Fully automatic flaw detection method for nickel-based alloy pipeline composite plates

Abstract

The present invention discloses a fully automatic flaw detection method for nickel-based alloy pipeline composite plates, which relates to the field of steel production technology, including: 1. repairing and calibrating the probe lifting mechanism and frame; 2. calibrating the automatic probe in combination with the DGS chart of the manual flaw detection equipment; 3. processing artificial defects similar to the interface layer to verify the probe accuracy; 4. systematic gain sensitivity; 5. using the same material to calculate the accurate sound velocity and sound wave attenuation; 6. determining the material attenuation measurement method. The fully automatic flaw detection of nickel-based alloy pipeline composite plates N06625+X65MS was first realized in the world, which greatly improved the production efficiency and delivery capacity of such steel plates.

Description

Technical Field

[0001] The invention relates to the technical field of steel production, and in particular to a fully automatic flaw detection method for a nickel-based alloy pipeline composite plate. Background Art

[0002] Compared with corrosion-resistant materials such as austenitic stainless steel, 625 nickel-based alloy has shown excellent resistance to pitting corrosion, intergranular corrosion and stress corrosion in various corrosion environments such as H2S, Cl- and alkali metals. In addition, it also has good corrosion resistance in high temperature and high pressure corrosion environments. However, due to the high nickel content (>58%) in 625 alloy, its expensive price limits its wide application. The composite plate of 625 alloy and low-cost pipeline steel not only has excellent corrosion resistance, but also greatly reduces the cost of use, and has the excellent mechanical properties of high-strength pipeline steel substrate. It has a very broad application prospect. Saudi Aramco alone has a demand of 10,000 tons / year. However, at present, only manual flaw detection can be used internationally to detect the quality of the internal and bonding layers of steel plates. The flaw detection efficiency is low and the defect missed detection rate is high, which cannot meet the delivery requirements. If fully automatic flaw detection is realized, it can break through the existing technology, greatly improve production capacity and delivery capacity, and quickly occupy the market. Summary of the invention

[0003] The present invention aims at solving the above technical problems, overcomes the shortcomings of the prior art, and provides a fully automatic flaw detection method for nickel-based alloy pipeline composite plates, comprising:

[0004] 1. Improving the sensitivity of flaw detection

[0005] ①Repair and calibrate the probe lifting mechanism and frame;

[0006] ② Calibrate the automatic probe in combination with the DGS chart of the manual flaw detection equipment;

[0007] ③Process artificial defects similar to the interface layer to verify the accuracy of the probe;

[0008] ④Systematic gain sensitivity

[0009] 2. Detection methods

[0010] ⑤ Use the same material to calculate the accurate sound speed and sound wave attenuation

[0011] The average sound velocity and material attenuation were measured through several pieces of pipeline steel with a thickness close to the thickness of the composite plate substrate;

[0012] The average sound velocity and material attenuation of several points are measured at different positions on the nickel-based alloy plate;

[0013] ⑥Determine the material attenuation measurement method

[0014] S1. Determine the steel plate to be tested and record it in the table;

[0015] S2. Measure the thickness T of the untested steel plate and record it in the table;

[0016] S3. Select the straight probe model and use the flaw detector;

[0017] S4, adjust the fifth bottom wave of the steel plate to 80% and read the dB value X1;

[0018] S5, adjust the bottom wave to 80%, and read the sixth bottom wave dB value X2;

[0019] S6. Calculate the attenuation coefficient of the steel plate being tested using the one-way attenuation coefficient α=(X2-X1) / T.

[0020] The technical solution further defined in the present invention is:

[0021] The above-mentioned fully automatic flaw detection method for nickel-based alloy pipeline composite plates includes step ①, regularly checking the lifting spring of the probe lifting mechanism, replacing the broken spring in time, and optimizing the spring material, using 55SiMn silicon-manganese spring steel to ensure the lifting accuracy of the probe; regularly checking the probe seat, using a dial indicator to measure the water film gap between the wear-resistant plate and the probe, and replacing it in time if the wear exceeds 2mm to ensure the accuracy of the equipment, and the water film gap reaches 0.3mm-0.35mm.

[0022] The fully automatic flaw detection method for nickel-based alloy pipeline composite plates described above, step ②, the DGS curve represents the curve of the relationship between the echo sound path, amplitude dB and defects, and is used to detect the defect area equivalent calculation. When using the DGS curve, first select a regular reflector as a reference body, and a 5mm flat-bottom hole as the displayed DGS curve. The probe is placed on the large flat-bottom reference body, and the reference signal at this time is recorded. Referring to this model, the automatic probe is adjusted to the same curve. If the same curve cannot be adjusted, the probe needs to be repaired or replaced with a new one until it meets the standard.

[0023] The above-mentioned fully automatic flaw detection method for nickel-based alloy pipeline composite plates, step ③, simulates the limit position of the composite plate bonding layer interface position 5mm away from the edge of the steel plate and adds an artificial defect 2mm away from the near surface of the body on the test plate.

