bluuebunny/crossref_metadata_2025 huggingface dataset:
L51979 Gas Decompression Behavior Following the Rupture of High Pressure Pipelines-Phase 1
Authors: Phillips  , Robinson
Published: August 2023

The ability to predict the behavior of a crack propagating in a steel natural gas transmission pipeline is of great importance. This is because a long-running fracture is costly, both in terms of the time taken for replacement, and associated lost revenue, and the cost of replacement of the pipe itself. The determination of ductile shear fracture arrest toughness levels requires an accurate knowledge of the gas decompression behavior following the rupture. In particular, there is a need to predict accurately the gas decompression wave velocity within the pipe as a function of initial pressure, temperature and gas composition. Although models developed in the 1970's have proved remarkably robust to date, even when stretched considerably beyond their range of validation, operational characteristics currently being considered range far beyond any that have been investigated on a realistic scale. There is, therefore, a need to produce a model that has been validated for conditions relevant to next generation pipeline projects.

This report describes the work carried out in Phase 1 of a project to produce such a model. In Phase 1 a review of current knowledge was carried out and the work required in Phase 2 of the project was specified. This report describes Phase 1 of the gas decompression project. The aim of Phase 1 was to review the current state of knowledge on pipeline decompression. Carrying out this work has enabled the requirements for the model, the extent of validation that will be required and the proposed technical approach to be identified.
L51865 Hydrotest Parameters to Help Control High-pH SCC on Gas Transmission Pipelines
Authors: Leis
Published: August 2023

This report develops and validates a probabilistic model for high pH SCC on pipelines that can help operators to:

quantify the condition of susceptible transmission pipelines
assess the efficiency of controls for such SCC based on after coolers and periodic hydrostatic re-testing
identify, evaluate, and control the related risks· prioritize rehabilitation to avoid in-service incidents.

The probabilistic model is an adaptation of a first-generation model for high pH SCC known as the Stress-Corrosion Cracking Life Prediction Model, (SCCLPM). Its validation follows from the close match between simulated cracking populations and incident occurrence and that observed for operating pipelines behavior. Because methods to simulate coating failure have not yet been developed, the model assumes the presence of a cracking environment, which according to field experience adds 3 years or more to the simulated pipeline life.
L51649 A Study of Processes for Welding Pipelines
Authors: Weston
Published: August 2023

The construction of a pipeline involves the joining, end to end, of a series of standard lengths of pipe together with other connections to the necessary valves, pumps, etc. Technically, when considered in isolation, this is a relatively simple joining operation and a number of processes can be used to perform it. When all of the production constraints are taken into consideration, however, the selection task becomes considerably more complex. Pipe diameter and wall thickness ranges are wide and new pipe materials are continuously becoming available. On land the terrain can vary from prairie to mountains and from swamps to urban surroundings. A significant proportion of pipe laying is also being done at sea in water depths which can exceed 3,300 feet (1000m). Regardless of all of these changing circumstances, one factor remains constant, a need to produce a technically acceptable pipeline at the lowest possible overall cost.

This report reviews the development of welding processes in two main categories, Fusion Welding and Forge Welding. Non Destructive Testing (NDT) is also reviewed. Within each category, each process is considered separately in terms of process principles, general applications, application to pipeline welding, equipment for pipe welding, consumables, process tolerance and skill requirements, weld quality and inspection, process economics, limitations and future developments. Similar areas areconsidered in the section on NDT.
L51456 Design Guidelines for Mined Cavern Storage of Natural Gas
Authors: Lachel
Published: August 2023

Mined cavern storage of natural gas is a technical and economically feasible alternative to surface storage. Favorable geologic environments exist in many locations, and the risk of cost overruns or unproductive expense can be minimized through a stepwise planning and design procedure. Design and construction techniques for underground structures are well precedented with numerous successful cavern projects completed for powerhouses, military purposes, and mines. A mined cavern storage system has been operating in an abandoned coal mine in Leyden, Colorado, for over 20 years, with another planned by a consortium of gas companies for the New York City area. We look forward to the day when mined cavern storage is recognized as a viable option during the planning of a gas storage system.

The manual begins with general geologic siting criteria, and proceeds to the various types of cavern storage systems, and then to a discussion of environmental and permitting requirements of the facility. Finally, the manual guides the reader through the stages of design and construction and presents the fundamentals of underground engineering.
L51474 Brittle Fracture Initiation of Heavy-Wall Components
Authors: Krishnaswamy  , Wilkowski
Published: August 2023

Pipeline valve bodies, fittings, flanges, and numerous other components are typically made of cast or forged low-alloy steels. The large wall thicknesses necessitated by the complex shapes of these components usually are not conducive to ductile fracture behavior. Nevertheless, there is a distinct need to have sufficient toughness in such components so that they will not be susceptible to catastrophic failure from defects that may remain after manufacturing and hydrostatic testing. The present practice for controlling toughness in such components consists of specifying arbitrary values of Charpy energy or percentage shear area at a given temperature to be determined on a coupon of the material made in a manner similar to the parent cast or forged component. These values are usually decided by agreement between the purchaser and manufacturer.

