JP2003053581A - Method for discriminating welding part and jig for discriminating welding part used therein - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for discriminating the presence or absence of defect in welding part which is convenient, allows quick and exact inspection and can be easily operated and a jig for discriminating welding part used therein. SOLUTION: This method for discriminating welding part features that marking lines k are drawn on the positions which are a specified length dimension L apart from a butt edge surface of joint parts of respective connected piping P1 , P2 and thereafter, a welding part W which is worked by subjecting the respective piping P1 , P2 to butt welding is confirmed in such a manner that the marking lines k are positioned on the positions a predetermined length distance L apart from the center Wao of the surface bead width Wa or within the error dimension position suggesting lines 18a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for evaluating and judging from the appearance whether or not a butt-welded portion of a pipe made of stainless steel or the like is correctly welded, and a jig used in the evaluation-judging method. It is possible to easily and accurately determine whether the axis of the joint butt section of the pipe before welding is confirmed, the proper position of the weld line of the butt weld section after welding, and the evaluation of the adequacy of the bead width are confirmed. TECHNICAL FIELD The present invention relates to a welded portion determination method and a welded portion determination jig used for the method.

[0002]

2. Description of the Related Art Stainless steel pipes are generally used as pipes for supplying semiconductor manufacturing gas to semiconductor manufacturing equipment and facilities used in semiconductor manufacturing. Among them, particularly thin stainless steel pipes are often used. Has been. In addition, butt welding by non-filler automatic TIG (TIG) welding, which enables highly reproducible welding, is generally performed for connecting and joining these pipes.

However, as the appearance of the welded portion of the butt joint after the pipe is welded, it is desired that the welded portion surface and the pipe surface are continuous and the welded appearance is not uneven. In particular, on the inner surface of the welded portion of the pipe, it is important that the backside of the welded portion and the inner wall surface of the pipe are flat. This is because excessive heat is applied to the weld at the time of butt welding, and there is a protrusion on the back surface of the weld, which means that the weld metal has reached the inner wall surface of the pipe more than necessary. As shown, extremely fine metal powder called fumes is generated in the pipe from the weld metal, and particles are generated by constantly hitting the gas on the convex portion, which becomes a source of gas pollution. In addition, since these welds have a weld metal with low corrosion resistance and a heat-affected zone, there is a problem that corrosion occurs in a wide range.

On the other hand, when the heat is insufficient, the weld metal does not reach the inner wall surface of the pipe, and there may be a recess due to the clearance between the abutting portions of the pipe. In this case, these recesses become dead spaces, dust particles are accumulated, and the accumulated particles are entrained in the gas along with the supply and circulation of the gas, thereby contaminating the gas. When a corrosive gas is used for semiconductor manufacturing, the presence of the dead space as described above easily causes crevice corrosion, and the metal corrosion products generated by the crevice corrosion are separated to contaminate the gas. There was a problem that it would end up. Furthermore, if a recess is formed on the inner wall surface of the pipe as described above, welding will be insufficient and the strength will not be as specified, so there is a risk of breakage due to some stress load depending on the size of the recess. .

For these reasons, it has been practiced to check the butt-welded portion after welding the pipes for the above-mentioned problematic state of the welded portion. Conventionally, as a check method, prior to butt welding, sample pipes of the same kind are welded in advance under common welding conditions, the pipes are cut, and the front bead width Wa and the back bead width Wb are measured. Was. That is, specifically, when the width Wb of the backside wave required for proper welding is Wb1≤Wb≤Wb2 (where Wb1 <Wb2), the beat width Wa in the table is Wa1≤Wa≤
It was arranged to collect data on the correlation between the back bead width Wb and the front bead width Wa, which is Wa2 (where Wa1 <Wa2). And these correlations are
Depending on the diameter, thickness, and material of the pipe used, samples were taken at different positions of the butt welding points along the circumference of the pipe (top surface, both side surfaces, bottom surface of the pipe).

Then, by confirming that the front bead width Wa is in the range of Wa1 to Wa2, the bead width W of the backside wave
The fact that b is Wb1 to Wb2 was read indirectly based on the data collected above. Specifically, a vernier caliper or the like is applied to the butt-welded portion to measure whether the front bead width Wa is within a predetermined dimension range, and the dimension is suitable for obtaining an appropriate backside bead width Wb. The state of the inner wall surface of the welded portion was judged based on the above correlation data to determine whether the bead width Wa was reached.

