A corrosion assessment method and system for the suitability of cargo media based on the liquid cargo holds of chemical tankers

Abstract

The present invention provides a method and system for corrosion assessment of the suitability of cargo media based on the liquid cargo holds of chemical tankers. The method includes: obtaining the corrosion test results of a stainless steel standard sample in a first cargo medium by using a first corrosion test method; determining whether to perform a second corrosion test method according to the corresponding first corrosion degree obtained by the first corrosion test method, and judging whether to process the thickness of the hull of the ship's transport hold for the corresponding cargo medium according to the judgment condition by using the first corrosion degree or the second corrosion degree. The present invention uses two different corrosion methods to judge the suitability of a certain cargo medium of a stainless steel material, analyzes the corrosion rate to obtain its corresponding index, and performs a suitability assessment based on the index to obtain a suitability assessment result. According to the suitability assessment result, it is determined whether the cargo is suitable for loading into the stainless steel of the liquid cargo hold of the chemical tanker, which makes the corrosion assessment of the stainless steel cargo suitability accurate and effective in the present invention.

Description

Technical Field

[0001] The present invention relates to the technical field of the suitability assessment of liquid cargo holds of chemical tankers, and specifically to a method and system for corrosion assessment of the suitability of cargo media based on the liquid cargo holds of chemical tankers. Background Art

[0002] Austenitic stainless steel has been widely used in the shipbuilding industry due to its good corrosion resistance, paramagnetism, and biocompatibility. However, the application of such steel in the shipbuilding industry has deficiencies such as low strength and high cost, which limit the scope of use of the material. Duplex stainless steel can effectively solve the above two deficiencies. Duplex stainless steel has good strength and toughness, weldability, and corrosion resistance at the same time. After years of development, duplex stainless steel has become the fourth stainless steel system alongside the austenitic, ferritic, and martensitic systems, and is currently widely used in fields such as petrochemical, papermaking, construction, and shipbuilding and offshore engineering.

[0003] Nickel-saving duplex stainless steel, with a yield strength more than twice that of austenitic stainless steel, can effectively reduce the plate thickness and cost as a ship structural material, meeting the needs of a resource-saving society, green ships, and ship lightweighting. However, due to the artificial reduction of the nickel addition amount in the steelmaking process, this inevitably leads to a decline in the corrosion resistance of the material. The prior art has not stipulated a corresponding cargo suitability assessment system and corrosion performance test method or system for the stainless steel materials of the liquid cargo holds of chemical tankers. Summary of the Invention

[0004] Object of the Invention: In view of the problems existing in the above prior art, the present invention constructs a method and system for corrosion assessment of the suitability of cargo media based on the liquid cargo holds of chemical tankers, and solves the problems of unclear and inaccurate suitability of the stainless steel materials of the liquid cargo holds for different types of cargo.

[0005] Technical Solution: The present invention provides a method for corrosion assessment of the suitability of cargo media based on the liquid cargo holds of chemical tankers, and the method includes:

[0006] Obtain the corrosion test results of a stainless steel standard sample in a first cargo medium by using a first corrosion test method, and then obtain the corresponding first corrosion degree and first corrosion rate;

[0007] Determine whether to perform a second corrosion test method according to the corresponding first corrosion degree obtained by the first corrosion test method, specifically:

[0008] Calculate the first corrosion degree of the corresponding stainless steel standard sample according to the corrosion test results of the stainless steel standard sample;

[0009] If the first corrosion degree of the corresponding stainless steel standard sample is large, then the second corrosion test method is carried out on the stainless steel standard sample and the comparison sample in the second cargo medium under the same parameters, and the corrosion test results of the stainless steel standard sample and the comparison sample in the second cargo medium are obtained. Furthermore, the second corrosion degree and the second corrosion rate corresponding to the second cargo medium are obtained, and the second corrosion degree and the second corrosion rate are used to determine whether to process the hull thickness of the chemical tanker's liquid cargo tank for the corresponding first cargo medium and the second cargo medium. Otherwise,

[0010] If the first corrosion degree of the corresponding stainless steel standard sample is small, then the first corrosion degree and the first corrosion rate are directly used to determine whether to process the hull thickness of the ship's transport tank for the corresponding first cargo medium and the second cargo medium;

[0011] Among them, the first corrosion test method is a high-temperature accelerated corrosion method, and the second corrosion test method is a comparative analysis corrosion method of the transport ship at the actual designed loading temperature.

[0012] Furthermore, it includes:

[0013] The first corrosion test method includes standard sample setting, specimen condition setting, corrosion test process and display of test results. Specifically:

[0014] Standard sample setting: Cut three duplex stainless steels of the same size and roughness as the stainless steel standard sample, and obtain the exposed surface area S and the mass W before the test 11 ;

[0015] Specimen condition setting: It includes a temperature control device, and the temperature control device at least includes a heater and a timer; an experimental container for containing the first cargo medium, and the solution volume of the first cargo medium is obtained according to the surface area of the stainless steel standard sample, and one corresponding stainless steel standard sample is placed in each experimental container;

[0016] Corrosion test process: Place the first cargo medium in the corresponding experimental container; start the temperature control device to heat the first cargo medium to boiling, and after the first cargo medium boils, put the corresponding stainless steel standard sample into it and start timing. The continuous boiling time T1 is set to 24h;

[0017] Take out the stainless steel standard sample from the first cargo medium, brush it in running water to remove the corrosion products on the specimen surface, and obtain the mass W after the test of the stainless steel standard sample after drying 12 ;

[0018] Display of test results: Calculate the first corrosion degree according to the image of the stainless steel standard sample after the test and obtain the first corrosion rate according to the corresponding mass.

[0019] Further, it includes:

[0020] The first goods medium includes: formic acid with a mass percentage concentration of not less than 98% m / m; capric acid with a mass percentage concentration of not less than 99% m / m; lactic acid, a saturated citric acid aqueous solution with a mass percentage concentration between 85% - 90% m / m; acetic anhydride, a saturated urea aqueous solution with a mass percentage concentration of not less than 98.5% m / m; acrylic acid with a mass percentage concentration greater than 99% m / m; a saturated aluminum sulfate solution with a mass content of 200 g / L; a saturated aluminum chloride / hydrochloric acid solution; a saturated ammonium sulfate aqueous solution; an ammonium thiosulfate solution with a mass percentage concentration of 60% m / m; a saturated iron chloride / hydrochloric acid solution; a saturated sodium bisulfite aqueous solution; n-butyric acid with a mass percentage concentration of 99.5% m / m; chloroacetic acid with a mass percentage concentration of 98% m / m; 3-chloropropionic acid with a mass percentage concentration of 98% m / m; a mixture of n-valeric acid with a mass percentage concentration of 64% m / m and 2-methylbutyric acid with a mass percentage concentration of 36% m / m; phosphoric acid with a mass percentage concentration greater than 99% m / m; propionic acid with a mass percentage concentration greater than 99.5% m / m; trimethylacetic acid with a mass percentage concentration of 99% m / m; a saturated sodium hydroxide aqueous solution; allyl chloride with a mass percentage concentration of 98% m / m; and benzyl chloride with a mass percentage concentration greater than 99.0% m / m.

[0021] Further, it includes:

[0022] The calculation formula of the first corrosion rate is expressed as:

[0023]

[0024] The first corrosion rate is used as the first condition for evaluating whether the stainless steel material corresponding to the stainless steel standard sample is suitable for the corresponding goods medium, and it is set that when CR1 ≤ 100 g / (m 2 ·h), the stainless steel material corresponding to the stainless steel standard sample meets the first condition.

[0025] Further, it includes:

[0026] The corresponding first corrosion degree obtained according to the first corrosion test method includes:

[0027] Preprocessing the images of the stainless steel standard samples obtained according to the first corrosion test method at different times. The preprocessing includes image screening, image downsampling, and image enhancement performed separately according to different goods media. The different times refer to the time when the first corrosion test method is completed, and the image enhancement is obtained based on the results of image downsampling;

[0028] Calculate the information entropy of the enhanced images corresponding to different first cargo media after image enhancement respectively, and obtain the weights corresponding to the enhanced images according to the information entropy. Then, fuse the enhanced images corresponding to each image according to the weights to obtain the final enhanced image;

[0029] Obtain the corrosion area corresponding to the final enhanced image, and obtain the pixel value of each pixel point in the corrosion area;

[0030] Calculate the corrosion intensity of the corresponding stainless steel standard sample under this cargo medium according to the pixel value of each pixel point and the corresponding color value;

[0031] Set the corrosion grade, and determine the first corrosion degree according to the corrosion intensity and the preset corrosion intensity threshold. If the corrosion intensity threshold is set to [0, 10], when the corresponding corrosion grade is less than 5, it is set as a small first corrosion degree, and when the corresponding corrosion grade is greater than or equal to 5, it is set as a large first corrosion degree.

