CN115855152A - Safety evaluation method for heated surface pipe of non-destructive in-service unit - Google Patents
Safety evaluation method for heated surface pipe of non-destructive in-service unit Download PDFInfo
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- CN115855152A CN115855152A CN202211514432.5A CN202211514432A CN115855152A CN 115855152 A CN115855152 A CN 115855152A CN 202211514432 A CN202211514432 A CN 202211514432A CN 115855152 A CN115855152 A CN 115855152A
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Abstract
The invention particularly relates to a safety evaluation method for a heated surface pipe of a non-destructive in-service unit. The safety evaluation method comprises the following steps: s1, macroscopically inspecting; s2, measuring the wall thickness; s3, component analysis; s4, metallographic detection; and S5, detecting the hardness of the thin-walled tube. Mainly aiming at the thin-wall pipe section with the wall thickness of 5-25mm, the materials are mainly concentrated on common carbon steel, low alloy steel, high alloy steel, stainless steel and the like. The on-site precise detection of the on-site Leeb hardness of the thin-walled pipe is realized, and meanwhile, the on-site supervision and detection means is combined to perform rapid safety evaluation on the pipe state of the heated surface of the in-service unit.
Description
Technical Field
The invention belongs to the technical field of field safety evaluation in the power generation industry, and particularly relates to a safety evaluation method for a heated surface pipe of a non-destructive in-service unit.
Background
The cogeneration is a high-efficiency energy production mode for the combined production of heat energy and electric energy, the cogeneration scale of China is the second place in the world, the thermal power generating unit is gradually changed into a flexible operation mode such as peak shaving from the basic nuclear action of a power generation system, the operation mode is more complex and the operation working condition is worse than that of the cogeneration unit of a common thermal power generating unit, and accidents are caused by early failure of important parts in recent years.
When the combined heat and power generation carries out deep peak regulation, the quality of industrial steam and heating steam is ensured not to be reduced, the output power index is ensured to meet the requirement, the coal-fired boiler is in a running state with severe load change, and the key parts such as a heating surface pipe and the like are greatly influenced by the equal start-up and stop times of the unit, the load lifting times and the peak regulation amplitude of the speed lifting rate. The means for carrying out safety evaluation on the heated surface tube of the boiler at the present stage is mainly that a laboratory carries out metal supervision on the heated surface tube subjected to spot inspection to carry out safety evaluation, and carries out reason analysis on the heated surface tube after the heated surface tube fails to work so as to carry out safety evaluation, but the two have limitations which can not meet the industrial requirements of safety performance evaluation of a field nondestructive heated surface tube bank and integral safety evaluation of overtemperature and overpressure of a large-area tube system, so that the search for a new technology and a new means to carry out field heated surface tube safety performance evaluation becomes more important.
In the past four years of non-stop accidents, the leakage percentage of the four pipes of the boiler is found to be 50%, the welding problem and the overtemperature phenomenon percentage of the four pipes in the leakage reason is up to 42%, the operation safety of the four pipes of the boiler is seriously threatened, and the increase of metal supervision and safety performance evaluation on the four pipes of the boiler becomes the first task in the present stage and in the future. However, the safety evaluation after the failure of four pipes of the boiler at the present stage is difficult to perform, such as short maintenance period, difficulty in large-range pipe cutting and sampling, increased safety risk due to welding after pipe cutting, difficulty in performing on-site welding and sampling on dissimilar steel welding seams, and incapability of realizing accurate detection on small-diameter thin-walled pipe materials with the thickness of less than 25mm temporarily by adopting a hardness mechanical property detection means on the site.
Disclosure of Invention
In order to solve the problems, the invention takes the problems as a breakthrough point, develops the technical research of rapid safety evaluation of the heated surface pipe of the non-destructive on-service unit with wide coverage and high economy based on-site hardness detection, can solve the technical problem of industry, can also meet the experimental mode of low carbon and environmental protection, and practically ensures the safe operation of the on-service unit.
The method comprises the following steps:
s1, macroscopic examination: judging the quality condition of the thin-wall heated surface pipe integrally by adopting an intuitive visual detection means;
s2, wall thickness measurement: measuring the thickness of the thin-wall heated surface pipe by using an ultrasonic thickness gauge;
s3, component analysis: judging the material of the thin-wall heated surface tube by adopting a handheld spectral analysis detector;
s4, metallographic detection: according to the component analysis result and the actual condition, performing tissue analysis on the thin-wall pipe by adopting a surface replica technology;
s5, detecting the hardness of the thin-walled tube: and carrying out on-site hardness detection work by adopting a standardized experimental process and matching with a Leeb hardness tester, substituting the real-time detection value into a correction formula for calculation to obtain a converted Brinell hardness value, and further realizing on-site hardness detection of thin-wall pipes of different materials and specifications.
