CN111721619A - Corrosion evaluation method for corrosion-resistant alloy overlaying layer of underwater oil and gas facility - Google Patents

Corrosion evaluation method for corrosion-resistant alloy overlaying layer of underwater oil and gas facility Download PDF

Info

Publication number
CN111721619A
CN111721619A CN202010787052.3A CN202010787052A CN111721619A CN 111721619 A CN111721619 A CN 111721619A CN 202010787052 A CN202010787052 A CN 202010787052A CN 111721619 A CN111721619 A CN 111721619A
Authority
CN
China
Prior art keywords
corrosion
layer
surfacing layer
sample
less
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.)
Granted
Application number
CN202010787052.3A
Other languages
Chinese (zh)
Other versions
CN111721619B (en
Inventor
安维峥
王竹
胡丽华
冯喆
常炜
朱莉娅
李大朋
马强
张雷
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
University of Science and Technology Beijing USTB
China National Offshore Oil Corp CNOOC
CNOOC Research Institute Co Ltd
Original Assignee
University of Science and Technology Beijing USTB
China National Offshore Oil Corp CNOOC
CNOOC Research Institute Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by University of Science and Technology Beijing USTB, China National Offshore Oil Corp CNOOC, CNOOC Research Institute Co Ltd filed Critical University of Science and Technology Beijing USTB
Priority to CN202010787052.3A priority Critical patent/CN111721619B/en
Publication of CN111721619A publication Critical patent/CN111721619A/en
Application granted granted Critical
Publication of CN111721619B publication Critical patent/CN111721619B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/02—Details
    • 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
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/02—Details
    • G01N3/04—Chucks
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces

Landscapes

  • Life Sciences & Earth Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Pathology (AREA)
  • Biodiversity & Conservation Biology (AREA)
  • Ecology (AREA)
  • Environmental & Geological Engineering (AREA)
  • Environmental Sciences (AREA)
  • Testing Resistance To Weather, Investigating Materials By Mechanical Methods (AREA)

Abstract

The invention provides a corrosion evaluation method of a corrosion-resistant alloy surfacing layer of an underwater oil and gas facility, which comprises the following steps: and quantitatively evaluating the corrosion resistance of the surfacing layer by comprehensively representing the texture state, the mechanical property, the overall corrosion rate and the local corrosion risk of the surfacing layer. The invention provides quantitative indexes mainly aiming at the corrosion resistance of the corrosion-resistant alloy surfacing layer of the underwater oil and gas facility, can evaluate the corrosion resistance of the surfacing material applied under corresponding working conditions, and guides material selection, welding process evaluation and corrosion control.

