CN108920421A - A kind of spot corrosion acts on the random failure probability evaluation method of failure of lower oil-gas pipeline system - Google Patents
A kind of spot corrosion acts on the random failure probability evaluation method of failure of lower oil-gas pipeline system Download PDFInfo
- Publication number
- CN108920421A CN108920421A CN201810620963.XA CN201810620963A CN108920421A CN 108920421 A CN108920421 A CN 108920421A CN 201810620963 A CN201810620963 A CN 201810620963A CN 108920421 A CN108920421 A CN 108920421A
- Authority
- CN
- China
- Prior art keywords
- oil
- gas pipeline
- corrosion
- random
- pipeline system
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000005260 corrosion Methods 0.000 title claims abstract description 131
- 230000007797 corrosion Effects 0.000 title claims abstract description 130
- 238000011156 evaluation Methods 0.000 title claims abstract description 20
- 238000000034 method Methods 0.000 claims abstract description 27
- 238000004458 analytical method Methods 0.000 claims abstract description 10
- 238000012544 monitoring process Methods 0.000 claims description 7
- 230000007547 defect Effects 0.000 claims description 6
- 238000005315 distribution function Methods 0.000 claims description 4
- 235000007164 Oryza sativa Nutrition 0.000 claims description 3
- 239000012530 fluid Substances 0.000 claims description 3
- 235000009566 rice Nutrition 0.000 claims description 3
- 240000007594 Oryza sativa Species 0.000 claims 1
- 238000004364 calculation method Methods 0.000 claims 1
- 230000000694 effects Effects 0.000 abstract description 8
- 239000007789 gas Substances 0.000 description 90
- 238000004088 simulation Methods 0.000 description 5
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- 230000007613 environmental effect Effects 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 241000209094 Oryza Species 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 239000003345 natural gas Substances 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 238000000342 Monte Carlo simulation Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005587 bubbling Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000012854 evaluation process Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 230000001568 sexual effect Effects 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
- G06F17/10—Complex mathematical operations
- G06F17/15—Correlation function computation including computation of convolution operations
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Mathematical Physics (AREA)
- Computational Mathematics (AREA)
- Theoretical Computer Science (AREA)
- Mathematical Analysis (AREA)
- Mathematical Optimization (AREA)
- Pure & Applied Mathematics (AREA)
- Data Mining & Analysis (AREA)
- Algebra (AREA)
- Databases & Information Systems (AREA)
- Software Systems (AREA)
- General Engineering & Computer Science (AREA)
- Computing Systems (AREA)
- Testing Resistance To Weather, Investigating Materials By Mechanical Methods (AREA)
Abstract
The invention discloses the random failure probability evaluation method of failure that a kind of spot corrosion acts on lower oil-gas pipeline system, include the following steps：1) in moment t, the corrosion depth and corrosion length of hot spot are measured；2) residual intensity of oil-gas pipeline corrosion point in moment t is calculated；3) oil-gas pipeline corrosion point random residual intensity is calculated；4) mean function and auto-covariance function of oil-gas pipeline corrosion point random residual intensity Z (t) are calculated；5) according to step 4) calculate random residual intensity Z andCross covariance function；6) based on the failure probability for passing through probability theory for the first time and calculating oil-gas pipeline system in Analysis of structural reliability；7) the random failure probability of the single hot spot of t moment is calculated；8) the random failure probability P of the oil-gas pipeline system under moment t time point corrosiveness is calculatedf,s(t), this method is capable of the random failure probability of the lower oil-gas pipeline system of accurate evaluation spot corrosion effect.
Description
Technical Field
The invention belongs to the technical field of oil and gas pipeline transportation, and relates to a random failure probability evaluation method of an oil and gas pipeline system under the action of pitting corrosion.
Background
After the reform is opened, Chinese oil and gas pipeline enterprises also enter the stage of the reform development, a large number of foreign oil and gas pipeline related advanced technologies are introduced, and the foreign advanced management experience is actively learned, so that the overall level of the construction of the oil and gas pipelines in China is obviously improved. The typical example is the West-east gas transmission project, the total length is about 4000 kilometers, and the West-east gas transmission project is the first world-level natural gas pipeline project independently designed and built in China. To date, China has formed a basic pipeline network traversing east-west and longitudinal north and south, and has very important significance for ensuring stable transportation of oil and gas fields, meeting the requirements of industrial production and people life on oil and gas energy, and ensuring sustainable, stable and balanced development of social economy.
