Leak Rate Testing of a Natural Pipeline Defect

2020 ◽  
Author(s):  
Robert M. Andrews ◽  
Joe Short
Keyword(s):  
Surface Roughness ◽  
Detection System ◽  
Crack Opening ◽  
Leak Rate ◽  
Good Prediction ◽  
Pressurized Water ◽  
Water Steam ◽  
Performance Requirements ◽  
Flow Through ◽  
Products Pipeline

Abstract If a stable through wall defect (leak) were to occur in a pipeline, the leak rate is an important factor for both safety and environmental assessments, and also to determine the performance requirements for a leak detection system. For a “large” leak, an assessment can be based on simple idealization as an orifice, but for narrow crack like defects this is not appropriate. The flow through a crack is dependent on factors such as the surface roughness and the crack opening. These issues have been extensively studied for nuclear pipework where the fluid is either pressurized water, steam or CO2, and guidance is given in Annex F of BS 7910. However, there is little published work for pipeline geometries and single phase liquids such as refined hydrocarbons. This paper presents the results of experiments measuring the leak rates through a tight axial through wall crack in a NPS 8 refined products pipeline. Leak rate measurements were made using water (for safety reasons) over a range of pressures. The data were fitted to a model for leakage through a tight crack that takes account of interaction of asperities in surface roughness. The fitted equation was then adjusted to take account of the different density and viscosity of the pipeline products. It was concluded that the model was able to give a good prediction of the measured leak rates and that the adjustments for the product properties were small.

Crack-Opening Displacement and Leak-Rate Calculations for Full Structural Weld Overlays

2009 ◽  
Author(s):  
D.-J. Shim ◽  
E. Kurth ◽  
F. Brust ◽  
G. Wilkowski ◽  
A. Csontos ◽  
...  
Keyword(s):  
Crack Opening ◽  
Nuclear Industry ◽  
Leak Rate ◽  
Opening Displacement ◽  
Primary Coolant ◽  
Pressurized Water ◽  
Weld Overlay ◽  
Water Reactors ◽  
The Impact ◽  
Weld Overlays

Full structural weld overlays have been used in the U.S. nuclear power industry for over twenty years in boiling water reactors (BWRs). Primary water stress corrosion cracking (PWSCC) in nickel-based dissimilar metal welds (DMWs) has been experienced in pressurized water reactors (PWRs) since the early 1990s. As a result, the nuclear industry is implementing full structural weld overlays (FSWOL) as a PWSCC mitigation technique that may be used on primary coolant lines previously approved for Leak-Before-Break (LBB). This work investigates the effect of the FSWOL on the leakage behavior of these lines with postulated defects. In this paper, finite element (FE) based crack-opening displacements (CODs) were developed for pipes with a FSWOL with postulated complex cracks. The COD solutions were then employed in standard leak-rate calculations, where equivalent crack morphology parameters were developed to consider a flow through two different crack morphologies, i.e., PWSCC through the DMW and corrosion fatigue through the weld overlay. The results of the sensitivity study and a discussion on the impact of the weld overlay on the leakage behavior concludes this paper.

Enhancement of Heat Transfer Performance in Nuclear Fuel Rod Using Nanofluids and Surface Roughness Technique

2015 ◽  
Author(s):  
Kang Liu ◽  
Titan C. Paul ◽  
Leo A. Carrilho ◽  
Jamil A. Khan
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Nuclear Fuel ◽  
Three Dimensional ◽  
Pressurized Water ◽  
Bulk Fluid ◽  
Fuel Rod ◽  
Dimensional Surface

The experimental investigations were carried out of a pressurized water nuclear reactor (PWR) with enhanced surface using different concentration (0.5 and 2.0 vol%) of ZnO/DI-water based nanofluids as a coolant. The experimental setup consisted of a flow loop with a nuclear fuel rod section that was heated by electrical current. The fuel rod surfaces were termed as two-dimensional surface roughness (square transverse ribbed surface) and three-dimensional surface roughness (diamond shaped blocks). The variation in temperature of nuclear fuel rod was measured along the length of a specified section. Heat transfer coefficient was calculated by measuring heat flux and temperature differences between surface and bulk fluid. The experimental results of nanofluids were compared with the coolant as a DI-water data. The maximum heat transfer coefficient enhancement was achieved 33% at Re = 1.15 × 105 for fuel rod with three-dimensional surface roughness using 2.0 vol% nanofluids compared to DI-water.