This report describes experimental research aimed at correlating typical impact tests to more fundamental fracture mechanics tests using various available correlations and to predict full-scale fracture behavior of heavy-walled pipeline components using the fracture mechanics parameters obtained. The components examined in this research task are: (1) a 4-inch, 600 pound class valve, (2) a quarter section of a 24-inch Arctic grade valve, and (3) a 16-inch diameter by 0.75-inch wall, 45 degree elbow. Small-scale tests conducted on the 4-inch valve material were standard Charpy V-notch impact, precracked Charpy impact, precracked Charpy slow bend, dynamic tear, and three-point bend - J/COD tests. Only Charpy V-notch impact and J/COD tests were performed on the 24- inch Arctic Grade valve and the 16-inch elbow.

This report describes a conservative approach to estimating failure stresses and tolerable flaw sizes to predict brittle fracture in heavy-wall components.
L51809 Buckling and Collapse of UOE Manufactured Steel Pipes
Authors: Foeken van , Gresnigt
Published: August 2023

In the past 20 years, much research has been conducted into buckling and collapse of pipelines under external pressure, bending or tension and combinations. Also many finite element analyses have been performed into the behavior of pipelines under these loads. The available test results show considerable scatter, which is considered to be caused by variations in the stress-strain relationship, the anisotropy of the steel, the Bauschinger effect, the geometrical deviations, the residual stresses, the test conditions, etc. The manufacturing method (seamless, UO, UOE) has a considerable influence on these properties and on the collapse and local buckling resistance.

In this project, design formulations for collapse and buckling with appropriate safety factors, calibrated against experimental and numerical models using probabilistic methods, have been selected for a practical range of design considerations. The project consisted of three parts: experiments, probabilistic calculations, and finite element calculations.
L51577 Prediction of SCC Susceptibility Based on Mechanical Properties of Line Pipe Steels
Authors: Christman
Published: August 2023

If a relationship between the deformation properties of a line pipe steel and its stress-corrosion cracking resistance can be established, then steels may be selected or designed for improved stress-corrosion resistance, based on their mechanical properties.

Benefit: In this research program three line pipe steels, removed from long-term service, were examined to determine if there is a correlation between their mechanical properties and stress-corrosion cracking resistance. The hypothesis was that the steel with the greatest tendency for strain hardening, under cyclic and monotonic stress conditions would also have the highest threshold stress for stress-corrosion crack initiation. This hypothesis was verified by the laboratory experiments, which showed the steel with the greatest tendency for strain hardening to have the highest resistance to stress-corrosion. Two other steels, with distinctly lower resistance to plastic deformation, had lower threshold stresses for stress-corrosion. This observation is consistent with the present concept of stress-corrosion crack growth, which holds that crack tip dissolution, and hence crack propagation, occurs because localized plastic deformation ruptures passive films or prevents film formation resulting in crack growth.

Result: The cyclic strain behavior of these three steels is consistent with their monotonic stress-strain curves. Both Steels A and B showed a point of extreme strain as the cyclic stress was increased. Their monotonic stress-strain curves both showed well pronounced yield points above which a considerable strain accompanied a small stress increment (low strain hardening). For both steels the rapid increase in cyclic strain occurred at approximately the elevated temperature yield point (\45 ksi for Steel A
L52273 Internal Repair of Pipelines
Authors: Bruce
Published: August 2023

External, corrosion-caused loss of wall thickness is the most common cause of repair for gas transmission pipelines. To prevent an area of corrosion damage from causing a pipeline to rupture, the area containing the corrosion damage must be reinforced. Since corrosion is a time dependent process, as pipelines become older, more repairs are required. Repair methods that can be applied from the inside of a gas transmission pipeline (i.e., trenchless methods) are an attractive alternative to conventional repair methods since pipeline excavation is precluded. This is particularly true for pipelines in environmentally sensitive and highly populated areas.

