe tester (vertical up/down; horizontal).

Internal Joint Testers have much more scope for variation and as specials can be -and have been - articulated, extended and wheeled. Special installation tools can beproduced to allow them to operate further into the pipeline, beyond the scope ofstandard testers.


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HYDROSTATIC TESTERS

All standard Flange Weld Testers (fig. 7) feature:

1. A suitably rated flange connection (typically ANSI)2. Polyurethane (PU), low hysteresis seal

3. Body section (to set the distance between the flange and the seal)4. Expander and pusher components (to deform the seal)5. Filling and venting ports (threaded to customer specifications)6. An energising system (mechanical or hydraulic)

7. Suitable fittings for coupling to pumps etc. (to customer specifications)

8. Orings and antiextrusion rings (to prevent pressure losses betweenadjacent components)

Fig 7.

Flange Weld Tester

h draulicall ener ised


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HYDROSTATIC TESTERS

1. Polyurethane (PU), low hysteresis seal (x 2)2. Body or body/spacer (to set the distance between the seals)

3. Expander and pusher components (to deform the seal)4. A venting chimney5. Filling and venting ports (threaded to customer specifications)

6. An energising system (mechanical or hydraulic)7. Suitable fittings for coupling to pumps etc. (to customer specifications)8. Orings and antiextrusion rings (to prevent pressure losses between

adjacent components)

Fig. 8a

Internal Joint Tester

mechanically energised


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HYDROSTATIC TESTERS

Special Productsare those testers outside the scope of standard testers, although

they may only vary from the standard pattern because, for example, a largediameter tester may be required to perform tests at pressures up to ANSI Class2500.

Pipeline Engineering recommend that only PE-supplied nitrile Orings and PTFEantiextrusion rings be carried as spares and replaced in accordance with theinstructions which accompany all PE testers.

Typical ancillary fittings comprise:

Hydraulic hand pump for energising hydraulic testers Hydraulic hand pump for carrying out hydrotest (all testers) Lifting shackles for vertical applications

Spanners for energising mechanical testers Hosing necessary for connecting pumps to tester Installation/insertion tools (for special applications)

2.0 SELECTION

To provide the user with the most suitable equipment for their application, PE wouldappreciate the following information:

Nominal pipeline diameter


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PIPELINE STOPPER SYSTEMS


3.1 Introduction

3.2 High Pressure Stoppers

3.2.1 Grip Lock Pipe Plugs

3.3 Medium Pressure Stoppers

3.3.1 Compression Pipe Plugs

3.4 Low Pressure Stoppers

3.4.1 Gas Seal Stoppers


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INTRODUCTION

1. INTRODUCTION

Within the life of any pipeline there comes a time when, for one reason or another,work must be done which requires that a normally closed pipeline system has to betemporarily interrupted. e.g. when removing in-line fittings or sections of pipeline.

Using conventional techniques, the pipeline would have to be shut down and possiblydrained before such work could proceed.

This can be a time-consuming, expensive and logistically complex business.However, by using a system of temporary stoppers, massive reductions in time andexpense can be achieved.

Pipeline Engineering manufacture a range of temporary stoppers collectively knownas Pipe Stopper Systems or simply Stoppers. Superbly engineered, they shareseveral important characteristics. All can be inserted into the pipeline to form a

reliable and re-usable temporary seal capable of safely retaining a specified pressurefor long periods. Most require no special facilities, are simple and quick to operatewith smaller diameter stoppers capable of being transported and energised by hand.The following chart indicates the general range of stoppers available from PipelineEngineering.

From the chart on page 2 we can see that there are 3 basic types of stopper:


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Piggable

Hyperbaric

Spheres

n

Piggable

Hi-d

ifferential

StopperPigs

SLHD-10

n

Inflatable

AirBags

n

T

riple

Tyre

n

Twin

Tyre

n

GasSeal

Stoppers

Single

Tyre

n

re sggable

PER

SYSTEMS

esuppliedwithwingnutsforenergisingbyhand

ksealingdiscswhichproduceapigwithahighinterferencefitinthePipeline.

rmoretyresbeinggritted

forincreasedgrip.


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Low pressure stoppers can bend like plastic if they are used beyond their strict

specifications and, when used for retaining gases, any stopper can easily take on thekilling properties of a bullet but again, only if used beyond its specification.