In the process of onshore oil and gas pipeline transportation, the geological disasters of the onshore oil and gas pipeline transportation are various in types and complex in environmental conditions, and the corrosion defect can cause that the pipe wall can not bear the working pressure finally and the pipeline fails along with the increase of the operation time, so that the research on the corrosion failure of onshore oil and gas pipelines is carried out, the prediction capability of pipeline failure accidents is improved, and the safe operation and stable supply of the pipeline are ensured. The corrosion is the most common and important factor causing the failure of oil and gas pipelines, and the material of any pipeline can be corroded and damaged in different degrees under the influence of external environmental factors, generally, the corrosion phenomenon becomes more and more serious along with the time, and finally, the pipeline can be completely failed. The oil and gas pipeline mainly faces two corrosive environments, namely an external corrosive environment in which the pipeline penetrates through soil and H in a conveying medium2S、CO2And the like, and the internal corrosive environment is formed by harmful substances. Pipeline accidents 10798 occurred in 1992 and 2012 in the United states, with the accidents caused by corrosion accounting for 18.5%; corrosion leakage accidents account for more than half of all pipeline accidents occurring in 2000 + 2012 of canada. The corrosion problem of oil and gas pipelines in China is also prominent, and domestic scholars find that 39.5 percent of accidents are caused by pipeline corrosion through statistics of natural gas pipeline accidents in Sichuan province; in a particularly serious accident of leakage and explosion of Donghuang oil pipelines in Qingdao in 2013, investigation shows that corrosion is one of important reasons for perforation and leakage of the pipelines.
The damage caused by corrosion to pipelines is classified into three major categories, bulk damage (localized corrosion), dispersion damage (pitting corrosion and hydrogen bubbling), and crack damage (stress corrosion cracking and corrosion fatigue). At present, the crack type damage of a corrosion pipeline is evaluated by utilizing a failure evaluation graph technology mainly based on an elasto-plastic fracture mechanical analysis method; aiming at the volume type damage of the corroded pipeline, the local corrosion defect of the pipeline is evaluated by adopting evaluation criteria and methods such as DNV-RP-F101 and the like internationally; at present, a plurality of methods for evaluating the dispersive damage of the corroded pipeline at home and abroad are available, and the most representative methods comprise: an APl579 criterion, an ASME B31G criterion and the like, but because the evaluation process is too complex and difficult to apply in engineering, the evaluation method is generally evaluated by a volumetric corrosion damage evaluation method in the actual process, the methods usually evaluate the corrosion condition of the pipeline based on uniform corrosion rate, theoretical support is provided for the integrity evaluation of the corrosion pipeline, but the influence of the environmental change on the corrosion condition of the pipeline should be considered in the actual process, so an evaluation method needs to be constructed, and the random failure probability of the oil and gas pipeline system under the action of pitting corrosion can be evaluated by the method to evaluate the corrosion damage condition of the oil and gas pipeline.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a random failure probability evaluation method of an oil and gas pipeline system under the action of pitting corrosion, and the method can accurately evaluate the random failure probability of the oil and gas pipeline system under the action of pitting corrosion.
