CN109668820A - The outer corrosion risk comprehensive evaluation method of buried pipeline - Google Patents
The outer corrosion risk comprehensive evaluation method of buried pipeline Download PDFInfo
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- CN109668820A CN109668820A CN201910062116.0A CN201910062116A CN109668820A CN 109668820 A CN109668820 A CN 109668820A CN 201910062116 A CN201910062116 A CN 201910062116A CN 109668820 A CN109668820 A CN 109668820A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N17/00—Investigating resistance of materials to the weather, to corrosion, or to light
- G01N17/006—Investigating resistance of materials to the weather, to corrosion, or to light of metals
Abstract
The invention discloses corrosion risk comprehensive evaluation methods outside a kind of buried pipeline, it is the following steps are included: obtain outer corrosion basic parameter, judge buried pipeline erosion resistant coating with the presence or absence of leak source according to the leak detection of outer corrosion basic parameter erosion resistant coating, and if there is no leak source, then show that Buried Pipeline risk is low, if there is leak source, then judge whether buried pipeline uses cathodic protection according to outer corrosion basic parameter cathodic protection, and if not using cathodic protection, then according to DC influence, AC influence and soil corrosivity carry out the judge of corrosion risk, if using cathodic protection, then according to DC influence, AC influence and soil corrosivity carry out the judge of corrosion risk.Its purpose is to provide corrosion risk comprehensive evaluation method outside a kind of buried pipeline, the blank of the outer corrosion risk Multi-factors synthetic judge of buried pipeline is made up, provides the outer corrosion risk of a set of comprehensive and systematic buried pipeline multifactor Multifactorial Evaluations For A Multiple-stage Model system.
Description
Technical field
The present invention relates to outer corrosion risk Indentification model technical field, in particular to the outer corrosion risk of buried pipeline is multifactor
The foundation of Multifactorial Evaluations For A Multiple-stage Model method.
Background technique
In practical projects, buried pipeline because corrosion caused by emergency event increase year by year, the corrosion risk that pipeline faces
Increasingly increase, however there are many factor for influencing corrosive pipeline, performance, cathodic protection level, soil environment feelings such as corrosion-inhibiting coating
The case where condition, alternating current-direct current annoyance level, sacrificial anode military service situation, stream discharging system etc., which factor is to influence pipe network corruption on earth
How is the correlation that the key factor and these key factors for losing risk are perforated with piping corrosion, becomes pipeline corrosion protection worker
The problem of concern.
Evaluation for the outer corrosion risk of buried pipeline, the presently mainly shape based on single factor or 2 factors
At, it can such as be evaluated according to corrosivity, steady-state DC risk of interferences of the national standard GB/T 19285-2003 to soil: (1) native
Earth resistivity < 20 Ω m, soil corrosivity are strong；Between 20 Ω of Ω m~50 m, soil corrosivity is soil resistivity
In；Soil resistivity > 50 Ω m, soil corrosivity are weak；(2) soil surface gradient < 0.5mV/m, DC influence risk are big；Soil
Earth is surface graded between 0.5mV/m~5mV/m, during DC influence risk is；Soil surface gradient > 5mV/m, DC influence risk
It is small.According to national standard GB/T 21448-2008, pipeline cathode protection level should reach following range: pipeline cathode protection current potential is (i.e.
Pipeline/polarizing current potential) it should be -850mV (CSE) or more negative, but cannot be more negative than -1200mV (CSE)；In anaerobic bacteria or
In SRB and other harmful bacteria soil, pipeline cathode protection current potential should be -950mV (CSE) or more negative；In soil resistivity 100
For Ω m into 1000 Ω m environment, cathodic protection potential is preferably defeated by -750mV (CSE)；It is greater than 100 Ω m in soil resistivity
In environment, cathodic protection potential is preferably defeated by -650mV (CSE)；According to NACE0177-2014, in order to ensure the safety of personnel, pipe
15V, but the influence for AC influence to pipeline cathode protection system is not to be exceeded in road AC influence voltage, does not provide clear
Explanation.Evaluation about pipeline corrosion risk under AC influence and cathodic protection collective effect simultaneously, there is also disputes at present:
It is believed that alternating current and cathodic protection potential can evaluate the corrosion risk of pipeline, it is believed that alterating and direct current current density
The ratio between can evaluate the corrosion risk of pipeline, it is believed that the ratio between alterating and direct current current density and cathodic protection potential can evaluate pipeline corruption
Erosion risk, but recent studies have indicated that, in the case where identical AC current density, identical cathodic protection are horizontal, in different soils environment
The corrosion risk of pipeline is also different.Buried pipeline suffers from multifactor comprehensive function during being actually on active service, therefore,
The outer corrosion risk appraisal procedure of current single factor test is required to further perfect, the multi-factor evaluation technology of outer corrosion risk
Still locate blank.
