External Corrosion Growth-Rate From Soil Properties

2010 ◽  
Author(s):  
Khalid A. Farrag
Keyword(s):  
Growth Rate ◽  
Corrosion Rate ◽  
Soil Properties ◽  
Growth Rates ◽  
Soil Conditions ◽  
Soil Parameters ◽  
Time Interval ◽  
Soil Redox Potential ◽  
Corrosion Rates ◽  
External Corrosion

External corrosion growth rate is an essential parameter to establish the time interval between successive pipe integrity evaluations. Actual corrosion rates are difficult to measure or predict. NACE Standard RP0502 [1] recommends several methods including comparison with historical data, buried coupons, electrical resistance (ER), and Linear Polarization Resistance (LPR) measurements. This paper presents a testing program and procedure to validate the use of the LPR and ER methods to enhance the estimation of corrosion growth rates and improve the selection of reassessment intervals of gas transmission pipelines. Laboratory and field tests were performed using the LPR and ER technologies. The evaluation of soil parameters that affect localized corrosion included its type, moisture content, pH, resistivity, drainage characteristics, chloride and sulfite levels, and soil Redox potential. The results show that the LPR device provides instantaneous measurement of corrosion potential and it may be used to reflect the variations of corrosion rates with the changes of soil conditions, moisture, and temperature. However, LPR measurements are more efficient in saturated soils with uncertainty about its validity in partially and totally dry soils. Consequently, seasonal changes in soil conditions make it difficult to estimate total corrosion growth rate. On the other hand, the measurements using the ER method provided consistent estimates for long-term corrosion growth rates. Corrosion growth rates were also evaluated from a previous study by the National Institute of Standards (NIST) [2]. A procedure was developed to correlate soil properties to corrosion rates from the ER measurements and NIST data. The procedure was implemented in a computer program to provide an estimate of corrosion rate based on the soil input data and allows the operator to use the ER probes to improve the reliability of corrosion rate estimates.

Predicting Corrosion Rates for Onshore Oil and Gas Pipelines

2006 ◽  
Author(s):  
J. M. Race ◽  
S. J. Dawson ◽  
L. Stanley ◽  
S. Kariyawasam
Keyword(s):  
Corrosion Rate ◽  
Growth Rates ◽  
Oil And Gas ◽  
Cost Effective ◽  
Management Plan ◽  
Assessment Method ◽  
Internal Corrosion ◽  
Corrosion Rates ◽  
External Corrosion ◽  
Comparison Of The Results

One of the requirements of a comprehensive pipeline Integrity Management Plan (IMP) is the establishment of safe and cost effective re-assessment intervals for the chosen assessment method, either Direct Assessment (DA), In-Line Inspection (ILI) or hydrotesting. For pipelines where the major threat is external or internal corrosion, the determination of an appropriate re-inspection interval requires the estimation of realistic corrosion growth rates. The Office of Pipeline Safety (OPS 2005) estimate that the ability to accurately estimate corrosion rates may save pipeline companies more than $100M/year through reduced maintenance and accident avoidance costs. Unlike internal corrosion, which occurs in a closed system, the rate of the external corrosion reaction is influenced by a number of factors including the water content of the soil, the soluble salts present, the pH of the corrosion environment and the degree of oxygenation. Therefore the prediction of external rates is complex and there is currently no method for estimating corrosion rates using either empirical or mechanistic equations. This paper describes a scoring model that has been developed to estimate external corrosion growth rates for pipelines where rates cannot be estimated using more conventional methods i.e., from repeat in-line inspection data. The model considers the effect of the different variables that contribute to external corrosion and ranks them according to their effect on corrosion growth rate to produce a corrosion rate score. The resulting score is then linked to a corrosion rate database to obtain an estimated corrosion rate. The methodology has been validated by linking the calculated corrosion rate scores to known corrosion rate distributions that have been measured by comparison of the results from multiple in-line inspection runs. The paper goes on to illustrate how the estimated corrosion rates can be used for the establishment of reassessment intervals for DA, ILI and hydrotesting, comparing the benefits of this approach with current industry recommended practice and guidance.