In order to achieve the purpose, the random failure probability evaluation method of the oil and gas pipeline system under the pitting corrosion effect comprises the following steps:
1) acquiring relevant parameters of the oil and gas pipeline system and relevant parameters of each corrosion monitoring point, wherein the relevant parameters of the oil and gas pipeline system comprise the external diameter D, the wall thickness b and the system operating pressure P of the oil and gas pipeline0And yield strength sigmayThe relevant parameters of the corrosion monitoring points comprise the depth h of the corrosion points0Length k of0Depth direction corrosion rate v1And the longitudinal corrosion rate v2；
2) At time t, the depth of corrosion h (t) ═ h of the corrosion site is measured0+v1t and etch length k (t) k0+v2t；
3) Calculating the residual strength of the corrosion point of the oil and gas pipeline at the moment t
4) Considering the randomness of the corrosion point residual strength of the oil and gas pipeline, a random variable β is introduced, and the corrosion point random residual strength Z (t) of the oil and gas pipeline is Z1(t)×β；
5) Calculating the mean function mu of the random residual intensity Z (t) of the corrosion point of the oil and gas pipelineZ(t)＝E[Z(t)]＝Z1(t)×E[β]＝Z1(t) and the autocovariance function CZZ(ti,tj)＝λ2ρ2Z1(ti)Z1(tj) Where λ is the coefficient of variation, ρ, of the random variable β2Is Z (t) at different time points t during the random variationiAnd tjThe correlation coefficient of (a);
6) calculating the random residual intensity Z andcross covariance function of
Wherein,andis a random variable Z andmean and standard deviation of (1), p1Is a random variable Z andthe correlation coefficient of (a);
7) according to the theory of Gaussian random process, the method comprises the following steps of 6):
8) failure probability of oil-gas pipeline system is calculated based on first-time crossing probability theory in structural reliability analysisWherein, Pf(0) For the failure rate of the oil and gas pipeline system at time t-0, v is the rate of upward flow, which is determined by rice criteria, i.e.At time t is P0The slope of the change of (a) is,is the time derivative of Z (t) in the random process, phi and phi are respectively a standard normal density function and a standard normal distribution function;
9) the failure probability P of the oil and gas pipeline system under the action of point corrosion is set as 0 at the moment tf(0) 0, constant P0Change slope ofRandom probability of failure of a single corrosion site at time t
10) Calculating the random failure probability P of the oil-gas pipeline system under the corrosion action of the time point at the moment tf,s(t) wherein,Pf,s(t) is the probability that the ith corrosion point on the oil and gas pipeline causes the random failure of the system at the moment t, and n is the number of the corrosion points on the oil and gas pipeline.
The specific operation of the step 3) is as follows:
31) calculating the residual strength of the corrosion point of the oil and gas pipelineWherein σfIs the fluid stress in the oil and gas pipeline, A is the projection area of the local corrosion defect in the longitudinal axis direction of the oil and gas pipeline, A0The projection area of the original longitudinal axis direction before the pipeline is corroded, and M is the bulging coefficient before the corroded pipeline fails, wherein A is h multiplied by k, A0＝b×k，σf＝1.15σyResidual strength of corrosion point of oil and gas pipeline
32) The residual strength of the corrosion point of the oil and gas pipeline at the moment t
The specific operation of calculating the failure probability of the oil and gas pipeline system in the step 8) is as follows:
81) at time t, the random residual intensity Z (t) of the corrosion point of the oil and gas pipeline is reduced to the operating pressure P for normal operation of the oil and gas pipeline system0When the oil and gas pipeline system is in failure state, the failure probability P of the oil and gas pipeline system is determinedf(t)＝P[H≤0]＝P[Z(t)≤P0]；
82) According to the structure canBy first-pass probability theory in sexual analysis, failure probability of oil and gas pipeline system can be converted intoWherein, Pf(0) The fault rate of the oil and gas pipeline system is when the time t is equal to 0, and v is the upward passing rate;
83) because the average value of the upward-flowing speed v is small, the failure probability of the oil-gas pipeline system can be expressed as
In the step 2), the corrosion depth h (t) h of the corrosion point is measured by adopting a linear model0+v1t and etch length k (t) k0+v2t。
The invention has the following beneficial effects:
in the method for evaluating the random failure probability of the oil and gas pipeline system under the pitting corrosion effect, a failure probability model is not established singly according to the failure criteria of the traditional oil and gas pipeline system, but on the basis of the failure probability model, the failure probability model is reconstructed by utilizing a first-time traversing probability theory in reliability analysis so as to improve the real reliability of an evaluation result, specifically, a random variable β is introduced by considering the randomness of the residual strength of the corrosion points of the oil and gas pipeline so as to calculate the random residual strength of the corrosion points of the oil and gas pipeline and enable the evaluation result to be more consistent with the actual situation, then the random failure probability of a single corrosion point at the time t is calculated based on the first-time traversing probability theory in structural reliability analysis, the random failure probability of the oil and gas pipeline system under the pitting corrosion effect at the time t is calculated according to the random failure probability of the single corrosion point at the time t, the failure time of the pipeline is evaluated quantitatively, theoretical support is provided for mastering the actual corrosion progress of the pipeline, and a reasonable.