An efficient stopper must posses 2 essential, and quite different, characteristics. Itmust have:

1. The ability to create SEAL, retaining the d.p. acting across it2. The ability to HOLD its longitudinal position with the pipe whilst under

pressure.

Figure 2 illustrates the common factors which determine the holding, or gripping,ability of all stoppers under load. These are:

A. The differential load to which the stopper is beingsubjected

B. The maximum force with which the stopper can gripethe pipe wall

C. The coefficient of friction, or the frictional resistance,between the surfaces in contact (the type of materialand its condition are major factors rusty pipe wallsprovide a much better gripping surface than smoothpipe walls).

D. The total area of contact of the stopper with the pipewall (The area to which the gripping force can beapplied).

Fig 2. Factors influencingStopper efficiency


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At high pressures, the friction grip of the elastomeric sealing elements on the pipe

wall is insufficient to hold the stopper against the d.p. that would eventually force thestopper out of the pipe. Such stoppers must incorporate a means of anchoringthemselves within the pipe.

Figure 4 shows how Pipeline Engineerings GripLock Pipe Plugs achieve this by incorporatingsegmented, toothed vice-rings which, when thestopper is energised, expand radially and bite into

the pipe wall. These vice-ring segments aremounted circumferentially around the body of thestopper on a taper so that, as the d.p. attempts toforce the stopper out of the pipe, the effect of thetaper translates any backwards motion to the vice-rings that then bite deeper into the pipe wall,increasing the security of the stopper in proportionwith the load being applied to the stopper. Such stoppers are described as beingself-energising.

Further means of differentiating stoppers can be found in characteristics that effecttheir deployment:

1. Energising Systems

Energising systems are those used to create the sealing and holding forces betweenthe stopper and the pipe wall. There are 4 such systems used throughout the range

Fig 4. Vice-ring anchoring mechanism


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2. Methods of Deployment Within the Pipeline

Stoppers can be defined as being either piggable or non-piggable. Standard stoppers designed to be piggableinclude Piggable Hyperbaric Spheres and Hi-differentialStopper Pigs, both of which require facilities to launchand/or receive them. (Refer to section 4.5 to see howHyperbaric Spheres are used). Non-piggable stoppers areusually manipulated manually, either directly by hand or byusing Extendable rods which are used to push the stopper

into position at the work site. Wheels are often added to thestopper to make this task easier, as shown in figure 5. Forspecial applications, however, many conventional non-piggable stoppers can bedesigned to be piggable (within certain design limits). It is in situations like thesewhere the advice of an experienced manufacturer, like Pipeline Engineering, isindispensable.

3. Environmental Suitability

All stoppers, with the exception of Inflatable Air Bags, utilise an elastomeric seal usually polyurethane. Although it has many excellent physical characteristics and isuniversally popular for such applications, polyurethane is susceptible to manychemicals as well as to high temperatures. For these reasons, alternative elastomersmay need to be specified where necessary or periods of deployment carefullycontrolled and even avoided where aggressive chemicals or high temperatures areinvolved.

Fig 5. Gas Seal Stopper

(With wheels)


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HIGH PRESSURE STOPPERS

2.1 GRIP LOCK PIPE PLUGS

2.1.1 DESCRIPTION

The Grip Lock Pipe Plug is offered by Pipeline Engineering as a temporary pipelinestopper system for high pressure applications. It has a number of features thatmake it particularly suitable for repeated use at high pressure.

1. Self-energising, heavy duty gripping mechanism2. Major components either forged or machined from solid steel bar3. Rugged, square section, low hysteresis elastomeric sealing element4. Easily maintained with spares available for critical parts5. Heavy duty construction

Grip Lock Pipe Plugs are supplied with one of two energising systems, dependingupon the diameter of the pipe in which the plug is to be used:

1. Mechanical energising is typically offered on stoppers for use in pipelines upto and including 6 ns.

2. Hydraulic energising is typically offered on stoppers for use in pipelines 8 nsand over.

Plugs are offered as standard up to 16 and are capable of withstanding pressures upto 207 bar, depending upon diameter. For use in applications over 16 it is alwaysbest to seek the expert advice of the manufacturer.