Summary of the invention
The technical problem to be solved in the present invention is to provide corrosion risk comprehensive evaluation methods outside a kind of buried pipeline, make up and bury
The blank of the outer corrosion risk Multi-factors synthetic judge of ground pipeline, provide the outer corrosion risk of a set of comprehensive and systematic buried pipeline mostly because
Plain Multifactorial Evaluations For A Multiple-stage Model system.
The outer corrosion risk comprehensive evaluation method of buried pipeline of the present invention, comprising the following steps:
Outer corrosion basic parameter is obtained, the outer corrosion basic parameter includes erosion resistant coating leak detection, soil corrosivity, cathode guarantor
Shield, DC influence and AC influence,
Judge that buried pipeline erosion resistant coating whether there is leak source according to the leak detection of outer corrosion basic parameter erosion resistant coating, and
If there is no leak source, it is concluded that Buried Pipeline risk is low,
If there is leak source, then judge whether buried pipeline uses cathode to protect according to outer corrosion basic parameter cathodic protection
Shield, and
If not using cathodic protection, corrosion risk is carried out according to DC influence, AC influence and soil corrosivity
Judge, if carrying out corrosion risk using cathodic protection according to DC influence, AC influence and soil corrosivity and commenting
Sentence.
The outer corrosion risk comprehensive evaluation method of buried pipeline of the present invention, if not using cathodic protection described in wherein,
The specific steps of corrosion risk judge are carried out according to DC influence, AC influence and soil corrosivity are as follows:
If there is DC influence, then corrosion risk is carried out according to DC corrosion judging quota under the conditions of no cathodic protection and commented
Sentence,
If there is AC influence, then corrosion risk is carried out according to AC corrosion judging quota under the conditions of no cathodic protection and commented
Sentence,
If be without the corrosion risk that DC influence and AC influence or DC influence and AC influence are assessed it is low,
Corrosion risk judge is carried out according to soil corrosivity.
The outer corrosion risk comprehensive evaluation method of buried pipeline of the present invention, if wherein described using cathodic protection, basis
DC influence, AC influence and soil corrosivity carry out the specific steps of corrosion risk judge are as follows:
If there is DC influence, then comment according to there is under the conditions of cathodic protection DC corrosion judging quota carry out corrosion risk
Sentence,
If there is AC influence, then comment according to there is under the conditions of cathodic protection AC corrosion judging quota carry out corrosion risk
Sentence,
If be without the corrosion risk that DC influence and AC influence or DC influence and AC influence are assessed it is low,
According to cathodic protection polarization potential EcpCorrosion risk judge is carried out, and
If Ecp≤-850mVCSE, then corrosion risk is low,
If cathodic protection polarization potential is just in -0.85VCSE, then corrosion risk judge is carried out according to soil corrosivity.
The outer corrosion risk comprehensive evaluation method of buried pipeline of the present invention, wherein described according to direct current under the conditions of no cathodic protection
Corrode the specific steps that judging quota carries out corrosion risk judge are as follows: pipeline polarization potential EcpRelative to spontaneous potential forward direction
The time scale for deviating 20mV is r, and as r≤5%, corrosion risk is low；As 5% < r < 15%, corrosion risk is medium water
It is flat；As r >=15%, corrosion risk is high.
The outer corrosion risk comprehensive evaluation method of buried pipeline of the present invention, wherein described according to being exchanged under the conditions of no cathodic protection
Corrode the specific steps that judging quota carries out corrosion risk judge are as follows: as AC corrosion current density icorr≤30A/m2When, exchange
Corrosion risk is low；As AC corrosion current density 30A/m2< icorr< 100A/m2When, AC corrosion risk is medium level；When
AC corrosion current density icorr≥100A/m2When, AC corrosion risk is high.
The outer corrosion risk comprehensive evaluation method of buried pipeline of the present invention, under conditions of not using cathodic protection, wherein
The specific steps that corrosion risk judge is carried out according to soil corrosivity are as follows:
If only obtaining soil resistivity, as 50 Ω m of soil resistivity >, corrosion risk is low；When 20 Ω m≤
When soil resistivity≤50 Ω m, corrosion risk is medium level；As 20 Ω m of soil resistivity <, corrosion risk is high；
If obtain soil resistivity, pipeline spontaneous potential, oxidation-reduction potential, soil pH value, the soil texture,
Soil moisture content, soil salt content and soil Cl-Content, the then single-phase Testing index evaluation score such as following table of soil corrosivity
N in upper table1+N2+N3+N4+N5+N6+N7+N8=N, as 0≤N≤5, corrosion risk is low；It is rotten as 5 < N≤19
Erosion risk is medium level；As 19 < N≤32, corrosion risk is high.