Description

Corrosion evaluation method for corrosion-resistant alloy overlaying layer of underwater oil and gas facility
Technical Field
The invention belongs to the field of corrosion performance evaluation, and particularly relates to a corrosion evaluation method for a corrosion-resistant alloy overlaying layer of an underwater oil and gas facility by comprehensively representing the texture state, the mechanical property, the overall corrosion rate and the local corrosion risk of the overlaying layer.
Background
With the rapid growth of economy in China, the domestic demand for energy is remarkably increased, and the domestic energy exploitation key points are gradually turning to deep water environments. In the process of ocean oil and gas development, it is usually difficult to separate and dewater oil and gas media in time, so that various production facilities face extremely harsh internal corrosion environments, and meanwhile, underwater production systems face the challenges of severe sea conditions and complex ocean environments, are directly exposed to external seawater, and the problem of corrosion of the underwater facilities is extremely severe.
The stainless steel and the nickel-based alloy have excellent fatigue strength and stress corrosion cracking resistance, and are one of important structural materials in the marine oil and gas exploitation process. However, stainless steels and nickel-based alloys are expensive and not suitable for large-scale applications. In order to reduce the cost, carbon steel is usually used as a base pipe, and stainless steel or nickel-based alloy is deposited on the surface of the carbon steel in a surfacing mode so as to meet the corrosion resistance requirement of underwater facilities.
The build-up welding operation of metals results in a number of complex unbalanced thermal cycling processes near the work location of the sheet that cause structural and compositional changes that affect the quality of the weld to varying degrees. Uneven heating and cooling during welding can cause significant changes in the composition and structure of the heat affected zone and nearby metals, and even residual stresses, which can cause certain areas of the weld overlay to become corrosion sensitive.
Currently, there is no clear and comprehensive evaluation method for the corrosion resistance of a weld overlay.
Disclosure of Invention
The invention aims to provide a comprehensive and quantitative corrosion evaluation method for a corrosion-resistant alloy overlaying layer of an underwater oil and gas facility.
The invention provides a corrosion evaluation method of a corrosion-resistant alloy overlaying layer of an underwater oil and gas facility, which comprises the following steps: and quantitatively evaluating the corrosion resistance of the surfacing layer by comprehensively representing the texture state, the mechanical property, the overall corrosion rate and the local corrosion risk of the surfacing layer.
The method specifically comprises the following steps:
(1) testing harmful phase proportion and mechanical property of matrix and weld joint near the overlay welding layer, determining the types of matrix and internal structure near the overlay welding layer by using an optical microscope, estimating harmful phase content, inspecting welding defects, observing by using a metallographic microscope, measuring the volume fraction of harmful phase image by using image analysis software or by using a grid method, and obtaining the harmful phase proportion ξHarmful phaseMeasuring the hardness of a matrix and a cross section near the surfacing layer through a hardness experiment, obtaining the yield strength of the surfacing layer through a tensile experiment test, marking as a, and obtaining a mechanical property parameter ξ through calculation by using a formulaMechanics of forcePreliminarily judging the applicability of the surfacing layer by comparing the strength information of the surfacing layer with the design stress condition;
Figure BDA0002622389930000021
wherein a isSign boardA is a weld overlay yield strength value obtained by a tensile test, which is a standard value given in ISO 15156;
(2) sampling based on a sampling principle aiming at the surfacing layer, and carrying out a corrosion simulation experiment according to the determined environmental parameters of the corrosion simulation experiment; taking out the test sample after the experiment is finished, cleaning, dehydrating, drying, removing corrosion products on the surface of the test sample, and recording the quality loss W of the corrosion sample; measuring the local corrosion depth to obtain the maximum pitting depth d; observing the cracking condition;
(3) preliminarily evaluating the corrosion resistance of the overlaying layer after the step (2), and when one of the following conditions a) to c) occurs, judging that the corrosion resistance of the overlaying layer does not meet the requirement:
a) general corrosion rate V of corrosion couponAll-purposeLess than 0.5mm/a, but at one or more locations corrosion pits of the order of millimetres in diameter are present;
b) one or more samples have cracking conditions in the stress corrosion test;
c) failure phenomena such as cracking and the like occur at the joint position between the welding layers;
(4) if the failure problem in the step (3) does not occur in the surfacing layer, calculating the numerical values of all the influence factors for evaluating the corrosion resistance of the surfacing layer, and calculating the overall corrosion rate and the local corrosion rate according to the corrosion weightlessness W of the surfacing layer obtained by the sample weight loss analysis in the step (2) and the measured maximum pit depth d of the spot, wherein the calculation formula is as follows:
Figure BDA0002622389930000022
Figure BDA0002622389930000023
in the formula vAll-purposeThe corrosion rate (mm/a) is determined by K8.76 × 104W is sample weight loss (g) and A is sample surface area (cm)2) T is the experimental time(s) and D is the density (g/cm)3)；
vOfficeLocal corrosion rate (mm/a); d is the maximum pit depth (mm);
(5) assigning values to evaluation indexes for evaluating the corrosion resistance of the overlaying layer according to the values of the influence factors calculated in the steps (1) and (4),
the assignment method comprises the following steps:
a. general corrosion Rate index F1
When v isAll-purposeWhen the grain size is less than or equal to 0.2mm/a, F1Is 2
