Intelligent Pigging

Modern intelligent or 'smart' pigs are highly sophisticated instruments that include electronics and sensors that collect various forms of data during their trip through the pipeline. They vary in technology and complexity depending on the intended use and the manufacturer. 

Intelligent Pig

Source : https://www.nord-stream.com/media/picture_library/rgb_small/en/2013/08/intelligent-pig_3488_20130827.jpg

The electronics are sealed to prevent leakage of the pipeline product into the electronics since products can range from being highly basic to highly acidic and can be of extremely high pressure and temperature. Many pigs use specific materials according to the product in the pipeline. Power for the electronics is typically provided by onboard batteries which are also sealed. Data recording may be by various means ranging from analog tape, digital tape, or solid state memory in more modern units.

The technology used varies by the service required and the design of the pig, each pigging service provider may have unique and proprietary technologies to accomplish the service. Surface pitting and corrosion, as well as cracks and weld defects in steel/ferrous pipelines are often detected using magnetic flux leakage (MFL) pigs. Other 'smart' pigs use electromagnetic acoustic transducers to detect pipe defects. Caliper pigs can measure the roundness of the pipeline to determine areas of crushing or other deformations. Some smart pigs use a combination of technologies, such as providing MFL and caliper functions in a single tool. Trials of pigs usingacoustic resonance technology have been reported.

During the pigging run the pig is unable to directly communicate with the outside world due to the distance underground or underwater and/or the materials that the pipe is made of. For example, steel pipelines effectively prevent any significant radio communications outside the pipe. It is therefore necessary that the pig use internal means to record its own movement during the trip. This may be done by odometers, gyroscope-assisted tilt sensors and other technologies. The pig records this positional data so that the distance it moves along with any bends can be interpreted later to determine the exact path taken.

Pipeline defects include:

• General Corrosion

• Grooving Corrosion

• Small Pitting

• Girth Weld Anomalies

• Hard Spots

• Laminations and Hydrogen Induced Cracking (HIC)

• Erosion Wall Thinning

• Ovality

Intelligent Piggs can detect defects to an extremely high degree of accuracy, with the more advanced piggs able to detect depth sizing to within ±0.5mm, depth of pitting or corrosion to within ±1.0mm, and GPS location of defects to within 1.5m.

Types of Intelligent or Smart Pigs

Magnetic flux leakage (MFL)

• High and low resolution axial

• Circumferential (TFL or transverse flux inspection)

Ultrasonics

• Normal beam (wall thickness)

• Angle beam (cracks)

Inspection and Data Analysis

Inspection is carried out by using advanced ultrasonic, GPS, and magnetic technologies; able to identify even minuscule defects in pipelines.

Once data collection is complete, advanced data analysis can begin.

Due to the accuracy of data collected, only the necessary excavations, remediation, or direct inspections are completed; eliminating needless maintenance costs. The analysis identifies future risks to the pipeline, allowing for forward planning of upcoming maintenance.

Inspection Report Based on Pig's Component

Source : http://www.energyglobal.com/media/content/williamsonpigQandA.jpg

References : 

https://en.wikipedia.org/wiki/Pigging

http://www.contractresources.com/content/services/intelligent-pigging

http://osfm.fire.ca.gov/pipeline/pdf/conference/inlineinspection.pdf

Dega Damara Aditramulyadi

Student ID : 15512046

Course      : KL4220 Subsea Pipeline

Lecturer   : Prof. Ir. Ricky Lukman Tawekal, MSE, Ph. D.

                  Eko Charnius Ilman, ST, MT

Ocean Engineering Program, Institut Teknologi Bandung

http://www.ocean.itb.ac.id/en/

Seamless Pipe

The main seamless tube manufacturing processes came into being toward the end of the nineteenth century. As patent and proprietary rights expired, the various parallel developments initially pursued became less distinct and their individual forming stages were merged into new processes. 