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Below a certain diameter (typically 8 ns) Grip Lock Pipe Plugs incorporate a

mechanical energising system. The reason for this is that stoppers above thisdiameter are consequently heavier and are energised more efficiently usinghydraulics. Mechanical stoppers are energised either by turning a hexagonal nut inwhich a spanner or turning a wing nut by hand. Hydraulic stoppers are connected toa hand pump via fittings that can be specified by the client.

Installation is simple: Taking care not to damage the elastomeric seal, the de-energised plug is inserted into the pipe (which should have been cleared of debris,

mill scale or rust). Hydraulic plugs can be connected to the hand pump at this pointor prior to insertion. The plug is then pressurised either by turning the nut clockwiseto expand both the seal and the vice ring, or by operating the hand pump until therequired inflation pressure is reached. If the seal is not fully effective and the internalpressure is leaking, then the inflation pressure can be increased. However, it isimportant to note that it is possible to swage the pipe when applying excessivepressure. At this point the plug is fully energised and any filling and/or monitoring canbe done through the central port provided on al Grip Lock Pipe Plugs. Oncompletion, the stopper can be removed simply by venting the internal pipeline

pressure and de-energising the seal.

2.1.3 CONSTRUCTION


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2.1.3 CONSTRUCTION (Continued)


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MEDIUM PRESSURE STOPPERS

3.0 COMPRESSION PIPE PLUGS

3.1.1 DESCRIPTION

The Compression Pipe Plug is offered by Pipeline Engineering as a temporarystopper system for medium pressure applications. It has a number of features thatmake it particularly suitable for its intended use:

1. Durable elastomeric sealing elements provide large circumferential contactarea with Pipeline Engineering One or more sealing elements can be grittedto increase gripping power

2. Major components cut or machined from solid steal3. Easily maintained with spares available for critical parts4. Heavy duty construction

Compression Pipe Plugs are supplied with one of two energising systems, dependingupon the diameter of the pipe in which the plug is to be used.

1. Mechanical energising is typically offered on stoppers for use in pi0pelines upto and including 6 ns

2. Hydraulic energising is typically offered on stoppers for us in pipelines 8 nsand over

Plugs are offered as standard up to 16 and are capable of withstanding pressures up


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Installation is simple. Taking care not to damage the elastomeric seals, the de-

energised plug is inserted into the pipe (which should have been cleared of debris,mill scale or rust). Hydraulic plugs can be connected to the hand pump now or priorto insertion. The plug is then pressurised either by turning the nut clockwise toexpand the seal or by operating the hand pump until the required inflation pressure isreached. If the seal is not fully effective and the internal pressure is leaking, then theinflation pressure can be increased. At this point, the plug is fully energised and anyfilling and/or monitoring can be done through the central port provided on allCompression Pipe Plugs. On completion, the stopper can be removed by simplyventing the internal pipeline pressure and de-energising the seal.

3.1.3 CONSTRUCTION


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LOW PRESSURE STOPPERS

4.1 GAS SEAL STOPPERS

4.1.1 DESCRIPTION

The Gas Seal Stopper is offered by Pipeline Engineering as a temporary pipelinestopper system for low pressure applications. It has a number of features whichmake it particularly suitable for its intended use:

1. Inflatable rubber sealing elements provide large circumferential contact withPipeline Engineering Sealing elements will accommodate ovality, irregularityand diameter variations in pipelines/drains/sewers

2. Available in large diameters3. Easily maintained with spares available for critical parts4. Heavy duty construction

Gas Seal Stoppers are available in one, two and three seal (or tyre) versions, all of

which can be inflated pneumatically or hydraulically using a hand or foot pump. Theyare available in a range of diameters from 4 to 60 and are capable of withstandingpressures up to 10 bar, depending upon diameter. Such a stopper must have threeseals and be adequately strutted.

Typical applications include:

1. Emergency isolation for inspection/repair2. Gas exclusion at a welding site


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4.1.2 FUNCTION

All Gas Seal Stoppers are inflated either hydraulically or pneumatically using a handor foot pump. Sealing elements are braced by steel or aluminium rings supporting 3sides so that expansion is directed against the pipe wall.

Installation is simple. Taking care not to damage the sealing elements, the deflatedstopper is inserted in the pipe (which should have been cleared of debris, mill scaleor rust).