When the thickness is 0.2mm/a<vAll-purposeWhen the grain size is less than or equal to 0.5mm/a, F1Is 1
When the thickness is 0.5mm/a<vAll-purposeWhen F is present1Is 0
b. Local corrosion rate index F2
When v isOfficeWhen the grain size is less than or equal to 0.2mm/a, F2Is 2
When the thickness is 0.2mm/a<vOfficeWhen the grain size is less than or equal to 1.3mm/a, F2Is 1
When the thickness is 1.3mm/a<vOfficeWhen F is present2Is 0
c. Harmful phase ratio index F3
When ξHarmful phaseWhen the content is less than or equal to 1 percent, the content is 2
When the content is 1 percent<ξHarmful phaseWhen the content is less than or equal to 3 percent, the content is 1
When the content is 3 percent<ξHarmful phaseWhen is 0
d. Mechanical Property index F4
The weld overlay was evaluated according to the mechanical parameters given in ISO15156, mechanical index F4The assignment method is as follows:
completely meets the standard requirement and is 2;
within 3% of the standard deviation (finger ξ)Mechanics of forceLess than or equal to 3%) to 1;
more than 3% of the standard deviation (finger ξ)Mechanics of forceGreater than 3%) to 0;
(6) and quantitatively scoring the corrosion resistance of the corrosion-resistant alloy surfacing layer through the indexes: corrosion resistance of overlay layer of 10F1+10F2+10F3+20F4(ii) a The corresponding corrosion risk is evaluated according to the score.
In the step (2), the principle of sampling the weld overlay in the corrosion simulation experiment is as follows: the sample is cut along the direction of the overflowing surface in the actual service process when the corrosion-resistant alloy overlaying layer is sampled, and only the actual overflowing surface is exposed during corrosion evaluation, so that the non-overflowing surface of the sample can be sealed by using a sealing material which does not react with the experimental environment, and the non-overflowing surface of the sample can not contact with an experimental medium in the whole experimental process;
the environmental parameters of the corrosion simulation experiment are determined according to the actual production service environment, the experiment medium is the prepared simulation solution or the field produced liquid is directly used,
preparing a simulation solution by adopting an analytically pure grade reagent and deionized water;
pure gas or mixed gas is used for simulating an actual corrosive gas environment, the experimental period is determined according to the working condition provided on site, and the evaluation of the corrosion-resistant alloy welding line is carried out for 720 hours;
the corrosion simulation experiment comprises a general corrosion experiment, a stress corrosion experiment, a gap corrosion experiment and the like;
the corrosion simulation experiment is carried out in a reaction kettle, and a corrosion coupon, a stress corrosion sample and a slit corrosion sample can be loaded in the same reaction kettle, so that a plurality of experiments can be carried out simultaneously;
the maximum pit depth d is measured by a pit depth measuring instrument or a laser confocal microscope and the like, and the method comprises the following specific operations: depth measurement is carried out on the pitting pits by using a laser mode through a confocal microscope, and a 3d morphology picture can be directly obtained, so that specific depth data are obtained;
in the step (3) a), the step (c),
Figure BDA0002622389930000041
in the formula vAll-purposeThe corrosion rate (mm/a) is determined by K8.76 × 104W is sample weight loss (g) and A is sample surface area (cm)2) T is the experimental time(s) and D is the density (g/cm)3)；
Estimating the size of the corrosion pit by visual observation or measuring the size of the corrosion pit by adopting a metallographic microscope to determine whether the diameter of the corrosion pit is in a millimeter level;
in the step (3) b), the cracks with larger sizes can be observed by naked eyes, and the cracks which can not be observed by the naked eyes need to be observed by a metallographic microscope;
in the step (3) c), the cracks with larger sizes can be observed by naked eyes, and the cracks which can not be observed by the naked eyes need to be observed by a metallographic microscope;
in the step (6), the score is 100 points and is full, the score is 100-80 points and is qualified, the score is tested, the score is 79-60 points and is classified into a risk area, the risk area is consulted with related collaborators to determine the service risk, the score is less than 60 points and is not recommended to be used, and if the score is used, an additional corrosion inhibition method is required or materials are required to be replaced.
Compared with the prior art: compared with a common corrosion experiment, the corrosion evaluation method for the corrosion resistance of the surfacing layer of the underwater oil and gas facility can comprehensively evaluate various properties of the surfacing layer. Meanwhile, the results are quantitatively evaluated, the selection of a surfacing layer material in the oil and gas field development process is effectively guided, a producer is helped to know the potential corrosion risk, and the corrosion failure risk of equipment and pipelines adopting surfacing layers is reduced.
The invention provides quantitative indexes mainly aiming at the corrosion resistance of the corrosion-resistant alloy surfacing layer of the underwater oil and gas facility, can evaluate the corrosion resistance of the surfacing material applied under corresponding working conditions, and guides material selection, welding process evaluation and corrosion control.
Drawings
FIG. 1 is a schematic diagram of a weld overlay structure and a sampling method.
FIG. 2 is a partial erosion profile.
Detailed Description
The present invention will be described below with reference to specific examples, but the present invention is not limited thereto.
The experimental methods used in the following examples are all conventional methods unless otherwise specified; reagents, materials and the like used in the following examples are commercially available unless otherwise specified.
The invention provides a corrosion evaluation method for a corrosion-resistant alloy surfacing layer of an underwater oil and gas facility, which is characterized by quantitatively evaluating the corrosion resistance of the surfacing layer through comprehensive characterization of the organization state, the mechanical property, the overall corrosion rate and the local corrosion risk of the surfacing layer, and specifically comprises the following steps:
