CN102662193B - Method for fast detecting plugging degree of oxide skins on inner wall of austenitic stainless steel tubes - Google Patents

Abstract

The invention belongs to the technical field of check and maintenance of the high-temperature heated surface of a boiler in the electric industry and particularly relates to a method for fast detecting the plugging degree of oxide skins on the inner wall of austenitic stainless steel tubes. The method is suitable for fast detecting the plugging degree of oxide skins on the inner wall of austenitic stainless steel tubes, achieves the purpose of fast detecting the plugging condition of oxide skins on the inner wall of austenitic stainless steel tubes through an MF500M magnetic detector, is not limited by field detection space or field detection environment, is not needed to be externally connected with a power supply or additionally provided with a steady magnetic field, has the remarkable advantages of being stable in measured data, high in accuracy and simple and convenient in data processing, and is especially suitable for fast check of plugging of the oxide skins on the inner wall of austenitic stainless steel tubes. In addition, the method is strong in practicality and pertinence and has good application value.

Description

Austenic stainless steel inside pipe wall oxide skin chocking-up degree method for quick

Technical field

The invention belongs to the technical field of the inspection of power industry boiler high temperature heating surface, maintenance, relate in particular to a kind of austenic stainless steel inside pipe wall oxide skin chocking-up degree method for quick, be applicable to austenic stainless steel inside pipe wall oxide skin chocking-up degree to carry out fast detecting.

Background technology

Large and super-critical, the coal-fired unit boiler high temperature of ultra supercritical heating surface generally adopt Austenitic stainless steel pipe in recent years, although this kind of steel pipe has good high-temperature behavior and welding performance, but in boiler running process, inevitably produce inner wall oxide film, this kind of oxide film is because the difference of thermal expansivity and steel pipe can come off and form oxide skin to be deposited under high-temperature surface near elbow in the process of boiler startup and stoppage in transit, and the safety on unit, stable operation produce a series of impacts.

The detection method of at present, austenitic stainless steel elbow inner wall oxide skin being piled up is mainly radiographic inspection film making and applies outside steady magnetic field and inside pipe wall oxide skin magnetize to recycling magnetic-field-sensitive element the magnetization value signal of the oxide skin generation being magnetized is detected to two kinds of methods.Front a kind of radiographic inspection is subject to boiler high temperature heating surface arrangement space restriction, and the effect of film making is bad, and site operation workload is large, and radiographic inspection method affects other service works of boiler and carry out, and cannot meet boiler maintenance construction period; A kind of rear method is implemented too loaded down with trivial details, need to separately connect power supply, connection wire that need to be very long is unfavorable for the inspection of large-sized boiler heating surface, to Static magnetic field that requirement is set is very high, be subject to the impact of actual testing environment, detect data fluctuating very large, the scene of can not completing is quick, the testing requirement of accurate location.

Summary of the invention

In order to solve technical matters of the prior art, the invention provides a kind of austenic stainless steel inside pipe wall oxide skin chocking-up degree method for quick, its objective is realize measurement data stability and accuracy rate high, and data processing feature simply and easily.

The present invention is achieved by the following technical solutions:

Austenic stainless steel inside pipe wall oxide skin chocking-up degree method for quick, comprises MF500M magnetism detector, and detecting step is:

(1) first MF500M magnetism detector is connected, main frame connects wire, and wire connects magnetization value test probe, start;

(2) by oxide skin, stop up reference block and apart from front, aim at MF500M probe according to the Austenitic stainless steel pipe wall thickness that will test, calibration 100% stopping state, records corresponding magnetization value Diff as calibration value (M);

(3) choose cross section, choose three characteristic cross-sections of bend pipe, choose cross section, place, bend pipe outer arc summit as interface (A), by steam flow bend pipe steam admission side and the tangent normal section of bend pipe, as interface (B), the tangent normal section of bend pipe steam output side and bend pipe is as interface (C);

(4) according to steam flow direction by selected interface (A) take minimum point as the clockwise quartern of starting point, the magnetization value everywhere of the described quartern is designated as respectively to A1, A2, A3 and A4, and interface (B), interface (C) make the mark same with interface (A); First measure interface (A) minimum point magnetization value A1, if A1 is greater than 10% of M, be less than 30% of M, judge that this section of bend pipe may have oxide skin to pile up, continue to measure A2, A3, A4 value, if A2, A3, A4 wherein any value are greater than 30% of M, or (A2+A3+A4)/3 be greater than 20% of M, judges that this section of bend pipe has oxide skin to pile up; If A1 value is greater than 30% of M, judge that this section of bend pipe has oxide skin to pile up;

(5) with measuring equally interface (B) and interface (C) with the measuring method of measuring interface (A), and make corresponding judged result.

Advantage of the present invention and effect are:

Detection method of the present invention is by being used MF500M magnetism detector to reach the object to austenic stainless steel inside pipe wall oxide skin stopping state fast detecting, the oxide skin difference that is magnetic of specifically utilizing Austenitic stainless steel pipe and its inside pipe wall to come off to pile up, the in the situation that of known Austenitic stainless steel pipe wall thickness, size, specification, material, by get the not magnetic Austenitic stainless steel pipe magnetization of point measurement value in particular cross section position, judge fast the magnetic oxide skin chocking-up degree of this inside pipe wall band.Display measurement position magnetization value changes, and can carry out measurement data storage, analysis, output; Data acquisition modes is easy, flexible, can in high-temperature surface maintenance process, fast, accurately reach the object of austenic stainless steel inside pipe wall oxide skin chocking-up degree judgement.The present invention is not subject to Site Detection space and environmental limit, without external power supply, without additional steady magnetic field, there is measurement data stable, accuracy rate is high, and data processing is distinguishing feature simply and easily, is specially adapted to the quick inspection that austenic stainless steel inside pipe wall oxide skin is stopped up.It is practical, with strong points, has good using value.