Hydrostatic pressure testing was conducted on pipe sections with simulated corrosion damage repaired with glass fiber-reinforced composite liners, carbon fiber-reinforced composite liners, weld deposition, an adhesively bonded steel patch, and adhesively bonded/helically wound steel strip. To benchmark pipeline material performance, additional pipe sections were evaluated in the virgin and in the corrosion damaged/un-repaired conditions. Three repair technologies exhibited burst pressures that were greater than the burst pressures of the un-repaired pipe sections: adhesively bonded/helically wound steel strip repair exhibited the highest performance with burst pressures ranging from 0.4% to 144% higher; carbon fiber-reinforced liner repair had burst pressures ranging from 4% to 17% higher; and glass fiber-reinforced liner repair had burst pressures ranging from 1% to 7% higher. Two repair technologies exhibited burst pressures that were lower than the burst pressures of the un-repaired pipe sections: adhesively bonded steel patch repair was 1% lower and weld deposition repair was10% lower.
L51665 Hydrotest Strategies for Gas Transmission Pipelines Based on Ductile-Flaw-Growth Considerations
Authors: Leis  , Brust
Published: August 2023

Historically safe operation of thousands of miles of gas- transmission pipeline underscores the merits of hydrotesting. The hydrotest is applied to remove defects, which might exist in the line and could be critical in subsequent service. The hydrotest involves a proof pressurization that is designed to remove defects that could otherwise become critical in service by failing these defects during the time the line is held at the over-pressure. Water is used as the pressurization media to avoid the potential for running fracture, which is possible in cases where defects become critical during the test when using more compressible media (e.g., gases). Hydrotesting is not the only means to ensure defects that could become critical in subsequent service are identified and removed from a line. For example, inline inspection (ILI) procedures are available that permit the identification of specific types of defects, such as corrosion. But because not all lines can be inspected with ILI tools and the need to find types of defects that are not currently detected by inline procedures, hydrotesting remains the method of choice in the USA for natural gas transmission lines.

The objective of this study was to determine the growth of various flaw sizes as a result of having been subjected to combinations of test pressures and hold times and to assess the subsequent serviceability of pipelines containing those flaws in gas-transmission service. The purpose of the flaw-growth calculations is to define hydrotest procedures for gas-transmission pipelines that remove flaws that could become critical in service while minimizing the growth of any remaining flaws. This report is the fourth in a series of topical reports dealing with quasi-static ductile flaw growth in pipelines, such as can occur in a hydrotest. Prior reports presented relevant material properties, the theoretical analysis, and the model development and validation. This report presents the results and analysis of an extensive parametric study of ductile flaw growth as a function of maximum test pressure, hold time, flaw geometry, and strength and toughness of the pipe steel representative of submerged-arc welded pipe in grades from X52 through X70 with a yield-to-ultimate ratio less than 0.90.
PR-186-063516-R01 Stress Corrosion Cracking in Areas of Local Deformation
Authors: Brongers
Published: August 2023

Local areas of deformation (wrinkles and dents) have been recognized as one of the leading causes of failures in both gas and liquid pipelines.This research had four objectives: (1) update the industry survey of GRI Project 8756 on SCC at deformations, (2) demonstrate that a crack mouth monitoring technique can be used on full-scale pipe samples with dents to study the mechanical component of near-neutral-pH stress corrosion growth, (3) evaluate the effect of dents on the SCC crack growth rate (CGR), as compared with pipe base metal, and (4) investigate whether hydrotesting can be used as an effective means of mitigation of SCC at dents, i.e., slow down the CGR.
L51407A Pipeline Nomograph for Point Sources A
Authors: Unknown Author
Published: August 2023

This item consists of two nomographs plotting pipe thickness, modulus of elasticity, equivalent charge weight, standoff distance, and circumferential or longitudinal stress. The two graphs cover different ranges of equivalent charge density and standoff distance. The equivalent energy release for several different types of explosives are provided.
L51704 Design Guideline for High-Strength Pipe Fittings
Authors: Wilkowski  , Eiber
Published: August 2023

This report presents guidelines based on the study of current practices in the design and manufacture of high-pressure pipe fittings (size tees, reducing tees, elbows, and caps) from 4 to 12 inches. Based on fitting measurements, finite-element models for linear analysis were developed and the results were compared to existing standards. The models were verified with two experimental burst tests. Tensile strength proved to be the most significant factor for burst pressure and fatigue. For fittings of unknown origin, the tensile strength can be estimated with non-destructive material hardness tests. Yield strength showed no effect on burst pressure or fatigue due to cyclical pressure loading.
L51743 Stress Corrosion Cracking of Pipelines in Contact with Near-Neutral pH Solutions
Authors: Parkins
Published: August 2023

While much has been learned about low pH stress corrosion cracking in the decade since it was recognized, a review of the published papers and reports since the last overview of the subject in 1992 indicates that there is still much to be understood about this matter. Most of the laboratory studies have involved dilute solutions based upon those found in the vicinity of cracks in operating lines, but the possible role of bacteria, for which there is supporting field evidence, has not received systematic study. The trans-granular service cracking has been reproduced in the laboratory, most readily when relatively high stresses and/or strains are applied to specimens, but there is still difficulty in reproducing cracking in the laboratory with stressing conditions similar to those on an operating pipeline.

