Pigging..A Good Year for Developments and Operational Success

Everybody believed in 2000 that high oil prices would lead to a boom in our industry, but nothing of the sort happened. During the year, oil companies continued to consolidate and introduce further efficiencies and cost reductions. Contractors were squeezed relentlessly. The high price of oil ($25-$35 per barrel) enabled oil companies to rebuild their balance sheets and fund their merger and acquisition activities. Although significant earnings and cash surpluses are being reported and expenditure is expected to build up in the coming year, operators will not want to be caught again and thus will remain prudent. Their longer-- term investments will be based at around $13-$15 per barrel, not at the current levels of around S25 per barrel.

However, it is an inescapable fact that while demand exceeds supply, exploration and development activity must increase over the coming years to bring supply and demand into balance and oil prices down to a non-inflationary price. In view of this, we are seeing a major recovery as many new projects are moving from the drawing board to EPC contractors. So there is a higher level of orders for pig traps, signalers and closures as newpipelines projects are started. Pigs will follow once the lines are built and ready for commissioning. Although competition will remain fierce, a much higher level of activity is now forecast for the immediate future.

A significant number of pigging developments have recently matured-to the benefit of pipeline operators worldwide. Here, we touch on some of those that are influencing cost-effectiveness and efficiency.

EDG has introduced a revolutionary new pig launcher/trap device claimed to save time and increase reliability of scheduled maintenance. They integrate and automate three essential requirements - swabbing, hatching and smart pigging functions and reduce dramatically the number of times the launcher has to be opened. Both worker and environmental safety are improved because the accidental release of hydrogen sulfide is lessened. A further benefit of the new equipment is that it can be operated from shore. Now successfully used offshore, EDG is looking to install similar systems for other pipelines. TD Williamson continues to enhance its extremely comprehensive pigging and general pipeline services range and is offering a video specifically covering its cleaning services.

Knapp Polly Pig has further enhanced its Ultra-Pig, Ultra-Seal, K-Disc and BDG-- K ranges for deepwaterpipelines as has Girard Industries whose extensive portfolio includes the latest Hi-T Pigalert signalers. KiddPipeline & Specialties' latest patented products include both mechanical and electrical pressure-balanced pig passage indicators which are available with extensions for below-grade installation and recent versions of its reinforced scaper pig cups and flow switches.

Mahoney Technical Products, too, has newer models of both sphere and detectors available. And EnduroPipeline Services claims to have developed a range of exceptionally reliable pig signalers called the Pig Popper which are simple to install and use.

From Inpipe Products comes its latest MarkIII signaler with special features-they have omni-directional triggers, are not directionally sensitive during installation, all wettable moving parts are in stainless steel and they are not pressure-sensitive. Said to remain stable under almost any conditions, they are much lighter than previous models and can be used at temperatures up to 160 deg C. They also have a new balanced-pressure sphere to largely eliminate the time wasted in dissipating ingressed gas collected during service-without the need for sealing apparatus such as sealing valves.

CDI's latest CD42 pipeline pig location and tracking systems are said to allow pipeline operators the advantage of microprocessor control. The technology includes a special but simple graphical menu system created specifically for pigging. Features also permit much faster and accurate locationing of stationary pigs.Pipeline Inspection Company also has refined models of its Spy electronic pig trackers that can pick up signals from 20 to 100 feet of free air space, withstand high pressures and temperatures and transmit up to 500 hours with just standard alkaline batteries.

GD Engineering introduced its Versatile pig range in sizes from 4 inches to 60 inches. They can be fitted with cups, discs or a combination of both and all parts are interchangeable. Bodies are available in either mild or stainless steel and pulling bars are fitted front and rear. Up to 5% removable by-pass is fitted as standard and they are capable of traversing bends down to 1.5D. GD's Bandlock 2 quick opening closures are now available in sizes from 6-120-inch, in carbon and stainless steel and specialty alloys, from ANSI 150# to 2500# for allpipeline and related applications.

BJ Pipeline Cleaners has new models of its successful HZ heavy scraping pigs with a leaf-spring design for added force against pipe walls and the renowned Pitmaster brush pigs so useful for cleaning the pits caused by microbiologically influenced corrosion. Insitu Pipeline Systems has further improved its Insitu pipelinecleaning and coating systems. These first mechanically and chemically clean the line which is then given a corrosion-resistant epoxy coating using Uraflex pigs.