Drawings
FIG. 1 is a schematic view of a pipe pitting corrosion;
FIG. 2 is a flow chart of the present invention;
FIG. 3 is a graph of system failure probability curves obtained by different methods;
fig. 4 different correlation coefficients p2Influence graph to system failure probability;
FIG. 5 different operating pressures P0Influence graph to system failure probability;
FIG. 6 different etch rates v1And v2Influence graph to system failure probability;
FIG. 7 is a graph of the effect of different pipe sizes D and b on the probability of system failure;
FIG. 8 different yield strengths σyInfluence graph on system failure probability.
Detailed Description
The invention is described in further detail below with reference to the accompanying drawings:
referring to fig. 1 and 2, the random failure probability evaluation method of the oil and gas pipeline system under the pitting corrosion effect includes the following steps:
1) acquiring relevant parameters of the oil and gas pipeline system and relevant parameters of each corrosion monitoring point, wherein the relevant parameters of the oil and gas pipeline system comprise the external diameter D, the wall thickness b and the system operating pressure P of the oil and gas pipeline0And yield strength sigmayThe relevant parameters of the corrosion monitoring points comprise the depth h of the corrosion points0Length k of0Depth direction corrosion rate v1And the longitudinal corrosion rate v2；
2) At time t, the depth of corrosion h (t) ═ h of the corrosion site is measured0+v1t and etch length k (t) k0+v2t；
3) Calculating the residual strength of the corrosion point of the oil and gas pipeline at the moment t
4) Considering the randomness of the corrosion point residual strength of the oil and gas pipeline, a random variable β is introduced, and the corrosion point random residual strength Z (t) of the oil and gas pipeline is Z1(t)×β；
5) Calculating the mean function mu of the random residual intensity Z (t) of the corrosion point of the oil and gas pipelineZ(t)＝E[Z(t)]＝Z1(t)×E[β]＝Z1(t) and the autocovariance function CZZ(ti,tj)＝λ2ρ2Z1(ti)Z1(tj) Where λ is the coefficient of variation, ρ, of the random variable β2Is Z (t) at different time points t during the random variationiAnd tjThe correlation coefficient of (a);
6) calculating the random residual intensity Z andcross covariance function of
Wherein,andis a random variable Z andmean and standard deviation of (1), p1Is a random variable Z andthe correlation coefficient of (a);
7) according to the theory of Gaussian random process, the method comprises the following steps of 6):
8) failure probability of oil-gas pipeline system is calculated based on first-time crossing probability theory in structural reliability analysisWherein, Pf(0) For the failure rate of the oil and gas pipeline system at time t-0, v is the rate of upward flow, which is determined by rice criteria, i.e.At time t is P0The slope of the change of (a) is,is the time derivative of Z (t) in the random process, phi and phi are respectively a standard normal density function and a standard normal distribution function;
9) the failure probability P of the oil and gas pipeline system under the action of point corrosion is set as 0 at the moment tf(0) 0, constant P0Change slope ofRandom probability of failure of a single corrosion site at time t
10) Calculating the random failure probability P of the oil-gas pipeline system under the corrosion action of the time point at the moment tf,s(t) wherein,Pf,s(t) is the probability that the ith corrosion point on the oil and gas pipeline causes the random failure of the system at the moment t, and n is the number of the corrosion points on the oil and gas pipeline.