The plug is then pressurised by operating the pump until the required inflationpressure is reached. Most seals with respect to this type of equipment are gained atless than 9 bar g. If the seal is not fully effective and the internal pressure isleaking, then the inflation pressure can be increased. Caution: The inflation pressureshould never exceed 20 bar g. At this point the plug is fully energised and any fillingand/or monitoring can be done through the central port provided on all Gas SealStoppers. On completion the stopper can be removed simply by venting the internalpipeline pressure and deflating the seal.

4.1.3 CONSTRUCTION


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4.2 INFLATABLE AIR BAGS

4.2.1 DESCRIPTION

Inflatable Air Bags are offered by Pipeline Engineering as a temporary pipelinestopper system for low pressure applications. They have a number of featureswhich make them particularly suitable for their intended use:

1. Large diameters available up to 962. Inflatable bladder with accommodate ovality, irregularity and diameter

variations in pipelines/drains/sewers3. Bags can be compressed to pass through small holes in pipes4. Robust and easy to use

Inflatable air bags are available in a range of diameters from 2 to 96, although largerdiamteres are available as specials and are capable, when used with suitable

mechanical bracing in the pipe, of withstanding pressures up to 8 bar, dependingupon diameter. The primary use of Inflatable Air Bags however, is for low pressuretesting at a few pounds per square inch. A 4 diameter nylon covered bar wouldtypically be capable of withstanding 2.5 psi unsupported in a cast iron pipe. Theability of the bag to hold against higher internal pipeline pressures can be improvedby using double length bags with restraining loops for attachment of restraining wires.Properly anchored, these bags will hold against internal pipeline pressures of up to75% of their safe working pressure (inflation pressure).


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4.2.3 CONSTRUCTION

Fig 9a. Inflatable Gas Bag (Spherical)


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4.3 DRAIN PLUGS

4.3.1 DESCRIPTION

Drain Plugs are offered by Pipeline Engineering as a temporary pipeline stoppersystem for low pressure applications. They have a number of features which makethem particularly suitable for their intended use:

1. Large diameters available up to 362. Cost-effective3. Robust and easy to use

Drain Plugs are available in a range of diameters from 3 to 36 and are capable ofwithstanding pressures up to 1 psi depending upon diameter. The primary use ofDrain Plugs is, however, for low pressure exclusions of liquids or gases at a fewpounds per square inch.


1. Low pressure, air, water or smoke testing of pipes and drains2. Low pressure plugging of pipes and drains3. Gas exclusion at a welding site4. Monitoring of internal pipeline pressure5. Venting and draining of pipes and drains


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4.3.3 CONSTRUCTION

Fig 10. Drain Plug


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4.4 HI-DIFFERENTIAL STOPPER PIG (SLHD-10)

4.4.1 DESCRIPTION

Hi-differential Stopper Pigs are offered by Pipeline Engineering to act as a primarypressure barrier situated deeper in the pipeline when used in conjunction with othertypes of stopper situated local to the work-site. They have a number of featureswhich make them particularly suitable for their intended use:

1. Large diameters available up to 562. Extremely hard wearing and reliable Omnithane seals3. Custom built for intended purpose4. Pigging allows access to remote work-sites

Hi-differential Stopper Pigs are available in a range of diameters from 4 to 56 andare capable of withstanding pressures up to 2 bar d.p. depending on diameter.

Fittings are available for gauging plates and transmitters (for location purposes).


1. Acting as the primary barrier in a pig train]Acting as the initial pressure barrierwhen undertaking hyperbaric repairs

4.4.2 FUNCTION


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4.4.3 CONSTRUCTION


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4.5 PIGGABLE HYPERBARIC SPHERES

4.5.1 DESCRIPTION

Piggable Hyperbaric Spheres are offered by Pipeline Engineering for subsea tie-inson pipelines. They have a number of features that make them particularly suitable fortheir intended use:

1. Specifically designed for subsea tie-ins2. Large diameters available up to 363. Cast from extremely hard wearing and reliable Omnithane4. Bi-directionally piggable

Piggable Hyperbaric Spheres are constructed from three layers of polyurethane acore, an intermediate seamless layer to provide strength and a softer outer layer toensure absolute sealing qualities. An internal tie-rod prevents excessive longitudinal

expansion and assists in increasing the pressure between the pipe wall and thesphere which enables a tight seal in the pipeline. They are available in a range ofdiameters from 4 to 36 and are capable of withstanding pressures between 1 bar gand 3 bar g, depending on diameter. 4 bar g to 6 bar g is required to pig them fromthe pipeline.

