Nearly every day at GTI,

GTI Senior Technician Peter Mulligan prepares a pipe sample to test its resistence to rapid crack propagation.

N

early every day at GTI, plastic pipe is pressurized, pulled, bent, destroyed, or subjected to a number of other purposeful abuses—all for the sake of studying safety and reliability.

With plastic pipe now accounting for more than 90% of new gas pipe installation, plastic pipe services and research activities have grown considerably at GTI. In recent years, GTI capabilities have been enhanced with new laboratories, state-of-the-art equipment, and leading expertise.

“The overriding concerns in all areas of gas operations are long-term field reliability and safety,” explains Dr. Michael Mamoun, Institute Engineer, who heads GTI’s Plastic Pipe Services. “When it comes to plastic pipe, the industry has many questions and needs. Our job is to answer those questions and help them meet their needs in the most efficient manner possible.”

For more than 50 years, GTI has been testing pipe and piping prod-ucts to enhance technologies, reduce costs, and forecast the long-term field performance of plastic pipe systems.

From the routine to the research challenge, investigators address a wide range of issues. Common concerns are the reliability of pipes subjected to impinging rocks, bending, and squeeze-off; the effects of defects and scratches; maximum pressures for particular pipes or fittings at a given tempera-ture; and joining techniques.

“A gas company’s investment in new plastic pipe can be in

the millions of dollars,” notes Dr. Mamoun. “Companies commonly send us samples of new or existing pipe for testing to ensure that the pipe meets specifications for safety and performance.”

Conducted in one of the largest plastic pipe laboratories in North America, GTI offers clients a full range of American Society of Test-ing and Materials (ASTM) tests, as well as custom testing procedures.

GAS OPERATIONS

news

FEBRUARY 2006 VOLUME 3, NUMBER 1

PLASTIC PIPE SERVICES

The Source for Infrastructure Safety & Reliability

Specific testing capabilities include: > Hydrostatic Stress-Rupture Testing > Quick-Burst Pressure Testing > PENT Testing to Measure the

Potential for Slow Crack Growth > Tensile Testing

> Cyclic Fatigue Testing

> Rapid Crack Growth Propagation (RCP) Testing

> Brittle Fracture Testing > UV and Chemical Resistance

Testing

> Field Failure Analysis > Multi-Flow, Density, and

Crystallinity Testing.

Plastic Pipe

continued from front page GTI works closely with customers to clearly understand their needs, develop guidance and solutions, and deliver results quickly and confidentially.

The staff in GTI’s plastic materials group collectively has more than 100 years of experience, and has published more than 300 reports, technical papers, and studies on plastic pipe topics.

GTI testing laboratories are accred-ited by the American Association for Laboratory Accreditation (A2LA) to cover numerous specific tests and ASTM test procedures. (GTI laborato-ries also meet the requirements of ISO/IEC 17025-1999.)

Testing facilities include: > A 25-foot-high large-scale test

facilitywhere pipes of all sizes are subjected to long-term hydrostatic stress-rupture and pressure-burst testing. In addition to an array of testing apparatus, the facility

houses chambers of various sizes to test the ability of pipe to withstand various simulated installations, soil conditions, and environmental extremes. > The Materials Analysis &

Charac-terization Laboratory,where scanning electron microscopy and other methods are used to find the causes of material failures.

> GTI’s “Pipe Farm”—a field site containing buried pipe of differ-ent materials and diameters, located at different burial depths and orientations, in various soil types. This facility is used to evaluate the effects of external loads (including train and auto-motive loads) and the general field environment on plastic piping materials. The facility is also routinely used to evaluate new and developing tools and equipment used to find and repair buried pipe.

While Dr. Mamoun can point to significant past success, he notes that some of the industry’s most beneficial plastic pipe technologies are currently under development at GTI. These include:

> An inflatable bypass stopperfor use in the repair of damaged and leaking plastic pipe. The system is placed in the pipe through an insertion

tee, and into a ruptured pipe main upstream of the damaged area. When the bladder is remotely inflated at the point of damage, it temporarily shuts off the flow of gas through the damage opening, while allowing the gas to continue to flow through an annulus. The leak can then be repaired without the danger of blowing gas.