Pipeline Engineering's (PE) new twin-- module welding pigs have apparently proved successful for subsea tie-ins and also for emergency use both on- and off-- shore. They have a welding and a sealing module-which are required to effect a tie-in weld. The welding module has a unique Omnithane patented welding seat. When inflated, this pushes a flexible heat-- resistant backing material against the underside of the joint being welded. This reduces to near zero the volume of the gas and removes the possibility of blowback, a regular problem caused when the welding habitat fluctuates due to wave motion. The backing strips help to increase the speed of hyberbaric welding.

Modular design for PE's Chameleon range of pigs has helped reduce prices and improve delivery times. The functionality of its Unisig pig signalers has been improved with cost savings, too. The company has also just launched a range of rapid opening closures said to reduce radically the time it takes to safely gain access into pig traps and other pressure retaining vessels-down to as little as 30 seconds. It is unlocked by simply removing the vent safety plug and turning a handle through 22.50. They can be used on pig traps, filters and metering systems in sizes from 6-to-60 inches in diameter. Said to meet all the main international design codes and standards, they are already gaining acceptance by operators worldwide.

Plugging

In Oman, PE recently isolated the feeder and export lines to an oil pumping station. This was to allow the installation of larger pumping facilities. In all, two 12-- inch, two 18-inch and one 20-inch high-- pressure plugs were used. Due to the high number of lines, many of the field activities had to be completed in parallel. Although hot tapping was considered, a major saving was made by using these plugs, the shutdown work being completed four days ahead of schedule. Also, offshore Thailand, PE provided double block and bleed isolation in a straight section of a 32-inch forged equal tee. The double block and bleed plug was less than 12 inches in length, with an overall diameter to suit a 32-inch pipe. The plug enabled gas export to continue via the tee, while valve refurbishment took place immediately behind the plug.

Inpipe Products has a new Hydroplug which is designed to block and retain hazardous vapors in a line. This has two inflatable tires to seal against the pipe wall and hold it in position. The cavity in between is then filled with water or nitrogen to 3Bar to provide the gas-free barrier. The pipeline or vessel into which it is fitted can be vented through the plug's body. Currently available from 2-to-24 inches, the plugs can be used on pipes with wall thicknesses between schedules 10 and XS and are claimed to withstand a differential pressure of SBar on the downstream side. And who can forget Inpipe's epic 50+hour closing of New Zealand's North Island main offshore gas supply line to change the emergency shutdown valve?

Gel Pigging

Although it is an established technology, gel pigging has moved on significantly. Enhancement of flow assurance in deep subsea pipelines and flow lines, by regularly controlling hydrate and wax removal, looks set to be improved even further with the use of competitively priced new liquid gel concentrates and fluids. Development work continues into optimum mixes of longer-life gels and additives in the pig chain and further economies in gel usage. Special attention is going into making a commercial skid-- mounted modular unit that could lead to greater confidence in on-line continuous blending. Molded solid-gel pigs are now available that offer adequate strength and elastic properties for even quite long runs including tight bends and constricting objects such as valves. Gel pigging could soon be transformed from pre-commissioning and remedial activity into a mainline pigging tool.

BJ Process and Pipeline Services is in the forefront of this methodology. It is offering a speedy, economical method of cleaning and drying long pipelines. Its BJ Gel Pig can suspend and then remove large quantities ofpipeline debris, often in just one pass. It can enhance pipeline sweeping and the displacement of products and also remove stuck conventional pigs-and it's an effective way to apply inhibitors and biocides. BJ also sees a significant and growing market for its services in the conversion of lines such as redundant crude oil pipelinesfor use with natural gas or finished products. They say it's quicker and very cost-effective.