The specific operation of the step 3) is as follows:
31) calculating the residual strength of the corrosion point of the oil and gas pipelineWherein σfIs the fluid stress in the oil and gas pipeline, A is the projection area of the local corrosion defect in the longitudinal axis direction of the oil and gas pipeline, A0The projection area of the original longitudinal axis direction before the pipeline is corroded, and M is the bulging coefficient before the corroded pipeline fails, wherein A is h multiplied by k, A0＝b×k，σf＝1.15σyResidual strength of corrosion point of oil and gas pipeline
32) The residual strength of the corrosion point of the oil and gas pipeline at the moment t
The specific operation of calculating the failure probability of the oil and gas pipeline system in the step 8) is as follows:
81) at time t, the random residual intensity Z (t) of the corrosion point of the oil and gas pipeline is reduced to the operating pressure P for normal operation of the oil and gas pipeline system0When the oil and gas pipeline system is in failure state, the failure probability P of the oil and gas pipeline system is determinedf(t)＝P[H≤0]＝P[Z(t)≤P0]；
82) According to the first-time crossing probability theory in the structural reliability analysis, the failure probability of the oil-gas pipeline system can be converted intoWherein, Pf(0) The fault rate of the oil and gas pipeline system is when the time t is equal to 0, and v is the upward passing rate;
83) because the average value of the upward-flowing speed v is small, the failure probability of the oil-gas pipeline system can be expressed as
In the step 2), the corrosion depth h (t) h of the corrosion point is measured by adopting a linear model0+v1t and etch length k (t) k0+v2t。
In fig. 3, the specific steps of calculating the failure probability of the pitting corrosion oil and gas pipeline by using the Monte Carlo simulation method are as follows:
1a) state function W ═ Z (t) -P for constructing pitting corrosion pipeline0Wherein P is0For the operating pressure at which the pipe system is operating normally,h0、k0、σy、v1、v2b and D are basic random variables;
2a) determining k0、σy、v1Probability density function f (x) of random variables such as b and Di) And a probability distribution function F (x)i)；
3a) For each random variable, generating a plurality of uniformly distributed random numbers between [0,1]
Wherein i represents the number of variables, i is 1,2, …, N, j represents the number of simulations, j is 1,2, …, N;
4a) for a given F (x)ij) Can be represented by the formula in step 3a)Solve out corresponding xijSo for each variable xiEach time of simulation, a set of random numbers (x) can be obtained1j，x2j，x3j，…，xnj)；
5a) Substituting the random number obtained by each simulation into the state function in the step 1a) to calculate a W value, and counting the failure for 1 time when the W value is less than zero;
6a) repeating the steps 3a), 4a) and 5a) for N times of simulation, wherein the total failure rate is L times, and the failure probability P of the oil-gas pipeline system is determinedfL/N, where T is the operating time of the piping system.
Simulation experiment
A section of a finished petroleum pipeline with the grade X60 is selected as a research object, and specific data related to pipeline evaluation are collected and shown in the table 1.
TABLE 1
The oil and gas pipeline is inspected to be in good flatness and free of corrosion pits in an early stage, no leakage points are detected, the corrosion pits can be seen at individual positions along with the lapse of time, and the corrosion data of the monitoring points are shown in a table 2.
TABLE 2
As can be seen from fig. 3, the change curves of the system failure probability which are obtained by the two methods and increase with time are similar, and the smaller the system failure probability is, the more similar the change of the probability curve is, which indicates that the lower the acceptable risk of the system is, the more effective the invention is.
As can be seen from fig. 4, the system failure probability curves have similar trends under different correlation coefficient conditions, so that the correlation coefficient between time points with different fracture degrees has negligible influence on the failure of the oil and gas pipeline; in addition, according to random process theory and related research, the probability of occurrence of events is exaggerated on the assumption that no correlation exists among different time points, so that the deterioration of the point corrosion oil and gas pipeline is conservatively evaluated, and pipeline leakage accidents can be prevented in advance.
As can be seen from fig. 5, as the operating pressure of the system increases, the safe life of the oil and gas pipeline changes significantly, for example, when the acceptable failure probability of the system is 0.1, the operating pressure of the system changes from 4.95Mpa to 6.65Mpa, and the safe life of the oil and gas pipeline under the action of pitting corrosion changes from 32 years to 15 years, which can help the maintenance manager to clearly implement the time for pipeline maintenance under the acceptable operating pressure of the system.
As can be seen from FIG. 6, the corrosion rate is a key factor affecting the failure probability of the pipeline system, and the pitting corrosion on the oil and gas pipeline system is performed under the same acceptable evaluation criteria if the corrosion rate v is10.1 mm/year and v24.5 mm/year to v10.2 mm/year and v2When the service life of the system is 9 mm/year, the safe service life of the system is changed from 25 years to 12 years; if the corrosion rate is doubled, the safe life of the system is changed from 25 years to 38 years. Therefore, accurately measuring the corrosion rate of pitting corrosion pipelines is important for the reliability prediction of oil and gas pipeline systems.
As shown in fig. 7, under the same acceptable evaluation criteria, when the pipeline geometry is changed from DN600 to DN900, the safe life of the system is changed from 12 years to 22 years, which indicates that the thicker the pipeline wall of the large-diameter pipeline is, the lower the probability of the pipeline system failing when other parameters of the oil and gas pipeline system are kept constant.