step 1: test of structure and mechanical property of surfacing layer
Firstly, using an optical microscope to carry out primary observation, determining the tissue type, estimating the content of harmful phases, checking welding defects and obtaining the proportion of the harmful phases ξIs harmful to. Further analysis can confirm the structure type by means of SEM, EDS, EBSD and the like, and the element distribution and the grain orientation in the weld joint area are obtained.
And measuring the hardness of the matrix and the cross section near the surfacing layer through a hardness experiment, and obtaining the mechanical property parameters of the surfacing layer through a tensile experiment. Through comparing build-up welding layer intensity information and the design stress condition, the suitability of the build-up welding layer is preliminarily judged: if the strength of the surfacing layer is lower than the design stress, the surfacing layer is considered not to meet the design requirements, the following corrosion simulation experiment is not required to be carried out, and the surfacing layer can be judged to be not applicable; otherwise, the corrosion resistance evaluation should be further performed according to the following procedure.
Step 2: corrosion simulation experiment
The experimental parameters can be determined according to the actual production service environment, the experimental medium can be prepared by preparing a simulation solution or directly using field produced liquid, and an analytically pure grade reagent and deionized water are adopted for preparing the simulation solution.
The sample is cut along the direction of the overflowing surface in the actual service process when the corrosion-resistant alloy overlaying layer is sampled, and only the actual overflowing surface is exposed during corrosion evaluation, so that the non-overflowing surface of the sample can be sealed by using a sealing material which does not react with the experimental environment, and the non-overflowing surface of the sample can not contact with an experimental medium in the whole experimental process.
The corrosion simulation experiment should follow the following steps:
the samples should be degreased and polished before the experiment. The degreasing should be performed by cleaning with solvent such as acetone or alcohol in ultrasonic wave, and the polishing should be performed by polishing the experimental sample with waterproof sand paper, and the surface smoothness arithmetic mean deviation Ra should be less than 0.1. The experimental sample should use and be no less than 6 corrosion lacing film, 3 four-point bend or other self-control area load samples, wherein 3 corrosion lacing film are used for utilizing weightlessness method test corrosion-resistant alloy build-up layer comprehensive corrosion rate, and 3 corrosion lacing film are used for sample surface morphology analysis in addition, and then survey build-up layer local corrosion rate, and 3 four-point bend samples are used for analyzing the corrosion-resistant cracking ability of build-up layer.
3 hanging pieces for comprehensive corrosion determination need to be numbered in advance, the exposed area of a sample is measured and calculated before an experiment, the sample is weighed, the calculation of the surface area is accurate to 1%, and an analytical balance with the precision not less than +/-0.1 mg is used during weighing. And sealing other surfaces by using a clamp made of polytetrafluoroethylene or other materials, and only keeping the overflowing surface as an experimental surface. After all the samples are treated, scrubbing the working surface with alcohol, drying with cold air, and placing in a drying dish for later use.
Parameters of the corrosion simulation experiment should be determined according to the working conditions provided on site. The experimental container can be a glass container or a pressure container selected from experimental parameters. The experimental period is set according to the actual working conditions and the material types, and the evaluation of the corrosion-resistant alloy welding line can be carried out for 720 hours. Pure gases or mixtures of gases may be used to simulate an actual corrosive gas environment. The parameters of the corrosion environment need to be controlled to be stable in the experimental process.
And step 3: overlaying layer evaluation index and calculation method
And (4) taking out the sample after the experiment is finished, cleaning with deionized water, dehydrating with acetone, and drying with cold air. Correctly selecting a rust remover and rust removing time according to the related requirements of GB/T16545-2015 cleaning corrosion products on corrosion samples of metals and alloys, removing the corrosion products on the surfaces of the samples, and recording the quality loss W of the corrosion samples; measuring the local corrosion depth by using a laser confocal microscope or other depth testing instruments to obtain the maximum local corrosion depth d; and observing the cracking condition of the four-point bend or other self-made load-bearing samples by using an optical microscope.
(1) General corrosion rate vAll-purpose
Calculating to obtain the general corrosion rate v of the overlaying layer by utilizing a weight loss methodAll-purpose，
Figure BDA0002622389930000061
Wherein v is corrosionRate (mm/a), K8.76 × 104W is sample weight loss (g) and A is sample surface area (cm)2) T is the experimental time(s) and D is the density (g/cm)3)。
(2) Local corrosion rate vOffice
With the maximum local corrosion depth d, the local corrosion rate can be calculated as follows:
Figure BDA0002622389930000062
wherein d is the maximum local etch depth (mm).
(3) Mechanical Property parameter ξMechanics of force
The yield strength obtained in the experiment was compared with the standard data given in ISO15156, and the mechanical properties ξ were calculated according to the following formulaMechanics of force：
Figure BDA0002622389930000063
Wherein a isSign boardFor the standard values given in ISO15156, a is the actual value tested in step one.
And 4, step 4: evaluation of Corrosion resistance of Corrosion resistant alloy overlay
The samples should first be checked for the following:
(1) the average corrosion value of the corrosion coupon sample is satisfactory, but corrosion pits with the diameter of millimeter level appear at one or more positions.