Further, the step S1 includes:
checking the content: whether the thin-wall heated surface pipe has integral deformation and local deformation; the inner and outer surfaces of the pipe wall are not corroded, cracked or damaged; presence or absence of forming, assembly defects and welding defects;
an inspection means: the examination can be carried out by naked eyes or by means of a low power magnifying glass, a reflector, an endoscope and a flashlight;
and (3) checking: the method comprises the following steps of firstly, carrying out overall inspection and weld joint inspection on a thin-wall heated surface tube by eyes, and observing whether the surface of the tube wall has defects or not by irradiating single-beam light of a flashlight during visual inspection; when the detected part can not be close to the observation, the observation is carried out by a reflector or an endoscope, when the surface of the pipe wall has the problems of cracks or corrosion and dirt, the metal surface is wiped by abrasive cloth and then observed by a magnifying glass, and whether other methods are needed to be carried out on some parts or not is judged on the basis.
Further, the step S2 specifically includes:
s21, calibration: calibrating a standard test block configured by a detection instrument, adjusting the reading of the instrument to be consistent with the thickness of the test block, and then measuring the thickness of the steel material;
s22, preparation: the surface of the pipe wall is required to be smooth and flat, and when the requirement cannot be met, the pipe wall is polished;
s22, measurement: the couplant is adopted during thickness measurement, the probe is placed stably, and the pressure is proper; multipoint measurements were used.
Further, the multipoint measurement method is a method in which a plurality of measurements are performed with one measurement point as the center, and the minimum value is taken as the measured thickness value.
Further, the step S3 specifically includes:
s31, before analysis, checking whether an incident slit, a light path lens, an electrode condition, argon purity and pressure of the spectrometer are normal or not;
s32, keeping the analysis conditions and the environmental conditions of the detected material and the standard substance strictly consistent during analysis;
and S33, analyzing the detected material with uniform components, exciting and measuring for at least three times, and taking the average value as an analysis result, wherein the analysis result is expressed by percentage.
Further, the step S4 specifically includes:
s41, grinding a sample: fine grinding by using a grinding wheel of a handheld sample grinding device;
s42, polishing: polishing by using diamond polishing paste by adopting a mechanical polishing means;
s43, corrosion: adopting wiping type corrosion;
s44, replication: performing replica molding by using an acetone solution;
s45, observation: and observing the metallographic structure by adopting a portable microscope on site after the remodeling to obtain a structure judgment conclusion.
Further, the duplicating operation is:
dripping an acetone solution onto the etched replica point by a dropper, covering a replica film, extruding bubbles in the replica film by hand from one end after the replica film is covered on the replica point, drying the replica film, and removing and marking; the marked carrier is used, after cutting, the back of the replica film is directly adhered to the adhesive sticker on the current surface, the original seal paper of the adhesive sticker is covered, the replica film is pressed flat by hand, and the replica film is clamped by another carrier for storage.
Further, the standardized experimental process in step S5 specifically includes:
s51, polishing: roughly polishing by using an angle grinder with a grinding wheel, removing oxide skin and exposing metallic luster; vertically grinding the grinding trace of the previous grinding trace by using an angle grinder with a No. 200 abrasive paper blade wheel until the grinding trace of the grinding wheel is removed; vertically polishing the previous polishing trace by using portable metallographic polishing equipment with a polishing head until the polishing trace of the sand paper blade wheel is removed; smearing polishing paste, and vertically polishing the polishing paste and the last polishing trace by using portable metallographic polishing equipment with a polishing head until the polishing paste is in a mirror surface state;
s52, clamping: when the Richter hardness is detected, a laboratory bench clamp or a special field clamping device is used for stably clamping a detected sample, a threaded handle of the bench clamp or clamping equipment is loosened, the detected sample is put in, and the threaded handle of the clamping equipment is screwed so that the sample is firmly fixed and cannot be clamped tightly until the sample deforms;
s53, hardness measurement: adjusting a corresponding experiment angle on an adjustment interface of the Richter hardness tester, aligning the polished detection surface, holding the hardness tester by one hand to couple the support ring with the detected surface, ensuring that the impact direction of the D-type impact body of the Richter hardness tester is vertical to the detected surface, pressing a button of the portable Richter hardness tester by the other hand to release the impact body, and reading and recording.
