PIPELINE INTEGRITY MANAGEMENT

Based on a workshop sponsored by PTTC’s West Coast Region on November 19-20, 1998, in Ventura, CA.

BOTTOM LINE

Like reservoir management practices, pipeline management requires a delicate balance of many factors, including technical and managerial skills, financial resources, and environmental compliance. Within the constraints imposed by this balance, the commercial success of the pipeline must be maximized.

PROBLEM ADDRESSED

As pipeline infrastructures age, inspection and maintenance programs are needed to maintain integrity and promote longevity. However, the selection of appropriate, yet cost-effective, methods is still widely considered to be more of an art than science. There are numerous factors to consider in pipeline management: design, construction, operation, protection, inspection, maintenance, repair, and rehabilitation. Measurement and evaluation of pipeline integrity also is critically important, since many states (including California) now require regular inspections to confirm that integrity.

KEY WORDS:

Pipeline Management, Pipeline Integrity, Intelligent Pigs, Magnetic Flux Leakage, Ultrasonic Tools, Risk Assessment

SPEAKERS

Pipeline Integrity Management:
Sam Darbaghi, Pipeline Integrity Management Services

Pipeline Regulations:
Bruce Hesson, California Division of Oil, Gas, and Geothermal Resources

Marina Voskanian, California State Lands Commission

Theresa Bell, US Minerals Management Service

TECHNOLOGY OVERVIEW

Regulations covering pipelines as set forth by the California Department of Conservation’s Division of Oil, Gas, and Geothermal Resources can be found in sections 1760 and 1774 of the Code of Regulations. Federal regulations set forth by the Minerals Management Service (MMS) are contained in 30 CFR 250 Subpart J. Several other agencies also are involved in pipeline regulation.

In California, operators of all pipelines in environmentally sensitive areas must develop and submit a Pipeline Management Plan (PMP) to the State Oil and Gas Supervisor. The PMP must include a schedule for performing tests at two-year (maximum) intervals to ensure the integrity of the pipeline. Safety equipment and testing requirements imposed by the State Lands Commission for offshore pipelines are more stringent.

Pipeline integrity involves structural, operational, economic, and environmental factors, among others. A key management tool involves qualitative and quantitative or probabilistic risk assessment (including both hazard identification and evaluation), as well as risk control and reduction (i. e., preventive and mitigation measures). Performance monitoring and evaluation through periodic reviews of the management system also are important. The goal of such programs is to use inspection, monitoring, and maintenance to prevent structural integrity problems, especially those that jeopardize public safety, the business operation, or the environment.

Several large historical databases provide ways to analyze various elements of pipeline integrity loss. Factors include materials transported, diameter, length, construction materials, age, and operating environment. Most often, spillages result from third-party accidents. Mechanical failure and internal-or external-origin corrosion are the next most common causes.

There are three aspects to consider in dealing with pipeline integrity: prevention of loss, detection of loss, and response in the event of a loss. To prevent loss of integrity, pipeline inspections are a first-line defense. They may be proactive (i. e., searching for potential problems) or reactive (i. e., looking for damage already present that may cause imminent danger or loss of integrity).

On land, external pipeline inspection often is a visual observation. Submarine environments use remotely operated vehicles equipped with video transmitters or other technologies (such as external acoustic sonar or laser-scan line imagers).

Tools for internal pipeline inspection (referred to as “intelligent pigs”) perform a wide variety of specific functions, such as geometric surveys, metal loss, and detecting cracks or leaks. A detailed 3-D geometric survey of the pipeline allows mapping of the interior curvature to help analyze stress and compatibility with other internal pigs. These surveys often include caliper tools to measure anomalous shapes. Dents or other geometric compromises of pipeline shape may be due to physical contact, stress, or deformation induced by improper installation, erosion, or shifting of the substrate. Dents can affect the strength and performance of the pipeline and may result in damage to critical interior or exterior protective coatings. The acceptability of dents, and their likelihood of compromising the pipeline’s integrity, can be quantitatively calculated.

Tools for detecting metal loss, primarily from corrosion, are based either on electrical/ magnetic measurement or acoustic measurements. The choice of the proper tool depends on many factors, especially the type of inspection desired and the nature of the fluid (product) in the pipeline. Magnetic-flux leakage tools rely on induced currents in the pipe wall for their information and are compatible with most pipeline products. These tools, however, are not as accurate at measuring wall thickness, nor do they detect metal loss inside the pipe wall. Ultrasonic-based tools give good direct measurements of wall thickness, but do not perform well in multiphase product fluids or at high rates of fluid transport.

In any in-line survey, accurately locating anomalies is critical. The simplest, but perhaps the least accurate, method to locate them relies upon an odometer mounted on the pig, which usually is accurate to within 0.5 m per km of pipe traveled. Other locating devices use inertial guidance systems— systems that rely on sophisticated dead-reckoning devices similar to those used to guide missiles. These systems often are coupled with other devices to detect and count pipe welds. Some systems are simple electromagnetic transmissions sent to hand-held receivers on the surface of the ground or contained in remotely operated undersea vehicles. Some pigs use Global Positioning Survey techniques for location through a satellite network.

LESSONS LEARNED

Ultimately, pipelines will fail. Integrity cannot be guaranteed 100%, but careful monitoring, inspection, and maintenance programs greatly reduce the risk of failures that could cause disastrous consequences to human life, the environment, and business operations. Ensuring that risks are “as low as is reasonably practicable” remains the guiding principle.

Baseline surveys, run immediately after pipeline installation, serve to identify problems associated with installation of the pipeline. They also serve as reference points for comparison with later surveys to enable a projection of pipeline degeneration with time as a result of corrosion or other factors.

CONNECTIONS:

Pipeline Integrity Management:
Sam Darbaghi
Pipeline Integrity Management Services, Ltd.
H8 Minister Ct., Hillcrest Rd. Ealing
London, UK W51HH
Phone 011-44-181-997-3830, Fax 011-44-181-997-2871

Pipeline Regulations:
Bruce Hesson
California Division of Oil, Gas, and Geothermal Resources
1000 S. Hill Rd., Suite 116, Ventura, CA 93003
Phone 805-654-4761, Fax 805-654-4765
website www.consrv.ca.gov

Marina Voskanian, Chief Reservoir Engineer
California State Lands Commission
ARCO Towers, 200 Oceangate, 12th Floor
Long Beach, CA 90802-4333
Phone 562-590-5291, Fax 562-590-5215
website www.slc.ca.gov

Theresa Bell
Minerals Management Services
US Department of Interior, 770 Paseo
Camarillo Camarillo, CA 93010
Phone 805-389-7561, Fax 805-389-7592

For information on PTTC’s West Coast Region and its activities contact:
Iraj Ershaghi, Director, Petroleum Engineering Program, HEDCO-316
University of Southern California, Los Angeles, CA 90089-1211
Phone 213-740-8076, Fax 213-740-7982, E-mail ershaghi@archie.usc.edu

Disclaimer: No specific application of products or services is endorsed by PTTC. Reasonable steps are taken to ensure the reliability of sources for information that PTTC disseminates; individuals and institutions are solely responsible for the consequences of its use.

The not-for-profit Petroleum Technology Transfer Council is funded primarily by the US Department of Energy’s Office of Fossil Energy, with additional funding from universities, state geological surveys, several state governments, and industry donations.

Petroleum Technology Transfer Council, 2916 West T. C. Jester, Suite 103, Houston, TX 77018
Toll-free 1-888-THE-PTTC; Fax 713-688-0935; E-mail hq@pttc.org; web www.pttc.org