(2) Cracking occurs in one or more than one parallel sample in the stress corrosion test.
(3) The bonding between the welding layers has failure phenomena such as cracking and the like.
When the above-mentioned situation occurs, it is considered that the material is not passed, and the materials should be discussed with the partner, the experiment should be repeated, the sample should be examined, the experimental conditions should be revised, and the detailed rules should be implemented.
If the above situation does not occur, the evaluation indexes of the surfacing layer can be assigned according to the following formula:
(1) general corrosion Rate index F1
According to different corrosion rates, the overall corrosion rate index F1And (4) carrying out assignment, wherein the assignment method comprises the following steps:
when v isAll-purposeWhen the thickness is less than or equal to 0.2mm/a, the thickness is 2
When the thickness is 0.2mm/a<vAll-purposeWhen the grain size is less than or equal to 0.5mm/a, the grain size is 1
When the thickness is 0.5mm/a<vAll-purposeWhen is 0
(2) Local corrosion rate index F2
According to local corrosion rate to F2And (4) carrying out assignment, wherein the assignment method comprises the following steps:
when v isOfficeWhen the thickness is less than or equal to 0.2mm/a, the thickness is 2
When the thickness is 0.2mm/a<vOfficeWhen the thickness is less than or equal to 1.3mm/a, the thickness is 1
When the thickness is 1.3mm/a<vOfficeWhen is 0
(3) Harmful phase ratio index F3
According to different parent metals and welding processes, counting the number of harmful phases precipitated in a weld joint tissue, counting the proportion of harmful phases by selecting random field counting or applying image software, and according to the index F of the proportion of harmful phases to the proportion of harmful phases3And (4) carrying out assignment, wherein the assignment method comprises the following steps:
when ξHarmful phaseWhen the content is less than or equal to 1 percent, the content is 2
When the content is 1 percent<ξHarmful phaseWhen the content is less than or equal to 3 percent, the content is 1
When the content is 3 percent<ξHarmful phaseWhen is 0
(4) Mechanical Property index F4
The weld overlay was evaluated according to the mechanical parameters given in ISO15156, mechanical index F4The assignment method is as follows:
completely meets the standard requirement and is 2.
Within 3% of the standard deviation, 1.
0 with a standard deviation of 3% or more.
The corrosion resistance of the corrosion resistant alloy surfacing layer can be quantitatively scored through the indexes:
corrosion resistance of overlay layer of 10F1+10F2+10F3+20F4
And 5: comprehensive conclusion
And evaluating the corresponding corrosion risk according to the score, wherein the score is 100 and full, the score is 100-80 and qualified, the score is 79-60 and tested, the score is a risk area, the risk area is determined by commenting with related collaborators, the service risk is not recommended below 60, and if the corrosion risk area is put into use, an additional corrosion inhibition method is required or materials are required to be replaced.
Examples
The corrosion risk of a 625 overlaying layer is researched, the overlaying layer is made of a nickel-based alloy 625, and the base material is X65.
The sample was cut along the weld line, leaving only the upper weld overlay portion.
The sample is subjected to mechanical property, metallographic structure and hardness test. And (4) preparing a metallographic sample, and carrying out metallographic observation on the middle welding seam part of the metallographic sample by using an optical microscope, wherein no harmful phase is found. And respectively testing the hardness of the weld zone, the heat affected zone and the base material at 3 points, wherein the hardness test result meets the requirements of the ISO-15156 standard. And (4) manufacturing a tensile sample, and testing to obtain corresponding mechanical property parameters, wherein the result meets the ISO-15156 standard requirement.
The test is carried out by adopting a long-period corrosion simulation experiment, the experimental environment is specified according to the field working condition, wherein the total pressure is 13.7MPa, and CO is2The partial pressure is 0.50MPa, the temperature is 30 ℃, the water content is 2-5%, the liquid phase flow rate is 0.77m/s, the test period is 720h, and the main ionic components in the solution are shown in Table 1. The experimental sample respectively includes 6 corrosion lacing films, 3 four-point bending samples, wherein 3 corrosion lacing films are used for comprehensive corrosion rate determination, the other 3 corrosion lacing films are used for sample surface morphology analysis, and the 3 four-point bending samples are used for testing the sensitivity of the surfacing layer to stress corrosion cracking.
Table 1 experimental simulated conditions environment
Figure BDA0002622389930000081
After the soaking experiment is finished, the test sample is taken out, and the cracking condition is found on the surfaces of 3 four-point bent samples. The local corrosion condition occurring in the weld joint area is observed and measured by using SEM, and the corrosion morphology is shown in FIG. 2:
obvious local corrosion occurs near a weld joint fusion line, and the overall corrosion rate is calculated by a weight loss method to be 0.2mm/a<vAll-purposeLess than or equal to 0.5mm/a, and low corrosion rate; and (3) analyzing the corrosion morphology, determining the maximum local corrosion depth, and calculating to obtain that the local corrosion rate is greater than 1.3mm/a and the local corrosion risk of the surfacing layer is higher.
By combining the data, the general corrosion rate is 0.2mm/a<vAll-purposeLess than or equal to 0.5mm/a, F1Is 1, local corrosion rate is more than 1.3mm/a, F20, no harmful phase detected, less than 1%, F3Is 2, the mechanical properties meet the requirements related to ISO15156-3, F4Is 2. According to the evaluation formula of the corrosion resistance of the overlaying layer:
10F1+10F2+10F3+20F4
the calculated corrosion resistance of the corrosion-resistant alloy overlaying layer is 10+0+20+40 to 70, which indicates that the X65 and 625 overlaying materials have certain corrosion risk, and the materials need to be negotiated with a construction party before being put into application so as to ensure the normal service of the materials.