[0024] In the aforementioned fully automatic flaw detection method for nickel-based alloy pipeline composite plates, step ④, the sensitivity dB value setting is adjusted accordingly, so that the near-surface defect wave is significantly higher than the DAC curve, and the unbonded layer is effectively detected.

[0025] The fully automatic flaw detection method for the nickel-based alloy pipeline composite plate described above, step ⑤, measures the average sound velocity and material attenuation through 20 pieces of pipeline steel with a thickness close to the thickness of the composite plate substrate; and measures the average sound velocity and material attenuation of 20 points at different positions on the nickel-based alloy plate surface.

[0026] The beneficial effects of the present invention are:

[0027] (1) The present invention solves the current situation that nickel-based alloy pipeline composite plate N06625+X65MS can only be manually inspected and cannot meet the needs of mass production and supply by improving equipment accuracy, studying theoretical methods of flaw detection, and formulating judgment standards through theoretical calculations, thereby realizing fully automatic flaw detection of nickel-based alloy pipeline composite plate N06625+X65MS;

[0028] (2) After flaw detection on the test plate in the present invention, it is determined that artificial defects 2 mm away from the near surface can be detected, proving that the system sensitivity meets the requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is the DGS curve diagram;

[0030] Figure 2 This is the defect location comparison test diagram;

[0031] Figure 3 This is a simulation diagram of the defect detected by the oblique probe;

[0032] Figure 4 This is the reflection situation of the fully automatic ultrasonic flaw detection method in composite materials. DETAILED DESCRIPTION

[0033] This embodiment provides a fully automatic flaw detection method for a nickel-based alloy pipeline composite plate, comprising:

[0034] 1. Improving the sensitivity of flaw detection

[0035] Nickel-based alloy pipeline composite plate N06625+X65MS involves multiple UT inspection standards: API Spec 5L Appendix K Table SA-578 / SA-578M, ASTM A265, ASME BPVC Volume 5 Chapter 5, etc. Since these standards are aimed at the inspection of different materials and parts, such as pipeline substrate, nickel-based alloy, composite interface, etc. The composite interface bonding layer is almost close to the near-surface blind area of ​​the automatic flaw detector at a depth of 3mm, and the unbonded situation in this area must be monitored.

[0036] ①Repair and calibrate the probe lifting mechanism and frame

[0037] Regularly check the lifting spring of the probe lifting mechanism, replace the broken spring in time, and optimize the spring material. Use 55SiMn silicon-manganese spring steel, which has high strength, good elastic limit, high yield ratio, and good toughness. It can better adapt to working conditions under high stress and ensure the lifting accuracy of the probe. Regularly check the probe seat, use a dial indicator to measure the water film gap between the wear-resistant plate and the probe, and replace the spring with a wear of more than 2mm in time to ensure the accuracy of the equipment. The water film gap reaches 0.3mm-0.35mm.

[0038] Calibrate automatic probes with DGS charts for manual flaw detection equipment

[0039] like Figure 1-3 The DGS curve represents the relationship between the echo path, amplitude dB and defects, and is used to calculate the equivalent defect area. When using the DGS curve, first select a regular reflector as a reference body, and a 5mm flat-bottom hole as the displayed DGS curve. Place the probe on the large flat-bottom reference body and record the reference signal at this time. Refer to this model to adjust the automatic probe to the same curve. If the same curve cannot be adjusted, the probe needs to be repaired or replaced with a new one until it meets the standard.

[0040] ③Process artificial defects similar to the interface layer to verify the accuracy of the probe

[0041] On the test plate, simulate the interface position of the composite plate bonding layer at the extreme position of 5mm from the edge of the steel plate and add an artificial defect of 2mm from the near surface of the body;

[0042] ④Systematic gain sensitivity

[0043] Since the bonding interface is located near the ultrasonic near-field, the automatic flaw detector determines defects by making a DAC curve based on defects of different depths in the standard. When the defect wave exceeds the DAC curve, the instrument alarms and records the defect. The focal length of the GE one-transmitter-four-receiver probe is 12mm, and the feedback on defects in the near-field area is unclear. It is obviously inappropriate to determine the defect equivalent based on the DAC curve in the standard. The present invention measures the accurate sound velocity and dB attenuation values ​​of the two different materials of the composite plate respectively, and then makes corresponding adjustments to the sensitivity dB value setting of the flaw detection system based on the data, so that the near-surface defect wave is significantly higher than the DAC curve. This can effectively detect the unbonded layer;

[0044] like Figure 4The reflection of the fully automatic ultrasonic flaw detection method in composite materials (interface wave and bottom wave) is mainly determined by the difference in acoustic impedance of the two layers of composite materials, the quality of the composite layer and the attenuation of ultrasonic waves in the second layer of composite materials. When the acoustic impedance of the two layers of composite materials is the same or close to the composite quality, the interface wave (interface reflection wave of the first and second layers) is very low, while the amplitude of the bottom wave (bottom wave square wave of the second layer) is high (determined by the ultrasonic attenuation of the second layer of material, the bottom wave is low when the attenuation is large). When the acoustic impedance of the two layers of composite materials is the same or close to the composite quality, the interface wave is high, while the bottom wave is low or completely disappears.