Further, the correction formula in step S5 is as follows, wherein HBW represents brinell hardness, HLD represents hardness in richter:
carbon steel: HBW =0.0349HLD 2 -8.4112HLD+633.5749；
Low alloy steel: HBW = -0.0271HLD 2 +10.6691HLD-852.687；
High alloy steel: HBW = -0.0313HLD 2 +7.1042HLD-176.8095；
Stainless steel HBW = -0.0744HLD 2 +24.5256HLD-1801.6606。
The invention has the beneficial effects that: the invention particularly provides a quick safety evaluation method for a heating surface pipe of a non-destructive in-service unit, which is suitable for heating surface pipe parts of various coal-fired thermal power generating units, mainly aiming at thin-wall pipe sections with the wall thickness of 5-25mm, and mainly focusing materials on relatively common carbon steel, low alloy steel, high alloy steel, stainless steel and the like. The on-site precise detection of the on-site Leeb hardness of the thin-walled pipe is realized, and meanwhile, the on-site supervision and detection means is combined to perform rapid safety evaluation on the pipe state of the heated surface of the in-service unit.
Drawings
FIG. 1 is a flow chart of the method of the present invention.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The method provided by the embodiment comprises the following steps:
s1, macroscopic examination: judging the quality condition of the thin-wall heated surface pipe integrally by adopting an intuitive visual detection means;
s2, wall thickness measurement: measuring the thickness of the thin-wall heated surface pipe by using an ultrasonic thickness gauge;
s3, component analysis: judging the material of the thin-wall heated surface tube by adopting a handheld spectral analysis detector;
s4, metallographic detection: according to the component analysis result and the actual situation, performing tissue analysis on the thin-walled tube by adopting a surface replica technology;
s5, detecting the hardness of the thin-walled tube: and carrying out on-site hardness detection work by adopting a standardized experimental process and matching with a Leeb hardness tester, substituting the real-time detection value into a correction formula for calculation to obtain a converted Brinell hardness value, and further realizing on-site hardness detection of thin-wall pipes of different materials and specifications.
The step S1 includes:
checking the content that whether the thin-wall heated surface pipe has integral deformation and local deformation; the inner and outer surfaces of the pipe wall are not corroded, cracked or damaged; presence or absence of forming, assembly defects and welding defects;
an inspection means: the examination can be carried out by naked eyes or by means of a low power magnifier, a reflector, an endoscope and a flashlight;
and (3) checking: the method comprises the following steps of firstly, carrying out overall inspection and weld joint inspection on a thin-wall heated surface tube by eyes, and observing whether the surface of the tube wall has defects or not by irradiating single-beam light of a flashlight during visual inspection; when the detected part can not approach to the observation, the observation is carried out by a reflector or an endoscope, when the surface of the pipe wall has the problems of cracks or corrosion and dirt, the metal surface is wiped by abrasive cloth and then observed by a magnifying glass, and on the basis, whether other methods are needed to be carried out on some parts is judged.
The step S2 specifically comprises the following steps:
s21, calibration: calibrating a standard test block configured by a detection instrument, adjusting the reading of the instrument to be consistent with the thickness of the test block, and then measuring the thickness of the steel material;
s22, preparation: the surface of the pipe wall is required to be smooth and flat, and when the requirement cannot be met, the pipe wall is polished;
s22, measurement: the couplant is adopted during thickness measurement, the probe is placed stably, and the pressure is proper; a multi-point measurement method is adopted.
The multi-point measurement method is to measure for multiple times by taking one measurement point as a center, and take the minimum value as the measured thickness value.
The step S3 specifically comprises the following steps:
s31, before analysis, checking whether an incident slit, a light path lens, an electrode condition, argon purity and pressure of the spectrometer are normal or not;
s32, keeping the analysis conditions and the environmental conditions of the detected material and the standard substance strictly consistent during analysis;
and S33, analyzing the detected material with uniform components, exciting and measuring for at least three times, and taking the average value as an analysis result, wherein the analysis result is expressed by percentage.
The step S4 specifically comprises the following steps:
s41, grinding a sample: fine grinding by using a grinding wheel of a handheld sample grinding device;
s42, polishing: polishing by using diamond polishing paste by adopting a mechanical polishing means;
s43, corrosion: adopting wiping type corrosion;
s44, replica: performing replica molding by using an acetone solution;
s45, observation: and observing the metallographic structure by adopting a portable microscope on site after the remodeling to obtain a structure judgment conclusion.