Claims (7)

1. A corrosion evaluation method for a corrosion-resistant alloy overlaying layer of an underwater oil and gas facility comprises the following steps: and quantitatively evaluating the corrosion resistance of the surfacing layer by comprehensively representing the texture state, the mechanical property, the overall corrosion rate and the local corrosion risk of the surfacing layer.
2. The method of claim 1, wherein: the method comprises the following steps:
(1) testing harmful phase proportion and mechanical property in a matrix and a welding seam tissue near the surfacing layer; determining the type of matrix and internal structure near the overlay welding layer by using an optical microscope, estimating the content of harmful phases, inspecting welding defects, observing by using a metallographic microscope and measuring the harmful phases by using image analysis software or by using a gridding methodLike volume fraction, harmful phase ratio ξ is obtainedHarmful phaseMeasuring the hardness of a matrix and a cross section near the surfacing layer through a hardness experiment, obtaining the yield strength of the surfacing layer through a tensile experiment test, marking as a, and obtaining a mechanical property parameter ξ through calculation by using a formulaMechanics of forcePreliminarily judging the applicability of the surfacing layer by comparing the strength information of the surfacing layer with the design stress condition;
Figure FDA0002622389920000011
wherein a isSign boardA is a weld overlay yield strength value obtained by a tensile test, which is a standard value given in ISO 15156;
(2) sampling based on a sampling principle aiming at the surfacing layer, and carrying out a corrosion simulation experiment according to the determined environmental parameters of the corrosion simulation experiment; taking out the test sample after the experiment is finished, cleaning, dehydrating, drying, removing corrosion products on the surface of the test sample, and recording the quality loss W of the corrosion sample; measuring the local corrosion depth to obtain the maximum pitting depth d; observing the cracking condition;
(3) preliminarily evaluating the corrosion resistance of the overlaying layer after the step (2), and when one of the following conditions a) to c) occurs, judging that the corrosion resistance of the overlaying layer does not meet the requirement:
a) general corrosion rate V of corrosion couponAll-purposeLess than 0.5mm/a, but at one or more locations corrosion pits of the order of millimetres in diameter are present;
b) one or more samples have cracking conditions in the stress corrosion test;
c) failure phenomena such as cracking and the like occur at the joint position between the welding layers;
(4) if the failure problem in the step (3) does not occur in the surfacing layer, calculating the numerical values of all the influence factors for evaluating the corrosion resistance of the surfacing layer, and calculating the overall corrosion rate and the local corrosion rate according to the corrosion weightlessness W of the surfacing layer obtained by the sample weight loss analysis in the step (2) and the measured maximum pit depth d of the spot, wherein the calculation formula is as follows:
Figure FDA0002622389920000012
Figure FDA0002622389920000013
in the formula vAll-purposeThe corrosion rate (mm/a) is determined by K8.76 × 104W is sample weight loss (g) and A is sample surface area (cm)2) T is the experimental time(s) and D is the density (g/cm)3)；
vOfficeLocal corrosion rate (mm/a); d is the maximum pit depth (mm);
(5) assigning values to evaluation indexes for evaluating the corrosion resistance of the overlaying layer according to the values of the influence factors calculated in the steps (1) and (4),
the assignment method comprises the following steps:
a. general corrosion Rate index F1
When v isAll-purposeWhen the grain size is less than or equal to 0.2mm/a, F1Is 2
When the thickness is 0.2mm/a<vAll-purposeWhen the grain size is less than or equal to 0.5mm/a, F1Is 1
When the thickness is 0.5mm/a<vAll-purposeWhen F is present1Is 0
b. Local corrosion rate index F2
When v isOfficeWhen the grain size is less than or equal to 0.2mm/a, F2Is 2
When the thickness is 0.2mm/a<vOfficeWhen the grain size is less than or equal to 1.3mm/a, F2Is 1
When the thickness is 1.3mm/a<vOfficeWhen F is present2Is 0
c. Harmful phase ratio index F3
When ξHarmful phaseWhen the content is less than or equal to 1 percent, the content is 2
When the content is 1 percent<ξHarmful phaseWhen the content is less than or equal to 3 percent, the content is 1
When the content is 3 percent<ξHarmful phaseWhen is 0
d. Mechanical Property index F4
The weld overlay was evaluated according to the mechanical parameters given in ISO15156, mechanical index F4The assignment method is as follows:
completely meets the standard requirement and is 2;
within 3% of the standard deviation (finger ξ)Mechanics of forceLess than or equal to 3%) to 1;
more than 3% of the standard deviation (finger ξ)Mechanics of forceGreater than 3%) to 0;
(6) and quantitatively scoring the corrosion resistance of the corrosion-resistant alloy surfacing layer through the indexes: corrosion resistance of overlay layer of 10F1+10F2+10F3+20F4(ii) a The corresponding corrosion risk is evaluated according to the score.
3. The method of claim 2, wherein: in the step (2), the principle of sampling the surfacing layer in the corrosion simulation experiment is as follows: and cutting the sample along the direction of the overflowing surface in the actual service process when the corrosion-resistant alloy overlaying layer is sampled, and only exposing the actual overflowing surface during corrosion evaluation.
4. A method according to claim 2 or 3, characterized in that: the environmental parameters of the corrosion simulation experiment are determined according to the actual production service environment, the experiment medium is the prepared simulation solution or the field produced liquid is directly used,
preparing a simulation solution by adopting an analytically pure grade reagent and deionized water;
pure gas or mixed gas is used for simulating an actual corrosive gas environment, the experimental period is determined according to the working condition provided on site, and 720 hours are adopted for corrosion resistant alloy weld joint evaluation.
5. The method according to any one of claims 2-4, wherein: the maximum pit depth d is determined by means of a pitting depth finder or a laser confocal microscope.
6. The method according to any one of claims 2-5, wherein:
in the step (3) a), the step (c),
Figure FDA0002622389920000031
in the formula vAll-purposeThe corrosion rate (mm/a) is determined by K8.76 × 104W is sample weight loss (g) and A is sample surface area (cm)2) T is the experimental time(s) and D is the density (g/cm)3)；
Estimating the size of the corrosion pit by visual observation or measuring the size of the corrosion pit by adopting a metallographic microscope to determine whether the diameter of the corrosion pit is in a millimeter level;
in the step (3) b), the cracks with larger sizes are observed by naked eyes, and the cracks which cannot be observed by the naked eyes are observed by a metallographic microscope;
in the step (3) c), the cracks with larger sizes are observed by naked eyes, and the cracks which cannot be observed by the naked eyes are observed by a metallographic microscope.
7. The method according to any one of claims 2-6, wherein: in the step (6), the score is 100 points and is full, the score is 100-80 points and is qualified, the score is tested, the score is 79-60 points and is classified into a risk area, the risk area is consulted with related collaborators to determine the service risk, the score is less than 60 points and is not recommended to be used, and if the score is used, an additional corrosion inhibition method is required or materials are required to be replaced.
CN202010787052.3A 2020-08-07 2020-08-07 Corrosion evaluation method for corrosion-resistant alloy overlaying layer of underwater oil and gas facility Active CN111721619B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202010787052.3A CN111721619B (en) 2020-08-07 2020-08-07 Corrosion evaluation method for corrosion-resistant alloy overlaying layer of underwater oil and gas facility