The outer corrosion risk comprehensive evaluation method of buried pipeline of the present invention, wherein described according to there is direct current under the conditions of cathodic protection
Corrode the specific steps that judging quota carries out corrosion risk judge are as follows: EcpFor pipeline polarization potential, r is pipeline polarization potential Ecp
The time scale of forward migration: work as Ecp> -0.85VCSEAnd r≤5% or Ecp> -0.80VCSEAnd r≤2% or Ecp>-
0.75VCSEAnd when r≤1%, corrosion risk is low；Work as Ecp> -0.85VCSEAnd 5% < r < 20% or Ecp> -0.80VCSEAnd 2%
< r < 15% or Ecp> -0.75VCSEAnd when 1% < r < 5%, corrosion risk is medium level；Work as Ecp> -0.85VCSEAnd r
>=20% or Ecp> -0.80VCSEAnd r >=15% or Ecp> -0.75VCSEAnd when r >=5%, corrosion risk is high.
The outer corrosion risk comprehensive evaluation method of buried pipeline of the present invention, wherein described exchange under the conditions of cathodic protection according to having
Corrode the specific steps that judging quota carries out corrosion risk judge are as follows: as AC corrosion current density icorr≤30A/m2When, corrosion
Risk is low；As AC corrosion current density 30A/m2< icorr< 100A/m2And cathodic protection polarization potential -1.20VCSE< Ecp
< -0.95VCSEWhen, corrosion risk is medium level；As AC corrosion current density icorr≥100A/m2When, corrosion risk is high；
Or work as 30A/m2< icorr< 100A/m2And cathodic protection polarization potential Ecp< -1.20VCSEWhen, corrosion risk is high；Or work as 30A/
m2< icorr< 100A/m2And cathodic protection polarization potential Ecp> -0.95VCSEWhen, corrosion risk is high.
The outer corrosion risk comprehensive evaluation method of buried pipeline of the present invention, under conditions of using cathodic protection, wherein described
The specific steps of corrosion risk judge are carried out according to soil corrosivity are as follows:
If only obtaining soil resistivity, as 50 Ω m of soil resistivity >, corrosion risk is low；When 20 Ω m≤
When soil resistivity≤50 Ω m, corrosion risk is medium level；As 20 Ω m of soil resistivity <, corrosion risk is high；
If obtain soil resistivity, pipeline spontaneous potential, oxidation-reduction potential, soil pH value, the soil texture,
Soil moisture content, soil salt content and soil Cl-Content, the then single-phase Testing index evaluation score such as following table of soil corrosivity
N in upper table1+N2+N3+N4+N5+N6+N7+N8=N, as 0≤N≤5, corrosion risk is low；It is rotten as 5 < N≤19
Erosion risk is medium level；As 19 < N≤32, corrosion risk is high.
The outer corrosion risk comprehensive evaluation method difference from prior art of buried pipeline of the present invention is in the present invention really
It accepts the judging quota based on corrosion rate, proposes AC and DC and interfere the outer corrosion risk judging quota of lower buried pipeline, outside
Multifactor multilayer analysis comprehensive evaluation system is established in corrosion risk evaluation for the first time, to comprehensive system carries out the outer corruption of buried pipeline
There are important meanings for erosion judge, and the outer corrosion risk of buried pipeline is reasonably accurate evaluated convenient for engineers and technicians.
The present invention will be further explained below with reference to the attached drawings.
Detailed description of the invention
Fig. 1 is the flow chart of the outer corrosion risk comprehensive evaluation method of buried pipeline of the present invention.
Specific embodiment
As shown in Figure 1, the outer corrosion risk comprehensive evaluation method of buried pipeline of the present invention the following steps are included:
Outer corrosion basic parameter is obtained, the outer corrosion basic parameter includes erosion resistant coating leak detection, soil corrosivity, cathode guarantor
Shield, DC influence and AC influence,
Judge that buried pipeline erosion resistant coating whether there is leak source according to the leak detection of outer corrosion basic parameter erosion resistant coating, and
If there is no leak source, it is concluded that Buried Pipeline risk is low,
If there is leak source, then judge whether buried pipeline uses cathode to protect according to outer corrosion basic parameter cathodic protection
Shield, and
If not using cathodic protection, corrosion risk is carried out according to DC influence, AC influence and soil corrosivity
Judge,
If carrying out commenting for corrosion risk according to DC influence, AC influence and soil corrosivity using cathodic protection
Sentence.