If meaningful modeling of low pH cracking is to be achieved, there is need for more data on crack initiation and the early stages of growth with stressing conditions no overly excessive by comparison with service conditions. There is also a need, related to modeling, of an understanding of the mechanistic aspects of cracking, since while it is known, not least from visible evidence of corrosion on the sides of cracks, that dissolution occurs within the crack enclave, there is indirect evidence that the ingress of hydrogen into the steel may be involved also in the overall crack growth process. If hydrogen is involved then existing models based upon high pH cracking, and involving a quantifiable dissolution mechanism, will not be directly applicable to the low pH problem.
L51589 Investigation of Sulfide-Stress Cracking at Pipe Seam Welds
Authors: Cialone  , Williams
Published: August 2023

A metallurgical investigation was undertaken to identify the factors that are responsible for sensitivity to sulfide-stress cracking (SSC) in the heat-affected zone (HAZ) of microalloyed high-strength line-pipe steels, when the HAZ does not contain regions of high hardness. Sustained-load tests were conducted in the NACE laboratory sour-gas environment to determine the regions in which SSC initiated, and thereby to identify which regions were most sensitive to SSC.
L52303 Development of Techniques to Assess the Long-Term Integrity of Wrinkled Pipeline
Authors: Dinovitzer
Published: August 2023

The objective of the project was to develop a numerical model than may be used to predict the wrinkle formation and post formation behavior of a pipeline considering the effect of soil confinement and define the specifications for the development of a comprehensive wrinkle integrity assessment process.

The result of this research is the development of wrinkle assessment techniques that could be used directly or could be used to codify maintenance guidelines. This project focused specifically on the pipe soil interaction modeling wrinkle formation as a result of the relative movement of the pipe and soil. The structural model developed and validated in this program and previous work could be applied to wrinkle bends, however, this issue is not specifically addressed in this report. In addition, the project development efforts focused on the monotonic soil interaction event of idealized (e.g., no secondary degradation like corrosion features) pipe segments. The project completed a critical review of existing structural and soil modelling techniques to identify the most suitable technologies for this application. The soil-pipe interaction under soil movement was found to be best represented using the LS-DYNA Multi-material Eulerian technique which permitted the application of a number of suitable soil constitutive models. This analysis tool permitted the consideration of a range of soil types and large soil displacements. Having defined the most suitable tool set, several pipe soil interaction models were developed. These models were used to illustrate the types of analyses that could be completed and the capabilities of the models to illustrate the sensitivity of the scenario loads, displacements to changes in soil, pipe and other parameters. The modeling results were discussed to demonstrate that their trends and results were in line with intuitive assumptions and engineering judgment. Additional models were developed to simulate large scale pipe-soil interaction laboratory test programs. The results of the simulated test programs were compared with the laboratory results as an initial validation of the modeling techniques and tools. The simulated soil displacement patterns, pipe strains and pipe displacement were shown to agree well with experimental results and as such illustrated the ability of the models to reproduce idealized pipe-soil interaction events. Full-scale soil displacement events were modeled to illustrate the application of the modeling tools to forecast or predict the effects of axial and transverse soil movements on buried pipeline segments. These results were used to illustrate the methods and assumptions inherent in the application of the modeling tools to predict soil loading on pipeline systems.
L51783 100000 Hour Design Life of Turbo Compressor Packages
Authors: Cooke
Published: August 2023

The gas pipeline industry continues to respond to the challenges of competitive markets and the need to manage the cost of service effectively. A major cost element being reviewed by the industry is the operating and maintenance expense for its fleet of older turbo compressor units. Many turbo-machinery manufacturers and operators typically quote 100,000 hours as a design limit for service life of turbo compressor components. The Pipeline Research Committee initiated this study to review the life limiting criteria for certain critical components and determine if the design target of 100,000 hours can be safely and reliably met or extended with special component management practices. The first phase of the project was to select the turbomachinery components that would be included in the review. Committee members were surveyed with a detailed questionnaire designed to identify critical components based on: high hours (eg. at or approaching 100,000 hours), the most common engine types operated by the member organizations, and the components of greatest concern from a risk and expense point of view. The selection made covers a wide range of engine types that are of interest to most of the committee companies. This selection represents some 78% of the "high hour" units operated by the committee and includes components from GE Frame 3 and Frame 5, Solar Saturn, Rolls Royce Avon, and Cooper RT56 engines. The report goes into detail regarding the various damage mechanisms which can be the main life limiting factor of the component; creep, fatigue, environmental attack, wear and microstructure instability. For each of the component types selected, the study identifies the life limiting criteria and outlines how the components may be managed for extended life. Many of the selected components can be reliably operated beyond 100,000 hours by following the management practices set out in the report. The decision to continue to operate components or replace with new components is usually based on either a predetermined engineering life limit or retirement for cause. Operating life limits are based on engineering calculations that establish the component life, beyond which the risk of failure is high. Such limits assume a standard, or most often, a worst case set of operating conditions to be conservative for all types of service. Retirement for cause is based on specific inspection techniques applied at appropriate intervals to ensure that damage below a defined limit is identified and the parts are then removed for either refurbishment or retirement.
L51724 Fiber Optic Pressure Sensor Development
Authors: Taylor
Published: August 2023

