阅读说明：本技术 一种用于直缝焊管水耦合超声波探伤的设备调整方法 (Equipment adjusting method for water coupling ultrasonic flaw detection of straight welded pipe ) 是由 周长忠 眭凌峰 于 2018-05-28 设计创作，主要内容包括：本发明涉及一种用于直缝焊管水耦合超声波探伤的设备调整方法,本发明选用了尺寸匹配的耐磨块,并通过选用合适的探头尺寸以及检测频率,使探头的声束扩散角降低,而且同组探头的声束水平中心被调整到一条直线上,同时探伤前钢管表面杂质被清洗干净,本发明能解决长期困扰直缝焊管自动超声波探伤耦合监控的问题。(The invention relates to a method for adjusting equipment for water coupling ultrasonic flaw detection of a longitudinal welded pipe, which selects a wear-resistant block with matched size, reduces the sound beam diffusion angle of a probe by selecting proper probe size and detection frequency, adjusts the horizontal centers of sound beams of the same group of probes to be on a straight line, and simultaneously cleans impurities on the surface of a steel pipe before flaw detection.)

1. a method for adjusting equipment for water coupling ultrasonic flaw detection of a longitudinal welded pipe is characterized by comprising the following steps of: the equipment adjusting method comprises the following steps:

(1) Selecting a wear-resistant block matched with the outer diameter of the steel pipe to be subjected to flaw detection, and mounting the steel pipe in a central circle of the wear-resistant block;

(2) Selecting a probe with a small sound beam spread angle under the condition that the diameter and the detection frequency of the probe meet the flaw detection requirements, wherein the sound beam spread angle is inversely proportional to the diameter of the probe and the detection frequency of the probe;

(3) Adjusting the horizontal centers of the sound beams of the probes in the same group to enable the horizontal centers of the sound beams of the probes in the same group to be on the same straight line;

(4) Aiming at different detection functions of different probes, a proper coupling monitoring method is selected, namely: carrying out layered flaw detection on the straight probe by using a bottom wave method; selecting a surface wave method for longitudinal flaw detection of the single crystal inclined probe; the method comprises the following steps of (1) carrying out tandem flaw detection on an inclined probe by selecting a wave transmitting method of the same group of probes;

(5) And after the equipment is adjusted, carrying out water coupling ultrasonic flaw detection on the steel pipe.

2. the equipment adjustment method according to claim 1, wherein in the step (1), the wear-resistant blocks are matched with the steel pipes according to the following principle: the outer diameter of the wear-resistant block with the central circle diameter of R is matched with the outer diameter of the steel pipe of R to (R + 50).

3. The apparatus adjusting method according to claim 1, wherein in the step (2), the beam spread angle of the probe is:

θ＝70×v/Df

Where θ is the sound beam spread angle of the probe, v is the ultrasonic propagation velocity, D is the diameter of the probe, and f is the detection frequency of the probe.

4. the method for adjusting equipment according to claim 1, wherein the method for adjusting equipment is characterized in that a water cleaning device is provided, and the water cleaning device is started before flaw detection to clean impurities on the surface of the steel pipe and ensure the cleanliness of the surface of the steel pipe.

5. The device adjusting method according to claim 1, wherein in the step (3), the horizontal beam center of the probes in the same group is adjusted by:

The same group of probes comprises a first probe and a second probe, the first probe is fixed, the sound beam of the second probe is aligned to the first probe, the second probe is rotated, when the echo amplitude of the first probe reaches the maximum, the rotation of the second probe is stopped, and the second probe is fixed at the current position;

After the second probe is fixed, aligning the sound beam of the first probe with the second probe, rotating the first probe, stopping the rotation of the first probe when the echo amplitude of the second probe reaches the maximum, and fixing the first probe at the current position.

Technical Field

The invention relates to an equipment adjusting method for water coupling ultrasonic flaw detection of a longitudinal welded pipe.

Background

During the production of steel pipes, due to various contingencies, there are inevitable defects on the walls of the steel pipes, such as: longitudinal cracks, transverse cracks, folds, delaminations, etc. The steel pipe is harsh in general conditions in the using process, if the steel pipe is defective, the steel pipe can be broken in use to cause accidents and even more serious consequences, such as high-temperature and high-pressure water pipe explosion, pipeline leakage for conveying toxic chemical raw materials in a chemical plant and high-pressure pipeline explosion for conveying natural gas, which can cause great economic loss and even casualties. Therefore, all the manufacturers producing steel pipes in the world have perfect nondestructive testing equipment to carry out online flaw detection on the steel pipes.

ultrasonic waves, which are high-frequency mechanical waves, have a large energy loss when propagating through air, and are generally transmitted from a transmission probe to the surface of a steel pipe to be tested through a coupling medium such as water in actual flaw detection.

Considering that the water coupling effect directly influences the flaw detection reliability, part of users of high-end welded pipe products clearly require to monitor the water coupling condition, and the dynamic improvement value of the coupling monitoring gain of the flaw detection system is used as the technical condition for the qualified suppliers to admit.

