JP2017150901A - Creep damage place screening gauge and method for evaluating life of pipe line - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a creep damage place screening gauge capable of efficiently performing screening for previously restricting pipe lines to be targeted before evaluating the life irrespective of the specification of the pipe line, and a method for evaluating the life of the pipe line.SOLUTION: A creep damage place screening gauge comprises: a gauge body 2; a receiving part 3 formed to notch the front edge of the gauge body 2 and receiving a pipe line 100 entered from the front; a rod 4 movable back and forth to the pipe line 100 received in the receiving part 3 and attached to the gauge body 2; and a display for displaying a position at the head end 4b of the rod 4. The receiving part 3 is formed by a pair of slopes 3a separated from each other as they go ahead, and the pair of slopes 3a is inclined at same angle θ to the movement path CL1 of the rod 4.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a creep damage location screening gauge for narrowing down the number of pipes to be subjected to a life evaluation concerning creep damage, and a pipe life evaluation method using the creep damage spot screening gauge.

Pipes that are used for a long time at high temperatures and high pressures in boilers, chemical plants, etc., gradually expand due to creep damage, resulting in outer diameter distortion (outer diameter creep distortion). It is known that there is a correlation between the outer diameter distortion and the life of the pipe. The outer diameter of the pipe is measured to determine the outer diameter distortion, and the life of the pipe is predicted from the outer diameter distortion. .
In order to accurately predict the life of the pipe, it is necessary to accurately measure the outer diameter of the pipe. For this purpose, it is necessary to attach a measurement jig to the pipe to create a situation suitable for measurement and carefully measure. For this reason, the time required for one measurement becomes long, and a considerable time is required when the number of pipes for measurement increases. In addition to the measurement work, jig installation work is also required, so it is difficult for a single worker to perform a series of measurement work including jig installation work, which requires multiple workers. Become.

  In particular, in reaction tubes used for reformers, the outer diameter of the reaction tube for the purpose of predicting the life of the reaction tube (pipe) is small because the outer diameter distortion is small even when creep damage progresses as the strength increases. Measurement takes time. In other words, with the reformer reaction tube, as the strength increases, the deformation rate, which is a measure of the progress of creep deterioration, is as small as 5% or less. Therefore, highly accurate outer diameter measurement is required, and the time required for the measurement is accordingly reduced. It will be long.

Patent Document 1 discloses a technique that can reduce the time and labor required for measuring the outer diameter distortion by narrowing down the pipes for which the outer diameter distortion should be obtained in advance. Hereinafter, the technique disclosed in Patent Document 1 will be described. In the description, reference numerals used in Patent Document 1 are shown in parentheses for reference.
In the technique disclosed in Patent Document 1 (see paragraph [0023], FIG. 2-4, etc.), a screening step is performed before the step of measuring the outer diameter of the pipe to obtain the outer diameter strain (outer diameter strain measuring step). To narrow down the pipes that need to measure the outer diameter distortion.

  In this screening step, a standard gauge (10) is used. The standard gauge (10) has a substantially U-shape having two reference surfaces (12, 14) spaced apart from each other by a predetermined distance, and the distance between the reference surfaces (12, 14) is outside. An interval corresponding to the allowable value of radial distortion is set. With the reference surface (12, 14) sandwiching the outer peripheral surface of the pipe (16), the standard gauge (10) is moved in the axial direction of the pipe (16) or rotated in the circumferential direction. Is to be determined whether or not should be the object of outer diameter strain measurement. In other words, when the movement or rotation of the standard gauge (10) is hindered, it is assumed that there is an inflated part whose outer diameter exceeds the reference value, and this pipe (16) is the target of the outer diameter strain measurement, otherwise Is excluded from the measurement of outer diameter strain.

JP2013-148476A

However, in the technique disclosed in Patent Document 1, whether or not the outer diameter of the pipe (16) exceeds a reference value defined as the distance between the reference surfaces (12, 14) of the standard gauge (10). Since the outer diameter strain measurement is determined, the versatility of the standard gauge (10) is low.
In other words, the reference value differs depending on the piping specifications such as pipe size, material, and wall thickness. Therefore, it is necessary to examine the reference value for each piping specification, and a standard gauge is prepared for each piping specification. Must.