Specifically, their application is as a diver-installable stopper for hyperbaric use andwhich can subsequently be retrieved by pigging.

D i d A li i M l


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4.5.3 CONSTRUCTION

Fig 12b. Piggable Hyperbaric Sphere

D i d A li ti M l


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SELECTION

5.0 SELECTION

To provide the user with the most suitable equipment for their application, PipelineEngineering would appreciate the following information:

Nominal Pipeline Diameter

Pipe wall thickness (ANSI pipe schedule) or minimum internal pipe diameter

Maximum internal pipeline pressure at the stopper

Pipe construction material (and whether the pipe is lined)

Pipe wall condition at the worksite

Distance to the worksite from the point if insertion

Points of ovality of deformation within the Pipeline Engineering Minimum bendradius (if the worksite lies beyond a bend)

Duty cycle of the stopper (Expected length of time under load)

Type of fittings and number of ports required

D i d A li ti M l


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PIG SIGNALLERS


4.1 Introduction

4.2 UniSig BossPig Signallers

4.3 UniSig FlangePig Signallers

4.4 UniSig ValvePig Signallers

4.5 Selection

Design and Application Man al


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PIG SIGNALLERS

INTRODUCTION

1.0 INTRODUCTION

1.1 DESCRIPTION AND PURPOSE

Once a pig has been inserted into a pipe system its position cannot be visuallyconfirmed directly. A system is therefore required to indicate a pigs position, eithercontinuously or intermittently at pre-determined points in the pipeline. Continuousdetection is known as pig tracking whilst intermittent detection is referred to as pig

signalling. Each method involves the use of specialised equipment which, in mostinstances, must be incorporated into the pig or piping system before the pig islaunched.

Pig tracking requires an active transmitting source to be attached to the pig, withvarious technologies being used to provide that source - electro-magnetic, acousticand radioactive. Pig signalling, however, falls into two categories: intrusive and non-intrusive. Non-intrusive signallers are predominantly electro-magnetic and, along

with pig tracking techniques, are covered more fully elsewhere. Pipeline Engineeringhave applied their case experience to produce a wide range of intrusive pig signallerswhich are represented on the chart on page 2.

Intrusive pig signallers are, by definition, static, mechanically actuated and provide amomentary indication of a pigs presence at a specific point in the pipeline. Becausethe actuating mechanism is a mechanical trigger that intrudes into the pipeline, asignaller must also incorporate a satisfactory means of retaining the pressure within



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PIG SIGNALLERS

PIG SIGNALLERS

Minimum Pipe Size: 2 ns

ANSI Class 1500 (Class 2500 Specials)

UniSigBoss UniSigFlange UniSigValve

2 Flange Mounted Signaller Ball Valve Mounted Signaller

Not removable under pressure (1 Reduced Bore)

Removable under pressure

Standard Ring Type Joint Raised Face 1 Nipolet Mounted 2 Flange Mounted

Hot-Tappable (RTJ) (RF)

Removable under pressure

Extended

Non hot-tappable Ring Type Joint

Not removable under (RTJ)pressure



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PIG SIGNALLERS

Fig 1. Signaller Mounting Methods

UniSig FlangeMounted Signallers are also classified according to the flange face

type:

1. Raised Face (RF)2 Ring Type Joint (RTJ)



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PIG SIGNALLERS

1.2 FUNCTION

Installation

Signallers can be installed into the line under one or both of the following conditions:

1. When the pipeline is in-service and under line pressure

2. When the pipeline is at the construction stage or is out of service (no internalline pressure)

Installing a pig signaller directly into the pipelinewhilst that pipeline is in-service is known as hot-tapping and requires a welding boss or weld-o-flange to be attached to the pipeline through whichthe hot tapping can take place (Fig 3). Pipeline

Engineering have carefully developed their UniSigBoss Pig Signaller to be fully compatible with thehot-tapping tools of leading manufacturers, TDWilliamson and IPSCO. Hot-tapping is a detailedoperation with significant hazards and safety issuesreflected in the development of the UniSig whichallows the operational procedures of the toolmanufacturers to be followed without modification.