Seamless Pipe

Source : http://www.bemafotra.com/fr/wp-content/uploads/2014/01/Welded-Carbon-Round-Steel-Pipes-ERW-pipes-Welded-Round-Tubes.jpg

Today, the state of the art has developed to the point where preference is given to the following modern high-performance processes:

• The continuous mandrel rolling process and the push bench process in the size range from approx. 21 to 178 mm outside diameter.
• The multi-stand plug mill (MPM) with controlled (constrained) floating mandrel bar and the plug mill process in the size range from approx. 140 to 406 mm outside diameter.
• The cross roll piercing and pilger rolling process in the size range from approx. 250 to 660 mm outside diameter.

 Manufacturing Process

Mandrel Mill Process

In the Mandrel Mill Process, a solid round (billet) is used. It is heated in a rotary hearth heating furnace and then pierced by a piercer. The pierced billet or hollow shell is rolled by a mandrel mill to reduce the outside diameter and wall thickness which forms a multiple length mother tube. The mother tube is reheated and further reduced to specified dimensions by the stretch reducer. The tube is then cooled, cut, straightened and subjected to finishing and inspection processes befor shipment.

Mandrel Mill Process

Source : http://www.wermac.org/pipes/pipemaking.html

Mannesmann Plug Mill Process

In the Plug Mill Process, a solid round (billet) is used. It is uniformly heated in the rotary hearth heating furnace and then pierced by a Mannesmann piercer. The pierced billet or hollow shell is rollreduced in outside diameter and wall thickness. The rolled tube simultaneously burnished inside and outside by a reeling machine. The reeled tube is then sized by a sizing mill to the specified dimensions. From this step the tube goes through the straightener. This process completes the hot working of the tube. The tube (referred to as a mother tube) after finishing and inspection, becomes a finished product.

Mannesmann Plug Mill Process

Source : http://www.wermac.org/pipes/pipemaking.html

Tolerances 

The wall thickness tolerance of 12.5 % for hot rolled seamless pipes is specified fundamentally in ASTM A999 or EN ISO 1127 T2. However, wall thickness differences caused by the manufacturing procedure may lead to a possible eccentricity, that is, to a deviation from symmetry (Diagram 2). Normally the tolerance for wall thicknesses of welded pipes is defined in ASTM A999 or EN ISO 1127 T3. The evenness of the steel plate or coil thickness ensures that the wall thickness tolerance remains constant across the entire pipe body and much better than the required ± 10 %. This means there cannot be any eccentricity. Particularly for orbital welding or subsequent welding processes on building sites, a constant wall thickness and thus the exclusion of any eccentricities is a crucial criterion.

The wall thickness tolerance

Source : http://www.butting.com/fileadmin/daten/redakteure/Download/EN/Prospekte_EN/BUTTING_Seamless_or_welded_pipes.pdf

Corrosion Resistance

The pipes welded on the basis of the valid calculations (AD-data sheet 2000 / ANSI B 31.3 / ASME VIII) are of exactly the same quality as seamless pipes, providing a 100 % weld check has been performed. With the production of longitudinally welded pipes, carefully selected welding procedures are used, combined with the state-of-the-art testing technologies (e. g. digital X-ray inspection). In the process, the corrosion resistance in the weld area is kept constant by using higher alloyed welding additives, i. e. at least at the level of the base material. The assessment of the interior pressure calculation for seamless pipes is 100 %. This can also be ensured with welded pipes when combined with a complete weld check (welding factor v = 1.0). As a result of this reliability of the production process, the longitudinal seam in the welded pipes does not constitute a weak point. Circumferential welding with both seamless and longitudinally welded pipes must therefore be performed to a high-quality level and must take account of the specific parameters.

References :
http://www.wermac.org/pipes/pipemaking.html

http://www.butting.com/fileadmin/daten/redakteure/Download/EN/Prospekte_EN/BUTTING_Seamless_or_welded_pipes.pdf

Dega Damara Aditramulyadi

Student ID : 15512046

Course      : KL4220 Subsea Pipeline

Lecturer   : Prof. Ir. Ricky Lukman Tawekal, MSE, Ph. D.

                  Eko Charnius Ilman, ST, MT

Ocean Engineering Program, Institut Teknologi Bandung

http://www.ocean.itb.ac.id/en/

Gas Hydrates In Subsea Pipeline

Gas hydrates are of great importance for a variety of reasons (Figure-1). In offshore hydrocarbon drilling and production operations, gas hydrates cause major, and potentially hazardous flow assurance problems.

