CN103439408A - Ultrasonic detection method for weld joint of small-caliber pipe shelf angle - Google Patents

Abstract

The invention provides an ultrasonic detection method for a weld joint of a small-caliber pipe shelf angle. A digital ultrasonic fault detector is adopted to calculate and determine the refraction angle of a probe utilizing the formula that beta is equal to or larger than tan<-1>[(H+L0)/2T] according to weld joints of pipe shelf angles in various specifications, so that the acoustic beam axis of the primary reflection wave can reach the end part of a pipe adapter, wherein H is the sum of the weld joint of the shelf angle, the depth of a header groove and the insertion depth of the pipe adapter, and T is the wall thickness of the pipe adapter; a monocrystal transverse wave angle probe with a corresponding refraction angle is adopted for detection from the outer side of the pipe shelf, so that a defect at the root part of the welt joint of the shelf angle can be effectively detected, a defect wave and structural wave can be accurately identified, missed detection and wrong detection during the detection of the workpieces can be reduced, and the accuracy of the detection work can be greatly improved.

Description

A kind of ultrasonic detection method of small-bore base fillet weld

Technical field

The present invention relates to a kind of ultrasonic weld seam detection method, be specifically related to the detection for small-bore base fillet weld (lack of penetration form) internal soundnesses such as boiler headers.

Background technology

Now, while adopting conventional ultrasonic detection method to be detected the small-bore base fillet weld of lack of penetration structure, the insertion portion of pipe is because there is lack of penetration gap in the fillet weld root, be equivalent to exist at the root of weld seam the termination of a pipe, this termination produces more intrinsic echoed signal in conventional ultrasound examination, bring very large impact to the judgement of normal defects echo, cause detecting the undetected and flase drop of workpiece, domesticly so far there is no one for the small-bore base fillet weld of plug-in type (lack of penetration form) ultrasonic detection method and test stone.

Summary of the invention

The deficiency existed for overcoming existing ultrasonic weld seam detection method, the invention provides a kind of ultrasonic detection method of small-bore base fillet weld, adopt digital ultrasonic flaw detector, base fillet weld for different size, adopt the monocrystalline transverse wave double-bevel detector of corresponding refraction angle to be detected from the base outside, accurately defect recognition ripple and structure ripple, detect contingent undetected and flase drop in workpiece thereby reduce.

For realizing above-mentioned purpose, technical scheme of the present invention is:

A kind of ultrasonic detection method of small-bore base fillet weld, ultrasonic detection device comprises digital ultrasonic flaw detector and monocrystalline transverse wave double-bevel detector, wherein the frequency of monocrystalline transverse wave double-bevel detector is 5MHz, and wafer size is 6mm * 6mm or 8mm * 8mm, the Front distance distance L ₀≤ 5mm, the weld inspection method based on described ultrasonic detection device comprises the steps:

Step 1: according to β>=tan ^-1[(H+L ₀)/2T] calculate and determine the probe refraction angle, make the beam axis of primary reflection can reach the end of pipe adapter, wherein H is fillet weld height, header groove depth and pipe adapter insertion depth sum, the wall thickness that T is pipe adapter;

Step 2: the refraction angle of verification probe, select in calibration block the cross-drilled hole identical or close with institute test tube joint twice wall thickness as calibration point, its calibration block adopts the DL-1 series Special test block in power industry standard DL/T820-2002 " pipeline welded joint ultrasonic inspection techniques rules ", if the acoustical behavior of tested test specimen and Special test block there are differences, should to refraction angle and the sensitivity of probe, revise accordingly according to the test specimen velocity of sound etc.;

Step 3: by the depth localization method, adjust the base line scanning ratio;

The drafting of step 4:DAC curve and Scanning sensitivity, the drafting of DAC curve is made the first reference point with institute's identical or close cross-drilled hole of test tube joint twice wall thickness, and this cross-drilled hole echo is adjusted into to all over the screen 80%, in the situation that do not change gain, draw successively, the scope of DAC curve should comprise whole weld seam and heat-affected zone, and Scanning sensitivity is DAC curve gain 10dB;

Step 5: all crackle incomplete fusions in surveyed area are defective; It is defective that the defect reflection wave amplitude is more than or equal to Φ 1 * 15 o'clock, and it is defective that the Indicated defect length under Φ 1 * 15-10dB sensitivity is greater than 10mm.

Base fillet weld for different size, adopt the monocrystalline transverse wave double-bevel detector of corresponding refraction angle to be detected from the base outside, can effectively detect the root defect in fillet weld, accurately defect recognition ripple and structure ripple, thus greatly improved the accuracy of testing.

The accompanying drawing explanation

Fig. 1 is that schematic diagram is chosen at refraction angle.

In figure: β is probe refraction angle, L ₀for Front distance distance, the height that G is fillet weld, S is the header groove depth, and C is the pipe adapter insertion depth, and T is the pipe adapter wall thickness.