Effects of Inline Inspection Sizing Uncertainties on the Accuracy of the Largest Features and Corrosion Rate Statistics

2010 ◽  
Author(s):  
Luc Huyse ◽  
Albert van Roodselaar
Keyword(s):  
Corrosion Rate ◽  
Time Interval ◽  
Corrosion Rates ◽  
Course Of Action ◽  
Distribution Parameters ◽  
Statistical Analysis Method ◽  
The Difference ◽  
External Corrosion ◽  
The Cost ◽  
Subsea Pipelines

With the increased acceptance of the use of probabilistic fitness-for-service methods, considerable effort has been dedicated to the estimation of the corrosion rate distribution parameters. The corrosion rate is typically computed from the difference in anomaly size over a specific time interval. The anomaly sizes are measured through either in-line inspection or direct assessment. Sizing accuracies for inline inspection methods are reasonably well established and in many cases the sizing uncertainty is non-negligible. In many approaches that are proposed in the literature the time-averaged corrosion rates are computed without explicitly considering the effect of the sizing uncertainties and as a result considerable interpretation and engineering judgment is required when estimating corrosion rates. This paper highlights some of the effects of the sizing uncertainties and the resulting biases that occur in the subsequent reliability calculations. These assessments are used to determine the most appropriate course of action: repair, replacement, or time of next inspection. The cost for repair or replacement of subsea pipelines is much higher than for onshore pipelines. For subsea applications, it is therefore paramount that the risk calculations, and therefore the corrosion rate estimates, be as accurate as possible. In subsea applications, the opportunity to repair individual defects is often limited due to practical constraints and there is merit in an approach that focuses on entire spools or pipeline segments. The proposed statistical analysis method is ideally suited to this application although the principles behind the analysis apply equally well to onshore lines subject to either internal or external corrosion threats.

Centennial-scale climate variability inferred from Las Gloces cave in Central Pyrenees: evidences of rapid changes during last glacial cycle

2021 ◽  
Author(s):  
Ana Moreno ◽  
Miguel Bartolomé ◽  
Carlos Sancho ◽  
Eneko Iriarte ◽  
Ánchel Belmonte ◽  
...  
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Time Interval ◽  
Glacial Period ◽  
Last Deglaciation ◽  
Glacial Cycle ◽  
Last Glacial Period ◽  
The Holocene ◽  
Last Glacial ◽  
Central Pyrenees