Naturally occuring methane clathrates are of great significance in their potential for as strategic energy reserve, the possibilities for CO2 disposal by sequestration, increasing awareness of the relationship between hydrates and subsea slope stability, the potential dangers posed to deepwater drilling installations, pipelines and subsea cables, and long-term considerations with respect to hydrate stability, methane (a potent greenhouse gas) release, and global climate change.

Figure-1 Major issues of gas hydrates. 

Source : http://www.pet.hw.ac.uk/research/hydrate/hydrates_why.cfm

Hydrates in Offshore Hydrocarbon Production Operations

Drilling

In drilling, record water depths are continuously being set by oil companies in the search of hydrocarbon reserves in deep waters. Due to environmental concerns and restrictions, water based drilling fluids are often more desirable than oil based fluids, especially in offshore exploration. However, a well-recognised hazard in deep water offshore drilling, using water based fluids, is the formation of gas hydrates in the event of a gas kick.

In deep-water drilling, the hydrostatic pressure of the column of drilling fluid and the relatively low seabed temperature, could provide suitable thermodynamic conditions for the formation of hydrates in the event of a gas kick. This can cause serious well safety and control problems during the containment of the kick. Hydrate formation incidents during deep-water drilling are rarely reported in the literature, partly because they are not recognised, Two cases have been reported in the literature where the losses in rig time were 70 and 50 days.

The formation of gas hydrates in water based drilling fluids could cause problems in at least two ways:

Gas hydrates could form in the drill string, blow-out preventer (BOP) stack, choke and kill line. This could result in potentially hazardous conditions, i.e., flow blockage, hindrance to drill string movement, loss of circulation, and even abandonment of the well.

As gas hydrates consist of more than 85 % water, their formation could remove significant amounts of water from the drilling fluids, changing the properties of the fluid. This could result in salt precipitation, an increase in fluid weight, or the formation of a solid plug.

The hydrate formation condition of a kick depends on the composition of the kick gas as well as the pressure and temperature of the system. As a rule of thumb, the inhibition effect of a saturated saline solution would not be adequate for avoiding hydrate formation in water depth greater than 1000 m. Therefore, a combination of salts and chemical inhibitors, which could provide the required inhibition, could be used to avoid hydrate formation.

Production

The ongoing development of offshore marginal oil and gas fields increases the risks of facing operational difficulties caused by the presence of gas hydrates. A typical area of concern is multiphase transfer lines from well-head to the production platform where low seabed temperatures and high operation pressures increase the risk of blockage due to gas hydrate formation (Figure-2). Other facilities, such as wells and process equipment, can also be prone to hydrate formation.

Different methods are currently in use for reducing hydrate problems in hydrocarbon transferlines and process facilities. The most practical methods are:

• At fixed pressure, operating at temperatures above the hydrate formation temperature. This can be achieved by insulation or heating of the equipment.
• At fixed temperature, operating at pressures below hydrate formation pressure.
• Dehydration, i.e., reducing water concentration to an extent of avoiding hydrate formation.
• Inhibition of the hydrate formation conditions by using chemicals such as methanol and salts.
• Changing the feed composition by reducing the hydrate forming compounds or adding non hydrate forming compounds.
• Preventing, or delaying hydrate formation by adding kinetic inhibitors.
• Preventing hydrate clustering by using hydrate growth modifiers or coating of working surfaces with hydrophobic substances.
• Preventing, or delaying hydrate formation by adding kinetic inhibitors.