The outer corrosion risk comprehensive evaluation method of buried pipeline of the present invention, if not using cathodic protection described in wherein,
The specific steps of corrosion risk judge are carried out according to DC influence, AC influence and soil corrosivity are as follows:
If there is DC influence, then corrosion risk is carried out according to DC corrosion judging quota under the conditions of no cathodic protection and commented
Sentence,
If there is AC influence, then corrosion risk is carried out according to AC corrosion judging quota under the conditions of no cathodic protection and commented
Sentence,
If be without the corrosion risk that DC influence and AC influence or DC influence and AC influence are assessed it is low,
Corrosion risk judge is carried out according to soil corrosivity.
The outer corrosion risk comprehensive evaluation method of buried pipeline of the present invention, if wherein described using cathodic protection, basis
DC influence, AC influence and soil corrosivity carry out the specific steps of corrosion risk judge are as follows:
If there is DC influence, then comment according to there is under the conditions of cathodic protection DC corrosion judging quota carry out corrosion risk
Sentence,
If there is AC influence, then comment according to there is under the conditions of cathodic protection AC corrosion judging quota carry out corrosion risk
Sentence,
If be without the corrosion risk that DC influence and AC influence or DC influence and AC influence are assessed it is low,
According to cathodic protection polarization potential EcpCorrosion risk judge is carried out, and
If Ecp≤-850mVCSE, then corrosion risk is low；
If cathodic protection polarization potential is just in -0.85VCSE, then corrosion risk judge is carried out according to soil corrosivity.
The outer corrosion risk comprehensive evaluation method of buried pipeline of the present invention, wherein described according to direct current under the conditions of no cathodic protection
Corrode the specific steps that judging quota carries out corrosion risk judge are as follows: pipeline polarization potential EcpRelative to spontaneous potential forward direction
The time scale for deviating 20mV is r, and as r≤5%, corrosion risk is low；As 5% < r < 15%, corrosion risk is medium water
It is flat；As r >=15%, corrosion risk is high.
The outer corrosion risk comprehensive evaluation method of buried pipeline of the present invention, wherein described according to being exchanged under the conditions of no cathodic protection
Corrode the specific steps that judging quota carries out corrosion risk judge are as follows: as AC corrosion current density icorr≤30A/m2When, exchange
Corrosion risk is low；As AC corrosion current density 30A/m2< icorr< 100A/m2When, AC corrosion risk is medium level；When
AC corrosion current density icorr≥100A/m2When, AC corrosion risk is high.
The outer corrosion risk comprehensive evaluation method of buried pipeline of the present invention, under conditions of not using cathodic protection, wherein
The specific steps that corrosion risk judge is carried out according to soil corrosivity are as follows:
If only obtaining soil resistivity, as 50 Ω m of soil resistivity >, corrosion risk is low；When 20 Ω m≤
When soil resistivity≤50 Ω m, corrosion risk is medium level；As 20 Ω m of soil resistivity <, corrosion risk is high；
If obtain soil resistivity, pipeline spontaneous potential, oxidation-reduction potential, soil pH value, the soil texture,
Soil moisture content, soil salt content and soil Cl-Content, the then single-phase Testing index evaluation score such as following table of soil corrosivity
N in upper table1+N2+N3+N4+N5+N6+N7+N8=N, as 0≤N≤5, corrosion risk is low；It is rotten as 5 < N≤19
Erosion risk is medium level；As 19 < N≤32, corrosion risk is high.
The outer corrosion risk comprehensive evaluation method of buried pipeline of the present invention, wherein described according to there is direct current under the conditions of cathodic protection
Corrode the specific steps that judging quota carries out corrosion risk judge are as follows: EcpFor pipeline polarization potential, r is pipeline polarization potential Ecp
The time scale of forward migration: work as Ecp> -0.85VCSEAnd r≤5% or Ecp> -0.80VCSEAnd r≤2% or Ecp>-
0.75VCSEAnd when r≤1%, corrosion risk is low；Work as Ecp> -0.85VCSEAnd 5% < r < 20% or Ecp> -0.80VCSEAnd 2%
< r < 15% or Ecp> -0.75VCSEAnd when 1% < r < 5%, corrosion risk is medium level；Work as Ecp> -0.85VCSEAnd r
>=20% or Ecp> -0.80VCSEAnd r >=15% or Ecp> -0.75VCSEAnd when r >=5%, corrosion risk is high.