The replica specifically operates as follows:
dripping an acetone solution onto the etched replica point by a dropper, covering a replica film, extruding bubbles in the replica film by hand from one end after the replica film is covered on the replica point, drying the replica film, and removing and marking; the marked carrier is used, after cutting, the back of the replica film is directly adhered to the adhesive sticker on the current surface, the original seal paper of the adhesive sticker is covered, the replica film is pressed flat by hand, and the replica film is clamped by another carrier for storage.
Step S5, the standardized experimental process specifically comprises the following steps:
s51, polishing: roughly polishing by using an angle grinder with a grinding wheel, removing oxide skin and exposing metallic luster; vertically grinding the grinding trace of the previous grinding trace by using an angle grinder with a No. 200 abrasive paper blade wheel until the grinding trace of the grinding wheel is removed; vertically polishing the previous polishing trace by using portable metallographic polishing equipment with a polishing head until the polishing trace of the sand paper blade wheel is removed; smearing polishing paste, and vertically polishing the polishing paste and the last polishing trace by using portable metallographic polishing equipment with a polishing head until the polishing paste is in a mirror surface state;
s52, clamping: when the Richter hardness is detected, a laboratory bench clamp or a special field clamping device is used for stably clamping a detected sample, a threaded handle of the bench clamp or clamping equipment is loosened, the detected sample is put in, and the threaded handle of the clamping equipment is screwed so that the sample is firmly fixed and cannot be clamped tightly until the sample deforms;
s53, hardness measurement: adjusting a corresponding experiment angle on an adjustment interface of the Richter hardness tester, aligning the polished detection surface, holding the hardness tester by one hand to couple the support ring with the detected surface, ensuring that the impact direction of the D-type impact body of the Richter hardness tester is vertical to the detected surface, pressing a button of the portable Richter hardness tester by the other hand to release the impact body, and reading and recording.
The correction formula in step S5 is as follows, where HBW represents brinell hardness, HLD represents hardness in richter:
carbon steel: HBW =0.0349HLD 2 -8.4112HLD+633.5749；
Low alloy steel: HBW = -0.0271HLD 2 +10.6691HLD-852.687；
High alloy steel: HBW = -0.0313HLD 2 +7.1042HLD-176.8095；
Stainless steel HBW = -0.0744HLD 2 +24.5256HLD-1801.6606。
Claims (9)
1. A safety evaluation method for a heated surface pipe of a non-destructive in-service unit is characterized by comprising the following steps:
s1, macroscopic examination: judging the quality condition of the thin-wall heated surface pipe integrally by adopting an intuitive visual detection means;
s2, wall thickness measurement: measuring the thickness of the thin-wall heated surface pipe by using an ultrasonic thickness gauge;
s3, component analysis: judging the material of the thin-wall heated surface tube by adopting a handheld spectral analysis detector;
s4, metallographic detection: according to the component analysis result and the actual situation, performing tissue analysis on the thin-walled tube by adopting a surface replica technology;
s5, detecting the hardness of the thin-walled tube: and carrying out on-site hardness detection work by adopting a standardized experimental process and matching with a Leeb hardness tester, substituting the real-time detection value into a correction formula for calculation to obtain a converted Brinell hardness value, and further realizing on-site hardness detection of thin-wall pipes of different materials and specifications.
2. The security evaluation method according to claim 1, wherein the step S1 includes:
checking the content: whether the thin-wall heated surface pipe has integral deformation and local deformation; the inner and outer surfaces of the pipe wall are not corroded, cracked or damaged; presence or absence of forming, assembly defects and welding defects;
an inspection means: the examination can be carried out by naked eyes or by means of a low power magnifying glass, a reflector, an endoscope and a flashlight;
and (3) checking: the method comprises the following steps of firstly, carrying out overall inspection and weld joint inspection on a thin-wall heated surface tube by eyes, and observing whether the surface of the tube wall has defects or not by irradiating single-beam light of a flashlight during visual inspection; when the detected part can not be close to the observation, the observation is carried out by a reflector or an endoscope, when the surface of the pipe wall has the problems of cracks or corrosion and dirt, the metal surface is wiped by abrasive cloth and then observed by a magnifying glass, and whether other methods are needed to be carried out on some parts or not is judged on the basis.