Fiber optic sensors have been under development in industrial and government laboratories around the world for over a decade The commercial market for fiber sensors for measuring parameters such as temperature, displacement, and liquid level is now estimated to exceed $50 M/year Aside from the commercial interest, the U S. Department of Defense has vigorously pursued the development of fiber gyroscopes and hydrophones In spite of the high level of research and devleopment activity, however, fiber sensors were not successfully applied in the relatively harsh environment of engine combustion chambers prior to 1991. The goal of this development is to demonstrate the utilization of a new fiber optic sensor technology in engines used for natural gas transmission. Presently, there is no way to continuously measure pressure in these engines over extended periods of operation. Reliable fiber optic sensor networks supplying data to computerized control systems for on-line engine balancing could lead to major reductions in the emission of NO, and other harmful combustion products. Fuel economies in the millions of dollars per year for companies in the natural gas transmission industry could also be realized.
L52241 Strain-Based Design - Strain Concentration at Girth Welds
Authors: Mohr
Published: August 2023

Strain-based design is used for many situations for pipelines where the loadings from forces other than the internal pressure can be the largest generators of stress and strain in the pipe wall. Such loadings can be generated by soil subsidence, frost heave, thermal expansion and contraction, landslides, pipe reeling, pipe laying, and several other types of environmental loading. Designing based on strain for these cases has an advantage over designing based on stress because these loadings tend to apply a given displacement rather than a given force to the pipe. Standards are much better developed for stress-based design than for strain-based design. While several standards are available that have some coverage of strain-based design, there is a tendency to cover only limited types of loading, as in API RP 1111 for offshore pipe laying.

This program aimed to improve guidelines for strain-based design of pipelines by studying cases with combinations of internal pressure and axial plastic strain in tension. Softened heat-affected zone (HAZ) regions have been observed to concentrate strain, particularly under internal pressure. HAZ softening has been observed for welds on X-70 and X-80 steels. Cases with little or no softening have also been observed for other welds in these same grades. This project extended these findings to X-100 steels, with cases of obvious softening and little or no softening observed. Higher heat inputs and larger weld volumes per pass associated with submerged arc welding (SAW) as compared to gas metal arc welding (GMAW) have been correlated with greater softening in each of these pipe grades.
PR-015-13611-R01 Evaluation of Selected Sampling Techniques on Hydrocarbon-Wet Gas Streams
Authors: George  , Grant  , Hawley
Published: August 2023

This project evaluated selected single-phase gas sampling methods as candidates for use in sampling hydrocarbon-wet gas streams and obtaining representative samples of only the gas phase, rather than samples of both the gas and liquid. Two spot sampling methods, the helium �pop� method and the floating piston cylinder method, were chosen for evaluation. To capture samples of only the gas phase required one or more arrangements for separating liquids from the sample stream. To this end, a coalescing filter and a vortex separator were chosen for testing with the two sampling methods. The various sampling approaches were tested using the Sampling Method Performance Verification Procedure of API MPMS Chapter 14.1, Appendix F, adapted as appropriate for use in hydrocarbon-wet gas streams. Preliminary tests at SwRI�s Metering Research Facility (MRF) were used to identify possible problems with the equipment and sampling procedures, so that the equipment and procedures could be corrected before the formal tests were conducted. The formal tests were performed at a field site carrying a hydrocarbon-wet gas stream from a shale formation. Results of the formal tests produced recommendations to improve the general ability of the chosen wet-gas sampling method to capture accurate samples of the gas phase, as well as recommended changes to the API Sampling Verification Procedure for testing wet-gas sampling methods.
L51706 Higher-Strength SMAW Filler Metals
Authors: Patchett B. M. , Bicknell A. C.
Published: August 2023

The welding of high strength steels in general, and for pipeline fabrication in particular, has shown that cracking due to hydrogen absorption during welding is more complex in these steels than in older, lower strength steels. In older steels, primary strengthening was accomplished with carbon, which caused hydrogen cracking in the base metal HAZ under reasonably predictable conditions involving microstructure, residual stress and hydrogen level. Pipeline steels were and are in the vanguard of change in strengthening philosophy. The change involves two areas of steel making, chemical composition and deformation processing. Pipeline steels now contain low carbon levels, in many cases less than 0.10%, and the resulting lack of strength is reclaimed by adding higher alloy levels to promote solution hardening (e.g. Mn), precipitation hardening (e.g. Cb, Cu) or transformation hardening (e.g. MO). In addition, alloy elements are added to improve toughness at high strength levels (e.g. Ni). At the same time, improvements have been made in reducing impurity and residual element levels, notably for S, P and O and N. Limitations on the effects of alloying additions on strength and toughness encouraged the use of deformation processing, primarily during rolling, to promote fine-grained microstructures to increase strength andtoughness simultaneously.