The outer corrosion risk comprehensive evaluation method of buried pipeline of the present invention, wherein described exchange under the conditions of cathodic protection according to having
Corrode the specific steps that judging quota carries out corrosion risk judge are as follows: as AC corrosion current density icorr≤30A/m2When, corrosion
Risk is low；As AC corrosion current density 30A/m2< icorr< 100A/m2And cathodic protection polarization potential -1.20VCSE< Ecp
< -0.95VCSEWhen, corrosion risk is medium level；As AC corrosion current density icorr≥100A/m2When, corrosion risk is high；
Work as 30A/m2< icorr< 100A/m2And cathodic protection polarization potential Ecp< -1.20VCSEWhen, corrosion risk is high；Work as 30A/m2<
icorr< 100A/m2And cathodic protection polarization potential Ecp> -0.95VCSEWhen, corrosion risk is high.
The outer corrosion risk comprehensive evaluation method of buried pipeline of the present invention, under conditions of using cathodic protection, wherein described
The specific steps of corrosion risk judge are carried out according to soil corrosivity are as follows:
If only obtaining soil resistivity, as 50 Ω m of soil resistivity >, corrosion risk is low；When 20 Ω m≤
When soil resistivity≤50 Ω m, corrosion risk is medium level；As 20 Ω m of soil resistivity <, corrosion risk is high；
If obtain soil resistivity, pipeline spontaneous potential, oxidation-reduction potential, soil pH value, the soil texture,
Soil moisture content, soil salt content and soil Cl-Content, the then single-phase Testing index evaluation score such as following table of soil corrosivity
N in upper table1+N2+N3+N4+N5+N6+N7+N8=N, as 0≤N≤5, corrosion risk is low；It is rotten as 5 < N≤19
Erosion risk is medium level；As 19 < N≤32, corrosion risk is high.
It confirmed the judging quota based on corrosion rate in the present invention, propose AC and DC and interfere lower buried pipeline outer rotten
Risk Evaluation index is lost, multifactor multilayer analysis comprehensive evaluation system is established for the first time in the evaluation of outer corrosion risk, to comprehensive system
There are important meanings for the outer corrosion judge of ground progress buried pipeline, reasonably accurate evaluate underground pipe convenient for engineers and technicians
The outer corrosion risk in road.
Below with reference to embodiment, invention is further described in detail.
In order to achieve the object of the present invention, a large amount of field test and simulating lab test data are had collected, it is first determined
With corrosion rate VcorrFor the high, medium and low three-level judging quota for assessing outer corrosion risk, as shown in table 1.
Table 1 assesses three-level index based on the outer corrosion risk of corrosion rate
| Outer corrosion risk classification | It is low | In | It is high |
| Corrosion rate Vcorr(mm/y) | ≤0.0254 | 0.0254~0.1 | ≥0.1 |
Corrosion rate V under the various disturbed conditions obtained based on scene and laboratorycorrWith interference parameter correlation
Analysis, establishes corrosion rate assessment models, comprehensively considers the exploitativeness at scene, it is determined that without the exchange under the conditions of cathodic protection
Corrosion risk judging quota has the AC corrosion Risk Evaluation index under the conditions of cathodic protection, dynamic under the conditions of no cathodic protection
State DC corrosion Risk Evaluation index (include steady-state DC) and there is the dynamic DC corrosion risk under the conditions of cathodic protection to comment
Index (comprising steady-state DC) is sentenced, respectively as shown in table 2~5.
Table 2 is without the AC corrosion Risk Evaluation index under the conditions of cathodic protection
| AC corrosion risk stratification | It is low | In | It is high |
| AC corrosion current density icorr(A/m2) | ≤30 | 30~100 | ≥100 |
Table 3 has the AC corrosion Risk Evaluation index under the conditions of cathodic protection
Table 4 is without the dynamic DC corrosion Risk Evaluation index (including steady-state DC) under the conditions of cathodic protection
Table 5 has the dynamic DC corrosion Risk Evaluation index under the conditions of cathodic protection (comprising steady-state DC)
Based on the corrosion judging quota of above-mentioned AC and DC interference, having combed influences the multiple of the outer corrosion risk of buried pipeline
Logic between factor, such as erosion resistant coating leak source, soil corrosivity, cathode protection condition, DC influence and AC influence level
Relationship establishes the outer corrosion risk comprehensive evaluation system based on five class factor of the external corrosion tri-layer relationships, wherein the first level
For the presence or absence of erosion resistant coating leak source, the second level is the presence or absence of cathodic protection, and third level is AC influence, DC influence and soil
Corrosivity.The outer corrosion risk Comprehensive Evaluation process of buried pipeline is as follows:
According to pipeline anticorrosion coating, whether there is or not leak sources to carry out the first hierarchical classification first: if erosion resistant coating is without leak source, buried metal
The outer corrosion risk of pipeline is low；If pipeline anticorrosion coating has leak source, the second layer is carried out according to whether pipeline applies cathodic protection
Subseries.