[0032] Further, it includes:

[0033] The image screening specifically includes: eliminating the abnormal first corrosion rates obtained from the three stainless steel standard samples under the same first cargo medium through the first corrosion test method, and deleting the sample images corresponding to the abnormal first corrosion rates. The determination method of the abnormal first corrosion rate is: calculate the pairwise differences among the three first corrosion rates obtained from the three stainless steel standard samples through the first corrosion test method, find the two first corrosion rates corresponding to the smallest absolute value of the difference, and obtain the corresponding abnormal first corrosion rate according to the box plot method.

[0034] Further, it includes:

[0035] Using the first corrosion degree and the first corrosion rate to directly determine whether to process the thickness of the cabin body of the ship transportation warehouse for the corresponding first cargo medium and the second cargo medium, including:

[0036] The corrosion grade is used as the second condition for evaluating whether the stainless steel material corresponding to the stainless steel standard sample is suitable for the corresponding cargo medium. When the corrosion grade is not greater than 3, it meets the second condition. Only when both the first condition and the second condition are met can it be determined that the chemical tanker liquid cargo tank corresponding to the stainless steel standard sample is suitable for the corresponding cargo medium, and whether to allow the corrosion allowance to be thinned is obtained according to the first corrosion rate.

[0037] Further, it includes:

[0038] The second corrosion test method includes standard sample setting, specimen condition setting, corrosion test process and display of test results. Specifically:

[0039] Standard sample setting: Cut two different types of duplex stainless steels with the same size and roughness, and use the stainless steel in the first corrosion test method as the stainless steel standard sample, and another different type of duplex stainless steel as the comparison sample, so as to obtain the exposed surface area S and the mass W before the test. 21 ;

[0040] Specimen condition setting: It includes a temperature control device, and the temperature control device at least includes a heater and a timer; an experimental container for containing the second goods medium, and the solution amount of the second goods medium is obtained according to the surface areas of the stainless steel standard sample and the comparison sample, and one corresponding stainless steel standard sample and comparison sample are placed in each experimental container.

[0041] Corrosion test process: Place the second goods medium in the corresponding experimental container; start the temperature control device to heat the second goods medium to the corresponding loading temperature, put the corresponding stainless steel standard sample and comparison sample, and start timing, and let it stand for T 21 hours, then take out the stainless steel standard sample and the comparison sample, wash them and then weigh them to get W 22 ;

[0042] Then, place the corresponding stainless steel standard sample and comparison sample back into the above test environment, and let it stand for T 22 hours, then take out the stainless steel standard sample, wash it and then weigh it to get W 23 ;

[0043] Display test results: Calculate the second corrosion degree based on the stainless steel standard sample and the comparison sample after the test, and obtain the second corrosion rate at different loading temperatures and different second goods media according to the corresponding mass.

[0044] Furthermore, it includes:

[0045] The second goods medium includes: concentrated sulfuric acid with a mass concentration of 98% m / m, nitric acid with a mass concentration between 65% - 68% m / m, and phosphoric acid with a mass concentration of 53% m / m. The loading temperatures include: 30°C, 40°C, and 50°C.

[0046] Furthermore, it includes:

[0047] The calculation formula for the second corrosion rate corresponding to different standing times is expressed as:

[0048]

[0049] The corrosion rates of different second cargo media at different loading temperatures of the stainless steel standard sample are obtained according to the above calculation formula; and the corrosion rates of different second cargo media at different loading temperatures of the comparison sample are obtained, and the corrosion rates corresponding to the two samples are compared and analyzed. Furthermore, the loading temperature is combined as the first condition for evaluating whether the comparison stainless steel can replace the standard stainless steel for fitting the cargo media.

[0050] Further, it includes:

[0051] Calculating the second corrosion degree based on the stainless steel standard sample and the comparison sample after the test includes:

[0052] Obtain the thicknesses of the standard sample and the comparison sample obtained from the same cargo medium at the same loading temperature after the test. The thickness of a single standard sample is denoted as D1, and the thickness of the comparison sample is denoted as D2;

[0053] The standard thickness under the same conditions obtained according to relevant standards is denoted as standard H;

[0054] Calculate the differences between the thicknesses D1, D2 and the standard thickness H for comparison; specifically, if |D1 - H| ≤ |D2 - H|, then the first fitting weight of the standard sample is greater than the corresponding weight of the comparison sample, and the first fitting weight is a parameter for measuring the fitting capabilities of the standard sample and the comparison sample;

[0055] Based on the corrosion areas corresponding to the standard sample and the comparison sample obtained from the same cargo medium at the same loading temperature, obtain the corrosion area occupancy rates, denoted as R1 and R2 respectively,

[0056] If R1 ≤ R2 and both are less than the occupancy rate setting threshold, then the second fitting weight of the standard sample is greater than the corresponding weight of the comparison sample, and the second fitting weight is a parameter for measuring the fitting capabilities of the standard sample and the comparison sample;

[0057] If R1 ≤ R2 and R2 is not less than the occupancy rate setting threshold, then the second fitting weight of the comparison sample is set to zero,

[0058] If R1 ≤ R2 and both are not less than the occupancy rate setting threshold, then neither the standard sample nor the comparison sample is used as the fitting material,

[0059] If R1 > R2 and both are less than the occupancy rate setting threshold, then the second fitting weight of the comparison sample is greater than the corresponding weight of the standard sample,

[0060] If R1 > R2 and R1 is not less than the occupancy rate setting threshold, then the second fitting weight of the standard sample is set to zero,

[0061] If R1 > R2 and both are not less than the occupancy rate setting threshold, then neither the standard sample nor the comparison sample can be used as the fitting material;

[0062] Based on the first and second fitting weights, the second corrosion degree of the standard sample and the comparison sample for a certain cargo medium at different loading temperatures is comprehensively obtained, which is used as the second condition for determining whether the comparison stainless steel can replace the standard stainless steel to fit the cargo medium.

[0063] Furthermore, it includes:

[0064] Using the second corrosion degree and the second corrosion rate to determine whether to process the thickness of the ship's transport hold for the corresponding first cargo medium and the second cargo medium, including:

[0065] If, at a certain loading temperature, the first condition and the second condition are met, that is, the comparison stainless steel can replace the standard stainless steel to fit the cargo medium, then calculate whether to allow the reduction of the corrosion allowance according to the second corrosion rate.

[0066] In addition, the present invention provides a corrosion assessment system for the suitability of cargo media in the liquid cargo holds of chemical tankers, and the system includes:

[0067] The first corrosion test calculation module is used to obtain the corrosion test results of the stainless steel standard sample in the first cargo medium by using the first corrosion test method, and then obtain the corresponding first corrosion degree and the first corrosion rate;

[0068] The judgment module is used to determine whether to perform the second corrosion test method according to the corresponding first corrosion degree obtained by the first corrosion test method. Specifically:

[0069] The first corrosion degree calculation unit is used to calculate the first corrosion degree of the corresponding stainless steel standard sample according to the corrosion test results of the stainless steel standard sample;

[0070] The judgment unit is used to process the thickness of the liquid cargo hold of the chemical tanker according to the comparison between the first corrosion degree and the second corrosion degree. Specifically:

[0071] If the first corrosion degree of the corresponding stainless steel standard sample is large, then perform the test of the second corrosion test method on the stainless steel standard sample and the comparison sample in the second cargo medium under the same parameters, obtain the corrosion test results of the stainless steel standard sample and the comparison sample in the second cargo medium, and then obtain the second corrosion degree and the second corrosion rate corresponding to the second cargo medium, and use the second corrosion degree and the second corrosion rate to determine whether to process the thickness of the liquid cargo hold of the chemical tanker for the corresponding first cargo medium and the second cargo medium. Otherwise,

[0072] If the first corrosion degree of the corresponding stainless steel standard sample is small, then directly use the first corrosion degree and the first corrosion rate to determine whether to process the thickness of the ship's transport hold for the corresponding first cargo medium and the second cargo medium;

[0073] Among them, the first corrosion test method is a high-temperature accelerated corrosion method, and the second corrosion test method is a comparative analysis corrosion method for a transport ship at the actual designed loading temperature.