As the reformer reaction tube, a centrifugal cast tube manufactured by centrifugal casting is often used. Centrifugal cast pipes have high inner diameter step accuracy but low outer diameter step accuracy. That is, even if the tubes have the same nominal outer diameter, the outer diameter varies greatly.
Since the technique disclosed in Patent Document 1 is based on the principle of determining whether or not the outer diameter strain measurement is necessary based on the deformation amount of the outer diameter, the variation in the outer diameter is a noise in making the determination. It becomes. In particular, as described above, the reformer reaction tube has a small outer diameter distortion even if creep damage progresses. Therefore, in order to accurately grasp the progress of creep damage, the slight expansion of the reaction tube is accurately measured. It is necessary to have a large variation in outer diameter.

  The present invention was devised in view of the problems as described above, so that screening for narrowing down target pipes in advance before performing life evaluation can be performed efficiently and irrespective of the specifications of the pipes. Another object of the present invention is to provide a creep damage spot screening gauge and a pipe life evaluation method.

  (1) In order to achieve the above-mentioned object, the creep damage spot screening gauge of the present invention is formed so as to cut out the gauge body and the front edge of the gauge body, and receives a pipe entering from the front. A stop portion, a rod attached to the gauge body so as to be capable of advancing and retreating with respect to the pipe received by the receiving portion, and a display portion for displaying a position of a tip of the rod, the receiving portion Is formed by a pair of inclined surfaces that are separated from each other as they go forward, and the pair of inclined surfaces are inclined at the same angle with respect to the advancing / retreating path of the rod.

  (2) In order to achieve the above object, in the pipe life evaluation method of the present invention, the life evaluation step for evaluating the life of the pipe, and the maximum bulge portion of the pipe before the life evaluation step are performed. A screening step for specifying, and in the screening step, using the screening gauge described in (1), the position of the tip of the rod is measured along the axial direction of the pipe, and based on the measurement result The maximum bulging portion is specified.

  (3) The piping is preferably a reformer reaction tube.

According to the screening gauge of the present invention, the position of the tip of the rod contacting the outer peripheral surface of the pipe set in the screening gauge can be measured as a value correlated with the outer diameter of the pipe. As a result, even if the bulging amount of the outer diameter is small, it is possible to amplify the bulging amount and detect it as the amount of change in the position of the tip of the rod, and easily grasp the bulging amount. Is possible. Further, the measurement is performed while moving the screening gauge in the tube axis direction, and the maximum expansion of the pipe is determined based on the distribution of the rod tip positions in the tube axis direction, that is, based on the relative comparison of the rod tip positions. The exit can be specified.
Therefore, screening for narrowing down target pipes before performing life evaluation can be performed efficiently and irrespective of the specifications of the pipes.

It is a schematic diagram which shows the structure of the gauge for creep damage location screening of one Embodiment of this invention, (a) is a top view, (b) is XX sectional drawing of (a). It is a typical top view for demonstrating the measurement principle of the gauge for creep damage location screening of this invention, Comprising: (a) shows the measurement of the reaction tube 100 before a swelling, (b) is the reaction after a swelling. The measurement of tube 100 'is shown. It is a flowchart for demonstrating the evaluation method of the reaction tube lifetime of one Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. Note that the embodiment described below is merely an example, and there is no intention to exclude various modifications and technical applications that are not explicitly described in the following embodiment. The configurations of the following embodiments can be implemented with various modifications without departing from the spirit thereof.

[1. Screening gauge configuration]
In the following embodiment, an example in which the present invention is applied to life evaluation of a reformer reaction tube will be described.
In the life evaluation method of this embodiment, as will be described later, before predicting the life of a pipe, a creep damage location screening gauge (hereinafter referred to as a screening gauge or gauge) is used to select from among a large number of pipes. Select pipes that require life prediction.
Hereinafter, the configuration of the screening gauge will be described with reference to FIG.
1A and 1B are schematic views showing a configuration of a screening gauge according to an embodiment of the present invention, in which FIG. 1A is a plan view and FIG. 1B is an XX cross-sectional view of FIG.