<p>Paleoclimate records from the Pyrenees covering last glacial period are scarce since many lakes were covered by the glaciers, glacier deposits just provide discontinuous information and in very few caves we can find speleothem growth during that cold and generally dry time period. Las Gloces cave, located close to Ordesa and Monte Perdido National Park (Central Pyrenees, Iberian Peninsula) at 1240 m a.s.l., is one the few examples to study that time interval. Thus, for the first time, we present a speleothem in the Pyrenees that was growing during the Maximum Ice Extent in the last glacial period in a cave located just 3 km away from the glacier. Two speleothems from las Gloces were sampled, one covering the Holocene and last deglaciation (last 16.6 ka) and the other one growing from MIS4 (67.8 ka) to Mid-Holocene (4.7 ka), with two hiatuses at 50-47 ky and 30-21 ka coinciding with cold/dry periods. Both stalagmites were dated and analyzed for stable i sotopes and trace elements.</p><p> </p><p>During MIS4, the lowest growth-rates correspond with Heinrich Stadial (HS) 6 while there is an increase in growth rate during MIS3 onset, reaching the maximum at Greenland Interstadial (GI)-14. After this, and corresponding with HS5, the growing stopped and it will reactivate again during GI-12, but with low growth rates. A new interruption took place 30 ka ago, with a second hiatus (30-21 ka), corresponding with an important retreat of Central Pyrenees glaciers and maximum regional aridity. During last glacial period, δ<sup>13</sup>C and δ<sup>18</sup>O records vary with rather small amplitude of change (4 ‰ and only 1‰, respectively) and showing low correlation between them indicating they were likely affected by different influences. At 21 ka BP, there is a new speleothem growth that will be characterized by the heaviest δ<sup>13</sup>C and δ<sup>18</sup>O values in the record (0‰ and -7‰, respectively) that occurred during the global LGM period.</p><p> </p><p>Changes in the growth rate in those stalagmites could be related to precipitation oscillations during GS-GI cycles while the variation in δ<sup>13</sup>C could respond with changes in the temperature and rainfall on a glacial landscape with reduced vegetation cover. Differences in mean values of δ<sup>13</sup>C between MIS3 (-5‰) and Holocene (-9‰) represent a forest revegetation over the cave related with the climatic amelioration experienced during last deglaciation due to the increase in temperature and humidity. Drivers on δ<sup>18</sup>O change during MIS 3 are multiple and more complex but they may correspond to changes in amount of rainfall, temperature or moisture source. The drastic change in d<sup>18</sup>O during last deglaciation (from -10‰ at HS1 to -7 ‰ at the onset of the Holocene) could be additionally related to the well-known isotopic change of sea surface water due to the massive entrance of freshwater into the north Atlantic region.</p>

scholarly journals Changes in Grassland Chemical Soil Parameters Four Years after Cessation of Different Fertilisation with Compost and Slurry

2018 ◽  
Vol 66 (1) ◽  
pp. 211-218
Author(s):  
Marie Štýbnarová ◽  
Oldřich Látal ◽  
Jan Hladký ◽  
Monika Hradilová ◽  
Jiří Skládanka ◽  
...  
Keyword(s):  
Soil Properties ◽  
Positive Influence ◽  
Point Of View ◽  
Soil Conditions ◽  
Soil Parameters ◽  
Chemical Soil ◽  
Organic Fertilisers ◽  
Small Plot ◽  
Stocking Rates

The aim of this study was to evaluate changes in chemical soil properties of permanent grasslands after the cessation of their regular utilisation and organic fertilisation. A long‑term small plot trial was established in 2004 in locality Rapotín. During 2004 – 2012 the experiment was fertilised with compost and slurry, both with the range of stocking rates 0.9, 1.4, and 2.0 livestock units (LU).ha−1 (corresponding to 54, 84, and 120 kg N.ha−1). It was further observed the unfertilised grassland as control. The plots were cut 2 – 4 times per year depending on given dose of fertiliser. During 2013 –2016 the regular management was ceased and the grasslands were completely abandoned. It was found statistically significant influence of the year and the type of fertiliser almost for all evaluated parameters. The dose of nitrogen was not significant. On the basis of our results we can conclude, that the both types of the organic fertilisers had a positive influence on the chemical soil properties, however, the compost manifested itself as the better fertiliser than the slurry from this point of view. In 2016, four years after the last application of the organic fertilisers, there were found the better chemical soil conditions in the treatments previously fertilised with compost.

FOLLICLE KINETICS IN THE OVARY OF THE CYCLIC MOUSE

1970 ◽  
Vol 64 (2) ◽  
pp. 304-323 ◽  
Author(s):  
Torben Pedersen
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Tritiated Thymidine ◽  
Ovarian Follicle ◽  
Medium Size ◽  
Time Interval ◽  
Pulse Labelling ◽  
Full Development ◽  
Time Required ◽  
Doubling Times

ABSTRACT The variations in size, numbers and growth rates of mouse ovarian follicles were investigated at different stages of the oestrous cycle. Autoradiographs were prepared of sections of ovaries after pulse-labelling with tritiated thymidine. By determining the growth rate of the granulosa cells expressed as their doubling times, it was possible to estimate the exact growth rates of whole follicles. The number of follicles which began developing during a particular time interval was also determined. The results show that the number of large follicles fluctuates with the cycle, and that the size of the largest follicles increases during the cycle. Follicles of medium size grow faster at oestrus that at any other time. This is in contrast to the large follicles, in which only minor variations in growth rate were noted. It was moreover shown, that more follicles begin to grow at oestrus than at other periods during the cycle. It was concluded, that the reduction in the number of small follicles with age is mainly due to follicle development rather than to the degeneration of small follicles. The time required for the full development of an ovarian follicle is 19 days.