[0074] Beneficial effects: The present invention uses two different corrosion methods to judge the suitability of a stainless steel material for a certain cargo medium, considering the corrosion degree and corrosion rate under two different states, that is, by setting the corrosion rates of different stainless steels in different liquid cargo holds at different time nodes under different temperatures with different cargo media; analyzing the corrosion rates to obtain corresponding indicators, and based on the indicators, conducting a suitability assessment to obtain a suitability assessment result, and deciding whether the cargo is suitable for loading the stainless steel of the chemical tanker liquid cargo hold according to the suitability assessment result. This makes the suitability corrosion assessment of the stainless steel cargo of the present invention accurate and effective, and is of great significance for the selection of the liquid cargo hold material of the chemical tanker and the determination of the list of suitable cargoes.

[0075] The present invention adopts different corrosion degree calculation methods for different corrosion tests. The first corrosion test method is a high-temperature test, while the second corrosion test method is a comparative test under the simulated actual loading temperature. Obviously, the corrosion degrees of the two tests on the stainless steel are significantly different. Therefore, different corrosion degree calculation methods greatly improve the accuracy of the corrosion rate and comparative analysis of the stainless steel material of the chemical tanker liquid cargo hold when loading different types of cargoes, so as to determine the suitability of the cargo and the evaluation of the acceptable corrosion allowance.

[0076] Based on the proportional relationship between the first corrosion rate and the first corrosion degree under the same conditions, and the present invention selects three identical samples under the same test conditions. Based on this, the test results are screened, that is, the abnormal images after the test among the three identical samples are removed, and the normal images are enhanced. Moreover, the present invention combines the corresponding multiple enhanced images through the image after downsampling the image, improving the image enhancement effect, and then accurately evaluating the first corrosion degree of the relevant samples through the finally combined enhanced image.

[0077] When calculating the second corrosion degree, the present invention simultaneously considers the thickness and the proportion of the corrosion area of the standard sample and the comparison sample, and considers the relationship between the proportion and the corresponding threshold, analyzes to obtain the corresponding weight parameter, and then combines the weight parameter to obtain the corresponding corrosion degree. Therefore, the second corrosion degree obtained by this consideration method is more accurate. Combining with the second corrosion rate, it has important reference value for evaluating whether the stainless steel material can replace the target stainless steel material to be suitable for the cargo medium and for calculating the corrosion allowance when the stainless steel material is loaded with the cargo medium. Description of the Drawings

[0078] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0079] Figure 1 It is a schematic diagram of the macroscopic surface of the original sample of the S32101 test described in the embodiments of the present invention;

[0080] Figure 2 It is a schematic diagram of the macroscopic surface of the original sample of the S2205 test described in the embodiments of the present invention;

[0081] Figure 3 It is a schematic diagram of the test process example of the second corrosion test described in the embodiments of the present invention;

[0082] Figure 4 It is a schematic diagram of the macroscopic surface of S32101 after 96-hour corrosion in 98% concentrated sulfuric acid at 30, 40, and 50 °C described in the embodiments of the present invention;

[0083] Figure 5 It is a schematic diagram of the macroscopic surface of S2205 after 96-hour corrosion in 98% concentrated sulfuric acid at 30, 40, and 50 °C described in the embodiments of the present invention;

[0084] Figure 6 It is a schematic diagram for comparative analysis of the corrosion rates of S32101 and S2205 in 98% concentrated sulfuric acid at 30, 40, and 50 °C described in the embodiments of the present invention;

[0085] Figure 7 It is a schematic diagram of the macroscopic surface of S32101 after 96-hour corrosion in 65%-68% nitric acid at 30, 40, and 50 °C described in the embodiments of the present invention;

[0086] Figure 8 It is a schematic diagram of the macroscopic surface of S2205 after 96-hour corrosion in 65%-68% nitric acid at 30, 40, and 50 °C described in the embodiments of the present invention;

[0087] Figure 9 Comparative analysis of the corrosion rates of S32101 and S2205 in 65%-68% nitric acid at 30, 40, and 50 °C described in the embodiments of the present invention;

[0088] Figure 10 It is a schematic diagram of the macroscopic surface of S32101 after 96-hour corrosion in 53% phosphoric acid at 30, 40, and 50 °C described in the embodiments of the present invention;

[0089] Figure 11Macrosurface example diagram of the corrosion of S2205 in 53% phosphoric acid at 30, 40, and 50 °C for 96 hours according to the embodiments of the present invention;

[0090] Figure 12 Comparative analysis of the corrosion rates of S32101 and S2205 in 53% phosphoric acid at 30, 40, and 50 °C according to the embodiments of the present invention;

[0091] Figure 13 Example diagram of the standard sample used in the first corrosion test method according to the embodiments of the present invention;

[0092] Figure 14 Example diagram of the test results of the first corrosion test method according to the embodiments of the present invention;

[0093] Figure 15 Example diagram of the inspection report of the first corrosion test method according to the embodiments of the present invention;

[0094] Figure 16 Flowchart of the corrosion assessment method for the suitability of cargo media in the liquid cargo hold of a chemical tanker according to the embodiments of the present invention;

[0095] Figure 17 Flowchart for determining the second corrosion test method according to the corresponding first corrosion degree obtained by the first corrosion test method according to the embodiments of the present invention. Detailed implementation manners

[0096] To better understand the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0097] As Figure 16 shown, the present invention provides a corrosion assessment method for the suitability of cargo media in the liquid cargo hold of a chemical tanker, and the method includes the following steps:

[0098] S1 Use the first corrosion test method to obtain the corrosion test results of the stainless steel standard sample in the first cargo medium, and then obtain the corresponding first corrosion degree and the first corrosion rate;

[0099] S2 Determine whether to perform the second corrosion test method according to the corresponding first corrosion degree obtained by the first corrosion test method. Specifically, as Figure 17 shown:

[0100] S21 Calculate the first corrosion degree of the corresponding stainless steel standard sample according to the corrosion test results of the stainless steel standard sample;

[0101] S22 If the first corrosion degree of the corresponding stainless steel standard sample is large, conduct the second corrosion test on the stainless steel standard sample and the comparison sample in the second cargo medium under the same parameters, obtain the corrosion test results of the stainless steel standard sample and the comparison sample in the second cargo medium, and then obtain the second corrosion degree and the second corrosion rate corresponding to the second cargo medium. Then, use the second corrosion degree and the second corrosion rate to determine whether to process the hull thickness of the cargo tank of the chemical tanker for the corresponding first cargo medium and the second cargo medium. Otherwise,

[0102] S23 If the first corrosion degree of the corresponding stainless steel standard sample is small, directly use the first corrosion degree and the first corrosion rate to determine whether to process the hull thickness of the ship transportation tank for the corresponding first cargo medium and the second cargo medium;

[0103] Among them, the first corrosion test method is a high-temperature accelerated corrosion method, and the second corrosion test method is a comparative analysis corrosion method of the transport ship at the actual designed loading temperature.

[0104] Furthermore, in this embodiment: The first corrosion test method includes standard sample setting, specimen condition setting, corrosion test process, and display of test results, specifically including:

[0105] Standard sample setting: Cut three pieces of a certain type of duplex stainless steel with the same size and roughness as the stainless steel standard sample, and obtain the exposed surface area S and the mass W before the test 11 ;

[0106] In this embodiment, the size is set to 20mm×30mm, and the surface roughness is the normal delivery state of the steel mill.

[0107] Specimen condition setting: It includes a temperature control device, and the temperature control device at least includes a heater and a timer; an experimental container for containing the first cargo medium, and the solution volume of the first cargo medium is obtained according to the surface area of the stainless steel standard sample, and one corresponding stainless steel standard sample is placed in each experimental container.

[0108] The experimental environmental conditions are (23±2)°C, (50±5)%RH.

[0109] In this embodiment, no specific restrictions are imposed on the temperature control device, as long as it meets the requirements of this test. That is, on the basis of the heater and timer set in this embodiment, a control device and a display screen can also be added.

[0110] Corrosion test process: Place the first goods medium in the corresponding experimental container; Start the temperature control device to heat the first goods medium to boiling. After the first goods medium boils, put in the corresponding stainless steel standard sample and start timing. The continuous boiling time T1 is set to 24h; The time T1 in the embodiment of the present invention can be adjusted according to the ship type and the operation cycle of the ship. For example, for domestic trade ships, it is generally set to 96h, and for foreign trade ships, the time is doubled. However, since the cost of the experiment is very high due to the long time, a certain temperature can be increased to exchange for a certain time cost. Specifically, about +5°C can reduce the time by 20%, but the specific situation needs to be determined according to the customer's needs.