As shown in fig. 8, the failure probability curves of the oil and gas pipeline system are similar under different yield strength conditions, and the smaller the failure probability of the system is, the more similar the probability curve changes are, which indicates that the lower the acceptable risk of the system is, the smaller the effect of the yield strength on the failure probability of the corrosive pipeline system is.
The matters not described in detail in the present specification belong to the prior art known to those skilled in the art, and the above embodiments are only for illustrating the present invention and not for limiting the present invention. Although the related embodiments of the present invention and the accompanying drawings are disclosed for illustrative purposes, those skilled in the art will appreciate that; various substitutions, changes, modifications and the like are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, all equivalent technical solutions also belong to the scope of the present invention, and the protection scope of the present invention should be defined by the claims, not limited to the disclosure of the best embodiment and the accompanying drawings.
Claims (4)
1. A random failure probability evaluation method of an oil and gas pipeline system under the action of pitting corrosion is characterized by comprising the following steps:
1) acquiring relevant parameters of the oil and gas pipeline system and relevant parameters of each corrosion monitoring point, wherein the relevant parameters of the oil and gas pipeline system comprise the external diameter D, the wall thickness b and the system operating pressure P of the oil and gas pipeline0And yield strength sigmayThe relevant parameters of the corrosion monitoring points comprise the depth h of the corrosion points0Length k of0Depth direction corrosion rate v1And the longitudinal corrosion ratev2；
2) At time t, the depth of corrosion h (t) ═ h of the corrosion site is measured0+v1t and etch length k (t) k0+v2t；
3) Calculating the residual strength of the corrosion point of the oil and gas pipeline at the moment t
4) Considering the randomness of the corrosion point residual strength of the oil and gas pipeline, a random variable β is introduced, and the corrosion point random residual strength Z (t) of the oil and gas pipeline is Z1(t)×β；
5) Calculating the mean function mu of the random residual intensity Z (t) of the corrosion point of the oil and gas pipelineZ(t)＝E[Z(t)]＝Z1(t)×E[β]＝Z1(t) and the autocovariance function CZZ(ti,tj)＝λ2ρ2Z1(ti)Z1(tj) Where λ is the coefficient of variation, ρ, of the random variable β2Is Z (t) at different time points t during the random variationiAnd tjThe correlation coefficient of (a);
6) calculating the sum of random residual intensities Z according to the calculation result of the step 5)Cross covariance function of
Wherein,andis a random variable Z andmean and standard deviation of (1), p1Is a random variable Z andthe correlation coefficient of (a);
7) according to the theory of Gaussian random process, the method comprises the following steps of 6):
8) failure probability of oil-gas pipeline system is calculated based on first-time crossing probability theory in structural reliability analysisWherein, Pf(0) For the failure rate of the oil and gas pipeline system at time t-0, v is the rate of upward flow, which is determined by rice criteria, i.e. At time t is P0The slope of the change of (a) is,is the time derivative of Z (t) in the random process, phi and phi are respectively a standard normal density function and a standard normal distribution function;
9) the failure probability P of the oil and gas pipeline system under the action of point corrosion is set as 0 at the moment tf(0) 0, constant P0Change slope ofRandom probability of failure of a single corrosion site at time t
10) Calculating the random failure probability P of the oil-gas pipeline system under the corrosion action of the time point at the moment tf,s(t) wherein,Pf,s(t) is the probability that the ith corrosion point on the oil and gas pipeline causes the random failure of the system at the moment t, and n is the number of the corrosion points on the oil and gas pipeline.