Structural Reliability of Free Spanning Pipelines

2014 ◽  
Author(s):  
F. Van den Abeele ◽  
F. Boël ◽  
J.-F. Vanden Berghe
Keyword(s):  
Soil Properties ◽  
Fatigue Damage ◽  
Structural Reliability ◽  
Flow Direction ◽  
Unit Weight ◽  
Soil Conditions ◽  
Soil Parameters ◽  
Span Length ◽  
Form Analysis ◽  
Reliability Method

When installing subsea pipelines on an uneven seabed, the free spans can be vulnerable to fatigue damage caused by vortex induced vibrations (VIV). Indeed, even moderate currents can induce vortex shedding, alternately at the top and the bottom of the pipeline, at a rate determined by the flow velocity. Each time a vortex sheds, a force is generated in both the in-line and cross-flow direction, causing an oscillatory multi-mode vibration. This vortex induced vibration can give rise to fatigue damage of submarine pipeline spans, especially in the vicinity of the girth welds. Traditional design for VIV is recommended in DNV-RP-F105, which limits the allowable free span length and implies whether (and when) seabed interventions are required. The traditional DNV-RP-F105 design method is based on a semi-empirical approach, where the allowable span length depends on the pipe properties (diameter, wall thickness, coating, steel SN_curves, …), the sea state (current velocity, wave induced velocity and period) and the soil conditions (submerged unit weight, undrained shear strength, bearing capacity,…). All these input parameters, however, exhibit a certain extent of scatter and uncertainty. This paper presents a risk based evaluation of free spans, by applying the principles of structural reliability theory to the problem of long free spanning pipelines subjected to VIV. First, a fully deterministic on-bottom roughness analysis is performed to introduce numerical tools for free span analysis. Then, a sensitivity analysis on soil parameters is presented to show significant influence of soil properties on free span predictions. To study the implications of uncertainty in soil properties, a First Order Reliability Method (FORM) analysis is presented at the end of this paper, where the soil properties are introduced as stochastic variables.

Growth Rates of Intertidal Molluscs as Indicators of Effects of Unexpected Incidents of Pollution

1973 ◽  
Vol 30 (9) ◽  
pp. 1385-1388 ◽  
Author(s):  
Robert Black
Keyword(s):  
Growth Rate ◽  
Mytilus Edulis ◽  
Growth Rates ◽  
Littorina Littorea ◽  
Time Interval ◽  
Elemental Phosphorus ◽  
Phosphorus Pollution ◽  
Nonlethal Effects

Shells of living molluscs contain a record of previous growth rate if the time interval between check marks is known. The check marks in Mytilus edulis and Littorina littorea are probably annual marks. Growth rates of Mytilus in 1969, the year of significant elemental phosphorus pollution at Long Harbour, Newfoundland, were no different from those in preceding or succeeding years. No Littorina alive in 1969 occurred at Long Harbour, but they were abundant at other locations. This sort of analysis, used with caution because effects of pollutants may be confounded with effects of other variables, provides a method of examining nonlethal effects of unexpected polluting events.