According to the second hierarchical classification, if pipeline does not have cathodic protection (including no application cathodic protection or existing yin
Pole protection is entirely ineffective), then it carries out carrying out third level classification according to DC influence, AC influence and soil corrosivity: (1)
If any DC influence, then Risk Evaluation is carried out according to DC corrosion judging quota under the conditions of no cathodic protection, as shown in table 4；(2)
If any AC influence, then Risk Evaluation is carried out according to AC corrosion judging quota under the conditions of no cathodic protection, as shown in table 2；(3)
Corrosion risk such as without DC influence and AC influence or alternating current-direct current interference assessment be it is low, then carried out according to soil corrosivity rotten
Risk Evaluation is lost, if only obtaining soil resistivity data, can refer in GB/T 21447-2018 in 4.3 sections " by resistivity
Divide soil corrosivity grade " soil corrosivity judge is carried out, as shown in table 6；If obtaining multiple soil parameters, such as soil
Resistivity, pipeline spontaneous potential, oxidation-reduction potential, soil pH value, the soil texture, soil moisture content, soil salt content
And soil Cl-The parameters such as content can refer to the regulation in GB/T 19285-2014 in 4.2 sections and be judged, such as 7~8 institute of table
Show.
Table 6 divides soil corrosivity grade by resistivity
| Grade | It is weak | In | By force |
| Soil resistivity (Ω m) | >50 | 20~50 | <20 |
In table 6, soil corrosivity grade is that the corrosion risk grade of buried pipeline works as soil resistivity as known from Table 6
When 50 Ω m of >, corrosion risk is low；As 20 Ω m≤soil resistivity≤50 Ω m, corrosion risk is medium level；When
When 20 Ω m of soil resistivity <, corrosion risk is high.
The single-phase Testing index evaluation score of 7 soil corrosivity of table
8 Evaluating Soil Corrosivity grade of table
As known from Table 8, as 0≤N≤5, corrosion risk is low；As 5 < N≤19, corrosion risk is medium level；When 19
When < N≤32, corrosion risk is high.
According to the second hierarchical classification, if there are cathodic protection systems for pipeline, it is also desirable to according to DC influence, AC influence
And soil corrosivity carries out third level classification: (1) if any DC influence, then according to there is DC corrosion under the conditions of cathodic protection
Judging quota carries out Risk Evaluation, as shown in table 5；(2) if any AC influence, then according to there is AC corrosion under the conditions of cathodic protection
Judging quota carries out Risk Evaluation, as shown in table 3；(3) such as corruption without DC influence or AC influence or alternating current-direct current interference assessment
Lose risk be it is low, cathodic protection polarization potential reach national standard GB/T 21448 requirement, i.e. cathodic protection polarization potential Ecp(V,CSE)
Meet Ecp(V,CSE)≤-850mVCSE, then corrosion risk is low；(4) it is such as interfered without DC influence or AC influence or alternating current-direct current
The corrosion risk of assessment be it is low, cathodic protection polarization potential or potential shift are unsatisfactory for the requirement of national standard GB/T 21448, then according to
Soil corrosivity carries out corrosion risk judge can refer in GB/T 21447-2018 if only obtaining soil resistivity data
" soil corrosivity grade is divided by resistivity " in 4.3 sections and carry out soil corrosivity judge, as shown in table 6；If obtained more
A soil parameters, such as soil resistivity, pipeline spontaneous potential, oxidation-reduction potential, soil pH value, the soil texture, soil
Moisture content, soil salt content and soil Cl-The parameters such as content can refer to the regulation in GB/T 19285-2014 in 4.2 sections and carry out
It judges, as shown in table 7~8.
Embodiment:
(1) for certain pipeline by AC influence, deficiency of protection coating area is 1cm2, when no cathodic protection, when alternating current is close
Spend icorrFor 200A/m2When, the corrosion rate of pipe line steel reaches 0.28mm/y, and the outer corrosion risk of pipeline is high.
(2) there are erosion resistant coating leak source, the cathodic protection polarization potential E of pipeline for certain pipelinecp=-1.2VCSE, alternating current is close
Spend icorrFor 130A/m2, pipeline, which has occurred, corrodes leakage accident, and outer corrosion risk is high.