Electrodes for the SMAW process have been developed for welding high-strength pipeline steels by using core wires made from high-strength microalloyed skelp extruded with cellulosic (Exx10) and low hydrogen (Exx16) flux coatings. The required alloy elements for high-strength deposits were therefore obtained from the core wire and not ferroalloy powders added to the flux, as is standard industrial practice. The idea behind this change was two fold: to avoid the possibility of introducing impurities from the varying sources of ferro alloy powders, including oxygen from the oxidized powder surfaces, and also to provide a closer match of the microalloy level to modern pipeline steel chemistries. The unknowns in this work were the effects of lower impurities/similar alloy content on the mechanical properties in the cast microstructure of a weld, compared to a pipe, and of the effect on electrode welding behaviour of a flux containing no ferro powders other than FeSi.
L51735 Time-Dependent Polarization Behavior as a Function of Soil Type
Authors: Orazem  , Carson
Published: August 2023

Cathodic protection requirements for buried structures have traditionally been predicted by use of anode resistance equations which take into account the influence of anode geometry on the current distribution at the anode and the influence of soil resistivity on the driving force required to pass current to the structure to be protected. The conventional anode resistance formulas used for CP design were developed for bare pipes protected by remote anodes. Under these conditions, the current density at the anode is so much larger than that on the pipe that the current and potential distribution around the pipe can be ignored in resistance calculations. The current and potential distribution on the pipeline must, however, be considered for coated pipes with coating holidays or when anodes are placed in close proximity to the pipe.

The objectives of this work were: 1. to develop and apply new experimental techniques for identifying the time-dependent polarization behavior of pipeline grade steel as a function of the ionic composition of typical soil leachate and to develop and apply methods to interpret the results in terms of fundamental physical processes; 2. to measure the time-dependent polarization of FBE-coated coupons with and without machined coating holidays that expose bare steel; and 3. to establish an approach for predicting the polarization behavior of coated coupons with coating holidays that expose bare steel. by comparing the predictions for the polarization of coupons with holidays with experimental values.
L52127 Evaluation of Soil Resistivity Measurement Techniques
Authors: Wakelin
Published: August 2023

The measurement and interpretation of soil resistivity data is a fundamental aspect of pipeline corrosion engineering; nevertheless, very little information has been specifically published to assist pipeline corrosion personnel with these tasks.

The purpose of this project was to evaluate the various techniques and instruments which are available for the measurement of soil resistivity, and also to consider the methods which are available to interpret the data. Although large amounts of information have already been published on this subject in other fields of engineering, much of this literature is not applicable to pipeline corrosion applications. A test method which might be considered a standard practice in one field of engineering may not be applicable to pipeline corrosion engineering at all, and so it was important that this evaluation be conducted by a pipeline corrosion engineer on behalf of all pipeline corrosion engineers. It was anticipated that this report might serve as a soil resistivity reference for the pipeline and corrosion industries, and possibly for electrical engineers in general, who are interested in the investigation of the earth's electrical characteristics.
L52333 NDE and Inspection Techniques Applied to Composite Wrap Repairs
Authors: Lee  , Wall  , Burch
Published: August 2023

The objective includes:

Assess commercially available inspection methods to validate integrity of composite repair systems.
Identify applicability to inspect composite overwrap and parent metal for both onshore and sub-sea pipelines (where information is available).
Identify sources of data to include other users of composite materials(aerospace/aircraft, naval/ship repairs).
Identify procedures and technologies to assess inspection effectiveness and provide a gap analysis.
Interface with other PRCI projects on long-term testing of composite repairs and other joint industry projects on composite repairs to improve our understanding of long term durability of repairs.
Identify global experience with composite repairs; not just North America.

For general wall loss, radiography or electromagnetic techniques appear to be the best candidates. Standard radiography techniques can detect changes in wall thickness over a large area. Saturated low frequency systems, e.g. SLOFEC are good for a quick rapid scan of the area of interest. Pulsed eddy current, e.g. PEC, is also available for a general survey of the underlying substrate. For pinhole leaks, the electromagnetic techniques do not have sufficient resolution to detect defects of order 20 mm (0.8 in.) diameter and less. Standard radiography techniques can detect pinhole leaks down to diameters of 3 mm (0.12 in.) or less. Tangential radiography techniques are generally good for defect sizing but there are practical limitations with chord length (i.e. beam path through the pipe wall). Ultrasonic techniques could offer a potential solution but is currently limited due to the high attenuation of the composite repair material where through the repair inspection could only detect large diameter defects greater than 25 mm (1 in.) diameter on thin repairs less than 5 mm (0.2 in.). Detecting pin hole defects by applying the ultrasound along the axial direction of the substrate, effectively skipping the ultrasound under the repair, showed more promise.