Figure-2 A large gas hydrate plug formed in a subsea hydrocarbon pipeline. Picture from Petrobras (Brazil)

Source : http://www.pet.hw.ac.uk/research/hydrate/hydrates_why.cfm

Hydrates and Seafloor Stability

A significant part of the gas hydrate geohazard problem is related to how they alter the physical properties of a sediment. If no hydrate is present, fluids and gas are generally free to migrate within the pore space of sediments. However, the growth of hydrates converts what was a previously a liquid phase into a solid, reducing permeability, and restricting the normal processes of sediment consolidation, fluid expulsion and cementation. These processes can be largely stalled until the BHSZ is reached, where hydrate dissociation will occur. Dissociation of hydrates at the BHSZ can arise through an increase in temperature due to increasing burial depth (assuming continued sedimentation) or an increase in sea bottom-water temperatures, and/or a decrease in pressure (e.g., lowering of sea level). Upon dissociation, what was once solid hydrate will become liquid water and gas. This could lead to increased pore-fluid pressures in under-consolidated sediments, with a reduced cohesive strength compared to overlying hydrate-bearing sediments, forming a zone of weakness. This zone of weakness could act as a site of failure in the event of increased gravitational loading or seismic activity (Figure-3).

The link between seafloor failure and gas hydrate destabilization is a well established phenomenon, particularly in relation to previous glacial-interglacial eustatic sea-level changes. Slope failure can be considered to pose a significant hazard to underwater installations, pipelines and cables, and, in extreme cases, to coastal populations through the generation of tsunamis.

Figure-3 Potential scenario whereby dissociation of gas hydrates may give rise to subsea slope failure and massive methane gas release

Source : http://www.pet.hw.ac.uk/research/hydrate/hydrates_why.cfm 

Source : 

http://www.pet.hw.ac.uk/research/hydrate/hydrates_why.cfm

Dega Damara Aditramulyadi

Student ID : 15512046

Course      : KL4220 Subsea Pipeline

Lecturer   : Prof. Ir. Ricky Lukman Tawekal, MSE, Ph. D.

                  Eko Charnius Ilman, ST, MT

Ocean Engineering Program, Institut Teknologi Bandung

http://www.ocean.itb.ac.id/en/ 

Pipeline Connection System (Flange Method)

Various method exist for joining ends of subsea pipelines. These methods include the following:

• ·         Flanged connection
• ·         Atmospheric welding
• ·         Hyperbaric Welding
• ·         Mechanical Connectors

Flanged Method

Flanges are pre-installed on each pipe end during laying. The pipe ends are positioned approximately in line with the flanges 50-200 ft apart. An adjustable fixture (template) is lowered to the seabed and temporary attached to the flanges. The fixture is locked in position, released, and raised to the surface. A rigid pipe spool is prepared to match the exact dimensions of the fixture, lowered to the seabed, and bolted into place.

Figure 1. Flange Connection

Source :

http://www.unitedpipeline.com/Products/Tite-Liner/~/media/Images/United/slurry-flange-connection.ashx

A swivel-ring flange is used on one spool end to facilitate alignment of the bolt holes in the flanges. This method is generally limited to applications involving relatively small diameters and shallow water, although flanges have been used to at least 36-in diameter and in 500-ft water depths in the North Sea.

Flanges are low in cost, but they can take a long time to install and may leak during pressure testing. A leaking flange can be difficult to diagnose. In one installation, it took 2 weeks to locate the source of a small leak during a hydrotest, which was due to a leaking flange. However, flanges are considered trouble-free once they have been installed and tested. Flanges are sometimes used at the foot of risers to facilitate replacement of a riser.

The process of tightening large flanges has been made considerably easier and faster by the use of a hydraulic bolt-tensioning tool. The Hydra-Tight tool, sold in the U.S. by Flexatalic Gasket Co., has been used in the North Sea for several years. It consists of a series of hydraulically operated tensioners which are attached to protruding ends of the flange studs. Hydraulic power provided from the surface causes the tensioners to tension each stud uniformly. The nuts may then be tightened in as little as 3 hr using the Hydra-Tight tool. The primary advantage, however, is uniform tensioning of the studs. This reduces the likelihood of a leak, especially for large flanges.

A variation of the flanged spool that is gaining wider acceptance is the use of a ball flange to accommodate angular misalignment. Small diameter lines (10-12 in. or less) in 200-300 ft of water may often be lifted to the surface to make a connection using a ball connector. The pipe is dewatered, if necessary, and one end is raised by one or more lifting points. A ball-connector half is welded to this first pipe end. A joint or two of pipe are first welded on to bridge any gap between the two pipe ends.