(3) there are DC influences for certain gas pipeline, and no cathodic protection, corrosion potential is -0.61VCSE, pipeline polarization electricity
The time of position forward migration 20mV is 386s, total testing time 2716s, the time ratio of pipeline polarization potential forward migration 20mV
Example r is 14%, corrosion rate 0.062mm/y, and outer corrosion risk is medium level.
(4) certain gas pipeline is there are DC influence, cathodic protection system operational excellence, pipeline polarization potential just in-
0.85VCSETime be 97s, total testing time 2613s, time scale r be 3.5%, corrosion rate 0.00123mm/y,
Outer corrosion risk is low.
(5) there are DC influences for certain pipeline, and cathodic protection system operational excellence, pipeline polarization potential is just in -0.80VCSE's
Time is 132s, and total testing time 981s, time scale r are 13%, corrosion rate 0.0654mm/y, and outer corrosion risk is
Medium level.
(6) there are DC influences for certain pipeline, and cathodic protection system operational excellence, pipeline polarization potential is just in -0.75VCSE's
Time is 447s, and total testing time is 1078s, and time scale r is 41%, corrosion rate 0.1476mm/y, outer corrosion wind
Danger is high.
Embodiment described above only describe the preferred embodiments of the invention, not to model of the invention
It encloses and is defined, without departing from the spirit of the design of the present invention, those of ordinary skill in the art are to technical side of the invention
The various changes and improvements that case is made should all be fallen into the protection scope that claims of the present invention determines.
Claims (9)
1. a kind of outer corrosion risk comprehensive evaluation method of buried pipeline, which comprises the following steps:
Obtain it is outer corrode basic parameter, the outer corrosion basic parameter include erosion resistant coating leak detection, soil corrosivity, cathodic protection,
DC influence and AC influence,
Judge that buried pipeline erosion resistant coating whether there is leak source according to the leak detection of outer corrosion basic parameter erosion resistant coating, and
If there is no leak source, it is concluded that Buried Pipeline risk is low,
If there is leak source, then judge whether buried pipeline uses cathodic protection according to outer corrosion basic parameter cathodic protection, with
And
If not using cathodic protection, commenting for corrosion risk is carried out according to DC influence, AC influence and soil corrosivity
Sentence,
If carrying out the judge of corrosion risk according to DC influence, AC influence and soil corrosivity using cathodic protection.
2. the outer corrosion risk comprehensive evaluation method of buried pipeline according to claim 1, which is characterized in that if described do not have
Have using cathodic protection, then carries out the specific steps of corrosion risk judge according to DC influence, AC influence and soil corrosivity
Are as follows:
If there is DC influence, then corrosion risk judge is carried out according to DC corrosion judging quota under the conditions of no cathodic protection,
If there is AC influence, then corrosion risk judge is carried out according to AC corrosion judging quota under the conditions of no cathodic protection,
If be without the corrosion risk that DC influence and AC influence or DC influence and AC influence are assessed it is low, according to
Soil corrosivity carries out corrosion risk judge.
3. the outer corrosion risk comprehensive evaluation method of buried pipeline according to claim 1, which is characterized in that if described adopt
With cathodic protection, then the specific steps of corrosion risk judge are carried out according to DC influence, AC influence and soil corrosivity are as follows:
If there is DC influence, then according to there is DC corrosion judging quota under the conditions of cathodic protection to carry out corrosion risk judge,
If there is AC influence, then according to there is AC corrosion judging quota under the conditions of cathodic protection to carry out corrosion risk judge,
If being low, basis without the corrosion risk that DC influence and AC influence or DC influence and AC influence are assessed
Cathodic protection polarization potential EcpCorrosion risk judge is carried out, and
If Ecp≤-850mVCSE, then corrosion risk is low,
If cathodic protection polarization potential is just in -0.85VCSE, then corrosion risk judge is carried out according to soil corrosivity.
4. the outer corrosion risk comprehensive evaluation method of buried pipeline according to claim 2, which is characterized in that described according to nothing
DC corrosion judging quota carries out the specific steps of corrosion risk judge under the conditions of cathodic protection are as follows: pipeline polarization potential EcpRelatively
It is r in the time scale of spontaneous potential forward migration 20mV, as r≤5%, corrosion risk is low；As 5% < r < 15%
When, corrosion risk is medium level；As r >=15%, corrosion risk is high.
5. the outer corrosion risk comprehensive evaluation method of buried pipeline according to claim 2, which is characterized in that described according to nothing
AC corrosion judging quota carries out the specific steps of corrosion risk judge under the conditions of cathodic protection are as follows: when AC corrosion current density
icorr≤30A/m2When, AC corrosion risk is low；As AC corrosion current density 30A/m2< icorr< 100A/m2When, exchange is rotten
Erosion risk is medium level；As AC corrosion current density icorr≥100A/m2When, AC corrosion risk is high.