However, since the caliper used for the measurement has a thick end face of the measuring needle, it is difficult to measure it with an accuracy of 0.2 mm. Further, in the field piping, the butt welding portion is located at a high place or on the back surface of the device, and thus the measurement operation is difficult and it is difficult to perform accurate measurement. In addition, the data collected as described above is the diameter of the pipe, the wall thickness, the material, and on each of these different pipes, at each of several welded portions along the butt-welded pipe peripheral portion, Since they were different from each other, therefore, there were a lot of target data to be collated, and the confirmation work required considerable labor and man-hours.

For some reason, such as the butt-welding state shown in FIG. 7, the end face 51 (P12) of the butt-welding portion of the pipes P1 and P2 and the welding electrode (not shown) are deviated and welded at the time of welding. Even if the bead weld line 52 of the part deviates from the end face 51 of the butt weld part, the front bead width Wa is Wa.
When it is 1 to Wa2, it is determined that the bead width Wb of the back wave is formed in Wb1 to Wb2. However, as described above, the bead welding line 52 of the welded portion is not the end surface 51 of the butt welded portion.
Since it is offset from the end face 51
There was a problem in that the inner wall surface of the steel did not melt and a recess was formed. Even if the end position 51 (P12) of the butt-welding portion of the pipes P1 and P2 and the target position of the electrode are the same, the weld metal is caused by either one of the pipes due to the influence of trace impurities in the pipes, and a similar recess is formed. May occur. Moreover, when the welding line 52 is deviated in this manner, the deviation of the welding line cannot be visually confirmed in appearance. Especially, when such a deviation is minute, it is even more serious. Therefore, since the front beat width Wa is within the proper management size, there is a possibility that a butt-welding product is regarded as a passing product and a welding defect product is erroneously manufactured and provided.

Further, there is a possibility that a step may be formed on the inner wall surface of the butt-welded portion of the connected pipes due to the misalignment of the axes of the one pipe connected by butt welding and the other pipe (center misalignment). is there. When a step is formed on the inner wall surface of the welded portion in this way, the welding conditions of the butt welded portion are partially different, and the weld metal reaches the inner wall surface at a part of the welded portion and welds at the other portion. There is a problem that metal does not reach the inner wall surface at all, different welding states are formed depending on the welding position of the welded part, and similar to the above, problems such as contamination of supply gas due to entrainment of particles, occurrence of crevice corrosion, etc. Was to occur.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to provide a pipe reliably connected by butt welding without welding defects. Of the present invention is to obtain a welded portion determination method used for the welded portion determination method and the operation method that can easily and quickly and accurately inspect the displacement of the weld pipe and the misalignment of the welded pipe. This is a problem to be solved.

[0011]

According to the method of determining a welded portion of the present invention, a fixed length distance L from a butt end surface of a joint portion of a pipe is used.
After drawing a marking line at the position, the welded portion obtained by butt-welding the pipe is referenced to the front bead width of the welded portion, and the marking line position is a predetermined length distance L from the center of the front bead width. It is characterized by confirming that it is located at an appropriate position or an allowable error dimension position. In the present invention, the allowable error length distance is L ± minimum backside bead width × 1 /
It can be within 2. In the present invention, it is preferable that the reference bead width of the weld bead is a bead width that is confirmed to be an appropriate width. The butt processing of the pipe is performed by checking the scribe line drawn from the butt end face of the joint part of the pipe at a position of a constant length L, measuring and checking the length L, and butt welding the two pipes. It is possible to adopt a method of butt-welding after confirming the presence or absence of misalignment.