2. The method for assessing the random failure probability of an oil and gas pipeline system under the action of pitting corrosion according to claim 1, wherein the specific operations of step 3) are:
31) calculating the residual strength of the corrosion point of the oil and gas pipelineWherein σfIs the fluid stress in the oil and gas pipeline, A is the projection area of the local corrosion defect in the longitudinal axis direction of the oil and gas pipeline, A0The projection area of the original longitudinal axis direction before the pipeline is corroded, and M is the bulging coefficient before the corroded pipeline fails, wherein A is h multiplied by k, A0＝b×k，σf＝1.15σyResidual strength of corrosion point of oil and gas pipeline
32) The residual strength of the corrosion point of the oil and gas pipeline at the moment t
3. The method for evaluating the random failure probability of the oil and gas pipeline system under the pitting corrosion action according to claim 1, wherein the specific operation of calculating the failure probability of the oil and gas pipeline system in the step 8) is:
81) at time t, following of corrosion point of oil and gas pipelineThe residual intensity Z (t) of the machine is reduced to the operating pressure P for normal operation of the oil and gas pipeline system0When the oil and gas pipeline system is in failure state, the failure probability P of the oil and gas pipeline system is determinedf(t)＝P[H≤0]＝P[Z(t)≤P0]；
82) According to the first-time crossing probability theory in the structural reliability analysis, the failure probability of the oil-gas pipeline system can be converted intoWherein, Pf(0) The fault rate of the oil and gas pipeline system is when the time t is equal to 0, and v is the upward passing rate;
83) because the average value of the upward-flowing speed v is small, the failure probability of the oil-gas pipeline system can be expressed as
4. The method for estimating the probability of random failure of an oil and gas pipeline system under the action of pitting corrosion according to claim 1, wherein the linear model is used in the step 2) to measure the corrosion depth h (t) h of the pitting corrosion0+v1t and etch length k (t) k0+v2t。
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810620963.XA CN108920421A (en) | 2018-06-15 | 2018-06-15 | A kind of spot corrosion acts on the random failure probability evaluation method of failure of lower oil-gas pipeline system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810620963.XA CN108920421A (en) | 2018-06-15 | 2018-06-15 | A kind of spot corrosion acts on the random failure probability evaluation method of failure of lower oil-gas pipeline system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN108920421A true CN108920421A (en) | 2018-11-30 |
Family
ID=64420942
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810620963.XA Pending CN108920421A (en) | 2018-06-15 | 2018-06-15 | A kind of spot corrosion acts on the random failure probability evaluation method of failure of lower oil-gas pipeline system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108920421A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110263364A (en) * | 2019-05-05 | 2019-09-20 | 四川大学 | A kind of oil-gas pipeline corrosion defect residual intensity algorithm considering decaying time variation |
| CN112949190A (en) * | 2021-03-08 | 2021-06-11 | 西南石油大学 | Fuzzy random reliability assessment method for crack defect-containing pipeline based on R6-FAD and BP-MCS |
| CN113252547A (en) * | 2021-03-31 | 2021-08-13 | 中车青岛四方机车车辆股份有限公司 | Aluminum alloy corrosion fatigue risk grade evaluation method based on environmental threshold |
| CN113592252A (en) * | 2021-07-12 | 2021-11-02 | 武汉理工大学 | Port crude oil loading risk visualization deduction method in task mode |
| CN114528700A (en) * | 2022-01-26 | 2022-05-24 | 西安三维应力工程技术有限公司 | Method for determining residual strength of oil pipe containing corrosion pits |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013169241A1 (en) * | 2012-05-09 | 2013-11-14 | Bp Corporation North America Inc. | Predictive corrosion coupons from data mining |
| CN104807966A (en) * | 2015-04-30 | 2015-07-29 | 上海化学工业区公共管廊有限公司 | Residual intensity and residual life computing method for pipe gallery pipelines |
| CN104834783A (en) * | 2015-05-12 | 2015-08-12 | 江苏科技大学 | Parameterized construction method of numerical model of pit-corrosion-randomly-distributed cylindrical shell |
| CN105302946A (en) * | 2015-10-13 | 2016-02-03 | 中国石油天然气股份有限公司 | Method and device for determining reliability of corroded pipeline |
-
2018
- 2018-06-15 CN CN201810620963.XA patent/CN108920421A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013169241A1 (en) * | 2012-05-09 | 2013-11-14 | Bp Corporation North America Inc. | Predictive corrosion coupons from data mining |