The first pipe end is lowered to the seabed so that it overlaps the second pipe end. A measurement is taken on bottom, and the second pipe end is raised to the surface. The pipe is cut, the second ball half is pipe end is welded on the pipe, and the pipe is lowered to the seabed. The two pipe ends are then lifted slightly and the ball halves are mated. The connected pipe is lowered to the seabed and the bolts are tightened to lock and seal the ball joint.

If the pipes must be dewatered for lifting, temporary end caps are attached to the ball halves before the pipe ends are lowered. After the pipes are flooded, the temporary caps are removed.

The ball connectors may also be used in pairs at the ends of a rigid spool for new construction or for a long spool repair when pipe ends can be lifted to the surface. Measurement of the required spool length must be accurately made since the ball connectors will provide only limited length adjustment. Moreover, an axial movement of about one pipe diameter is needed to mate the halves of a ball joint.

Figure 2. Gas Pipeline Flange

Source : http://www.deelat.com/blog/wp-content/uploads/2015/03/Pipe-Flange.jpg

Source:

Mouselli, A. H. Offshore Pipeline Design, Analysis, and Methods. USA: PennWell Books. 1981.

https://anakkelautan.wordpress.com/2014/02/01/pipeline-connection-system-flange-method/

Dega Damara Aditramulyadi

Student ID : 15512046

Course      : KL4220 Subsea Pipeline

Lecturer   : Prof. Ir. Ricky Lukman Tawekal, MSE, Ph. D.

                  Eko Charnius Ilman, ST, MT

Ocean Engineering Program, Institut Teknologi Bandung

http://www.ocean.itb.ac.id/en/

Flow Assurance for Offshore and Subsea Facilities

Flow assurance, by definition, focuses on the whole engineering and production life cycle from the reservoir through refining, to ensure with high confidence that the reservoir fluids can be moved from the reservoir to the refinery smoothly and without interruption.

Overview

The full scope of flow assurance is shown in Fig. 1. Flow assurance matters specific to subsea tieback systems are shown in Fig. 2. Flow assurance is sometimes referred to as “cash assurance” because breakdown in flow assurance anywhere in the entire cycle would be expected to lead to monetary losses. A few specific flow assurance issues are discussed next.

Fig. 1—Full scope of flow assurance (courtesy of MSL Engineering).

Fig. 2—Flow assurance matters for subsea tieback systems (courtesy of BP).

Special considerations

Pressure support consideration

It is necessary for sufficient pressure to be available to transport the hydrocarbons at the required flow rates from the reservoir to the processing unit. Matters that require consideration in this regard include:

§  Pressure loss in flowlines

§  Separator pressure setpoint

§  Pressure loss in wells

§  Artificial lift method selection

§  Remote multiphase boosting

§  Drag reduction

§  Slugging in horizontal wells

§  Gas lift system stability

§  Interaction with reservoir performance

Component and system design consideration

Components and systems should be designed and operated to ensure that flowrate targets are achieved and that flow is continuous. Issues to be taken into account include:

§  Hydrate formation

§  Wax deposition

§  Asphaltenes

§  Sand and solids transport

§  Corrosion

§  Erosion

§  Scale deposition

§  Interaction of slugging and pipe fittings

§  Interaction of slugging and risers

§  Relief and blow-down

§  Pigging

§  Liquid inventory management

§  Well shut-in pressure

Multiphase flow considerations

For multiphase flowlines, it is necessary for the process to be able to handle the fluid delivery, and consideration should be given to a number of issues including

§  Interaction with facilities performance

§  Slugging (steady state)

§  Slugging (transient)

§  Slug-catcher design

§  Severe slugging prevention

§  Effect of flow rate change

§  Temperature loss prediction

§  Piping layout

§  Remote multiphase metering

§  Gas and dense phase export

§  Oil and condensate export

§  Separator performance

Technology development

The need for well testing and overall production system optimization contributes to flow assurance issues. Significant advances have been made in this field. Flow assurance will continue to remain critical technology as deepwater developments progress and as longer tiebacks from subsea wellhead systems are considered.