Embodiment

As shown in Figure 1, a kind of ultrasonic detection method of small-bore base fillet weld, be Φ 60 * 10mm Fillet for specification, adopts the monocrystalline transverse wave double-bevel detector of corresponding refraction angle to be detected from the base outside, the steps include:

Step 1: according to β>=tan ^-1[(H+L ₀)/2T] calculate and determine the probe refraction angle, by actual measurement, the height G=14mm of fillet weld, depth S=the 14mm of header groove, the insertion depth C=2mm of pipe adapter, the wall thickness T=10mm of pipe adapter, the probe used is the small diameter tube dedicated probe, and Front distance is L ₀=5mm,

Shellfish: H=G+S+C=14+14+2=30mm

β≥tan ^-1[(H+L ₀)／2T]≥tan ^-1[(30+5)／20]≥60.3°

Can prepare by β=50 °, 55 °, 60 °, 65 °, 70 ° by probe, finally choose that angle approaches the most;

Step 2: the refraction angle of verification probe, select in calibration block the cross-drilled hole identical or close with institute test tube joint twice wall thickness as calibration point, its calibration block adopts the DL-1 series Special test block in power industry standard DL/T820-2002 " pipeline welded joint ultrasonic inspection techniques rules ", and the scope of application of Special test block sees the following form:

The test block numbering	R1	The scope of application	R2	The scope of application
					1	16	Φ32～Φ35	17.5	Φ35～Φ38
2	19	Φ38～Φ41	20.5	Φ41～Φ44.5
					3	22.5	Φ44.5～Φ48	24	Φ48～Φ60
4	30	Φ60～Φ76	38	Φ76～Φ79
					5	50	Φ90～Φ133	70	Φ133～Φ159

The radius that wherein R1, R2 are lower surface camber in test block;

Step 3: by the depth localization method, adjust base line scanning ratio, the position by the position of pipe adapter twice wall thickness (angle, pipe adapter outer end) corresponding to defectoscope screen display time scan line the 4th lattice;

The drafting of step 4:DAC curve and Scanning sensitivity, the drafting of DAC curve is made the first reference point with institute's identical or close cross-drilled hole of test tube joint twice wall thickness, and this cross-drilled hole echo is adjusted into to all over the screen 80%, in the situation that do not change gain, draw successively, the scope of DAC curve should comprise whole weld seam and heat-affected zone, and Scanning sensitivity is DAC curve gain 10dB;

Step 5: all crackle incomplete fusions in surveyed area are defective; It is defective that the defect reflection wave amplitude is more than or equal to Φ 1 * 15 o'clock, and it is defective that the Indicated defect length under Φ 1 * 15-10dB sensitivity is greater than 10mm.

Base fillet weld for different size, adopt the monocrystalline transverse wave double-bevel detector of corresponding refraction angle to be detected from the base outside, can effectively detect the root defect in fillet weld, accurately defect recognition ripple and structure ripple, detect contingent undetected and flase drop in workpiece thereby reduce, greatly improved the accuracy of testing.

Claims (1)

1. the ultrasonic detection method of a small-bore base fillet weld, ultrasonic detection device comprises digital ultrasonic flaw detector and monocrystalline transverse wave double-bevel detector, wherein the frequency of monocrystalline transverse wave double-bevel detector is 5MHz, and wafer size is 6mm * 6mm or 8mm * 8mm, the Front distance distance L ₀≤ 5mm, the weld inspection method based on described ultrasonic detection device comprises the steps:

Step 1: according to β>=tan ^-1[(H+L ₀)/2T] calculate and determine the probe refraction angle, make the beam axis of primary reflection can reach the end of pipe adapter, wherein H is fillet weld height, header groove depth and pipe adapter insertion depth sum, the wall thickness that T is pipe adapter;

Step 2: the refraction angle of verification probe, select in calibration block the cross-drilled hole identical or close with institute test tube joint twice wall thickness as calibration point, its calibration block adopts the DL-1 series Special test block in power industry standard DL/T820-2002 " pipeline welded joint ultrasonic inspection techniques rules ", if the acoustical behavior of tested test specimen and Special test block there are differences, should to refraction angle and the sensitivity of probe, revise accordingly according to the test specimen velocity of sound etc.;

Step 3: by the depth localization method, adjust the base line scanning ratio;

The drafting of step 4:DAC curve and Scanning sensitivity, the drafting of DAC curve is made the first reference point with institute's identical or close cross-drilled hole of test tube joint twice wall thickness, and this cross-drilled hole echo is adjusted into to all over the screen 80%, in the situation that do not change gain, draw successively, the scope of DAC curve should comprise whole weld seam and heat-affected zone, and Scanning sensitivity is DAC curve gain 10dB;

Step 5: all crackle incomplete fusions in surveyed area are defective; It is defective that the defect reflection wave amplitude is more than or equal to Φ 1 * 15 o'clock, and it is defective that the Indicated defect length under Φ 1 * 15-10dB sensitivity is greater than 10mm.

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