| CN104807966A (en) * | 2015-04-30 | 2015-07-29 | 上海化学工业区公共管廊有限公司 | Residual intensity and residual life computing method for pipe gallery pipelines |
| CN104834783A (en) * | 2015-05-12 | 2015-08-12 | 江苏科技大学 | Parameterized construction method of numerical model of pit-corrosion-randomly-distributed cylindrical shell |
| CN105302946A (en) * | 2015-10-13 | 2016-02-03 | 中国石油天然气股份有限公司 | Method and device for determining reliability of corroded pipeline |
Non-Patent Citations (3)
| Title |
|---|
| CHUN QINGLI: "Failure assessment and safe life prediction of corroded oil and gas pipelines", 《JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING》 * |
| 邵剑文: "海底管道的健康监测系统与评估研究", 《万方数据库》 * |
| 骆正山 等: "Frechet分布的海底油气管道腐蚀预测", 《腐蚀与防护》 * |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110263364A (en) * | 2019-05-05 | 2019-09-20 | 四川大学 | A kind of oil-gas pipeline corrosion defect residual intensity algorithm considering decaying time variation |
| CN112949190A (en) * | 2021-03-08 | 2021-06-11 | 西南石油大学 | Fuzzy random reliability assessment method for crack defect-containing pipeline based on R6-FAD and BP-MCS |
| CN113252547A (en) * | 2021-03-31 | 2021-08-13 | 中车青岛四方机车车辆股份有限公司 | Aluminum alloy corrosion fatigue risk grade evaluation method based on environmental threshold |
| CN113592252A (en) * | 2021-07-12 | 2021-11-02 | 武汉理工大学 | Port crude oil loading risk visualization deduction method in task mode |
| CN113592252B (en) * | 2021-07-12 | 2023-08-08 | 武汉理工大学 | Port crude oil loading risk visual deduction method in task mode |
| CN114528700A (en) * | 2022-01-26 | 2022-05-24 | 西安三维应力工程技术有限公司 | Method for determining residual strength of oil pipe containing corrosion pits |
| CN114528700B (en) * | 2022-01-26 | 2024-04-09 | 西安三维应力工程技术有限公司 | Method for determining residual strength of oil pipe containing corrosion pit |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108920421A (en) | A kind of spot corrosion acts on the random failure probability evaluation method of failure of lower oil-gas pipeline system | |
| Li et al. | Predicting corrosion remaining life of underground pipelines with a mechanically-based probabilistic model | |
| Zhou | System reliability of corroding pipelines | |
| CN103455682B (en) | A method of prediction hp-ht well corrosion set pipe residue lifetime | |
| Zelmati et al. | Probabilistic analysis of corroded pipeline under localized corrosion defects based on the intelligent inspection tool | |
| Zelmati et al. | A probabilistic approach to estimate the remaining life and reliability of corroded pipelines | |
| Zhang et al. | Safety and reliability assessment of external corrosion defects assessment of buried pipelines—Soil interface: A mechanisms and FE study | |
| Otegui | Challenges to the integrity of old pipelines buried in stable ground | |
| CN113468757B (en) | Method for evaluating reliability of corroded natural gas pipeline based on fuzzy random theory | |
| Zhangabay et al. | Factors affecting extended avalanche destructions on long-distance gas pipe lines | |
| Jiang et al. | An integrated risk analysis model for corroded pipelines subjected to internal pressures: Considering the interacting effects | |
| Wang et al. | Multi-objective maintenance strategy for corroded pipelines considering the correlation of different failure modes | |
| Jiang et al. | A study on burst failure mechanism analysis and quantitative risk assessment of corroded pipelines with random pitting clusters | |
| CN112284897A (en) | Method for treating micro-vibration abrasion damage of heat transfer pipe of steam generator of nuclear power unit | |
| Li et al. | Reliability analysis of Lan Chengyu corroded pipeline with associated defects | |
| Lu et al. | Theory and machine learning modeling for burst pressure estimation of pipeline with multipoint corrosion | |
| Velázquez et al. | Probabilistic analysis of different methods used to compute the failure pressure of corroded steel pipelines | |
| Li et al. | [Retracted] Prediction of Chemical Corrosion Rate and Remaining Life of Buried Oil and Gas Pipelines in Changqing Gas Field | |
| Zhang et al. | Plausible profile (Psqr) corrosion assessment model: refinement, validation and operationalization | |
| Stepovaja et al. | Methods for precautionary management for environmental safety at energy facilities | |
| Kariyawasam et al. | A Data Driven Validation of a Defect Assessment Model and its Safe Implementation | |
| Lin et al. | Application of HMC‐SS Method in Pipeline Reliability Analysis and Residual Life Assessment | |
| Ren et al. | Numerical simulation and ANN prediction of crack problems within corrosion defects | |
| Yasseri et al. | Remaining useful life (RUL) of corroding pipelines | |
| Farahani et al. | Probabilistic corrosion growth models of buried steel pipelines using inspection and soil survey data |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20181130 |
|
| RJ01 | Rejection of invention patent application after publication |