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PIG SIGNALLERS

When the magnet is withdrawn, themagnetic flux influencing thecomponents diminishes, the flagsprings into an upright position and/orthe proximity switch contact is broken.(This can be detected by a linkedcontroller). Immediately after the pig

has passed, the spring in the capreturns the magnet and the linkedtrigger to their respective restingpositions ready to detect the next pig from whichever direction it arrives. Theflag of an MV/MVE must be manuallyreset. Proximity switches, however, will be reset at the control panel.

Servicing and Replacement

Breakdown usually occurs as a result of scale, rust, hard waxes or sandaccumulating within the moving parts. For this reason it is essential that a regularmaintenance program is implemented. UniSig BossPig Signallers can be removedusing the relevant removal tool whilst UniSig FlangePig Signallers must be removedonly after ensuring that the pipeline is not under pressure. UniSig ValveMounted PigSignallers however are designed to be easily removable under line pressure as the

Fig 5. Intrusive Pig Signaller - Operating Principles



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PIG SIGNALLERS

UNISIG BOSSPIG SIGNALLERS

2.0 UNISIG BOSSPIG SIGNALLER


The UniSig BossPig Signaller is an intrusive, mechanically activated pig signallerdesigned to be mounted to the pipeline via a welding boss. Its design allows it to beinstalled by hot-tapping and it has been developed to be compatible with the weldingbosses and hot-tapping tools of other leading manufacturers.

The unit is activated by a mechanical, bi-directional trigger that protrudes into thepipeline. A unique orientation locking system allows the signaller internals to bequickly fitted within the welding boss and ensures that the trigger mechanism isalways correctly positioned in the direction of pig travel.

Detected pigs are indicated by one of three methods:

1. Mechanical/Visual (MV) integral, magnetically linked, sprung flag2. Electrical (E) removable, magnetically linked, proximity switch3. Combined (MVE) MV and E systems incorporated

UniSig Bosss, along with all pig signallers manufactured by Pipeline Engineering, use



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PIG SIGNALLERS

2.2 FUNCTION

Installation

The UniSig Bosscan be installed into the pipeline under the following conditions:

1. When the pipeline is under pressure (hot tapping)

2. When the pipeline is not under pressure

Installing the UniSig Bossdirectly into a pipeline that is in-service is known as hot-tapping, a detailed operation with significant hazards and safety issues. This isreflected in the development of the UniSig Boss that allows the operationalprocedures of the tool manufacturers to be followed without modification. If, however,the pipeline is not normally pressurised, then the installation of a pig signallerrequires standard fabrication techniques and no special tools.

Operation

When a pig passes beneath a correctly installed signaller, the pig discs push theprotruding bi-directional trigger forward in the direction of the pig travel. The trigger ishinged at two points that converts the angular motion gained from contact with the piginto axial motion, withdrawing a spring loaded, permanent magnet holder downthrough the cap At rest the proximity of the magnet at the top of the cap retains a



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PIG SIGNALLERS

2.3 CONSTRUCTION



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PIG SIGNALLERS

UNISIG FLANGEPIG SIGNALLERS

3.0 UNISIG FLANGEPIG SIGNALLER


The UniSig FlangePig Signaller is an intrusive, mechanically activated pig signaller

designed to be mounted via a 2 socket weld flange (Raised Face or Ring Type Joint)attached to the signaller welding boss. Its design allows it to be bolted to a matingflange attached to the pipeline.

The unit is activated by a mechanical bi-directional trigger that protrudes into thepipeline. (A trigger mounting extension gives the penetration necessary to accessthe pipeline through the mating flange). A unique orientation locking system allowsthe signaller internals to be quickly fitted and ensures that the trigger mechanism is

always correctly positioned in the direction of pig travel.

UniSig Flange signallers, along with all pig signallers manufactured by PipelineEngineering, use nitrile or viton O rings to withstand internal line pressures up tothose associated with ANSI Class 1500 (Class 2500 for specials). They areavailable in Raised Face (RF) and Ring Type Joint (RTJ) versions and are designedto be fitted to a minimum pipe diameter of 2ns.