The welding jig for judging the welded portion of the present invention is made of a flat plate, one portion of which is cut out at a right angle, and the length of the marking line position is formed by marking the length distance on each notched side. Distance measurement confirmation scale part, a cutout recess is provided on one side of the flat plate, and the gap size between the two opposite sides of the cutout recess is set to a size through which the target pipe can be inserted, and one pipe to be butt welded through the butt joint. And the other pipe, the misalignment detection part that detects the presence or absence of a step, the concave part with a predetermined bead width dimension that recognizes the appropriate bead width on one side of the flat plate, and the center of the concave part Based on, the welded part state measurement gauge part consisting of a suggestion line showing a proper position and a proper position permissible error position of a predetermined dimension L along the side, and a trapezoidal shape with a tapered notch on one side of the flat plate A recess is provided and two parallel The bead width evaluation gauge part that has a short side smaller than the minimum allowable bead width, a long side larger than the maximum allowable bead width, and markers are provided at the maximum and minimum allowable bead widths. And at least one of the above.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The method for determining a welded portion of the present invention is such that, before butt welding and connection, a marking line is drawn from a butt end surface of a joint portion of a pipe to a position of a constant length L, and then the pipe is butted. With respect to the welded portion subjected to the welding process, the marking line position is located at a position of a predetermined length distance L from the center of the front bead width or at an allowable error dimension position with reference to the front bead width of the welded portion. It is a method of determining the adequacy of the welded portion by confirming that.

The allowable error length distance position is L
It is a method of determining the weld state of the butt welded portion as a reliable state and determining the adequacy of the welded portion as being more reliable by setting it within ± minimum backside bead width × 1/2. Further, it is a method for determining a welded portion, in which the reference bead width of the welded portion as a reference is confirmed to be an appropriate width, and the appropriateness of the butt welded portion is further inspected and determined. Moreover, the butt welding process of the pipe is
Measure the length L of the marking line drawn from the butt end face of the pipe joint at a certain length L, and check the length L of the scribe line, and check if there is any misalignment between the butt joints of the two pipes to be butt welded. Since it is a method of inspecting and determining the welded portion after confirming the welded portion to be subjected to the butt welding process, an extremely excellent butt-welded connecting pipe without the defect of the welded portion is provided. This is a determination method that can be performed.

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 illustrates an example of a marking line marking tool for marking a marking line at a constant distance L from the butt-welding end surface of the joint portion of the pipe before the butt welding for the method for determining the welded portion of the present invention. 1A is a perspective view, and FIG.
(B) is a longitudinal sectional view along the longitudinal direction, and FIG.
(C) is an explanatory view of a pipe in which a marking line is engraved.
Further, FIG. 2 is a plan view for explaining an example of a welding portion determination jig used in the welding portion determination method of the present invention.

FIG. 1 illustrates an example of a marking line marking tool for marking a marking line on the pipe wall at a position of a certain distance L from the end face of the butt-welded portion before butt-welding each of the two pipes to be connected. To do. In FIG. 1, this marking line marking tool 1 has an insertion opening 2a at one end, and a through hole recess 2 having a bottom 2c into which a pipe is inserted along the central axis from the opening 2a. It is composed of a cylindrical pipe insertion portion 3 and a holding portion 4 that extends to the other end side. A lever member 5 is arranged on the holding portion 4 along the holding portion. The lever member 5 is provided with a scribing needle 6 at one end 5 a thereof.
Passes through the other end of the tubular pipe insertion portion 3 and penetrates the through hole recess 2
To the side wall 2b of the lever member 5 so as to pass through the side wall 2b so as to be vertically movable. The spring member 8 is arranged so as to urge it upward.

As a result, the marking needle 6 provided at the one end 5a of the lever member 5 is always kept protruding from the side wall 2b of the through hole concave portion 2 into the concave portion 2, and the pipe is inserted to mark the marking line. When inserting into the through hole recess 2 from the opening 2a, the other end 5c of the lever member 5 is grasped together with the holding portion 4, the marking needle 6 is moved to the outside of the through hole recess, and the pipe is inserted into the through hole recess 2. Just insert it. Then, after confirming that the butt end surface of the inserted pipe hits the bottom portion 2c of the bottomed through hole concave portion 2, the gripping force at the other end portion 5c of the lever member 5 is released, so that the marking needle 6 is piped. Abut. Then, by rotating the pipe or the marking line marking tool, the marking line k can be marked at a fixed position L from the end face P0 of the abutting portion of the pipe P as shown in FIG. 1 (C). The length of the marking line is preferably formed at a position where the marking line slightly comes out of the waramp when the pipe is installed in the warag for automatic TIG welding, because it can be roughly checked when setting the pipe in the waramp for welding.