Source : http://petrowiki.org/Flow_assurance_for_offshore_and_subsea_facilities

Dega Damara Aditramulyadi

Student ID : 15512046

Course      : KL4220 Subsea Pipeline

Lecturer   : Prof. Ir. Ricky Lukman Tawekal, MSE, Ph. D.

                  Eko Charnius Ilman, ST, MT

Ocean Engineering Program, Institut Teknologi Bandung

http://www.ocean.itb.ac.id/en/

Pipeline Gooseneck

A gooseneck (or goose neck) is a 180° pipe fitting at the top of a vertical pipe that prevents entry of water. Common implementations of goosenecks are ventilator piping or ducting for bathroom and kitchen exhaust fans, ship holds, landfillmethane vent pipes, or any other piping implementation exposed to the weather where water ingress would be undesired. It is so named because the word comes from the similarity of the pipe fitting to the bend in a goose's neck.

Gooseneck may also refer to a style of kitchen or bathroom faucet with a long vertical pipe terminating in a 180° bend. To avoid hydrocarbon accumulation, a thermosiphon should be installed at the low point of the gooseneck

Source :

http://en.wikipedia.org/wiki/Gooseneck_(piping)

http://www.vectortg.com/Images/17110/Acc-Gooseneck-Optima.jpg

Dega Damara Aditramulyadi

Student ID : 15512046

Course      : KL4220 Subsea Pipeline

Lecturer   : Prof. Ir. Ricky Lukman Tawekal, MSE, Ph. D.

                  Eko Charnius Ilman, ST, MT

Ocean Engineering Program, Institut Teknologi Bandung

http://www.ocean.itb.ac.id/en/

Pipeline Construction

Pipeline construction is divided into three phases, each with its own activities: pre-construction, construction and post-construction.

Pre-Construction

Surveying and staking

Once the pipeline route is finalized crews survey and stake the right-of-way and temporary workspace. Not only will the right-of-way contain the pipeline, it is also where all construction activities occur.

Preparing the right-of-way

The clearly marked right of way is cleared of trees and brush and the top soil is removed and stockpiled for future reclamation. The right-of-way is then leveled and graded to provide access for construction equipment.

Digging the trench

Once the right-of-way is prepare, a trench is dug and the centre line of the trench is surveyed and re-staked. The equipment used to dig the trench varies depending on the type of soil.

Stringing the pipe

Individual lengths of pipe are brought in from stock pile sites and laid out end-to-end along the right-of-way.

Construction

Bending and joining the pipe

Individual joints of pipe are bent to fit the terrain using  a hydraulic bending machine. Welders join the pipes together using either manual or automated welding technologies. Welding shacks are placed over the joint to prevent the wind from affecting the weld. The welds are then inspected and certified by X-ray or ultrasonic methods.

Coating the pipeline

Coating both inside and outside the pipeline are necessary to prevent it from corroding either from ground water or the product carried in the pipeline. The composition of the internal coating varies with the nature of the product to be transported. The pipes arrive at the construction site pre-coated, however the welded joints must be coated at the site.

Positioning the pipeline

The welded pipeline is lowered into the trench using bulldozers with special cranes called sidebooms.

Installing valves and fittings

Valves and other fittings are installed after the pipeline is in the trench. The valves are used once the line is operational to shut off or isolate part of the pipeline.

Backfilling the trench

Once the pipeline is in place in the trench the topsoil is replaced in the sequence in which it was removed and the land is re-contoured and re-seeded for restoration.

Post Construction

Pressure Testing

The pipeline is pressure tested for a minimum of eight hours using nitrogen, air, water or a mixture of water and methanol.

Final clean-up

The final step is to reclaim the pipeline right-of-way and remove any temporary facilities.

Source:

http://www.cepa.com/about-pipelines/pipeline-design-construction/pipeline-construction 

Dega Damara Aditramulyadi

Student ID : 15512046

Course      : KL4220 Subsea Pipeline

Lecturer   : Prof. Ir. Ricky Lukman Tawekal, MSE, Ph. D.

                  Eko Charnius Ilman, ST, MT

Ocean Engineering Program, Institut Teknologi Bandung

http://www.ocean.itb.ac.id/en/