Intelligent Pigging

Tuboscope Pipeline Services now has available the operator's optimum multi-- technology tool equipped to inspect pipelines by magnetic flux leakage (MFL) and to provide an inertial navigation and global positioning system. Now with just two pig runs, the data from four different technologies can be collected and analyzed. In one direction, a pig checks internal wall geometry changes and gives a 3-D map of the line's position, and in the reverse direction, another MFL pig detects corrosion defects distinguishing those which are internal from external. Recent enhancements include varying magnetic levels to better check metal loss and physical damage, multi-axis sensors for better anomaly length and width measurement multi-magnetic orientation, including circumference, to improve the detection and identification of longitudinal anomalies. These developments are said to greatly improve accuracy and reliability of surveys.

PII's latest Scale Wax Assessment Tool takes a cleaning pig fitted with lift-off sensors. The sensors measure the degree of lift off from the pipe wall at several locations around its circumference. In this way, real data can be provided on the status of the pipeline allowing action plans to be made for removal of any persistent debris.

The company's pioneering work on inspecting dual-diameter lines continues to pay off, especially in the U.S. and Russia where many pipelines were constructed using reduced bore valves for economic reasons. Recently in the North Sea, the multi-- diameter tool developed in conjunction with Statoil, was launched in a 28-inch subsea pipeline and, after several hundred meters, expanded to fit a 42-inch pipeline. Its task was then to carry on and inspect the 702 km (439 miles) gas export line to the Norwegian coast. As a result, the size of export riser base needed for the Asgard field was reduced, with significant cost savings. The same methodology can be used to reduce costs for other field developments, especially in deepwater where maintenance can be difficult and expensive.

PII has made great strides in high bypass speed control. Pipeline operators constantly face the challenge of keeping the product flowing. Revenue can be lost due to hydrotest down time, or in reducing gas flows to suit pig runs. Cleaning and gauging pigs can normally be run at full product speeds, but in some pipelines gas flow can exceed the maximum allowable speed for inspection tools. Upper speeds for inspection vary between 0.5 - 5 m/s, depending on pipe wall thickness, inspection technology and supplier. Just increasing pigging speed from 2 m/s to 4 m/s can bring massive savings in gas revenues.

Another advantage of the controlled bypass facility is that it provides effective speed control of the pig, which helps to maintain inspection performance. It also permits the tool to be used in pipelines with variable velocity profile due to inlets or outlets which may not be closed off during the inspection run. So recent controlled bypass allows increased gas velocities, typically up to 12 m/s with increasingly complex option kits, customized vehicle building to suit particular operator needs, and variable bypass control valves for operation down to a minimum speed of 0.5 m/s. Speed control is obtained if gas speed is less than bypass capability with valve wide open.

PII's latest work on transverse field inspection (TFI) and its TranScan range is good news for pipelineoperators with axially oriented defects, a significant problem often associated with features in and aroundpipeline seam welds. PII is now notching a string of successful experiences with TFI, which is an adaptation of the MFL principle to fine-tune the tool to find these axially oriented defects. Although TranScan is already an active and successful area of development for PI, its capabilities are being constantly extended and the whole market for its application remains to be discovered. At present, the philosophy is to run TranScan and its long-serving MagneScan ranges as stand-alone inspection services, but the option of combining these on one train has been examined.

Regarding data analysis and reporting, PII is building systems to provide more accurate assessment ofpipeline defects. This includes a method for calculating defect failure pressure along parallel lines to that used by RSTRENG (the standard for evaluating the remaining strength of externally corroded pipe). While RSTRENG uses the actual field measurements of the defect, PII's LADA (Length Adaptive Pressure Assessment) calculates effective area and therefore defect failure pressure using defect sizes predicted by the in-line inspection system analysis process. Experience is showing that LAPA users have to deal with lower populations of metal loss called out as `significant.' So, although new, the LAPA method is holding out considerable promise for realistic prioritization of repairs while still maintaining a consistent and prudent safety factor.

One of the striking benefits of the high resolution provided by PII inspection vehicles is said to be the high quality images produced for visualization of the condition of the pipe wall. The latest version of its PipeImage is a data processing application primarily intended for viewing high-resolution magnetic inspection surveys. It provides a complete visual representation of the pipeline inspection from trap to trap. The data can also be scaled, magnified and enhanced using the tools provided by PipeImage and navigation and annotation facilities are available to allow easy access to and labeling of interesting points throughout the inspection.