  In the following description, the side where the reformer reaction tube (pipe) 100 is set is referred to as the front, the opposite side is referred to as the rear, and the horizontal direction orthogonal to the front-rear direction is referred to as the width direction. That is, in FIGS. 1 (a) and 2 (a), (b), the left side of the page is the front, the right side is the back, and the vertical direction of the page is the width direction. In FIG. 1 (b), the horizontal direction of the page is The width direction and the direction perpendicular to the paper surface are the front-rear direction. Further, in FIG. 1 (a) and FIGS. 2 (a) and 2 (b), the direction perpendicular to the paper surface will be described as the thickness direction.

  As shown in FIG. 1 (a), the screening gauge 1 is formed so as to have a flat gauge body 2 and a front edge of the gauge body 2 cut out, and a receiving portion in which a reformer reaction tube 100 is set. 3, a rod 4 attached to the gauge body 2 so as to be capable of moving back and forth, and a scale plate 5 attached to the upper surface 2 b of the gauge body 2. The reaction tube 100 is set in the receiving portion 3 in a posture in which the tube axis direction is directed to the thickness direction of the gauge 1. Except for the scale plate 5, the gauge 1 has a symmetrical shape (symmetric with respect to the center line in the width direction of the gauge body 2 (hereinafter also referred to as gauge center line) CL0).

  A notch 2 a is formed at the front edge of the gauge body 2. The width of the notch 2a gradually decreases toward the rear. In the present embodiment, the notch 2a is formed in an isosceles trapezoidal shape with the upper base directed rearward. The receiving part 3 is constituted by a pair of inclined surfaces 3a formed in the gauge body 2 by providing a notch 2a.

Further, the gauge body 2 is formed with a groove 2c through which the rod 4 is inserted so as to be able to move forward and backward. The groove 2c is formed on the gauge center line CL0 in a plan view with respect to the gauge body 2 and penetrates from the wall surface 2d behind the notch 2a to the rear end face 2e. Further, as shown in FIG. 1B, the groove 2c opens to the upper surface 2b of the gauge body 2, and becomes narrower stepwise toward the upper surface 2b. That is, the lower groove 2c-1 on the lower rectangular transverse section and the upper groove 2c-2 on the rectangular transverse section narrower than the lower groove 2c-1 are integrally formed. The width dimension of the lower groove 2 c-1 is slightly wider than the width dimension of the rod 4, and the width dimension of the upper groove 2 c-2 is set to be narrower than the width dimension of the rod 4. With such a configuration, the rod 4 can be moved forward and backward while restricting the rod 4 from being removed from the groove 2c, and an indicator 4a described later provided on the upper surface of the rod 4 can be visually observed.
In FIG. 1B, for convenience, the rod 4 is shown with gaps in the vertical and horizontal directions with respect to the groove 2c.

In FIG. 1A (that is, in plan view), the rod 4 is arranged such that its axial center line CL1 is positioned on the gauge center line CL0. Further, the rod 4 has its distal end 4b projecting into the notch 2a, and can move forward and backward while the axial center line CL1 coincides with the gauge center line CL0 (in other words, the rod 4 is set in the receiving portion 3). The gauge body 2 is attached to the reaction tube 100 so that the reaction tube 100 can move forward and backward. Hereinafter, since the rod 4 moves along the axial center line CL1, the movement path of the rod 4 is described using the same reference CL1.
Here, each inclined surface 3a constituting the receiving portion 3 has the same angle (hereinafter also referred to as a receiving angle) θ with respect to the movement path CL1 of the rod 4 in a plan view. In other words, the angle between the slopes 3a (= 2 × θ) is equally divided by the movement path CL1 of the rod 4.

The rod 4 has a rectangular cross section as shown in FIG. 1B, and an indicator 4a having a width smaller than that of the upper groove 2c-2 is provided at the center of the upper surface of the rod 4 in the width direction. It is fixed. The scale plate 5 is attached to the upper surface 2b of the gauge body 2 at the side of the indicator 4a, that is, at the side of the groove 2c.
When measuring, as shown in FIG. 1A, the tip of the rod 4 (hereinafter referred to as “tube outer peripheral surface”) is contacted with the outer peripheral surface (hereinafter referred to as “tube outer peripheral surface”) 100a of the reaction tube 100 received by the receiving portion 3. 4b is moved. In this state, the scale 5a of the scale plate 5 positioned beside the indicator 4a can be read as a measured value (hereinafter referred to as B value, which will be described later) regarding the position of the rod tip 4b. . Therefore, the indicator 4a and the scale plate 5 constitute the display unit of the present invention.