> An evaluation of new plastic pipe (Polyamid 12) for use at higher pressures.PA12 piping systems have shown the potential for safe use at higher operating pressures and larger diameters than con-ventional plastic gas-distribution piping, without sacrificing flow capacity. Following a regimen of extensive testing of PA12 materials, researchers are developing a comprehensive data base of the physical properties of PA12 pipe with the goal of establishing construction, maintenance, and operating requirements.

> A new generation of plastic pipe materials.One project involves the development of specially manufactured plastics. The pipe goes through a process that makes it free of static discharge and that provides a magnetic “signature” to the pipe that makes it easily locatable from the surface with conventional locating devices.

“In addition to product develop-ment and testing, we also serve as industry consultants,” says Dr. Mamoun. “We offer solutions that help companies choose the right products for specific applications.”

Annually, more than one billion pounds of various types of plastic pipes are shipped for use in gas distribution; water treatment and distribution; oil, gas, and chemical production; and as conduits for telecommunications and other applications.

“Consequently,” says Dr. Mamoun, “Our work is no longer just within the realm of the natural gas industry. But for services to the gas industry, GTI is unsurpassed.”

For more information, contact Michael Mamoun, GTI Institute Engineer (847/768-0953; mike. mamoun@gastechnology.org).

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“The key to successful technol-ogy development is to focus on issues of critical importance to the industry, and then work in close collaboration with both the manufacturers and the users of the technology.”

– Michael Mamoun,

Developing Shoring Alternatives

G

TI is developing a new, lightweight shoring system in efforts to provide lower-cost methods for accessing, repairing, and rehabilitating underground pipes and facilities.

The advanced system provides an alternative to traditional utility shoring structures, which often require special transport and installation equipment and usually cannot accommodate crossing utility lines.

The new system will be easily transported (with one utility truck), can fit around crossing utility lines, and can be installed by one person without heavy equipment. Made from lightweight honeycombed aluminum, the system can be

manufactured in varying wall thick-nesses to meet OSHA standards. (A two-inch-thick panel can support 2,200 pounds at a four-foot span.)

The lightweight system is installed through a series of interlocking panels that are lowered into the excavation and form the walls of the shoring system. Installers can easily

place panels under, around, and above crossing gas pipes and other utility lines.

With this system, installations are conducted from outside the excavation using long-handled tools, which not only simplifies the process, but enhances the safety of the operation.

Designed for small (about five-by-five foot) excavations, the shoring system can be installed in about 20 minutes.

A patent is pending on the design. Commercialization of the shoring is under way and field demonstrations are planned for the spring of 2006.

Research support is being pro-vided by Alagasco, the American Public Gas Association, Atmos Energy, New York State Electric & Gas Corp., NW Natural, and Questar Gas Company through Operations Technology Development, NFP.

A video demonstration of the shoring system is available on CD-ROM. For a copy or for more information, contact Alicia Farag, GTI Engineer (847/544-3492; alicia.farag@gastechnology.org).

The lightweight shoring system is constructed of interlocking, hinged panels placed on corner posts. Long-handled tools allow installers to place panels under and around crossing utility lines to form a complete, safe shoring structure.

GTI High-Impact Innovations: Polyethylene Pipe

> It is estimated that GTI’s research on PE pipe has saved the gas industry more than $500 million since 1994.

> GTI has published more than 300 reports, technical papers, and studies on plastic pipe topics.

> GTI is the leader in new plastic pipe developments and guidelines for the industry. Under the sponsorship of various organizations, GTI has introduced a number of technology advances, including: — Piping for high-pressure applications

— Instruments to locate underground plastic piping — Sensors to identify joint quality and defects

— A self-loading trailer for large-diameter coiled plastic pipe — A tool to measure pipe ovality and the depths of scratches.

By contrast, the capacitive tomo-graphy sensor uses low frequencies with a multiple-element antenna to obtain better resolution. This low-frequency operation reduces the electronics cost while improving depth of penetration.

“Also,” notes GTI’s Brian Huber, Principal Engineer, “capacitive tomography has the added benefit of functioning very well in wet soils, which are a challenge for GPR.”