[0111] Take out the stainless steel standard sample from the first goods medium, brush it in running water to remove the corrosion products on the surface of the sample, and obtain the post-test mass W of the stainless steel standard sample after drying. 12 ;

[0112] Display the test results: Calculate the first corrosion degree based on the image of the post-test stainless steel standard sample and obtain the first corrosion rate based on the corresponding mass.

[0113] Further, in this embodiment, the first goods medium includes: formic acid with a mass percentage concentration of not less than 98% m / m; capric acid with a mass percentage concentration of not less than 99% m / m; saturated citric acid aqueous solution lactic acid with a mass percentage concentration between 85% - 90% m / m; acetic anhydride with a mass percentage concentration of not less than 98.5% m / m; acrylic acid with a mass percentage concentration greater than 99% m / m; saturated aluminum sulfate solution with a mass content of 200 g / L; saturated aluminum chloride / hydrochloric acid solution; saturated ammonium sulfate aqueous solution; ammonium thiosulfate solution with a mass percentage concentration of 60% m / m; saturated ferric chloride / hydrochloric acid solution; saturated sodium bisulfite aqueous solution; n-butyric acid with a mass percentage concentration of 99.5% m / m; chloroacetic acid with a mass percentage concentration of 98% m / m; 3-chloropropionic acid with a mass percentage concentration of 98% m / m; a mixture of n-valeric acid with a mass percentage concentration of 64% m / m and 2-methylbutyric acid with a mass percentage concentration of 36% m / m; phosphoric acid with a mass percentage concentration greater than 99% m / m; propionic acid with a mass percentage concentration greater than 99.5% m / m; trimethylacetic acid with a mass percentage concentration of 99% m / m; saturated sodium hydroxide aqueous solution; allyl chloride with a mass percentage concentration of 98% m / m; and benzyl chloride with a mass percentage concentration greater than 99.0% m / m.

[0114] In this embodiment, the specific experimental process and results corresponding to the above first corrosion test method are as follows:

[0115] The reagents used include:

[0116] Reagent 2: Formic acid (≥98% m / m)

[0117] Reagent 4: Decanoic acid (99% m / m)

[0118] Reagent 5: Saturated citric acid aqueous solution. Reagent 6: Lactic acid (85% - 90% m / m)

[0119] Reagent 7: Saturated urea aqueous solution

[0120] Reagent 8: Acetic anhydride (≥98.5% m / m)

[0121] Reagent 9: Acrylic acid (>99% m / m)

[0122] Reagent 10: Saturated aluminum sulfate solution (200 g / L)

[0123] Reagent 11: Saturated aluminum chloride / hydrochloric acid solution

[0124] Reagent 12: Saturated ammonium sulfate aqueous solution

[0125] Reagent 13: Ammonium thiosulfate solution (60% m / m)

[0126] Reagent 16: Saturated iron(III) chloride / hydrochloric acid solution

[0127] Reagent 17: Saturated sodium bisulfite aqueous solution

[0128] Reagent 18: n-Butyric acid (99.5% m / m)

[0129] Reagent 19: Chloroacetic acid (98% m / m)

[0130] Reagent 20: 3-Chloropropionic acid (98% m / m)

[0131] Reagent 22: Mixture of n-valeric acid (64% m / m) and 2-methylbutyric acid (36% m / m)

[0132] Reagent 23: Phosphoric acid (≥99% m / m)

[0133] Reagent 24: Propionic acid (≥99.5% m / m)

[0134] Reagent 25: Trimethylacetic acid (99% m / m)

[0135] Reagent 26: Saturated sodium hydroxide aqueous solution

[0136] Reagent 28: Allyl chloride (98% m / m)

[0137] Reagent 29: Benzyl chloride (>99.0% m / m)

[0138] The corresponding test results and inspection reports are as Figure 13 、 Figure 14 and 15 shown.

[0139] Among them, Method 1 is the first corrosion test method described above, and Method 2 is: soaking at 50°C

[0140] Completely immerse the test sample in the test reagent and maintain the temperature at 50°C

[0141] Method 3 is: soaking at room temperature

[0142] Completely immerse the test sample in the test reagent and maintain the temperature at room temperature. The laboratory environmental conditions for the above methods are: (23±2)°C, (50±5)%RH.

[0143] Furthermore, this embodiment further includes:

[0144] The calculation formula for the first corrosion rate is expressed as:

[0145]

[0146] The first corrosion rate is used as the first condition for evaluating whether the stainless steel material corresponding to the stainless steel standard sample is suitable for the corresponding goods medium, and it is set that when CR1≤100g / (m 2 ·h), the stainless steel material corresponding to the stainless steel standard sample meets the first condition.

[0147] Furthermore, it includes:

[0148] The corresponding first corrosion degree obtained according to the first corrosion test method includes;

[0149] Preprocess the images of the stainless steel standard samples obtained according to the first corrosion test method at different times. The preprocessing includes image screening, image downsampling, and image enhancement performed separately according to different goods media. And the different times refer to the time when the first corrosion test method is completed. The image enhancement is obtained based on the results of image downsampling;

[0150] Calculate the information entropy of the enhanced images corresponding to different first goods media after image enhancement, and obtain the weights corresponding to the enhanced images according to the information entropy. Fuse the enhanced images corresponding to each image according to the weights to obtain the final enhanced image;

[0151] Obtain the corrosion area corresponding to the final enhanced image, and obtain the pixel values of each pixel point in the corrosion area;

[0152] Calculate the corrosion intensity of the stainless steel standard sample corresponding to the goods medium according to the pixel value of each pixel point and the corresponding color value;

[0153] Set the corrosion level, and determine the first corrosion degree according to the corrosion intensity and the preset corrosion intensity threshold. If the corrosion intensity threshold is set to [0, 10], when the corresponding corrosion level is less than 5, it is set that the first corrosion degree is small; when the corresponding corrosion level is greater than or equal to 5, it is set that the first corrosion degree is large.

[0154] Further, it includes:

[0155] Among them, image screening specifically includes: eliminating the abnormal first corrosion rates obtained from the first corrosion test method for three stainless steel standard samples under the same first cargo medium, and deleting the sample images corresponding to the abnormal first corrosion rates. The determination method of the abnormal first corrosion rate is: calculate the pairwise differences among the three first corrosion rates obtained from the first corrosion test method for the three stainless steel standard samples, find the two first corrosion rates corresponding to the smallest absolute value of the difference, and obtain the corresponding abnormal first corrosion rate according to the box plot method.

[0156] Further, it includes:

[0157] Using the first corrosion degree and the first corrosion rate directly to judge whether to process the thickness of the ship transportation tank for the corresponding first cargo medium and the second cargo medium, including:

[0158] The corrosion level is used as the second condition for evaluating whether the stainless steel material corresponding to the stainless steel standard sample is suitable for the corresponding cargo medium. When the corrosion level is not greater than 3, it meets the second condition. Only when both the first condition and the second condition are met can it be determined that the chemical tanker liquid cargo tank corresponding to the stainless steel standard sample is suitable for the corresponding cargo medium, and whether to allow the reduction of the corrosion allowance is obtained according to the first corrosion rate.

[0159] In this embodiment, it also includes: The second corrosion test method includes standard sample setting, specimen condition setting, corrosion test process, and display of test results. Specifically:

[0160] Standard sample setting: Cut three duplex stainless steels of the same size and roughness of two different models, and use the stainless steel in the first corrosion test method as the stainless steel standard sample, and another different model of duplex stainless steel as the comparison sample, so as to obtain the exposed surface area S and the mass W before the test. 21 ;

[0161] In this embodiment, the comparison sample is S32101 and the standard sample is S2205. Since S2205 is recognized in the market as the chemical tanker with the best corrosion resistance, major chemical tanker owners are willing to use it as the cargo tank material for foreign trade chemical tankers. At the same time, it is already allowed to reduce the plate thickness and subtract the corrosion allowance. This material has been in service for more than 15 years and there is no record of cargo operation corrosion in the CCS records, but the price is very expensive. Therefore, a nickel-saving duplex stainless steel has been developed, with a price about 13,000 yuan cheaper per ton. Therefore, the evaluation method is to evaluate whether 32101 (or cheaper and more advanced stainless steel materials in the future) can replace S2205, reduce the plate thickness, and save money for the shipowner.