  In addition, the normal posture of the gauge 1 at the time of measurement is a posture that is perpendicular to the axis of the reaction tube 100, and when the gauge 1 is in contact with the reaction tube 100 at an angle during measurement (from a normal posture to a tilted posture). Measurement error may occur. Gauge 1 is obtained by increasing the contact area between inclined surface 3a and pipe outer peripheral surface 100a by setting the thickness dimension (the dimension in the direction perpendicular to the paper surface in FIG. 1A) of inclined surface 3a of gauge body 2 to be thicker. Can be prevented from contacting the reaction tube 100 at an angle. Similarly, the rod end 4b that is a contact surface with the reaction tube 100 also has a thickness dimension (a dimension in a direction perpendicular to the paper surface in FIG. 1A) and a width dimension (a dimension in the vertical direction in FIG. 1A). ) Is set to be large, the gauge 1 can be prevented from contacting the reaction tube 100 at an angle.

  The rod 4 is provided with stoppers 4c on the front and rear ends of the rod 4 so as not to slip forward or backward from the groove 2c. The indicator 4a is preferably colored with a different color from the rod 4 so that it can be easily identified, and the indicator 4a may be engraved on the rod 4.

The B value will be described with reference to FIGS. 2 (a) and 2 (b).
The circles in FIGS. 2A and 2B show the outer shape of the reaction tube, FIG. 2A shows the measurement before bulging, and FIG. 2B shows the measurement after bulging. In FIG. 2 (b), the distance, position, etc. that change compared to before bulging are indicated by adding “′” to the end of the reference numerals used in FIG. 2 (a).

そして、上式（１）を下式（２）,（３）,（４）と順次変形すると、反応管１００の外径Ｄ（＝２×Ａ）は下式（４）に示すようになる。受止角θは一定であるから、反応管１００の外径Ｄと距離Ｂとは比例関係となる。

The radius A, the distance B, and the receiving angle θ of the reaction tube 100 before bulging in FIG. 2A geometrically satisfy the relationship of the following expression (1). The distance B is the distance between the rod tip 4b in contact with the pipe outer peripheral surface 100a and the intersection B0 when each inclined surface 3a is virtually extended backward (that is, the distance between the pipe outer peripheral surface 100a and the intersection B0). .

Then, when the above equation (1) is sequentially transformed into the following equations (2), (3), (4), the outer diameter D (= 2 × A) of the reaction tube 100 becomes as shown in the following equation (4). . Since the receiving angle θ is constant, the outer diameter D of the reaction tube 100 and the distance B are in a proportional relationship.

Similarly, the outer diameter D ′ (= 2 × A ′) of the swelled reaction tube 100 ′ in FIG. 2B is expressed as shown in the following formula (5) by the distance B ′ and the receiving angle θ. Is done.

受止角θは一定であること、及び、距離Ｂ，Ｂ′とロッド先端４ｂの位置Ｂ１，Ｂ１′とは一義的な対応関係にあることから、上式（４），（５）は、反応管１００，１００′の外径を直接計測しなくてもＢ値（ロッド先端４ｂの位置Ｂ１，Ｂ１′）を計測することで、反応管１００，１００′の外径に相関する寸法として計測することができ、上式（６）は、反応管１００，１００′のＢ値を比較することで膨出傾向を把握できることを意味する。 Further, the bulging rate Rb of the reaction tube is the rate of change of the outer diameter [= (D−D ′) / D]. From the above equations (4) and (5), the distance as shown in the following equation (6) It can be obtained from B and B ′.