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202010787052.3A CN111721619B (en) 2020-08-07 2020-08-07 Corrosion evaluation method for corrosion-resistant alloy overlaying layer of underwater oil and gas facility

Publications (2)

Publication Number Publication Date
CN111721619A true CN111721619A (en) 2020-09-29
CN111721619B CN111721619B (en) 2022-12-20

Family

ID=72574255

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202010787052.3A Active CN111721619B (en) 2020-08-07 2020-08-07 Corrosion evaluation method for corrosion-resistant alloy overlaying layer of underwater oil and gas facility

Country Status (1)

Country Link
CN (1) CN111721619B (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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
CN113945508A (en) * 2021-09-28 2022-01-18 国网浙江省电力有限公司绍兴供电公司 Device for testing corrosion influence of power grid on buried pipe network
CN115112549A (en) * 2022-06-17 2022-09-27 天津大学 Sampling method for evaluation test of corrosion resistance of metal surfacing layer

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102156089A (en) * 2011-01-18 2011-08-17 中国石油天然气股份有限公司 Method for evaluating corrosion in buried pipeline
CN102967547A (en) * 2012-11-07 2013-03-13 中国电器科学研究院有限公司 Method for measuring corrosion rate of steel structure in full-service life period
CN104122196A (en) * 2014-07-15 2014-10-29 北京工业大学 Method for evaluating corrosion of DC stray current on high strength steel for oil gas pipeline under stress condition
JP2015081901A (en) * 2013-10-24 2015-04-27 株式会社東芝 Nuclear facilities soundness evaluation method and nuclear facilities soundness evaluation system
CN106896052A (en) * 2017-01-25 2017-06-27 北京航空航天大学 A kind of aluminium alloy seawater accelerated corrosion test method
CN107271359A (en) * 2017-04-27 2017-10-20 复旦大学 Nearby stray electrical current causes the synthetic determination method that buried gas metal pipeline corrodes to a kind of subway line
CN107557616A (en) * 2017-09-27 2018-01-09 宝钢特钢有限公司 A kind of temperature gas cooled reactor steam generator abros tubing and its manufacture method
CN109781611A (en) * 2018-12-10 2019-05-21 苏州热工研究院有限公司 Method for quantitatively evaluating for long service PWR of Nuclear Power Station main pipeline stress corrosion cracking
CN109813612A (en) * 2019-03-04 2019-05-28 鞍钢股份有限公司 A kind of test method of oil well pipe anti-H 2 S stress corrosion performance
CN111089831A (en) * 2020-01-03 2020-05-01 北京科技大学 Corrosion resistance evaluation method of low-alloy structural steel