The automatic ultrasonic flaw detection equipment for welding seam configured by domestic and foreign welding pipe manufacturing enterprises adopts flaw detection mode of fixing steel pipe and linearly scanning the inner and outer surfaces of welding seam with probe. Different from the requirement of the full-circumferential detection of a seamless steel pipe, as only the weld joint needs to be subjected to flaw detection, in order to avoid energy loss in the ultrasonic wave propagation process, a water film method rather than a local water immersion method is adopted for coupling between the probe and the surface of the steel pipe, and the coupling effect and stability are obviously inferior to those of the latter.

the existing automatic ultrasonic flaw detection equipment for the longitudinal welded pipe has the following defects in the coupling monitoring method: 1) the wear-resistant block is unreasonable in structural design and large in specification span range, so that the wear-resistant block is poor in fit tightness with the surface of the steel pipe, and poor coupling caused by water loss is easily caused during flaw detection. 2) The method for installing the probe and confirming the center of the sound beam is improper, so that the centers of the sound beams are not on the same horizontal line after the same group of probes are installed, and unnecessary diffusion attenuation of the ultrasonic wave is caused. 3) The probe is not suitable for manufacturing size and detection frequency, so that the sound beam diffusion angle is too large, and the sound energy attenuation is serious. 4) The surface quality of the steel pipe is poor, and the original design of the equipment does not consider the surface cleaning function of the steel pipe. 5) The improper selection of the coupling monitoring echo form causes the excessive increase of the coupling monitoring gain dynamic increasing value.

Disclosure of Invention

the invention aims to provide an adjusting method of equipment for water coupling ultrasonic flaw detection of a longitudinal welded pipe, which selects a wear-resistant block with matched size, reduces the spread angle of sound beams of a probe by selecting proper probe size and detection frequency, adjusts the horizontal centers of the sound beams of the same group of probes to be on a straight line, and cleans impurities on the surface of the steel pipe before flaw detection so as to solve the problem of the existing flaw detection equipment in the aspect of coupling monitoring.

In order to achieve the purpose, the scheme of the invention is as follows: an equipment adjusting method for water coupling ultrasonic flaw detection of a longitudinal welded pipe, comprising the following steps of:

(1) Selecting a wear-resistant block matched with the outer diameter of the steel pipe to be subjected to flaw detection, and mounting the steel pipe in a central circle of the wear-resistant block;

(2) Selecting a probe with a small sound beam spread angle under the condition that the diameter and the detection frequency of the probe meet the flaw detection requirements, wherein the sound beam spread angle is inversely proportional to the diameter of the probe and the detection frequency of the probe;

(3) Adjusting the horizontal centers of the sound beams of the probes in the same group to enable the horizontal centers of the sound beams of the probes in the same group to be on the same straight line;

(4) Aiming at different detection functions of different probes, a proper coupling monitoring method is selected, namely: carrying out layered flaw detection on the straight probe by using a bottom wave method; selecting a surface wave method for longitudinal flaw detection of the single crystal inclined probe; the method comprises the following steps of (1) carrying out tandem flaw detection on an inclined probe by selecting a wave transmitting method of the same group of probes;

(5) And after the equipment is adjusted, carrying out water coupling ultrasonic flaw detection on the steel pipe.

Further, according to the equipment adjusting method of the present invention, in the step (1), the matching principle of the wear-resistant block and the steel pipe is as follows: the outer diameter of the wear-resistant block with the central circle diameter of R is matched with the outer diameter of the steel pipe of R to (R + 50).

Further, according to the device adjusting method of the present invention, in the step (2), the sound beam spread angle of the probe is:

θ＝70×v/Df

Where θ is the sound beam spread angle of the probe, v is the ultrasonic propagation velocity, D is the diameter of the probe, and f is the detection frequency of the probe.

further, according to the equipment adjusting method provided by the invention, the water cleaning device is arranged, and the water cleaning device is started before flaw detection, so that impurities on the surface of the steel pipe are cleaned, and the cleanliness of the surface of the steel pipe is ensured.

Further, according to the device adjusting method of the present invention, in the step (3), the method for adjusting the horizontal center of the acoustic beam of the probes in the same group includes:

the same group of probes comprises a first probe and a second probe, the first probe is fixed, the sound beam of the second probe is aligned to the first probe, the second probe is rotated, when the echo amplitude of the first probe reaches the maximum, the rotation of the second probe is stopped, and the second probe is fixed at the current position;

after the second probe is fixed, aligning the sound beam of the first probe with the second probe, rotating the first probe, stopping the rotation of the first probe when the echo amplitude of the second probe reaches the maximum, and fixing the first probe at the current position

the invention achieves the following beneficial effects: the invention selects the wear-resistant blocks with matched sizes, and the proper probe size and detection frequency are selected, so that the sound beam spread angle of the probe is reduced, the horizontal centers of the sound beams of the same group of probes are adjusted to be on a straight line, and the impurities on the surface of the steel pipe are cleaned before flaw detection.

Drawings

FIG. 1 is a flow chart of the method of the present invention;

FIG. 2 is a schematic diagram showing the distribution of probes of the ultrasonic automatic flaw detection equipment for weld joints;

FIG. 3 is a top view of the wear block;

Fig. 4a and 4b are schematic diagrams for adjusting the horizontal center of the sound beams of the same group of probes.