[0162] Specifically:

[0163] For S32101 and S2205, 27 pitting corrosion specimens of 20mm×30mm are cut from the heads of the steel plates. The surface roughness is the normal delivery state of the steel mill, and pickling and passivation are not carried out for this corrosion. Corrosion simulation experiments are carried out at 30, 40, and 50 °C respectively in three erosion reagents (all of laboratory-grade purity): 98% concentrated sulfuric acid, 65%-68% nitric acid, and 53% phosphoric acid, providing the corrosion rate and surface macro photo results. Among them, the corrosion rate and surface macro photo results of S2205 stainless steel are provided for comparative analysis with S32101. The corrosion time is 96h. See the original macro surface photo in Figure 1-2 , and see the test process in Figure 3 .

[0164] Specimen condition setting: including a temperature control device, which at least includes a heater and a timer; an experimental container for containing the second cargo medium, and the solution volume of the second cargo medium is obtained according to the surface areas of the stainless steel standard sample and the comparison sample, and one corresponding stainless steel standard sample and comparison sample are placed in each experimental container;

[0165] Corrosion test process: Place the second cargo medium in the corresponding experimental container; start the temperature control device to heat the second cargo medium to the corresponding loading temperature, put in the corresponding stainless steel standard sample and comparison sample, and start timing. Let it stand for T 21 hours, then take out the stainless steel standard sample and comparison sample, wash them and weigh to get W 22 ;

[0166] Then, place the corresponding stainless steel standard sample and comparison sample back into the above test environment, and after standing for T 22 hours, take out the stainless steel standard sample, wash it and weigh to get W 23 ;

[0167] Display test results: Calculate the second corrosion degree based on the standard stainless steel samples and comparison samples after the test, and obtain the second corrosion rate at different loading temperatures and different second product media according to the corresponding mass.

[0168] Furthermore, this embodiment further includes:

[0169] The second product medium includes: concentrated sulfuric acid with a mass concentration of 98% m / m, nitric acid with a mass concentration between 65% - 68% m / m, and phosphoric acid with a mass concentration of 53% m / m. The loading temperatures include: 30°C, 40°C, and 50°C.

[0170] The specific experimental results and evaluation analysis process are as follows:

[0171] (1) Concentrated sulfuric acid (98%)

[0172] The comparative corrosion test results of S32101 and S2205 in 98% concentrated sulfuric acid are as follows. The macroscopic surface of the specimens is as Figure 4 、 5 shown. The comparison of corrosion rates is shown in Table 1 and Figure 6 shown.

[0173] After 96 hours under the condition of 98% concentrated sulfuric acid at 30°C, the overall corrosion conditions of S32101 and S2205 are good and basically the same. The average corrosion rates of S32101 and S2205 in 98% concentrated sulfuric acid at 30°C for 96 hours are 27.0 and 13.4 mdd respectively, and the average corrosion rate of S32101 is higher than that of S2205. The annual corrosion thinning rates of S32101 and S2205 are 0.126 and 0.019 mm / a.

[0174] After 96 hours under the condition of 98% concentrated sulfuric acid at 40°C, the surface corrosion condition of S32101 is good, and local corrosion marks appear on S2205. The average corrosion rates of S32101 and S2205 in 98% concentrated sulfuric acid at 40°C for 96 hours are 24.9 and 25.2 mdd respectively, and the average corrosion rate of S32101 is basically the same as that of S2205. The annual corrosion thinning rates of S32101 and S2205 are 0.116 and 0.118 mm / a.

[0175] After 96 hours under the condition of 98% concentrated sulfuric acid at 50°C, the overall corrosion conditions of S32101 and S2205 are good and basically the same. The average corrosion rates of S32101 and S2205 in 98% concentrated sulfuric acid at 50°C for 96 hours are 59.9 and 85.7 mdd respectively, and the average corrosion rate of S32101 is slightly lower than that of S2205. The annual corrosion thinning rates of S32101 and S2205 are 0.280 and 0.401 mm / a.

[0176] Table 1: Corrosion Rates of S32101 and S2205 in 98% Concentrated Sulfuric Acid at 30, 40, and 50°C for 96h

[0177]

[0178] As Figure 6 shown, by comparing and analyzing the corrosion rates of S32101 and S2205 in 98% concentrated sulfuric acid at 30, 40, and 50°C, it can be seen that the corrosion rate of the standard sample in 98% concentrated sulfuric acid at 30°C is greater, and the corrosion rate of the comparison sample in 98% concentrated sulfuric acid at 40 and 50°C is greater.

[0179] (2) Nitric Acid (65%-68%)

[0180] The results of the comparative corrosion test of S32101 and S2205 in 65%-68% nitric acid are as follows. The macroscopic surfaces of the specimens are as Figure 7 、 8 shown. The comparison of corrosion rates is shown in Table 2 and Figure 9 shown.

[0181] After 96h under the condition of 65%-68% nitric acid at 30°C, the overall surface corrosion of S32101 and S2205 is good and basically the same. The average corrosion rates of S32101 and S2205 in 65%-68% nitric acid at 30°C for 96h are 1.2 and 0.9 mdd respectively, and the average corrosion rate of S32101 is slightly higher than that of S2205. The annual corrosion thinning rates of S32101 and S2205 are 0.006 and 0.004 mm / a.

[0182] After 96h under the condition of 65%-68% nitric acid at 40°C, local corrosion marks appear on S32101 and S2205. The average corrosion rates of S32101 and S2205 in 65%-68% nitric acid at 40°C for 96h are 1.5 and 1.4 mdd respectively, and the average corrosion rate of S32101 is slightly higher than that of S2205. The annual corrosion thinning rates of S32101 and S2205 are 0.007 and 0.007 mm / a.

[0183] After 96h under the condition of 65%-68% nitric acid at 50°C, large-area corrosion appears on S32101, and local corrosion marks appear on S2205. The average corrosion rates of S32101 and S2205 in 65%-68% nitric acid at 50°C for 96h are 4.3 and 3.2 mdd respectively, and the average corrosion rate of S32101 is slightly higher than that of S2205. The annual corrosion thinning rates of S32101 and S2205 are 0.020 and 0.015 mm / a.

[0184] Table 2: Corrosion Rates of S32101 and S2205 in 65%-68% Nitric Acid at 30, 40, and 50°C for 96h

[0185]

[0186] (3) Phosphoric acid (53%)

[0187] The results of the 53% phosphoric acid comparative corrosion test of S32101 and S2205 are as follows. The macroscopic surface of the specimen is as Figure 10 、 11 shown. The comparison of corrosion rates is shown in Table 3 and Figure 12 shown.

[0188] After 96 h under the condition of 53% phosphoric acid at 30 °C, the overall corrosion of S32101 and S2205 is good and basically the same. The average corrosion rates of S32101 and S2205 under the condition of 53% phosphoric acid at 30 °C for 96 h are 0.7 and 0.8 mdd respectively, and the average corrosion rate of S32101 is slightly lower than that of S2205. The annual corrosion thinning rates of S32101 and S2205 are 0.003 and 0.004 mm / a.

[0189] After 96 h under the condition of 53% phosphoric acid at 40 °C, the overall corrosion of S32101 and S2205 is good and basically the same. The average corrosion rates of S32101 and S2205 under the condition of 53% phosphoric acid at 40 °C for 96 h are 0.7 and 1.2 mdd respectively, and the average corrosion rate of S32101 is lower than that of S2205. The annual corrosion thinning rates of S32101 and S2205 are 0.003 and 0.006 mm / a.

[0190] After 96 h under the condition of 53% phosphoric acid at 50 °C, the overall corrosion of S32101 and S2205 is good and basically the same. The average corrosion rates of S32101 and S2205 under the condition of 53% phosphoric acid at 50 °C for 96 h are 2.3 and 1.1 mdd respectively, and the average corrosion rate of S32101 is higher than that of S2205. The annual corrosion thinning rates of S32101 and S2205 are 0.010 and 0.004 mm / a.

[0191] Table 3: Corrosion rates of S32101 and S2205 in 53% phosphoric acid for 96 h at 30, 40, and 50 °C

[0192]

[0193]

[0194] Based on the above result analysis, by comparing the simulated corrosion results of S32101 and S2205, the following conclusions can be drawn as the basis for drawing review:

[0195] (1), 98% concentrated sulfuric acid, 65%-68% nitric acid, and 53% phosphoric acid can be added to the list of suitable goods for S32101 produced by this steel plant.

[0196] (2) When S32101 and S2205 are loaded with 98% concentrated sulfuric acid goods, the temperature of the liquid cargo tank must be lower than 40°C during operation.