Non-Gaussian behavior of the internet topological fluctuations

2014 ◽  
Vol 25 (05) ◽  
pp. 1440012 ◽  
Author(s):  
Qu Chen ◽  
Jiang-Hai Qian ◽  
Ding-Ding Han
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
The Internet ◽  
Time Interval ◽  
Scaling Relation ◽  
Power Law Decay ◽  
Exponential Decrease ◽  
Non Gaussian ◽  
Growth Rate Distribution ◽  
Topological Fluctuations

The traditional Gibrat's hypotheses were once used to model the topological fluctuations of Internet. Although it seems to reproduce the scaling relation of Internet's degree distribution, the detailed micro-dynamics have never been empirically validated. Here, we analyze the distribution of degree growth rates of the Internet for various time scales. We find that in contrast to the traditional Gibrat's assumptions, none of the degree growth rates are normally distributed, but behaves as an exponential decrease on its body and a power-law decay on its tail. Moreover, the observed growth rate distribution turns out independent of the initial degree when the time interval enlarges to a year. Our observations do not consist with the traditional Gibrat law model and suggest a more complex fluctuation mechanism underlying the evolution of Internet.

scholarly journals Influence of soil properties on the heartwood colour of Juglans mandshurica var. sachalinensis in a cool temperate forest

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Kobayashi Makoto ◽  
Elizaveta Susloparova ◽  
Ikutaro Tsuyama ◽  
Takuya Shimase ◽  
Satoshi Nakaba ◽  
...  
Keyword(s):  
Soil Properties ◽  
Intraspecific Variation ◽  
Temperate Forest ◽  
Temperate Forests ◽  
Local Scale ◽  
Soil Conditions ◽  
Soil Parameters ◽  
Juglans Mandshurica ◽  
Cool Temperate ◽  
Cool Temperate Forest

AbstractHeartwood colour is often an important factor in determining timber prices. However, the determinants of intraspecific variation in heartwood colour, which is useful information for sustainable wood marketing, are little understood, especially at the local scale in cool temperate forests. Because heartwood is produced as a secondary compound and photosynthesis is regulated by nitrogen (N) in cool temperate forests, we hypothesized that (1) soil conditions determine heartwood colour even at a local scale within a tree species and (2) N, specifically, can be an important driver of the intraspecific variation in heartwood colour in the trees of cool temperate forests. To test these hypotheses, we investigated the relationship between the colour values (luminescence, redness, and yellowness) of heartwood from Juglans mandshurica var. sachalinensis and the soil parameters in a cool temperate forest. Among the soil properties, not soil N but soil magnesium (Mg) contents alone had a significant influence on the redness and yellowness of the heartwood. Higher soil Mg contents resulted in increased redness and yellowness of the heartwood in our study, probably due to the increase in phenolics and the colouring of the tannins in the heartwood with Mg. Our results indicate that even at a local scale, soil condition can determine the intraspecific variation in heartwood colour and that forest managers can utilize edaphic information to predict heartwood colour for timber marketing.

DECAY/GROWTH RATE ESTIMATION USING INSTANTANEOUS LYAPUNOV EXPONENT

2012 ◽  
Vol 22 (03) ◽  
pp. 1250047
Author(s):  
YUSUKE TOTOKI ◽  
TAKAMI MATSUO
Keyword(s):  
Growth Rate ◽  
Lyapunov Exponent ◽  
Nonlinear Systems ◽  
Growth Rates ◽  
Jacobian Matrix ◽  
Time Interval ◽  
Comparison Function ◽  
Infinite Time ◽  
Infinite Time Interval ◽  
The Mean

The Lyapunov exponent gives a measure of the mean decay/growth rates of the flows of nonlinear systems. However, the Lyapunov exponent needs an infinite time interval of flows and the Jacobian matrix of system dynamics. In this paper, we propose an instantaneous decay/growth rate that is a kind of generalized Lyapunov exponent and call the instantaneous Lyapunov exponent (ILE) with respect to a decay function. The instantaneous Lyapunov exponent is one of the measures that estimate the decay and growth rates of flows of nonlinear systems by assigning a comparison function and can apply a stable system whose decay rate is slower than an exponential function. Moreover, we propose a synchronization measure of two signals using the ILE.

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