3. The security evaluation method according to claim 1, wherein the step S2 is specifically:
s21, calibration: calibrating a standard test block configured by a detection instrument, adjusting the reading of the instrument to be consistent with the thickness of the test block, and then measuring the thickness of the steel material;
s22, preparation: the surface of the pipe wall is required to be smooth and flat, and when the requirement cannot be met, the pipe wall is polished;
s22, measurement: the couplant is adopted during thickness measurement, the probe is placed stably, and the pressure is proper; multipoint measurements were used.
4. The security evaluation method according to claim 3, wherein the multipoint measurement method is a method in which a plurality of measurements are performed centering on one measurement point, and a minimum value is taken as a measured thickness value.
5. The security evaluation method according to claim 1, wherein the step S3 is specifically:
s31, before analysis, checking whether an incident slit, a light path lens, an electrode condition, argon purity and pressure of the spectrometer are normal or not;
s32, keeping the analysis conditions and the environmental conditions of the detected material and the standard substance strictly consistent during analysis;
and S33, analyzing the detected material with uniform components, exciting and measuring for at least three times, and taking the average value as an analysis result, wherein the analysis result is expressed by percentage.
6. The security evaluation method according to claim 1, wherein the step S4 is specifically:
s41, sample grinding: fine grinding by using a grinding wheel of a handheld sample grinding device;
s42, polishing: polishing by using diamond polishing paste by adopting a mechanical polishing means;
s43, corrosion: adopting wiping type corrosion;
s44, replication: performing replica molding by using an acetone solution;
s45, observation: and observing the metallographic structure by using a portable microscope on site after the copying to obtain a structure judgment conclusion.
7. The security evaluation method according to claim 6, wherein the replica specific operation is:
dripping an acetone solution onto the etched replica point by a dropper, covering a replica film, extruding bubbles in the replica film by hand from one end after the replica film is covered on the replica point, drying the replica film, and removing and marking; the marked carrier is used, after cutting, the back of the replica film is directly adhered to the adhesive sticker on the current surface, the original seal paper of the adhesive sticker is covered, the replica film is pressed flat by hand, and the replica film is clamped by another carrier for storage.
8. The safety evaluation method according to claim 1, wherein the standardized experimental process of step S5 is specifically:
s51, polishing: roughly polishing by using an angle grinder with a grinding wheel, removing oxide skin and exposing metallic luster; vertically grinding the grinding trace of the previous grinding trace by using an angle grinder with a No. 200 abrasive paper blade wheel until the grinding trace of the grinding wheel is removed; vertically polishing the previous polishing trace by using portable metallographic polishing equipment with a polishing head until the polishing trace of the sand paper blade wheel is removed; smearing polishing paste, and vertically polishing the polishing paste and the last polishing trace by using portable metallographic polishing equipment with a polishing head until the polishing paste is in a mirror surface state;
s52, clamping: when the Richter hardness is detected, a laboratory bench clamp or a special on-site clamping device is used for stably clamping a detected sample, a threaded handle of the bench clamp or clamping equipment is loosened, the detected sample is put in, and the threaded handle of the clamping equipment is screwed so that the sample is firmly fixed and cannot be clamped too tightly until the sample deforms;
s53, hardness measurement: adjusting a corresponding experiment angle on an adjustment interface of the Leeb hardness tester, aligning the polished detection surface, holding the hardness tester by one hand to couple the support ring with the detected surface, ensuring that the impact direction of the D-type impact body of the Leeb hardness tester is vertical to the detected surface, pressing a button of the portable Leeb hardness tester by the other hand to release the impact body, reading and recording.
9. The safety evaluation method according to claim 1, wherein the correction formula in step S5 is as follows, wherein HBW represents brinell hardness and HLD represents richter hardness:
carbon steel: HBW =0.0349HLD 2 -8.4112HLD+633.5749；
Low alloy steel: HBW = -0.0271HLD 2 +10.6691HLD-852.687；
High alloy steel: HBW = -0.0313HLD 2 +7.1042HLD-176.8095；
Stainless steel: HBW = -0.0744HLD 2 +24.5256HLD-1801.6606。
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211514432.5A CN115855152A (en) | 2022-11-30 | 2022-11-30 | Safety evaluation method for heated surface pipe of non-destructive in-service unit |
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| CN202211514432.5A CN115855152A (en) | 2022-11-30 | 2022-11-30 | Safety evaluation method for heated surface pipe of non-destructive in-service unit |
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| CN115855152A true CN115855152A (en) | 2023-03-28 |
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