[0197] (3) When S32101 is loaded with 65%-68% nitric acid goods, the temperature of the liquid cargo tank must be lower than 40°C during operation; when S2205 is loaded with 65%-68% nitric acid goods, the temperature of the liquid cargo tank must be lower than 50°C during operation.

[0198] (4) When S32101 and S2205 are loaded with 53% phosphoric acid goods, the temperature of the liquid cargo tank must be lower than 50°C during operation.

[0199] (5) When S32101 is loaded with the above-mentioned 98% concentrated sulfuric acid, 65%-68% nitric acid and 53% phosphoric acid and strictly controls the operation quality, the structural calculation can be carried out according to 0 corrosion allowance.

[0200] And in this embodiment, in order to ensure the actual loading and operation conditions of the three strong acids, namely 98% concentrated sulfuric acid, 65%-68% nitric acid and 53% phosphoric acid, CCS will monitor the corrosion situation of the liquid cargo tank after the first loading and unloading of the chemical tanker built with this material.

[0201] All specimens in this experiment were not pickled and passivated. Therefore, if the specimens were pickled and passivated, the corrosion rate obtained would be smaller (more ideal) than the current results.

[0202] In the results of this experiment, there are 2 groups of data with large deviations. The subsequent 2 groups of data will be re-verified for possible human errors, but the above-mentioned drawing review basis is still valid.

[0203] Further, the above includes:

[0204] The calculation formula of the second corrosion rate corresponding to different standing times is expressed as:

[0205]

[0206] According to the above calculation formula, the corrosion rates of the stainless steel standard samples under different loading temperatures and different second cargo media are obtained; and the corrosion rates of the comparison samples under different loading temperatures and different second cargo media are obtained, and the corrosion rates corresponding to the two samples are compared and analyzed. Furthermore, the loading temperature is combined as the first condition for evaluating whether the comparison stainless steel can replace the standard stainless steel for fitting the cargo medium.

[0207] Further, this embodiment also includes:

[0208] Calculating the second corrosion degree according to the stainless steel standard sample and the comparison sample after the test includes:

[0209] Obtain the thicknesses of the standard sample and the comparison sample of the same goods medium at the same loading temperature after the test. Denote the thickness of a single standard sample as D1 and the thickness of the comparison sample as D2;

[0210] Denote the standard thickness under the same conditions obtained according to relevant standards as standard H;

[0211] Calculate the differences between the thicknesses D1, D2 and the standard thickness H for comparison; specifically, if |D1 - H| ≤ |D2 - H|, then the first fitness weight of the standard sample is greater than the corresponding weight of the comparison sample, and the first fitness weight is a parameter for measuring the fitness capabilities of the standard sample and the comparison sample;

[0212] Based on the corrosion areas corresponding to the standard sample and the comparison sample of the same goods medium at the same loading temperature, obtain the corrosion area occupancy rates, denoted as R1 and R2 respectively. If R1 ≤ R2 and both are less than the occupancy rate setting threshold, this threshold is set to about 20% and the specific value is not shown in this embodiment, then the second fitness weight of the standard sample is greater than the corresponding weight of the comparison sample, and the second fitness weight is a parameter for measuring the fitness capabilities of the standard sample and the comparison sample; if R1 ≤ R2 and R2 is not less than the occupancy rate setting threshold, then the second fitness weight of the comparison sample is set to zero; if R1 ≤ R2 and both are not less than the occupancy rate setting threshold, then neither the standard sample nor the comparison sample is used as a suitable material; if R1 > R2 and both are less than the occupancy rate setting threshold, then the second fitness weight of the comparison sample is greater than the corresponding weight of the standard sample; if R1 > R2 and R1 is not less than the occupancy rate setting threshold, then the second fitness weight of the standard sample is set to zero; if R1 > R2 and both are not less than the occupancy rate setting threshold, then neither the standard sample nor the comparison sample can be used as a suitable material;

[0213] Based on the first fitness weight and the second fitness weight, comprehensively obtain the second corrosion degree of the standard sample and the comparison sample for a certain goods medium at different loading temperatures, which is used as the second condition for determining whether the comparison stainless steel can replace the standard stainless steel to fit the goods medium.

[0214] Furthermore, this embodiment further includes:

[0215] Use the second corrosion degree and the second corrosion rate to determine whether to process the thickness of the ship transportation warehouse for the corresponding first goods medium and second goods medium, including:

[0216] If, at a certain loading temperature, the first condition and the second condition are met, that is, the comparison stainless steel can replace the standard stainless steel to fit the goods medium, then calculate whether to allow the reduction of the corrosion allowance according to the second corrosion rate.

[0217] In this embodiment, after calculating the MDD, there is a conversion formula to convert it into mm / year, which is the number of millimeters thinned per year. The plate replacement life of the ship's plates is approximately 13 - 20 years. Therefore, by matching the quarterly loading and operation time of the shipowner's plan with the thinning under relevant temperatures, it is possible to determine: 1. Whether this material can carry this medium; 2. The temperature at which it must be below when carrying this medium; 3. Whether it is allowed to thin the corrosion allowance.

[0218] The present invention evaluates whether the stainless steel material is suitable for loading this cargo based on the surface corrosion condition and corrosion rate of the standard sample obtained by the first corrosion test method. Based on the surface corrosion condition and corrosion rate of the standard sample and the comparison sample obtained by the first corrosion test method, it is evaluated whether the stainless steel material can replace the target stainless steel material to be suitable for loading this cargo medium. And based on the surface corrosion condition and corrosion rate of the standard sample and the comparison sample obtained by the first corrosion test method, it is evaluated whether the stainless steel material can perform 0 corrosion allowance calculation when loading this cargo medium.

[0219] In addition, the present invention provides a corrosion evaluation system for the suitability of cargo media in the liquid cargo holds of chemical tankers, which includes:

[0220] A first corrosion test calculation module, which is used to obtain the corrosion test results of a stainless steel standard sample in a first cargo medium by using the first corrosion test method, and then obtain the corresponding first corrosion degree and first corrosion rate;

[0221] A judgment module, which is used to determine whether to perform the second corrosion test method according to the corresponding first corrosion degree obtained by the first corrosion test method. Specifically:

[0222] A first corrosion degree calculation unit, which is used to calculate the first corrosion degree of the corresponding stainless steel standard sample according to the corrosion test results of the stainless steel standard sample;

[0223] A judgment unit, which is used to process the thickness of the hull of the liquid cargo hold of a chemical tanker according to the comparison between the first corrosion degree and the second corrosion degree. Specifically:

[0224] If the first corrosion degree of the corresponding stainless steel standard sample is large, then the second corrosion test method is performed on the stainless steel standard sample and the comparison sample in the second cargo medium under the same parameters, and the corrosion test results of the stainless steel standard sample and the comparison sample in the second cargo medium are obtained, and then the second corrosion degree and the second corrosion rate corresponding to the second cargo medium are obtained, and the second corrosion degree and the second corrosion rate are used to judge whether to process the thickness of the hull of the liquid cargo hold of the chemical tanker for the corresponding first cargo medium and the second cargo medium. Otherwise,

[0225] If the first corrosion degree of the corresponding stainless steel standard sample is small, directly use the first corrosion degree and the first corrosion rate to determine whether to process the thickness of the ship's transportation tank for the corresponding first cargo medium and the second cargo medium;

[0226] Among them, the first corrosion test method is a high-temperature accelerated corrosion method, and the second corrosion test method is a comparative analysis corrosion method of the transport ship at the actual designed loading temperature.

[0227] Other technical features of the corrosion evaluation system for the cargo medium compatibility of the liquid cargo tank of the chemical tanker according to the present invention are similar to the corresponding method, and will not be elaborated here.

[0228] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0229] Obviously, those skilled in the art can make various changes and modifications to the embodiments of the present invention without departing from the spirit and scope of the embodiments of the present invention. Thus, if these modifications and variations of the embodiments of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these changes and modifications.