Next, an example of the jig for determining the welded portion of the present invention will be described with reference to FIG. The welding jig 10 of the present invention has four sides 11a, 11b in which two adjacent sides are orthogonal to each other.
It is composed of a rectangular flat plate 11 composed of 11c and 11d. Then, on each side of the quadrangular shape, a length distance measurement confirmation scale part (w
Part), a misalignment detection part (x part), a weld part state measurement gauge part (y part), and a bead width evaluation gauge part (z part).

Below, the jig 1 for judging the welded portion of the present invention is used.
The configuration of each inspection and measurement gauge unit of No. 0 will be described. <Scaling line position distance measurement confirmation scale part (w part)>
As shown in the w part of FIG.
The two sides 12a-1, 12a-2 formed by cutting out one corner 12a at a right angle and intersecting at a right angle are provided with a scale of length (mm) with the intersection 12a-0 as a base point. There is.
Then, the end face of the butt portion of the pipe to be connected by butt welding is brought into contact with one side 12a-1 or 12a-2 forming a right angle, and thus is preliminarily marked with the marking line marking tool 1 shown in FIG. The length distance L of the marking line position is easily measured and confirmed. Two sides 12a-1, 12a
It is desirable to provide a recess at the intersection 12a-0 of -2. By providing this recess, even if an outwardly projecting portion is formed on the outer peripheral edge of the pipe end, the pipe is arranged along the sides 12a-1 and 12a-2, and accurate measurement is possible. It will be possible.

<Center misalignment detection section (x section)> Next, one side 13b of the two parallel sides 13a and 13b of the cutout concave portion 13 is tapered to one side 11a of the four sides of the rectangular flat plate. Is formed on the tapered stepped side cut out in the stepwise 13b1, 13b2, 13b3, and the gap dimensions n1, n2, n3 of the notched recesses are set to dimensions through which the target pipe can be inserted, and the pipes to be connected are When the butt placement is set during welding, the presence or absence of a step is detected by moving one of the butt-placed pipes to be welded toward the other via the butt portion, and the above-mentioned predetermined position L Before welding the pipes marked with the marking lines to each other, it is to confirm whether there is any misalignment between the pipes to be butt-welded.

The gap dimensions n1, n2, n3 of the notched recesses on the stepped side 13b are the dimensions through which the target pipe can be inserted, and the amount of misalignment allowable for the outer diameter of the target pipe is added. It is a dimension. The allowable amount of misalignment here is the amount of misalignment that does not cause the weld metal to reach the inner surface of the pipe and generate particles even if the axis is maximally misaligned, and is approximately 1/3 or less of the wall thickness of the pipe. Is preferred. When using the x portion, the butt setting portion of the pipes to be connected is placed in the notch recess 13,
The determination jig 10 is moved from one of the connecting pipes to the other pipe across the butt-setting part. If the axis is deviated, the misalignment detection section (x section) of the determination jig 10 is locked by the butt-setting section due to the step formed by the misalignment of the axis and cannot pass through, and the misalignment is easy. Can be confirmed. To confirm the misalignment, the judgment jig 10 is further inspected by a similar operation at a position rotated by 90 degrees along the circumferential direction of the pipe, so that the butt-setting part of the pipe is covered in all directions. Misalignment can be inspected.

<Welding part state measuring gauge part (y part)> One side 11b of the four sides is a recess 15 (bead width Amm) cut out with a predetermined bead width dimension for recognizing an appropriate bead width.
), 16 (for bead width Bmm), and a recessed portion 17 (for bead width Cmm) cut out by the bead width dimension arranged on the side 11c.
And the predetermined dimensions L and L ± minimum backside bead width × 1 / on the left and right along the sides with the centers 15a, 16a, 17a of these recesses 15, 16, and 17 as references.
Proposal line 1 showing proper position and allowable error dimension position with 2
It consists of 8 and 18a, and a welded part state measurement gauge part (y
Part) is formed. That is, the length from the center of the recesses 15, 16, 17 to the suggestion line 18 corresponds to the length from the butt end face of the pipe to the marking line k stamped at a predetermined distance L before welding. Even if the welding line is slightly deviated, there is no problem as long as the end face of the pipe is within the range of the bead width of the back wave (melted by the weld metal), and the allowable error position suggestion line 18a is generated depending on the required bead width of the back wave. It is provided. Specifically, since the required backside bead width is Wb1 to Wb2, the allowable error dimension position suggestion line 18a is W to the left and right of the proper position suggestion line 18.
b / 2 = 0.5 mm each.