Since the receiving angle θ is constant and the distances B and B ′ and the positions B1 and B1 ′ of the rod tip 4b have a unique correspondence, the above equations (4) and (5) are By measuring the B value (positions B1, B1 ′ of the rod tip 4b) without directly measuring the outer diameter of the reaction tubes 100, 100 ′, it is measured as a dimension correlated with the outer diameter of the reaction tubes 100, 100 ′. The above equation (6) means that the bulging tendency can be grasped by comparing the B values of the reaction tubes 100 and 100 ′.

  Here, even if the outer diameters of the reaction tubes are the same, the distances B and B ′ increase as the receiving angle θ decreases. Therefore, even if the deformation amount of the outer diameter due to the bulging is the same, the smaller the receiving angle θ, the smaller the change amount ΔB (= B′−B) of the distances B and B ′, that is, the B value change. A large amount can be measured. On the other hand, if the receiving angle θ is too small, the size of the gauge 1 becomes large, and the measurement work becomes difficult by the gauge 1. For this reason, it is necessary to set the receiving angle θ appropriately.

  In the reformer reaction tube, it is known from the results that the bulging rate Rb is broken at 5% or less. A preferable range of the acceptance angle θ for measuring the bulging rate Rb of 5% or less is considered to be 8 to 10 °. For example, if the acceptance angle θ is set to about 8.5 °, in a general-sized reaction tube, the distance B before bulging (bulging rate Rb = 0%) is 500 mm, and the bulging rate Rb is 1. The distance B when% is 505 mm. That is, a change in the outer diameter of 1% can be amplified and detected as a change amount of about 5 mm in the measurement by the B value. The size of the gauge 1 is commensurate with the distances B and B ', but if the distances B and B' are about 500 mm, the size of the gauge 1 should be small enough for an operator to handle alone. Can do.

[2. Evaluation method of reaction tube life]
Hereinafter, with reference to FIG. 3, the life evaluation method of piping as one Embodiment of this invention is demonstrated.
FIG. 3 is a flowchart for explaining a reaction tube lifetime evaluation method according to an embodiment of the present invention.
In the pipe life evaluation method of the present embodiment, as shown in FIG. 3, first, in step S1, life evaluation is performed from all reaction tubes 100 (for example, several hundreds) based on the result of temperature monitoring. Candidates for the reaction tube 100 (hereinafter also referred to as target piping) to be targeted are extracted. That is, the reformer measures the outlet temperature of the internal fluid gas in the reaction tube 100 for each predetermined number, grasps the high temperature region based on these measurement results, and sets the reaction tube (hereinafter referred to as the high temperature region). , Referred to as a high temperature reaction tube) as a candidate for target piping.

Next, in step S2, in the high temperature reaction tube extracted in step S1, a location where high temperature oxidation of the outer surface has progressed significantly is identified visually as a location with a high risk of creep damage (high risk location).
Next, in step S3 (screening step), the B value is measured while moving the gauge 1 in the tube axis direction of the reaction tube 100 for the high-risk point (damaged part) specified in step S2. That is, the B value is measured while changing the measurement point continuously or stepwise along the tube axis direction, and the maximum bulge portion where the B value is maximized is specified.

The measurement at each measurement store is performed by operating the gauge body 2 with one hand until the receiving portion 3 comes into contact with the pipe outer peripheral surface 100a, and when the pipe outer peripheral surface 100a comes into contact with the receiving portion 3 While maintaining the state, the rod 4 is pushed in by operating with the other hand until the rod tip 4b hits the pipe outer peripheral surface 100a. Then, the B value is read in this state (the receiving portion 3 is in contact with the pipe outer peripheral surface 100a and the rod tip 4b is in contact with the pipe outer peripheral surface 100a). The maximum bulge portion can be specified by comparing the B values.
Alternatively, if the gauge 1 is moved in the tube axis direction of the reaction tube 100 while maintaining the state in which the receiving portion 3 and the rod 4 are both pressed against the tube outer peripheral surface 100a, the position of the tube outer peripheral surface 100a (in other words, For example, the rod 4 naturally advances and retreats according to the outer diameter of the reaction tube 100, and the maximum bulge portion can be specified by observing the change in the B value according to the advance and retreat of the rod 4.