For delamination or debonding of the interface between the composite laminate and the steel substrate, laser shearography and microwave inspection appear to offer the best solution. Currently there is no single inspection technique that can be applied with confidence to the inspection of interfacial delaminations. Further developments are on-going to provide a solution to this challenging inspection problem. Acoustic emission is able to give an overall picture of the damage within the composite under live loads. It can be used as a QA tool to test the integrity of the repair. However, it is difficult to interpret the signals to gain any quantitative information about a particular defect.
L22274 Exhaust Emissions from Piston and Gas Turbine Engines Used in Natural Gas Transmission
Authors: Dietzmann  , Springer
Published: August 2023

A baseline emissions survey was conducted on stationary gas turbines and reciprocating engines used in natural gas transmission. A total of 59 reciprocating engines and nine gas turbines were tested over a ten-month period at ten different sites. Details are provided on the test procedure used and its development.Emission rates for all tests were calculated. For piston engines, emission rates were determined at or near the rated speed and load, and comparisons were made. Comparisons were also made between two and four stroke engines, as wells as turbocharged and normally aspirated versions of the same engine. Emission trends for a number of piston engines were developed as a function of engine operating parameters, such as ignition timing, scavenging air pressure, engine speed, and load. Gas turbine NOx concentrations were compared to the level currently under discussion as a possible proposed Federal standard.
L20030 Transient Flow in Natural Gas Transmission Systems
Authors: Atterbury
Published: August 2023

This book is designed to bring members of the natural gas industry a complete text covering the technical advances made as a result of the TRACOR-AGA Transient Flow Study. The study began in January 1962 and culminated in a seminar in October 1964. A major portion of this book is the treatment of nonlinear partial differential equations which constitute the dynamic model of the line section. Both numerical and analytical treatments are presented. Solutions of the mathematical model are presented in the form of transfer functions. Compatible treatment of compressor stations and pressure regulators is also investigated. Techniques for the treatment of complex systems made up of many line sections and compressor stations are given. Finally, some immediate applications of transient techniques are discussed in addition to the possible course of future natural gas transmission research.
L51431 Prediction of NO to NO2 Oxidation Downwind of Reciprocating Engine Natural Gas Compressor Stations
Authors: Bishop
Published: August 2023

This study was performed to develop a predictive equation for use as a chemical component of dispersion models used for estimating the ground level concentration of NO2 downwind of natural gas compressor stations. A dispersion model is used to estimate downwind NOx concentrations, while the chemical submodel presented in the report is used to predict downwind NO2/NOx ratios. The chemical component of the model takes into account four sources of NO2 in the compressor station exhaust plume:1) Combustion generated NO2;2) NO2 produced by thermal conversion;3) NO2 generated by reaction of NO in the exhaust with O3 in the ambient air; and4) NO2 in the ambient air.
L51477 Theoretical and Experimental Investigation of Mud Forces on Pipe
Authors: Schapery R.A.
Published: August 2023

Presents a mathematical model for predicting mud loading on offshore pipelines through a combination of experimental and theoretical studies. A dimensional analysis followed by three different sizes of drag box tests were conducted; the theory and test results are presented and compared.

Laboratory tests were made in a shear box using a small scale deeply buried vertical pile model to check test procedures and provide a link between the present work and extensive previous data by Marti at Texas A and M University. Maximum drag factors for rigidly held deeply buried horizontal pipes in the shear box .rere then examined and shown to be the same as for the deeply buried vertical pile. Next, normal and axial drag factors for deeply buried horizontal pipes oriented oblique to the flow in the shear box were obtained as a function of cross-flow angle in pressurized soil. Additional tests were made in the shear box to obtain drag factors on both partially recessed and shallow completely buried pipes rigidly held normal to the flow in unpressurized soil.
L51471 AGA-API Drop Weight Tear Test Round Robin Testing Program
Authors: Wilkowski  , Maxey  , Eiber
Published: August 2023

Reports the results of a two-phase round-robin program to examine the reproducibility of the precracked DWTT when used for impact-energy measurement.
L51541 Identification of Injected Storage Gas
Authors: Beavers
Published: August 2023

Gives the results of an investigation to develop procedures to differentiate between migrating storage gas and native gas. Considers several technologies with specific emphasis on tracers and compositional analysis. Includes floppy disk regression and factor analysis program intended to permit demonstration of the presence of storage gas in mixtures when native gas composition is unknown.
L51536 Safety Factors in Flaw Assessment of Girth Welds
Authors: Leggatt R. H. , Hodgson A. P. , Hayes B. , Chan S. W. K.
Published: August 2023