Detailed Description

The invention is described in further detail below with reference to the figures and specific examples.

FIG. 2 is the distribution of probes of the ultrasonic automatic flaw detection equipment for welding seams, in FIG. 1, 1 and 2 are longitudinal internal damage probes, 3 and 4 are longitudinal external damage probes, 5 and 6 are transverse probes, 7 and 8 are heat affected zone probes, and all the probes realize linear scanning of the welding seams through a driving trolley hung on a portal frame.

as shown in fig. 1, the method of the present invention comprises:

(1) The special wear-resistant blocks are processed, the application range of the wear-resistant blocks is reasonably distributed, and the fitting degree of the wear-resistant blocks and the surface of the steel pipe is improved.

The functions of the wear-resistant block are mainly as follows: firstly, protecting the probe; secondly, the surface fitting degree of the steel pipe is improved, and the water coupling effect is ensured. The probe is arranged in the circular hole in the figure 3, and the emitted ultrasonic waves are transmitted into the steel pipe through water coupling between the wear-resistant block and the surface of the steel pipe.

after the processing of wear-resisting piece was accomplished, for further improvement and the laminating degree on steel pipe surface, the steel pipe of different external diameter scope uses the wear-resisting piece of different R values, corresponds the principle: the steel pipe outer diameter ranges from R to (R + 50).

The specific correspondence is shown in table 1.

TABLE 1 specification of wear-resistant blocks and steel pipe application scope

serial number	Wear resistant block (R)	Applicable steel pipe outside diameter range (mm)
			1	219	219-269
2	250	250-300
			3	300	300-350
4	350	350-400
			5	400	400-450
6	450	450-500
			7	525	525-575

(2) selecting and installing proper probe to reduce probe sound beam spread angle

The basis for selecting the probe is as follows:

Sound beam spread angle theta 70 x lambda/D

wherein λ is the ultrasonic wavelength and D is the probe diameter.

and because lambda is v/f

where v is the ultrasonic propagation velocity and f is the probe detection frequency.

θ＝70×v/Df

When the ultrasonic wave propagation velocity v (v 3230m/s) is constant, the diffusion angle θ is inversely proportional to the probe outer diameter and the detection frequency. For example: the probe related parameter D is 14mm, f is 4MHz, in this case θ is 4 °.

Under the condition, the divergence angle of the sound beam is only 4 degrees, so that the divergence degree of the sound beam is greatly improved and reduced.

(3) The horizontal center of the sound beam of the same group of probes is adjusted, and the transmission efficiency among the same group of probes is improved

The adjustment method is illustrated in fig. 4a and 4b, where 9, 10 represent the first and second probes of the same set of inner or outer surface inspection probes, respectively. The method for confirming the center of the sound beam of the probe comprises the following steps:

As shown in fig. 4a, the first probe 9 is fixed, the sound beam direction of the second probe 10 is toward the first probe 9, the second probe 10 is rotated, and when the echo amplitude of the first probe 9 reaches the maximum, the rotation of the second probe 10 is stopped, and the installation position of the second probe 10 is fixed.

as shown in fig. 4b, the second probe 10 is fixed, the beam direction of the first probe 9 is directed toward the second probe 10, the first probe 9 is rotated, and when the echo amplitude of the second probe 10 is at its maximum, the rotation of the first probe 9 is stopped, and the installation position of the first probe 9 is fixed.

(4) Selecting proper coupling monitoring control method according to different detection probes and detection functions

The control methods of coupling monitoring are different according to the detection function and the type of the detection probe used. The common detection functions of the weld joint detection and the corresponding relation between the probe and the coupling monitoring control method are shown in a table 2.

TABLE 2 coupling monitoring control method classification

Detection function	Type of probe	Coupling control method
			layered flaw detection	Straight probe	bottom wave
Longitudinal flaw detection	Single crystal inclined probe	Surface wave
			Tandem flaw detection	Inclined probe	The same group of probes transmits waves

(5) Opening the water cleaning device to remove impurities on the surface of the steel pipe and ensure the surface cleanliness of the steel pipe

The head part of the water pipe is a flat nozzle, and the cleaning device has the characteristics of adjustable height, large spraying area and uniformity.

Before the detection is started, a valve switch of the water pipe is opened, the surface of the steel pipe is pre-cleaned by water, and the influence of surface impurities on coupling is reduced.

The method of the present invention will be described with reference to the detection of 355.6X 11.13 line pipes as an example:

the method comprises the following steps of (1) adjusting;

(1) Processing the wear-resistant blocks, and selecting the wear-resistant blocks with the R value of 350mm according to the table 1;

(2) selecting a proper detection probe (D is 14mm, the detection frequency f is 4MHz, and the diffusion angle theta is 4 degrees);

(3) The horizontal center of the installed probes is adjusted to ensure the consistency of the probes in the same group;

(4) setting a proper coupling monitoring method according to the contents in the table 2;

(5) before the detection is started, the water cleaning device is started.