Claims

1. A method for evaluating the corrosion suitability of cargo media based on the liquid cargo holds of chemical tankers, characterized in that, The method includes: Obtaining the corrosion test results of a stainless steel standard sample in a first cargo medium by using a first corrosion test method, and then obtaining the corresponding first corrosion degree and first corrosion rate; Determining whether to perform a second corrosion test method according to the corresponding first corrosion degree obtained by the first corrosion test method. Specifically: Calculating the first corrosion degree of the corresponding stainless steel standard sample based on the corrosion test results of the stainless steel standard sample; If the first corrosion degree of the corresponding stainless steel standard sample is greater than or equal to the corrosion intensity threshold, then conducting a test of the second corrosion test method on the stainless steel standard sample and the comparison sample in a second cargo medium under the same parameters, obtaining the corrosion test results of the stainless steel standard sample and the comparison sample in the second cargo medium, and then obtaining the corresponding second corrosion degree and second corrosion rate of the second cargo medium, and using the second corrosion degree and the second corrosion rate to determine whether to process the hull thickness of the chemical tanker's liquid cargo hold for the corresponding first cargo medium and second cargo medium. Otherwise, If the first corrosion degree of the corresponding stainless steel standard sample is less than the corrosion intensity threshold, directly using the first corrosion degree and the first corrosion rate to determine whether to process the hull thickness of the ship transportation hold for the corresponding first cargo medium and second cargo medium; Wherein, the first corrosion test method is a high-temperature accelerated corrosion method, and the second corrosion test method is a comparative analysis corrosion method of a transport ship at the actual designed loading temperature; The corresponding first corrosion degree obtained according to the first corrosion test method includes: Preprocessing the images of the stainless steel standard sample obtained according to the first corrosion test method at different times. The preprocessing includes image screening, image downsampling, and image enhancement respectively performed according to different cargo media. And the different times refer to the time corresponding to the completion of the first corrosion test method. The image enhancement is obtained based on the result of image downsampling; Calculating the information entropy of the enhanced images corresponding to different first cargo media after image enhancement respectively, and obtaining the weight corresponding to the enhanced image according to the information entropy. Fusing the enhanced images corresponding to each image according to the weight to obtain the final enhanced image; Obtaining the corrosion area corresponding to the final enhanced image, and obtaining the pixel value of each pixel point in the corrosion area; Calculating the corrosion intensity of the corresponding stainless steel standard sample in this cargo medium according to the pixel value of each pixel point and the corresponding color value; Setting corrosion grades, and determining the first corrosion degree according to the corrosion intensity and the preset corrosion intensity threshold. If the corrosion intensity threshold is set to [0, 10], when the corresponding corrosion grade is less than 5, it is set that the first corrosion degree is small; when the corresponding corrosion grade is greater than or equal to 5, it is set that the first corrosion degree is large; The calculation of the second corrosion degree according to the tested stainless steel standard sample and the comparison sample includes: Obtaining the thicknesses of the standard sample and the comparison sample of the same cargo medium at the same loading temperature after the test. The thickness of a single standard sample is denoted as D1, and the thickness of the comparison sample is denoted as D2; The standard thickness under the same conditions obtained according to relevant standards is denoted as standard H; Calculate the differences between the thicknesses D1, D2 and the standard thickness H for comparison; specifically, if |D1 - H| ≤ |D2 - H|, then the first fitting weight of the standard sample is greater than the corresponding weight of the comparison sample, and the first fitting weight is a parameter for measuring the fitting capabilities of the standard sample and the comparison sample; Based on the corrosion areas corresponding to the standard sample and the comparison sample obtained from the same goods medium at the same loading temperature, obtain the corrosion area occupancy rates, denoted as R1 and R2 respectively, If R1 ≤ R2 and both are less than the occupancy rate setting threshold, then the second fitting weight of the standard sample is greater than the corresponding weight of the comparison sample, and the second fitting weight is a parameter for measuring the fitting capabilities of the standard sample and the comparison sample; If R1 ≤ R2 and R2 is not less than the occupancy rate setting threshold, then the second fitting weight of the comparison sample is set to zero, If R1 ≤ R2 and both are not less than the occupancy rate setting threshold, then neither the standard sample nor the comparison sample is used as the fitting material, If R1 > R2 and both are less than the occupancy rate setting threshold, then the second fitting weight of the comparison sample is greater than the corresponding weight of the standard sample, If R1 > R2 and R1 is not less than the occupancy rate setting threshold, then the second fitting weight of the standard sample is set to zero, If R1 > R2 and both are not less than the occupancy rate setting threshold, then neither the standard sample nor the comparison sample can be used as the fitting material; Based on the first fitting weight and the second fitting weight, comprehensively obtain the second corrosion degree of the standard sample and the comparison sample for a certain goods medium at different loading temperatures, which is used as the second condition for determining whether the comparison stainless steel can replace the standard stainless steel to fit the goods medium.

2. The method for corrosion assessment of cargo medium suitability based on the liquid cargo tank of a chemical tanker according to claim 1, wherein The first corrosion test method includes standard sample setting, specimen condition setting, corrosion test process and display of test results. Specifically: Standard sample setting: Cut three duplex stainless steels of the same model with the same size and roughness as the stainless steel standard sample, and obtain the exposed surface area S and the mass W before the test 11 ; Specimen condition setting: It includes a temperature control device, and the temperature control device at least includes a heater and a timer; an experimental container for holding the first goods medium, and the solution volume of the first goods medium is obtained based on the surface area of the stainless steel standard sample, and one corresponding stainless steel standard sample is placed in each experimental container; Corrosion test process: Place the first goods medium in the corresponding experimental container; Start the temperature control device to heat the first goods medium to boiling. After the first goods medium boils, put the corresponding stainless steel standard sample in and start timing. The continuous boiling time T1 is set to 24h; Take out the stainless steel standard sample from the first goods medium, brush it in running water to remove the corrosion products on the surface of the sample, and obtain the post-test mass W of the stainless steel standard sample after drying 12 ; Display of test results: Calculate the first corrosion degree based on the image of the stainless steel standard sample after the test and obtain the first corrosion rate based on the corresponding mass.

3. The method for corrosion assessment of cargo medium suitability based on the liquid cargo tank of a chemical tanker according to claim 2, wherein The first cargo medium includes: formic acid with a mass percentage concentration of not less than 98% m / m; capric acid with a mass percentage concentration of not less than 99% m / m; saturated citric acid aqueous solution lactic acid with a mass percentage concentration between 85% - 90% m / m; saturated urea aqueous solution acetic anhydride with a mass percentage concentration of not less than 98.5% m / m; acrylic acid with a mass percentage concentration greater than 99% m / m; saturated aluminum sulfate solution with a mass content of 200 g / L; saturated aluminum chloride / hydrochloric acid solution; saturated ammonium sulfate aqueous solution; ammonium thiosulfate solution with a mass percentage concentration of 60% m / m; saturated iron chloride / hydrochloric acid solution; saturated sodium bisulfite aqueous solution; n-butyric acid with a mass percentage concentration of 99.5% m / m; chloroacetic acid with a mass percentage concentration of 98% m / m; 3-chloropropionic acid with a mass percentage concentration of 98% m / m; a mixture of n-valeric acid with a mass percentage concentration of 64% m / m and 2-methylbutyric acid with a mass percentage concentration of 36% m / m; phosphoric acid with a mass percentage concentration greater than 99% m / m; propionic acid with a mass percentage concentration greater than 99.5% m / m; trimethylacetic acid with a mass percentage concentration of 99% m / m; saturated sodium hydroxide aqueous solution; allyl chloride with a mass percentage concentration of 98% m / m; and benzyl chloride with a mass percentage concentration greater than 99.0% m / m.

4. The method for evaluating the corrosion suitability of cargo media based on the liquid cargo holds of chemical tankers according to claim 3, characterized in that, The calculation formula of the first corrosion rate is expressed as: The first corrosion rate is used as the first condition for evaluating whether the stainless steel material corresponding to the stainless steel standard sample is suitable for the corresponding goods medium, and it is set that when CR1 ≤ 100 g / (m 2 ·h), the stainless steel material corresponding to the stainless steel standard sample meets the first condition.

5. The method for corrosion assessment of the suitability of cargo media based on the liquid cargo tanks of chemical tankers according to claim 4, wherein The image screening specifically includes: eliminating the abnormal first corrosion rates obtained from the first corrosion test method for three stainless steel standard samples under the same first cargo medium, and deleting the sample images corresponding to the abnormal first corrosion rates. The determination method of the abnormal first corrosion rate is: calculating the pairwise differences among the three first corrosion rates obtained from the first corrosion test method for the three stainless steel standard samples, finding the two first corrosion rates corresponding to the smallest absolute value of the difference, and obtaining the corresponding abnormal first corrosion rate according to the box plot method.

6. The corrosion assessment method for cargo medium suitability based on the liquid cargo tank of a chemical tanker according to claim 4, wherein Directly using the first corrosion degree and the first corrosion rate to determine whether to process the thickness of the ship transportation tank body for the corresponding first cargo medium and the second cargo medium includes: The corrosion grade is used as the second condition for evaluating whether the stainless steel material corresponding to the stainless steel standard sample is suitable for the corresponding cargo medium. When the corrosion grade is not greater than 3, it meets the second condition. Only when both the first condition and the second condition are met can it be determined that the chemical tanker liquid cargo tank corresponding to the stainless steel standard sample is suitable for the corresponding cargo medium, and whether to allow the reduction of the corrosion allowance is obtained according to the first corrosion rate.