The tomography sensor itself is a flat array of electrodes that can be fabricated using printed-circuit-board techniques. The impedance measurement performed at each antenna element is not time critical. The image resolution is proportional to the number and spacing of the electrodes in the array. Measuring the complex impedance of the soil under the sensor array and compar-ing the results from adjacent sensor electrodes form the image. This process is repeated at varying frequencies to provide images at

T

he development of subsurface

imaging for locating plastic pipe has long been a challenge for the natural gas industry. However, GTI is advancing a new technology— called capacitive tomography —that has the potential to provide accurate images of underground plastic pipes and other buried objects.

Currently sponsored by Operations Technology Development, NFP, the capacitive tomography imaging sensor takes the form of a flat plate that can be placed on the ground to locate embedded objects in the soil directly beneath the sensor.

Utilities could realize significant operations savings if they had the ability to accurately locate under-ground plastic pipe.

Ground-penetrating radar (GPR)— which has been used for pipe location with varying success—requires a high-frequency electromagnetic signal to be injected into the soil. (The higher the frequency, the shorter the wavelength; and, there-fore, the greater the resolution of the image.) High-frequency radio waves are more readily absorbed by soil, reducing the range of GPR. Also, high-frequency time-of-flight measurements raise the cost of the associated electronics.

Capacitive Tomography Locates Buried Plastic Pipe

varying depths. The “stacking” of these images forms a three-dimen-sional tomographic map of objects beneath the sensor array.

In tests at GTI, various arrays have detected four-inch-diameter plastic pipe in wet soils at depths of greater than four feet.

Expected to be used as a final step before committing to an excavation, the technology also serves to enhance keyhole excavation operations. In addition to its application as a stand-alone imaging sensor, future developments could involve the application of the technology to the surfaces of digging and boring tools to detect obstacles.

The technology is currently under-going electronics simplification, system hardening, and further field testing in preparation for near-term commercialization.

For more information, contact Brian Huber, GTI Principal Engineer (847/768-0765; brian.huber@ gastechnology.org).

G

TI researchers are developing a system that can assess the condition of pipes directly through 18-inch-diameter “keyholes.”

“There is considerable industry interest in advancing keyhole technologies,” explains GTI’s Dennis Jarnecke, Senior Engineer. “Consequently, at GTI we’ve been working to develop a variety of tools that can be used in keyhole operations. This project has the promise of providing a way to determine the condition of a pipe without having to conduct exten-sive excavations or expenexten-sive alternatives.”

In this project, under the spon-sorship of Operations Technology Development, NFP, researchers at GTI are working with pipeline assessment provider American Investigation and Assessment, Inc. (AIA), to further develop, modify and enhance AIA’s Broadband Electromagnetic (BEM) commer-cial inspection system to allow for its use in keyhole excavations.

“BEM methods can identify and locate metal loss, cast-iron graphi-tization, and cracks,” Jarnecke notes. “However, BEM technology does not require contact with the metal to detect pits and other metal loss. In addition, systems can be light-weight and portable. We expect that using BEM technology over alternative pipeline-assessment methods can reduce inspection costs by as much as 50 percent.”

Recent developments using BEM sensors to inspect pipeline systems have proven effective overseas.

BEM technology has been used in the Australian oil and gas explo-ration industry for many years, and is currently being used in the mineral industry in the search for massive sulfide ore deposits. The technology has since been modi-fied for acquiring detailed infor-mation about the condition of surface or sub-surface ferrous pipelines and facilities. Public

Service Electric & Gas Corp. was the first utility to successfully use this technology in the United States in 2002 to evaluate the integrity of two critical 30-inch-diameter cast-iron mains in underwater crossings, operating at 15 psig, installed in 1914 in Newark, NJ.

In the inspection process, BEM technology induces eddy currents to flow in close proximity to a transmitter/receiver in a ferrous pipe. These eddy currents migrate with time, allowing operators to obtain a complete ferrous pipe profile. External pipe-wall condi-tion assessments are typically carried out on all types of ferrous pipelines to explore the integrity of the pipe wall. Individual readings are taken along the surface of a pipe. The coating (bitumen, poly-ethylene, or even concrete) does not need to be removed. With the aid of a temporary marked grid around the outside of the pipe allowing for accurate positioning of each reading taken, the wall can be scanned.