An investigation of the safety factors inherent in the procedure for assessment of long surface flaws using a two-dimensional elastic-plastic finite element model and compared with experimental results.
L51569 Hyperbaric Shielded Arc Welding
Authors: Author Unknown
Published: August 2023

A series of both manned and unmanned welds were completed in a hyperbaric chamber for depths between 100-500 feet. The effect of SMA welding with DEEN specifically, the weld metal carbon and oxygen levels, weld strength and ductility, weld metal toughness and HAZ hardness.Cranfield Institute of Technology
PR-015-15602-R01 Review of Ultrasonic Flow Meter Installation Effects
Authors: Thorson
Published: August 2023

A literature review was conducted in order to better understand the effects of installation effects on ultrasonic flow meters. Literature in the public domain was reviewed to analyze the state of knowledge and to provide information that is relevant when deciding to allocate limited research budgets. The results are summarized in this report and in a digital analysis tool that will be delivered separately from this report.
L51504 Investigation of Real-Time Radiographic Methods for Use in Pipeline Weld Inspection
Authors: Light
Published: August 2023

Conventional radiography has been the accepted nondestructive examination (NDT) method used for many years to either "accept" or "reject" a field weld in the pipeline industry. The cost of conventional radiography, however, increasingly has become a major concern in the cost effectiveness of laying new pipelines. The contributing factors to the high cost of conventional radiography are the costs of film and of the chemicals and manpower used to develop the film. Over the last few years, a newer approach to performing radiographic testing has been perfected. Called "real-time radiography," it uses radiographic sources with an optical imaging system. It has been developed now to the point that the sensitivity, contrast, and resolution of these imaging systems can be used to detect variations in material density equivalent to defects of interest in pipeline welds.

The first objective of Phase 1 was to investigate existing real-time radiographic systems and system components in terms of their application to inspection of field-produced girth welds in steel pipelines. The second objective was to recommend a real-time system (either existing as a whole unit or comprised of several key subsystems) to be used for a field demonstration during Phase 2 of the program. The incentive, or goal, for this two-phase program is to introduce real-time radiography to the pipeline industry as a faster and overall more cost effective alternative NDE method compared to conventional film radiography. In addition, real-time radiography would provide a means to interpret the condition of a weld soon after completion while the welding team is still in the near vicinity of the inspected weld. This would permit immediate repair, if necessary, which would greatly reduce cost.
L51657 Remote Field Eddy Current Detection of Stress-Corrosion Cracks - Phase II
Authors: Nestleroth
Published: August 2023

Stress-corrosion cracking (SCC) can occur in gas transmission pipelines. These cracks initiate on the exterior of the bulk pipe material and grow in the axial and radial direction. Access for comprehensive nondestructive inspection systems is generally limited to inside the pipe itself. Since these defects can lead to leaks and failures, a need of the gas pipeline industry is the in-line detection and characterization of stress-corrosion cracks. Previous research has shown the remote field eddy current (RFEC) technique can detect SCC in gas transmission lines.

The objective of this program is to quantify the SCC detection and characterization capability of this technique. The internal nature of the RFEC technique identifies it as a potential candidate for in-line inspection. The through-transmission nature of RFEC technique is a major advantage over other nondestructive tests since it ensures the complete inspection of the entire pipe wall. This electromagnetic inspection technique requires no coupling agent to transmit inspection energy from a source, to the defect, and then to the sensor. If it can be shown that the RFEC technique is effective in detecting, identifying, and sizing SCC and other defects, the technique is a candidate for in-line inspection implementation.
PR-377-063528-R01 Development of Guidelines for Identification SCC and Re-inspection Intervals
Authors: King Fraser
Published: August 2023

This report describes the development of a series of guidelines for the identification of SCC sites and the estimation of re-inspection intervals. These SCC Guidelines are designed to complement and supplement existing SCC Direct Assessment protocols by drawing on information from past R and D studies. Guidelines are presented for the various mechanistic stages of both high-pH and near-neutral pH SCC, namely; susceptibility, initiation, early-stage crack growth and dormancy, and late-stage crack growth.

The guidelines are designed to be broadly applicable, and include discussion of both high-pH and near-neutral pH SCC, gas and (hydrocarbon) liquid pipelines, existing and future pipelines, on local and regional scales in North America and internationally. The guidelines are designed to be of use to pipeline operators with prior experience of SCC and to those for whom this is a new or unknown integrity threat.

The report also describes how these guidelines can be implemented by operating companies and provides a list of the analyses that need to be performed, the necessary input data, and how the resultant information can be used to identify SCC sites and estimate reinspection intervals.

The main text is supported by four appendices where the interested reader can find much of the detailed background information.