scholarly journals Investigations on Crack Propagation Under Cyclical Isothermal and Thermo-Mechanical Loadings for a Type 304-L Stainless Steel Used for Pressurized Water Reactor

2015 ◽  
Author(s):  
C. Gourdin ◽  
F. Rossillon ◽  
P. Le Delliou ◽  
G. Perez ◽  
A. Fissolo
Keyword(s):  
Crack Propagation ◽  
Crack Opening ◽  
Current Method ◽  
Heating System ◽  
Thermal Fluctuations ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Running Water ◽  
Water Reactor ◽  
New Device

The integrity of structures exhibiting flaws in Pressurized Water Reactor (PWR) has to be assessed to meet safety criteria. This paper deals with crack-propagation under cyclic thermo-mechanical loadings, as encountered in class I austenitic pipes of PWR’s. To have a conservative and reliable assessment of the crack propagation due to the in-service loading, various codes and standards use simplified method. For example, RSE-M introduces a plastic correction depending on the proportion of the mechanical loading. An improvement of the current method requires additional investigations. Moreover, components loaded with transient or thermal fluctuations are not really in strength-controlled conditions. To this end, a new device called PROFATH was designed. The specimen is a pre-cracked thick-walled tube undergoing a set of thermal cycles and loaded with a static mechanical force. During the first part of the cycle, a high frequency induction coil heats the external wall. Then, the heating system stops and the specimen is cooled down by running water inside the tube. Finite element calculations show that only a region half-way along the tube should be heated to ensure adequate structural effect. In the heated zone, the machining of a sharp circumferential groove ensures the propagation of a unique crack. An electro-mechanical jack controls the level of the mechanical static load. To obtain a very precise thermal mapping, a specific specimen with dedicated instrumentation is used: 20 thermocouples are appropriately located on the outer surface and along the wall thickness. During the test, the crack-propagation is estimated through crack-opening measurements (compliance method). Now, three first tests have been carried out. These tests allow having an evaluation of the pertinence of the correction proposed by the RSE-M for a significant plasticity. Following tests are planned in order to have a confirmation or to propose an extension of the validity domain.

Effect of Surface Roughness on Gaseous Flow Through Microchannels

2000 ◽  
Author(s):  
Stephen E. Turner ◽  
Hongwei Sun ◽  
Mohammad Faghri ◽  
Otto J. Gregory
Keyword(s):  
Surface Roughness ◽  
Reynolds Number ◽  
Friction Factor ◽  
Reynolds Numbers ◽  
Helium Flow ◽  
Local Pressure ◽  
Aspect Ratios ◽  
Corrugated Surfaces ◽  
Flow Through ◽  
Effect Of Surface

Abstract This paper presents an experimental investigation on nitrogen and helium flow through microchannels etched in silicon with hydraulic diameters between 10 and 40 microns, and Reynolds numbers ranging from 0.3 to 600. The objectives of this research are (1) to fabricate microchannels with uniform surface roughness and local pressure measurement; (2) to determine the friction factor within the locally fully developed region of the microchannel; and (3) to evaluate the effect of surface roughness on momentum transfer by comparison with smooth microchannels. The friction factor results are presented as the product of friction factor and Reynolds number plotted against Reynolds number. The following conclusions have been reached in the present investigation: (1) microchannels with uniform corrugated surfaces can be fabricated using standard photolithographic processes; and (2) surface features with low aspect ratios of height to width have little effect on the friction factor for laminar flow in microchannels.

CONTINUOUS RADON-IN-WATER MONITORING—COMPARISON OF METHODS UNDER LABORATORY CONDITIONS AND RESULTS OF IN SITU MEASUREMENTS

2019 ◽  
Vol 186 (2-3) ◽  
pp. 406-412
Author(s):  
Petra Vyletělová ◽  
Aleš Froňka
Keyword(s):  
Response Time ◽  
Detection System ◽  
Response Delay ◽  
Detection Systems ◽  
Water Detection ◽  
Radon Diffusion ◽  
Flow Through ◽  
Continuous Monitor ◽  
Radon In Water

Abstract The extraction of dissolved radon from water to gas is the most common way to measure radon concentration in water continuously. The response delay of continuous radon-in-water detection system (continuous monitor + equilibrator) is influenced by the response time of the continuous monitor and a rate of an establishment of equilibrium in the equilibrator (exchanger unit). Two types of equilibrators were used in performed experiments to compare the response time of various detection systems—RAD AQUA that uses water spraying and equilibrator with ACCUREL® PP membrane that enables radon diffusion. Each of these was connected to the continuous monitor RAD7 or RM-3. The response delay after turning on the water flow through the equilibrator was determined. The fastest detection system was RAD7 + RAD AQUA that was subsequently tested during the insitu measurement of thermal water in the healing spa and water sources near Cheb and České Budějovice.