The project began in 2004 with an intensive survey of project sponsors and others in the industry to determine applications and needs for the BEM technology. In early 2005, a prototype tool was developed, modified, and tested at NW Natural, Southern California Gas Company, and National Fuel Gas Company.

Tests of the inspection system are being conducted on various types of pipes at varying conditions and with different coatings to determine the sensitivity and accuracy of the en-hanced BEM system. In addition, researchers are developing an array of sensors and long-handled tooling to allow the BEM device to take circumferential readings through small openings.

Following prototype modifica-tions, field tests will be conducted by gas utilities in 2006 to determine the need for further modifications.

For more information, contact Dennis Jarnecke, GTI Senior Engineer (847/768-0943; dennis.jarnecke@ gastechnology.org).

Pipe Assessments Through Keyholes

Pipe conditions can be assessed through 18-inch-diameter “keyholes” using BEM technology and long-handled tools.

Need More Information?

For more information or questions on any of the Gas Operations News articles, please contact:

Paul Armstrong

GTI Strategic Account Manager Northeast Gas Association Needham, MA

781/449-1141

paul.armstrong@gastechnology.org

GTI-06/00022-06IMG2.5M

Gas Technology Institute

1700 S. Mount Prospect Road Des Plaines, IL 60018-1804 www.gastechnology.org

Upcoming Courses and Conferences

Month Dates Program Location

March 21 - 24 External Corrosion Direct Assessment

(ECDA) Chicago

27 - 29 Internal Corrosion Direct Assessment

(ICDA) Chicago

April 24 - 28 Gas Distribution Operations Chicago

May 8 - 12 Gas Transmission Operations

and Construction Chicago

June 5 - 7 ECDA Inspection Tools Chicago

12- 15 Factors in Compressor Station Design Chicago July 17 - 21 Gas Distribution Engineering: Piping

and System Planning Program (Week 1) Chicago 24 - 28 Gas Distribution Engineering: Piping

and System Planning Program (Week 2) Chicago August 14-18 Measurement and Regulator Station

Design for Distribution Systems Chicago

September11-15 Transmission Pipeline Design

and Construction Practices Chicago

18 - 22 Measurement and Regulator Station

Design for Transmission Systems Chicago

October 22 - 25 Natural Gas Technologies Conference

& Exhibition Orlando

In addition to courses and conferences, GTI also provides educational opportunities in custom formats and via the internet.

For more information, go to the Training & Conferences area of the GTI website.

GTI offers training on three critical areas of pipeline integrity management:

> External Corrosion Direct Assessment (ECDA) > Internal Corrosion Direct

Assessment (ICDA) > ECDA Inspection Tools.

The workshops draw on exten-sive results from GTI’s nationally recognized research programs in direct assessment—research sup-ported by more than 30 companies and the American Gas Association.

Workshops are performance based. Participants work on actual pipeline data in table-top activities that guide them through all phases of ECDA and ICDA, including pre-assessment, indirect inspections, direct examinations, and post-assessment. The ECDA Tools workshop focuses on the theory, operation, and use of four of the most common ECDA inspection tools, and was developed at the request of many GTI customers to meet critical training needs.

For more information, contact Flo Kellogg, GTI Training Manager (847/768-0895; education@ gastechnology.org).

F

or decades, GTI has been providing gas industry work-shops and training from its Chicago-area base of operations. Today— in addition to web-based training, certified programs, and other train-ing options—GTI is increastrain-ingly involved in bringing training directly to the doors of gas companies.

To keep pace with changing industry regulations, GTI has expanded its training capabilities, and, based on the results of signifi-cant GTI research, is offering

work-shops focusing on pipeline integrity management.

“We’ve found a strong interest in the topic of pipeline integrity man-agement,” says Michael Dugan, Executive Director of Education at GTI. “And, in addition, our clients have found great benefits in having training brought on site, rather than sending individual personnel out of town. With on-site training, instruc-tion can be centralized, consoli-dated, and customized for a company’s specific needs.”