7. The method for evaluating the corrosion suitability of cargo media based on the liquid cargo tanks of chemical tankers according to claim 1, wherein The second corrosion test method includes standard sample setting, specimen condition setting, corrosion test process, and display of test results. Specifically: Standard sample setting: Two different types of duplex stainless steels with the same size and roughness are intercepted. The stainless steel in the first corrosion test method is used as the stainless steel standard sample, and another different type of duplex stainless steel is used as the comparison sample, so as to obtain the exposed surface area S and the mass W before the test. 21 ; Specimen condition setting: It includes a temperature control device, and the temperature control device at least includes a heater and a timer; an experimental container for containing the second cargo medium, and the solution volume of the second cargo medium is obtained according to the surface areas of the stainless steel standard sample and the comparison sample, and one corresponding stainless steel standard sample and comparison sample are placed in each experimental container; Corrosion test process: Placing the second cargo medium in the corresponding experimental container; Start the temperature control device to heat the second goods medium to the corresponding loading temperature, put in the corresponding stainless steel standard sample and comparison sample, and start timing. Let it stand for T 21 hours, then take out the stainless steel standard sample and comparison sample, wash them and weigh them to get W 22 ; Then, place the corresponding stainless steel standard sample and the comparative sample back into the above sample conditions, and let it stand for T 22 hours. After taking out the stainless steel standard sample, wash it and then weigh it to obtain W 23 ; Display test results: Calculate the second corrosion degree based on the stainless steel standard sample and the comparison sample after the test, and obtain the second corrosion rate at different loading temperatures and different second cargo media according to the corresponding mass.

8. The method for evaluating the corrosiveness of a chemical tanker's liquid cargo hold for cargo medium suitability according to claim 7, wherein The second cargo media include: concentrated sulfuric acid with a mass concentration of 98% m / m, nitric acid with a mass concentration between 65% - 68% m / m, and phosphoric acid with a mass concentration of 53% m / m. The loading temperatures include: 30°C, 40°C, and 50°C.

9. The method for corrosion assessment of the suitability of cargo media based on the liquid cargo holds of chemical tankers according to claim 7, characterized in that The calculation formula for the second corrosion rate corresponding to different standing times is expressed as: Obtain the corrosion rates of the stainless steel standard sample at different loading temperatures and different second cargo media according to the above calculation formula; and the corrosion rates of the comparison sample at different loading temperatures and different second cargo media, and conduct a comparative analysis of the corrosion rates corresponding to the two samples. Furthermore, combine the loading temperature as the first condition for evaluating whether the comparison stainless steel can replace the standard stainless steel to be suitable for loading this cargo medium.

10. The method for evaluating the corrosion suitability of cargo media based on the liquid cargo tanks of chemical tankers according to claim 9, wherein Use the second corrosion degree and the second corrosion rate to judge whether to process the thickness of the hull of the ship's cargo hold for the corresponding first cargo medium and the second cargo medium, including: If, at a certain loading temperature, the first condition and the second condition are met, that is, the comparison stainless steel can replace the standard stainless steel to be suitable for loading this cargo medium, then calculate whether to allow the reduction of the corrosion allowance according to the second corrosion rate.

11. A corrosion assessment system for the suitability of cargo media based on the liquid cargo holds of chemical tankers, characterized in that The system includes: The first corrosion test calculation module is used to obtain the corrosion test results of the stainless steel standard sample in the first cargo medium by using the first corrosion test method, and then obtain the corresponding first corrosion degree and the first corrosion rate. The judgment module is used to determine whether to conduct the second corrosion test method according to the corresponding first corrosion degree obtained by the first corrosion test method. Specifically: The first corrosion degree calculation unit is used to calculate the first corrosion degree of the corresponding stainless steel standard sample according to the corrosion test results of the stainless steel standard sample. The judgment unit is used to process the thickness of the hull of the chemical tanker's cargo hold according to the comparison between the first corrosion degree and the second corrosion degree. Specifically: If the first corrosion degree of the corresponding stainless steel standard sample is greater than or equal to the corrosion intensity threshold, then conduct the test of the second corrosion test method on the stainless steel standard sample and the comparison sample in the second cargo medium under the same parameters, obtain the corrosion test results of the stainless steel standard sample and the comparison sample in the second cargo medium, and then obtain the second corrosion degree and the second corrosion rate corresponding to the second cargo medium, and use the second corrosion degree and the second corrosion rate to judge whether to process the thickness of the hull of the chemical tanker's cargo hold for the corresponding first cargo medium and the second cargo medium. Otherwise, If the first corrosion degree of the corresponding stainless steel standard sample is less than the corrosion intensity threshold, then directly use the first corrosion degree and the first corrosion rate to judge whether to process the thickness of the hull of the ship's cargo hold for the corresponding first cargo medium and the second cargo medium. Among them, the first corrosion test method is the high-temperature accelerated corrosion method, and the second corrosion test method is the comparative analysis corrosion method of the transport ship at the actual design loading temperature. The corresponding first corrosion degree obtained according to the first corrosion test method includes: Preprocessing the images of the stainless steel standard samples obtained according to the first corrosion test method at different times. The preprocessing includes image screening, image downsampling, and image enhancement performed separately according to different product media. The different times refer to the times corresponding to the completion of the first corrosion test method. The image enhancement is obtained based on the results of image downsampling. Calculating the information entropy corresponding to the enhanced images after image enhancement performed separately under different first product media, obtaining the weights corresponding to the enhanced images according to the information entropy, and fusing the enhanced images corresponding to each image according to the weights to obtain the final enhanced image. Obtaining the corrosion area corresponding to the final enhanced image and obtaining the pixel values of each pixel point in the corrosion area. Calculating the corrosion intensity of the stainless steel standard sample corresponding to the product medium according to the pixel value of each pixel point and the corresponding color value. Setting corrosion grades, determining the first corrosion degree according to the corrosion intensity and the preset corrosion intensity threshold. If the corrosion intensity threshold is set to [0, 10], when the corresponding corrosion grade is less than 5, it is set as a small first corrosion degree; when the corresponding corrosion grade is greater than or equal to 5, it is set as a large first corrosion degree. The calculation of the second corrosion degree according to the stainless steel standard sample and the comparison sample after the test includes: Obtaining the thicknesses of the standard sample and the comparison sample obtained under the same loading temperature and the same product medium after the test. The thickness of a single standard sample is denoted as D1, and the thickness of the comparison sample is denoted as D2. The standard thickness under the same conditions obtained according to relevant standards is denoted as standard H. Calculating the differences between the thicknesses D1, D2 and the standard thickness H for comparison. Specifically, if |D1 - H| ≤ |D2 - H|, then the first fitting weight of the standard sample is greater than the corresponding weight of the comparison sample. The first fitting weight is a parameter for measuring the fitting capabilities of the standard sample and the comparison sample. Obtaining the corrosion area occupancy rates, denoted as R1 and R2 respectively, according to the corrosion areas corresponding to the standard sample and the comparison sample obtained under the same loading temperature and the same product medium. If R1 ≤ R2 and both are less than the occupancy rate setting threshold, then the second fitting weight of the standard sample is greater than the corresponding weight of the comparison sample. The second fitting weight is a parameter for measuring the fitting capabilities of the standard sample and the comparison sample. If R1 ≤ R2 and R2 is not less than the occupancy rate setting threshold, then the second fitting weight of the comparison sample is set to zero. If R1 ≤ R2 and both are not less than the occupancy rate setting threshold, then neither the standard sample nor the comparison sample is used as a fitting material. If R1 > R2 and both are less than the occupancy rate setting threshold, then the second fitting weight of the comparison sample is greater than the corresponding weight of the standard sample. If R1 > R2 and R1 is not less than the occupancy rate setting threshold, then the second fitting weight of the standard sample is set to zero. If R1 > R2 and both are not less than the occupancy rate setting threshold, then neither the standard sample nor the comparison sample can be used as a fitting material. The second corrosion degree of a certain cargo medium of the standard sample and the comparison sample at different loading temperatures is comprehensively obtained according to the first fitting weight and the second fitting weight, which is used as the second condition for determining whether the comparison stainless steel can replace the standard stainless steel for fitting the cargo medium.

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