Detected pigs are indicated by one of three methods:



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PIG SIGNALLERS

3.2 CONSTRUCTION

Installation

The UniSig FlangePig Signaller is installed in the line at the construction stage orwhen there is no internal line pressure. Installation requires only standard fabrication

techniques and no special tools

Operation

When a pig passes beneath a correctly installed signaller, the pig discs push theprotruding bi-directional trigger forward in the direction of the pig travel. The trigger ishinged at two points which converts the angular motion gained from contact with thepig into axial motion withdrawing a spring-loaded, permanent magnet holder down

through the cap. At rest, the proximity of the magnet at the top of the cap retains amechanical, spring-loaded flag and/or the contacts of an externally mountedproximity switch. When the magnet is withdrawn, the magnetic flux influencing thecomponents diminishes, the flag springs into an upright position and/or the proximityswitch contact is broken. (This can be detected by a linked controller or may simplybe used to activate an indicator lamp, siren, etc.) Immediately after the pig haspassed, the spring in the cap returns the magnet and the linked trigger to theirrespective resting positions ready to detect the next pig from whichever direction itarrives The flag of an MV/MVE must be manually reset proximity switches



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g pp

PIG SIGNALLERS

3.3 CONSTRUCTION



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g pp

PIG SIGNALLERS

UNISIG VALVEPIG SIGNALLERS

4.0 UNISIG VALVEPIG SIGNALLERS


The UniSig ValvePig Signaller is an intrusive, mechanically activated pig signaller,

designed to be attached to the pipeline via one of the following methods:

1. Weld neck flange2. Nipolet

The signaller/clamp assembly is welded to a 1 reduced bore valve which is, in turn,either welded to a 2 weld-neck flange for mating to the pipeline-mounted flange or a1 Nipolet for direct attachment to the pipeline.

The unit is activated by a mechanical, bi-directional trigger which protrudes into thepipeline. A unique orientation locking system allows the signaller internals to bequickly fitted and ensures that the trigger mechanism is always correctly positioned inthe direction of pig travel.

UniSig Valve signallers, along with all pig signallers manufactured by PipelineEngineering, use nitrile or viton O rings to withstand internal line pressures up to



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g pp

PIG SIGNALLERS

4.2 FUNCTION

Installation

The UniSig Valve Pig Signaller is installed in the line at the construction stage orwhen there is no internal line pressure. Installation requires only standard fabrication

techniques and no special tools

Operation

When a pig passes beneath a correctly installed signaller, the pig discs push theprotruding bi-directional trigger forward in the direction of the pig travel. The trigger ishinged at two points which converts the angular motion gained from contact with thepig into axial motion withdrawing a spring-loaded, permanent magnet holder downthrough the cap. At rest, the proximity of the magnet at the top of the cap retains amechanical, spring-loaded flag and/or contacts and externally mounted proximityswitch. When the magnet is withdrawn, the magnetic flux influencing the componentsdiminishes, the flag springs into an upright position and/or the proximity switchcontact is broken. (This can be detected by a linked controller or may simply be usedto activate an indicator lamp, siren, etc.) Immediately after the pig has passed, thespring in the cap returns the magnet and the linked trigger to their respective restingpositions ready to detect the next pig from whichever direction it arrives. The flag ofan MV/MVE must be manually reset Proximity switches however will be reset at



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PIG SIGNALLERS

4.3 CONSTRUCTION

Fig 9. UniSig Valve Signaller

(Assembly mounted on 1 Nipolet)



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PIG SIGNALLERSFig 10. UniSig Valve Signaller (Assembly mounted on 2 weld neck flange)

5.0 SELECTION

To provide the user with the most suitable equipment for their application, PipelineEngineering would appreciate the following information:

Pipeline contents

Pipeline construction (or mating) materials Output type (MV, MVE, E)

Installation and mounting requirements (Hot-tapping, Welding Boss, Flange) Servicing requirements (Valves, In-line serviceable UniSig Boss)

Location/elevation of pipeline relative to access areas (i.e. extended versionrequired?)

Internal pipeline pressure. (If greater than pressures associated with ANSI Class1500)

Spares requirements Electrical requirements (only applies to E or MVE types)

Any special requirements


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