The advent of stable inertial navigation systems and accurate GPS equipment has enabled accurate pipelinesurveying to be combined with an in line inspection tool. PII's latest combined ScoutScan MFL and pipelinemapping tool enables defects to be accurately and conveniently located. This is particularly attractive in remote areas where defect coordinates from the mapping pig can be combined with GPS data to allow repair crews to move directly and precisely to the correct excavation site.

RST Projects' innovative SAAM pigging technology offers a cost-effective approach to internally inspecting operational pipelines and gauging those under construction. It can be used to identify, locate and monitor dents, local out-of-- alignment features (mapping), status of in-line components, internal anomalies and zones of wax formation. Other applications include logging of pipeline process data and diagnosis of pigging problems and facilitating the optimization of pigging programs. New developments include a battery range of up to 336 hours (14 days), enabling operators to inspect very long pipelines, a miniature SAAM system capable of inspecting 6-inch pipelines, flow lines or loops. Now undergoing field trials is a SAAM 3-D mapping system which, in addition to standard capabilities, provides data about the vertical and horizontal profiles, enabling RST to give a local 3-D map of the pipeline. All of the systems now offer a higher temperature capability.

New DDL digital data loggers from Enduro Pipeline Services enable operators to determine the size and location of anomalies and many other features too -- such as pipeline mapping, sub-meter GPS coordinates to line features and line defect areas, bend analysis for direction and angle, river crossing profiles, pipelinebenchmarking, for improved excavation points with anomaly locations to o'clock position. Its new Squeal software package also allows users to link data collected from other corrosion tool inspection systems. Several formats and methods are possible, allowing mechanical defect locations to be checked with metal loss locations. Reports are presented on CDs with jpg files on the analysis of pipeline bends and anomaly locations. DDLs have a variable scale ranging from 1:1 to whatever the operator needs, a booked anomaly lising on two scales - first a 50:1 scale showing a weld log report, BenchMark locations and anomaly sizing and a second scale at an exploded view of 5:1.

The GTI and the U.S Dept. of Transportation, with the practical help of Tuboscope, are developing advanced tools and technology for locating mechanical damage in pipes such as gouges, dents, scrapes and other anomalies that often cause serious disruption to operations. The new research is focused on cold working, stresses and plastic strains associated with mechanical damage through the use of smart pigs. Research thus far has succeeded in decoupling MFL signals into its components, using magnetization, so that specific information on different types of damage can be identified and recorded. In parallel work, the SwRI is developing criteria to evaluate the actual effects of mechanical damage on pipe strength and likely life.

What's Next?

Profile Technologies has developed and successfully field-tested an innovative non-- invasive electromagnetic wave (EMW) inspection technology to rapidly screen pipelines above and below ground for external corrosion. This seems a cost-effective way of detecting and locating such defects, under insulation, with virtually no need to prepare a site specially or to have full access to the pipeline's surface. Apparently the tool can reliably isolate damaged lines in places where normal NDT methods would be impossible - road crossings, sleeved pipes, penetrations of pipelines through the walls of buildings or under streets. The EMW tools can perform global assessments of pipe segments from 2-to-60 inches in diameter and up to 250 feet in length, with one setup. It is said to locate external corrosion within 55 feet and can be applied to straight pipe or pipe segments with bends up to 450.

PE and Durham University in the UK are developing a self-powered tractor pig for removing wax from the inside of subsea oil flow lines. The pig uses bristle-based tractor technology, pioneered at the university, to crawl through the pipelines. The device is launched from an offshore platform and travels against the product flow to the wellhead. Once at the wellhead, the pig deploys a return mechanism and pigs the line back to the platform, dewaxing as it returns. Wax buildup reduces flow rates and therefore the efficiency of flow lines. As such, there is a limit to the distance a wellhead can be from the platform or production facility. This new pig will not only reduce production costs but will allow for longer and deeper flow lines. A laboratory version of the tractor device with its return mechanism is working successfully and operators are being sought who are interested in testing the product in their own flow line.

Some of the major contractors in the industry are working to produce an Industry Standard Pig Specification. However, with so many shifting variables and interests, this may prove a daunting task! Watch this space. P&GJ.

Sumber : "Pigging..A Good Year for Developments and Operational Success". 29 Januari 2014. http://search.proquest.com/docview/197489276?accountid=31562