Impact of Print Parameters on Pressure Drop in Turbulent Flow Through 3-D Printed Pipes

2020 ◽  
Author(s):  
Thomas G. Shepard ◽  
John Wentz ◽  
Tucker Bender ◽  
Derek Olmschenk ◽  
Alex Gutenberg
Keyword(s):  
Surface Roughness ◽  
Additive Manufacturing ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Acrylonitrile Butadiene Styrene ◽  
Industrial Applications ◽  
Relative Pressure ◽  
Fused Filament Fabrication ◽  
Pressure Drops ◽  
Flow Through

Abstract Flow conduits made via additive manufacturing, commonly referred to as 3-D printing, are of increasing interest for a variety of industrial applications due to the ability to create unique and conformal flow paths that would not be possible with other fabrication techniques. Fused filament fabrication (FFF) is an additive manufacturing technique that is seeing new interest in the creation of internal flow channels with its ability to print high-temperature polymers and soluble supports. Printing parameter choices in the FFF printing process result in surfaces that can have significant profile differences that may significantly impact the flow characteristics within the conduits. In this study, two print parameters were experimentally studied for turbulent water flow through circular pipes created by fused filament fabrication out of acrylonitrile butadiene styrene (ABS). The print layer orientation relative to the flow was investigated for printing layers parallel, perpendicular, and at 45 degrees from the flow axis. Layer thickness were varied from 0.254 mm to 0.330 mm and all channels were created using soluble support structures. Pressure drops were measured for fully developed flow through pipes with an inside diameter of 5 mm and Reynolds numbers up to 62,000. Results are presented in terms of relative pressure drops as well as the wall surface roughness that would lead to such impacts. These flow-determined grain surface roughnesses are then compared against measurements of print surface roughness.

Experimental and Analytical Leak Characterization for Axial Through-Wall Cracks in a Liquids Pipeline

2014 ◽  
Author(s):  
Mohamed R. Chebaro ◽  
Nader Yoosef-Ghodsi ◽  
David M. Norfleet ◽  
Jason H. Bergman ◽  
Aaron C. Sutton
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Internal Pressure ◽  
Crack Opening ◽  
Full Scale ◽  
Leak Rate ◽  
Propagation Mechanism ◽  
Element Analysis ◽  
Fea Model ◽  
Experimental Findings

Three pipeline sections containing defects of interest were non-destructively tested in the field, cut out and shipped to a structural laboratory to undergo full-scale testing. The common objectives of the experiments were to determine (1) the leak initiation pressure and (2) the leak rate at various specified internal pressures. While two spools (Specimens A and B) contained through-wall cracks, the third (Specimen C) had a partial through-wall crack with similar characteristics. The capacity of through-wall defects to withstand a level of internal pressure without leaking is due to the resultant local, compressive hoop residual stresses. Specimen C underwent full-scale pressure cycling to further comprehend the crack propagation mechanism in order to correlate it to field operation and analytical fatigue life predictions. To enhance the understanding of the physical crack behaviour as a function of internal pressure, a comprehensive finite element analysis (FEA) model was built using SIMULIA’s Abaqus software. The model inputs incorporated results from the above-mentioned laboratory tests, in addition to extensive radial, circumferential and axial residual stress measurements using the X-ray diffraction (XRD) technique, obtained on three pipe spools cut out from the same line. The resulting crack opening parameters from FEA were input into a closed-form fluid mechanics (FM) model, which was calibrated against a computational fluid dynamics (CFD) model, to determine the corresponding leak initiation pressures and leak rates. These outcomes were then compared to experimental findings. The FEA and FM models were subsequently employed to carry out a parametric study for plausible combinations of feature geometries, material properties, operational pressures and residual stresses to replicate field conditions. The key outcome from this study is the experimental and analytical demonstration that, for given fluid properties and pressures, the leak threshold and leak rate for through-wall cracks are primarily dependent upon the crack geometry and local residual stress distributions.

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