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102156089A (en) * 2011-01-18 2011-08-17 中国石油天然气股份有限公司 Method for evaluating corrosion in buried pipeline
CN102967547A (en) * 2012-11-07 2013-03-13 中国电器科学研究院有限公司 Method for measuring corrosion rate of steel structure in full-service life period
JP2015081901A (en) * 2013-10-24 2015-04-27 株式会社東芝 Nuclear facilities soundness evaluation method and nuclear facilities soundness evaluation system
CN104122196A (en) * 2014-07-15 2014-10-29 北京工业大学 Method for evaluating corrosion of DC stray current on high strength steel for oil gas pipeline under stress condition
CN106896052A (en) * 2017-01-25 2017-06-27 北京航空航天大学 A kind of aluminium alloy seawater accelerated corrosion test method
CN107271359A (en) * 2017-04-27 2017-10-20 复旦大学 Nearby stray electrical current causes the synthetic determination method that buried gas metal pipeline corrodes to a kind of subway line
CN107557616A (en) * 2017-09-27 2018-01-09 宝钢特钢有限公司 A kind of temperature gas cooled reactor steam generator abros tubing and its manufacture method
CN109781611A (en) * 2018-12-10 2019-05-21 苏州热工研究院有限公司 Method for quantitatively evaluating for long service PWR of Nuclear Power Station main pipeline stress corrosion cracking
CN109813612A (en) * 2019-03-04 2019-05-28 鞍钢股份有限公司 A kind of test method of oil well pipe anti-H 2 S stress corrosion performance
CN111089831A (en) * 2020-01-03 2020-05-01 北京科技大学 Corrosion resistance evaluation method of low-alloy structural steel

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
JINYANG ZHU 等: "In situ marine exposure study on corrosion behaviors of five alloys in coastal waters of western Pacific Ocean", 《JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T》 *
李渭亮 等: "CO2渗入对C110管柱在甲酸盐完井液中腐蚀行为的影响", 《材料保护》 *
税正伟等: "L245NCS/316L双金属复合管焊接接头组织性能分析", 《材料导报》 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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
CN113945508A (en) * 2021-09-28 2022-01-18 国网浙江省电力有限公司绍兴供电公司 Device for testing corrosion influence of power grid on buried pipe network
CN115112549A (en) * 2022-06-17 2022-09-27 天津大学 Sampling method for evaluation test of corrosion resistance of metal surfacing layer
CN115112549B (en) * 2022-06-17 2023-03-14 天津大学 Sampling method for evaluation test of corrosion resistance of metal surfacing layer

Also Published As

Publication number Publication date
CN111721619B (en) 2022-12-20

Similar Documents

Publication Publication Date Title
CN111721619B (en) Corrosion evaluation method for corrosion-resistant alloy overlaying layer of underwater oil and gas facility
Biezma et al. Non-destructive techniques for the detection of sigma phase in duplex stainless steel: A comprehensive review
Caines et al. Analysis of pitting corrosion on steel under insulation in marine environments
Prosek et al. Low-temperature stress corrosion cracking of austenitic and duplex stainless steels under chloride deposits
Ruiz-Cabañas et al. Materials selection for thermal energy storage systems in parabolic trough collector solar facilities using high chloride content nitrate salts
Shibata Application of extreme value statistics to corrosion
Nuhi et al. Reliability analysis for degradation effects of pitting corrosion in carbon steel pipes
Vukelic et al. Analysis of prolonged marine exposure on properties of AH36 steel
CN111982705A (en) Economical anti-H2S-CO2Stress corrosion performance testing method for oil well pipe
Roberge Statistical interpretation of corrosion test results
Latypova et al. Novel stress corrosion testing method for high‐strength steels
Larsson Evaluation of current methods for creep analysis and impression creep testing of power plant steels
Zhang et al. Research on TIG welding gap corrosion resistance of X52/825 metallurgical clad pipein H2S/CO2 environment
Gabetta et al. Engineering thoughts on hydrogen embrittlement
Eggum Hydrogen in low carbon steel: Diffusion, effect on tensile properties, and an examination of hydrogen’s role in the initiation of stress corrosion cracking in a failed pipeline
Álvarez et al. Fatigue life estimation of pre-corroded 42CrMo4 subjected to accelerated pitting corrosion method
CN114034272B (en) Method for measuring and calculating weld penetration of build-up welding
Pettersson et al. Corrosion testing of welds, a review of methods
Starokon Estimation of efficiency of the thermal diagnostic method for detecting corrosion defects of fixed offshore platforms
Holtam et al. An investigation into fatigue crack growth test methods in sour environment
Yahi et al. Experimental approach to monitoring the degradation status of pipelines transporting hydrocarbons
Mickalonis et al. The Use of electrochemical noise measurements with nuclear waste tanks
Hesketh et al. effect of pigging damage on sulfide stress corrosion cracking of type 316L stainless steel cladding
Ermakova et al. Fatigue and corrosion-fatigue crack growth behavior of wire arc additively manufactured parts
Vo Effect of Mechanical Loading Conditions on Near-neutral pH Stress Corrosion Cracking (NNpHSCC) Initiation and Early-stage Growth for Bent Pipeline

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
GR01 Patent grant
GR01 Patent grant