6. the outer corrosion risk comprehensive evaluation method of buried pipeline according to claim 2, which is characterized in that described according to soil
The specific steps of earth corrosivity progress corrosion risk judge are as follows:
If only obtaining soil resistivity, as 50 Ω m of soil resistivity >, corrosion risk is low；When 20 Ω m≤soil
When resistivity≤50 Ω m, corrosion risk is medium level；As 20 Ω m of soil resistivity <, corrosion risk is high；
If obtaining soil resistivity, pipeline spontaneous potential, oxidation-reduction potential, soil pH value, the soil texture, soil
Moisture content, soil salt content and soil Cl-Content, the then single-phase Testing index evaluation score such as following table of soil corrosivity
N in upper table1+N2+N3+N4+N5+N6+N7+N8=N, as 0≤N≤5, corrosion risk is low；As 5 < N≤19, corrode wind
Danger is medium level；As 19 < N≤32, corrosion risk is high.
7. according to corrosion risk comprehensive evaluation method outside buried pipeline described in claim requirement 3, which is characterized in that described to press
According to the specific steps for thering is DC corrosion judging quota under the conditions of cathodic protection to carry out corrosion risk judge are as follows: EcpIt polarizes for pipeline electric
Position, r are pipeline polarization potential EcpThe time scale of forward migration: work as Ecp> -0.85VCSEAnd r≤5% or Ecp> -0.80VCSE
And r≤2% or Ecp> -0.75VCSEAnd when r≤1%, corrosion risk is low；Work as Ecp> -0.85VCSEAnd 5% < r < 20% or Ecp
> -0.80VCSEAnd 2% < r < 15% or Ecp> -0.75VCSEAnd when 1% < r < 5%, corrosion risk is medium level；When
Ecp> -0.85VCSEAnd r >=20% or Ecp> -0.80VCSEAnd r >=15% or Ecp> -0.75VCSEAnd when r >=5%, corrode wind
Danger is high.
8. the outer corrosion risk comprehensive evaluation method of buried pipeline according to claim 3, which is characterized in that described according to having
AC corrosion judging quota carries out the specific steps of corrosion risk judge under the conditions of cathodic protection are as follows: when AC corrosion current density
icorr≤30A/m2When, corrosion risk is low；As AC corrosion current density 30A/m2< icorr< 100A/m2And cathodic protection polarizes
Current potential -1.20VCSE< Ecp< -0.95VCSEWhen, corrosion risk is medium level；As AC corrosion current density icorr≥100A/
m2When, corrosion risk is high；Or work as 30A/m2< icorr< 100A/m2And cathodic protection polarization potential Ecp< -1.20VCSEWhen, corrosion
Risk is high；Or work as 30A/m2< icorr< 100A/m2And cathodic protection polarization potential Ecp> -0.95VCSEWhen, corrosion risk is high.
9. the outer corrosion risk comprehensive evaluation method of buried pipeline according to claim 3, which is characterized in that described according to soil
The specific steps of earth corrosivity progress corrosion risk judge are as follows:
If only obtaining soil resistivity, as 50 Ω m of soil resistivity >, corrosion risk is low；When 20 Ω m≤soil
When resistivity≤50 Ω m, corrosion risk is medium level；As 20 Ω m of soil resistivity <, corrosion risk is high；
If obtaining soil resistivity, pipeline spontaneous potential, oxidation-reduction potential, soil pH value, the soil texture, soil
Moisture content, soil salt content and soil Cl-Content, the then single-phase Testing index evaluation score such as following table of soil corrosivity
N in upper table1+N2+N3+N4+N5+N6+N7+N8=N, as 0≤N≤5, corrosion risk is low；As 5 < N≤19, corrode wind
Danger is medium level；As 19 < N≤32, corrosion risk is high.
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| CN113361903A (en) * | 2021-06-02 | 2021-09-07 | 中国石油大学(北京) | Method, device and equipment for evaluating corrosion risk outside oil and gas pipeline |
| CN113361903B (en) * | 2021-06-02 | 2023-12-12 | 中国石油大学(北京) | Method, device and equipment for evaluating corrosion risk outside oil and gas pipeline |
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| CN113981453B (en) * | 2021-09-10 | 2023-11-28 | 北京市燃气集团有限责任公司 | Method and device for evaluating risk of stray current corrosion of gas pipe network with cathode protection |
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