  Note that a portion where the swelling is large in the reaction tube 100 is a portion that is easily heated by the heating source, and the portion can be estimated roughly from the positional relationship between the reaction tube 100 and the heating source (hereinafter, predicted as a portion where the swelling is large). The place where it will be called the predicted bulge point). Since step S3 is a screening step before performing later-described steps S4 and S5 for accurately performing life evaluation, it is considered sufficient that the measurement by the gauge 1 is performed at least for the predicted bulging portion.

Next, in step S4, the outer diameter of the reaction tube 100 at the maximum bulge portion specified in step S3 is precisely measured using a dedicated jig, and the wall thickness is measured by an ultrasonic flaw detection method. Then, by combining these measurement results, the inner diameter bulging rate of the reaction tube 100 is obtained, and the inner diameter bulging rate is evaluated to extract a tube that requires life evaluation.
Then, a replica is collected from the tube whose life evaluation is required in Step S5 (life evaluation step), and the life evaluation based on the metal structure is performed using the collected replica.

[3. Action / Effect]
According to one embodiment of the present invention, instead of directly measuring the outer diameter of the reaction tube 100, the B value is measured. Therefore, even if the bulge amount of the outer diameter is small, this bulge amount Can be detected as the amount of change in the B value, and the amount of swelling can be easily grasped.
Further, by using the gauge 1, it is possible to narrow down the number of reaction tubes 100 to be subjected to life evaluation. Further, measurement is performed for the single reaction tube 100 while moving the gauge 1 in the tube axis direction, and based on the distribution of the B value in the tube axis direction, that is, relative to the B value in the single reaction tube 100. Based on the comparison, the maximum bulge portion of the reaction tube 100 can be specified. Therefore, the “specification of the maximum bulging portion of the single reaction tube 100” and the “screening before performing the life evaluation of the reaction tube 100” can be efficiently performed with the size of the outer diameter of the reaction tube 100 and the outer diameter of the reaction tube 100. This can be done regardless of variations.

[4. Others]
(1) In the screening gauge 1 of the above-described embodiment, an urging means for urging the rod 4 forward may be provided between the rod 4 and the gauge body 2. According to such a configuration, if the gauge body 2 is pushed in until the receiving portion 3 comes into contact with the reaction tube 100, the rod tip 4 b naturally comes into contact with the reaction tube 100. There is no need to operate. Therefore, the measurement work can be performed more efficiently.

  (2) In the above embodiment, the display unit of the present invention is configured by the indicator 4a and the scale plate 5, but the configuration of the display unit is not limited to this. For example, the display unit of the present invention may be configured by an image display device that electrically detects and displays the B value.

  (3) In the above embodiment, the example in which the present invention is applied to the life evaluation of the reformer reaction tube has been described. However, the present invention can be used in general for a heating tube that creeps, for example, in a heating tube of a boiler. Can be applied.

DESCRIPTION OF SYMBOLS 1 Creep damage location screening gauge 2 Gauge body 2a Notch 3 Receiving part 3a Slope 4 Rod 5 Scale plate 100 Reformer reaction tube (pipe)
CL0 Gauge body 2 width direction center line CL1 Movement path of rod 4 θ Angle of inclined surface 3a with respect to movement path CL1 of rod 4

Claims (3)

The gauge body,
A receiving portion that is formed so as to cut out the front edge of the gauge body, and receives a pipe that has entered from the front,
A rod attached to the gauge body so as to be capable of advancing and retreating with respect to the pipe received by the receiving portion;
A display unit for displaying the position of the tip of the rod;
The receiving portion is formed by a pair of inclined surfaces that are separated from each other as they go forward, and the pair of inclined surfaces are inclined at the same angle with respect to the advancing / retreating path of the rod, Screening gauge. A life evaluation step for evaluating the life of the pipe;
Before performing the life evaluation step, comprising a screening step to identify the maximum bulge portion of the pipe,
In the screening step, the creep damage point screening gauge according to claim 1 is used to measure the position of the tip of the rod along the axial direction of the pipe, and based on the measurement result, the maximum bulge portion is measured. A method for evaluating the life of piping, characterized in that   The pipe life evaluation method according to claim 2, wherein the pipe is a reformer reaction pipe.

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