Accompanying drawing explanation

Below in conjunction with drawings and Examples, the present invention is further detailed explanation.

Fig. 1 is testing process schematic diagram of the present invention.

Embodiment

The present invention is austenic stainless steel inside pipe wall oxide skin chocking-up degree method for quick, using method and the application in austenic stainless steel inside pipe wall oxide skin chocking-up degree detects of object, especially MF500M magnetism detector that the MF500M magnetism detector by introducing reaches its detection.

MF500M magnetism detector is commercially available import instrument, comprises magnetization value measuring instrument main frame, containing display screen, control knob, magnetization value measuring sonde, probe wire, oxide skin, stops up reference block etc.

As shown in Figure 1, the technical scheme that the invention process detects is as follows:

1, first MF500M magnetism detector is connected, main frame connects wire, and wire connects magnetization value test probe, start;

2, by oxide skin, stop up reference block and apart from front, aim at MF500M probe according to the Austenitic stainless steel pipe wall thickness that will test, calibration 100% stopping state, records corresponding magnetization value Diff as calibration value M;

3, choose cross section, choose three characteristic cross-sections of bend pipe, choose cross section, place, bend pipe outer arc summit as interface A, by steam flow bend pipe steam admission side and the tangent normal section of bend pipe, as interface B, the tangent normal section of bend pipe steam output side and bend pipe is as interface C.

4, according to steam flow direction by selected interface A take minimum point as the clockwise quartern of starting point, the magnetization value everywhere of the described quartern is designated as respectively to A1, A2, A3 and A4, interface B, interface C make the mark same with interface A.First measure interface A minimum point magnetization value A1, if A1 is greater than 10% of M, be less than 30% of M, judge that this section of bend pipe may have oxide skin to pile up, continue to measure A2, A3, A4 value, if A2, A3, A4 wherein any value are greater than 30% of M, or (A2+A3+A4)/3 be greater than 20% of M, judges that this section of bend pipe has oxide skin to pile up; If A1 value is greater than 30% of M, judge that this section of bend pipe has oxide skin to pile up.

5, with measuring equally interface B and interface C with the measuring method of measuring interface A.

Specifically measuring process is for example:

Certain factory's high temperature reheater, wall thickness 5mm, first stops up oxide skin the positive magnetization intensity level test probe of aiming at of reference block, and obtaining its magnetization M is 400A/m.

Example 1:

Test 1 bend pipe of this high temperature reheater, A1 value is 28 A/m, is less than 10% of M, judges that thus this bend pipe does not have the oxide skin accumulation that comes off.

Example 2:

Test 1 bend pipe of this high temperature reheater, A1 value is 98A/m, be greater than 40 A/m, be less than 120 A/m and judge that this section of bend pipe may have oxide skin to pile up, continuing to measure A2 is 100 A/m, and A3 is 110 A/m, A4 is 90 A/m, A2, A3, A4 are all less than 120 A/m, but (A2+A3+A4)/3 be that 120 A/m are greater than 80 A/m, judge that this section of bend pipe has oxide skin to pile up.

Example 3:

Test 1 bend pipe of this high temperature reheater, A1 value is 158A/m, judges that this section of bend pipe has oxide skin to pile up.

Claims (1)

1. austenic stainless steel inside pipe wall oxide skin chocking-up degree method for quick, comprises MF500M magnetism detector, it is characterized in that:

(1) first MF500M magnetism detector is connected, main frame connects wire, and wire connects magnetization value test probe, start;

(2) by oxide skin, stop up reference block and aim at apart from front according to the Austenitic stainless steel pipe wall thickness that will test the probe of MF500M magnetism detector, calibration 100% stopping state, records corresponding magnetization value Diff as calibration value (M);

(3) choose cross section, choose three characteristic cross-sections of bend pipe, choose cross section, place, bend pipe outer arc summit as interface (A), by steam flow bend pipe steam admission side and the tangent normal section of bend pipe, as interface (B), the tangent normal section of bend pipe steam output side and bend pipe is as interface (C);

(4) according to steam flow direction by selected interface (A) take minimum point as the clockwise quartern of starting point, the magnetization value everywhere of the described quartern is designated as respectively to A1, A2, A3 and A4, and interface (B), interface (C) make the mark same with interface (A); First measure interface (A) minimum point magnetization value A1, if A1 is greater than 10% of M, be less than 30% of M, judge that this section of bend pipe may have oxide skin to pile up, continue to measure A2, A3, A4 value, if A2, A3, A4 wherein any value are greater than 30% of M, or (A2+A3+A4)/3 be greater than 20% of M, judges that this section of bend pipe has oxide skin to pile up; If A1 value is greater than 30% of M, judge that this section of bend pipe has oxide skin to pile up;

(5) with measuring equally interface (B) and interface (C) with the measuring method of measuring interface (A), and make corresponding judged result.

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