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ABSTRACT Work was performed to assess corrosion damage on a pipeline suspension bridge transporting liquid products. Corrosion had been previously detected and characterized using in-line inspection methods. The inspection results were graded and it was noted that several regions had corrosion levels that were of concern. The pipeline company requested that an evaluation be performed on the pipeline bridge that had been constructed during the 1950s. Evaluation involved construction of a detailed finite element model of the suspension bridge including details on the carrier pipe, an additional support pipe, primary catenary cable, and other supporting cables and wires. The analysis included variations in pipe wall thickness in relation to data collected from the in-line inspection tool run. Loading included gravity, internal pressure, and wind loads. Analysis stress results were then compared to design limit based on the rules of ASME B31.4. The final evaluation revealed that a very specific band of conditions (namely pressure and wind speed) were required to ensure the continued safe operation of the line. Recognizing the need to maintain the required operating pressure, coupled with the inability to control wind speed, led the pipeline company to make repairs to regions of the pipeline where stresses exceeded the code limits. This project was a clear demonstration of how inspection, analysis, and repair methods can work together to ensure the safe operation of pipelines. INTRODUCTION This paper provides details on the methods used to assess corrosion in a pipeline bridge. In this study a finite element analysis was done to determine the state of stress for an 8-inch nominal diameter pipe bridge subject to gravity, wind, internal pressure and tension loads from suspender cables used for support. Finite element models incorporating corrosion of the pipeline were modeled using local thin areas (LTAâ??s). This was achieved by defining a thinner section property for selected elements in the model based on actual inspection data provided by in-line inspection efforts. Also, a uniformly corroded pipeline was modeled to determine the minimum required wall thickness that would have adequate structural integrity and be in compliance with ASME B31.4. In addition, removal of suspender cables was simulated until stresses reached unacceptable levels according to B31.4. MODELING METHODOLOGY Engineering drawings of the bridge and its components as compiled by the operator were used to construct the finite element models. However, modifications not affecting the results of the study were made in instances where data was incomplete, missing, conflicting or deemed inconsequential. These modifications included not modeling the South and North towers as these structural components of the bridge were considered to be rigid in comparison to the stiffness of the pipeline that was the primary focus of the study. Consequently, the South and North ends of the catenary cable were fixed at the appropriate locations in space. Similarly, the supports for the wind cables were also fixed at the appropriate location in space. A more detailed description of the boundary conditions is provided in a following section.
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (1.00)
- Data Science & Engineering Analytics > Information Management and Systems (1.00)
ABSTRACT For the past decade there has been relatively wide acceptance in using composite materials to repair damaged has and liquid transmission pipelines. There have been numerous independent research programs performed by pipeline companies, research organizations, and manufacturers that have contributed to the acceptance of composites as a legitimate repair material. Additionally, insights have been gained by both pipeline operators and composite repair manufacturers during field installations. ASME has also responded by adding sections to both the ASME B31.4 and B31.8 pipeline codes, as well as currently developing a repair standard for nonmetallic composite repair systems by the Post Construction Committee. The purpose of this paper is to provide for the pipeline industry guidelines for using composite repair systems to repair pipelines and what information is needed to properly evaluate how composite materials should be used to repair high pressure pipelines. The contents of the paper will include discussions on what critical elements should be evaluated for each composite system, items of caution and concern, and the importance of evaluation to ensure safe long-term performance. BACKGROUND AND HISTORY There were three principal driving forces that led to the interest and investment in composite materials in the United States in the mid-1950s and 1960s: the designer's demand for lower weight and higher rigidity for aero- or space structures, electronics, sports equipment, and other applications; the solid-state theory's predictions of extremely high potential crystal strengths, more than one million psi tensile strengths, and elastic modulii of more than 100 million psi; and the flourishing U.S. economy. Advanced composites had come of age in the early 1960s with the development of high-modulus whiskers and filaments. While whiskers were easily made, their composites were of poor quality; but the 60 million modulus boron filaments reinforcing epoxy were very successful and were used in fighter aircraft and later in sporting goods equipment. As their costs came down over the years, the use of composites has migrated to oil and gas applications, including pipeline repair [1]. From a transmission pipeline standpoint, Clock Spring® (System A) is recognized as the first composite repair system that was widely used to repair pipelines. In 1991 the Gas Research Institute (GRI) initiated a research program at Southwest Research Institute (San Antonio, Texas) and Battelle Columbus Division (Columbus, Ohio) to thoroughly test a composite repair system that had been developed by industry. Over the next five years an intense research effort was carried out to assess the performance of System A that utilized an Eglass/polyester material and methacrylate adhesive. In order to use composite materials to repair transmission pipelines, the Office of Pipeline Safety (OPS) required the use of waivers before installations could take place [2]. First, OPS granted the Panhandle Eastern Corporation a waiver of § 192.713(a) to install System A over six corrosion anomalies on Line #2 in Ohio, subject to certain monitoring and reporting conditions (58 FR 13823; March 15, 1993).
- North America > United States > Texas > Bexar County > San Antonio (0.24)
- North America > United States > Ohio > Franklin County > Columbus (0.24)
- Materials (1.00)
- Energy > Oil & Gas > Midstream (1.00)
- Government > Regional Government > North America Government > United States Government (0.86)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Piping design and simulation (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Offshore pipelines (0.87)
ABSTRACT According to statistics compiled by the U.S. Office of Pipeline Safety, mechanical damage is one of the primary causes of pipeline failures in the United States. For more than 30 years a significant body of research has been collected in an effort to understand the failure mechanisms and mechanics associated with pipeline defects that include plain dents, wrinkle bends, and mechanical damage involving dents with gouges. In the U.S. organizations such as the Pipeline Research Council International, Gas Technology Institute, and the American Petroleum Institute have led the change in funding these research efforts, as well as other efforts from research organizations around the world. While some guidance is provided by the ASME B31.4 and B31.8 pipeline codes in assessing pipeline damage, there is no single document that captures the lessons learned from the extensive body of research and experience that currently exists. To a large extent this is related to the complexity of the subject; however, there is a significant need to develop for industry a method for ranking the severity of pipeline damage. At the present time there is no single method for doing this. This paper will provide insights on a proposed three-tiered system to help operators determine which defects represent the most serious threat to the mechanical integrity of their systems. The intent is to provide operators with a grading tool based on research testing, material characteristics, experience, and dent mechanics in order for repairs to be made in a manner that ensures the safe operation of pipeline systems. INTRODUCTION One of the most critical elements when assessing pipeline damage is classification of defects. There is a significant amount of information available in the open literature; however, one of the challenges is putting everything together in a manner that can be used to assess damage severity. This is one of the main purposes of this paper. The second purpose is to provide a systematic methodology for operators and pipeline service companies who are tasked with making decisions about what to do when pipeline damage occurs. Because of the extensive research that has been conducted world-wide relating to dented pipelines, it is possible to draw information required on a range of defect types. The driving motivation for many research programs is to develop a better understanding of damaged pipelines in an effort to characterize their behavior. As with many areas of engineering, the ability to accurately predict the response behavior of structures is important to ensure adequate safety and consistent performance. The complexities associated with damaged pipelines make this a challenging task. Material issues, corrosion, cyclic pressure conditions, soil-pipe interactions and complicated stress fields are but a few examples. Provided below are the major defect classifications that typically arise when assessing pipeline damage. Plain dents Constrained dents Gouges Mechanical damage Wrinkles
- Energy > Oil & Gas > Midstream (1.00)
- Government > Regional Government > North America Government > United States Government (0.67)