[0045] After flaw detection on the test board, it was determined that artificial defects 2 mm away from the surface could be detected, proving that the system sensitivity met the requirements.

[0046] 2. Detection methods

[0047] ⑤ Use the same material to calculate the accurate sound speed and sound wave attenuation

[0048] The sound velocity and material attenuation of 20 pieces of pipeline steel with a thickness of 18.4 mm (close to the thickness of the composite plate substrate) were measured, with an average sound velocity of 5723 m / s and a material attenuation of 0.1205 dB / mm. ;

[0049] By measuring the average sound velocity of 20 points at different positions on the nickel-based alloy plate, the material attenuation is 0.0987dB / mm. ;

[0050] ⑥Determine the material attenuation measurement method

[0051] .

[0052] If you want to test the nickel-based alloy pipeline composite plate on the fully automatic flaw detector, you must first conduct a sound velocity test and comparison on the ordinary pipeline and the nickel-based alloy pipeline. From the definition of wave velocity, wavelength and frequency, we can get: c=fλ or λ=c / f. From the above formula, we can see that the wavelength is proportional to the wave velocity and inversely proportional to the frequency. When the frequency is constant, the higher the wave velocity, the longer the wavelength; when the wave velocity is constant, the lower the frequency, the longer the wavelength. Therefore, the difference in different sound velocities will directly affect the detection results.

[0053] This invention is the first in the world to realize fully automatic flaw detection of nickel-based alloy pipeline composite plates N06625+X65MS, greatly improving the production efficiency and delivery capacity of this type of steel plates.

[0054] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. A fully automatic flaw detection method for nickel-based alloy pipeline composite plates, characterized in that: include:

1. Improving the sensitivity of flaw detection ①Repair and calibrate the probe lifting mechanism and frame; ② Calibrate the automatic probe in combination with the DGS chart of the manual flaw detection equipment; ③Process artificial defects similar to the interface layer to verify the accuracy of the probe; ④Systematic gain sensitivity; Among them, in the step ①, the lifting spring of the probe lifting mechanism is regularly inspected, the broken spring is replaced in time, and the spring material is optimized, using 55SiMn silicon manganese spring steel to ensure the lifting accuracy of the probe; Check the probe seat regularly, use a dial indicator to measure the water film gap between the wear-resistant plate and the probe, and replace it in time if the wear exceeds 2mm to ensure the accuracy of the equipment, and the water film gap reaches 0.3mm-0.35mm; In the step ②, the DGS curve represents the relationship between the echo path, amplitude dB and defects, and is used to detect the defect area equivalent calculation. When using the DGS curve, first select a regular reflector as a reference body, and a 5mm flat-bottom hole as the displayed DGS curve. The probe is placed on the large flat-bottom reference body, and the reference signal at this time is recorded. The automatic probe is adjusted to the same curve with reference to this model. If the same curve cannot be adjusted, the probe needs to be repaired or replaced with a new one until it meets the standard; In step ③, the test plate is simulated to have an interface position of the composite plate bonding layer at a limit position of 5 mm from the edge of the steel plate and an artificial defect of 2 mm from the near surface of the body; In step ④, the sensitivity dB value setting is adjusted accordingly so that the near-surface defect wave is significantly higher than the DAC curve, and the unbonded layer is effectively detected; 2. Detection methods ⑤ Use the same material to calculate the accurate sound speed and sound wave attenuation The average sound velocity and material attenuation were measured through several pieces of pipeline steel with a thickness close to the thickness of the composite plate substrate; The average sound velocity and material attenuation of several points are measured at different positions on the nickel-based alloy plate; ⑥Determine the material attenuation measurement method S1. Determine the steel plate to be tested and record it in the table; S2. Measure the thickness T of the untested steel plate and record it in the table; S3. Select the straight probe model and use the flaw detector; S4, adjust the fifth bottom wave of the steel plate to 80% and read the dB value X1; S5, adjust the bottom wave to 80%, and read the sixth bottom wave dB value X2; S6. Calculate the attenuation coefficient of the steel plate being tested using the one-way attenuation coefficient α=(X2-X1) / T.

2. The fully automatic flaw detection method for nickel-based alloy pipeline composite plates according to claim 1 is characterized in that: In the step ⑤, the average sound velocity and material attenuation are measured through 20 pieces of pipeline steel having a thickness close to the thickness of the composite plate substrate; and the average sound velocity and material attenuation are measured at 20 points at different positions on the nickel-based alloy plate surface.

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