The proper position suggestion line 18 and the two allowable error dimension position suggestion lines 18a are preferably provided on the left and right sides of the recesses 15, 16 and 17 for the sake of judgment, but they may be provided in only one direction. Further, since the range of the appropriate front bead width is Wa1 to Wa2, the horizontal length of the recess is the appropriate maximum and minimum values of the bead width Wa2, Wa1, and an intermediate value thereof (W
a2 + Wa1) / 2 etc., as described above, the recesses 15, 16, 1
By providing 7 and a plurality, the position of the front bead width can be easily determined along with the determination of the front bead width, and these recesses can be appropriately selected and used depending on the size of the bead width. Therefore, more accurate measurement can be performed. Further, it can be simply used as a measuring gauge for confirming the front bead width Wa in the cut concave portion.

<Bead Width Evaluation Gauge (z)> One side 11c among the four sides has a substantially trapezoidal concave portion 1 which is notched in a tapered shape.
9, the trapezoidal recess 19 has two parallel upper and lower short sides 1
9a is smaller than the minimum allowable bead width and long side 19b
Is set to be larger than the maximum allowable bead width, and markers 20a and 20b are provided at the maximum and minimum allowable bead widths.
Is provided to form a bead width evaluation gauge portion (z portion).

[0025]

EXAMPLE A method for determining a welded portion of the present invention using the above-described welded portion determination jig 10 of the present invention will be described below as an example. The required front bead width Wa in butt welding is Wa1 ≤ Wa ≤ Wa2 (where Wa1 <Wa
2). Therefore, when the front bead width Wa1 is the back bead width Wb = Wb1, and when the front bead width Wa2 is the back bead width Wb = Wb2.

The welded portion judging method of the present invention is a mode as shown in FIGS. 3, 4, 5, and 6, inspecting and confirming the following conditions relating to welding of pipes to check the adequacy of welding. To judge. ● Mark a marking line on the pipes connected by butt welding at a predetermined distance L from the butt end face. By using the marking line marking tool 1 shown in FIG. 1 above, the marking line k is marked at a position of a predetermined distance L from the butt end face P0 of each pipe P to be connected by the above-mentioned operation.

Check the position of the marking line k imprinted on the pipe P. As shown in FIG. 3, the marking line k is used by using the scale portion (w portion) for measuring the length and distance of the marking line position of the judgment jig 10 of the welding portion of the present invention shown in FIG. Is drawn to a position of a predetermined distance L from the butt end surface P0 of the pipe P. This is because the end face P0 of the butt portion of the pipe P has a side 12a-1 or 12a-2 forming a right angle.
Dimension scale 1 suggested by each
By reading 2b, it is measured and confirmed whether or not the length distance of the marking line position marked by the marking line marking tool 1 in advance as shown in FIG. 1 is at an appropriate L position.

Check the misalignment of the butt set position of the connecting pipes. As shown in FIG. 4, the pipes P1 and P2 to be connected are used by using the misalignment detection portion (x portion) provided on the side 11a of the welding jig 12 of the present invention shown in FIG.
The butt-set portion P12 of No. 1 is arranged in the notch recess 13 and the butt-set portion P12 from one pipe P1 of the connecting pipe
The determination jig 10 is moved across the pipe toward the other pipe P2. If the axis is misaligned, the misalignment detection part (x part) of the determination jig 10 is locked by the butt set part due to the step formed by the misalignment of the axis and cannot pass through, and the misalignment is easy. Can be confirmed. To confirm the misalignment, the judgment jig 10 is further inspected by the same operation again at a position rotated by 90 degrees along the circumferential direction of the pipe, so that the butt-setting part of the pipe can be seen in all directions. Misalignment can be inspected.

Evaluation of bead width. Using the bead width evaluation gauge portion (z portion) provided on the side 11c of the jig 10 for judging the welded portion of the present invention shown in FIG. 2 above, the bead width evaluation gauge portion (z portion) is connected by butt welding as shown in FIG. The trapezoidal recessed portion 19 of the bead width evaluation gauge portion (z portion) is applied to the front bead width Wa of the welded portion W of the pipe P1 + P2, and the target front bead width Wa is the maximum width of the trapezoidal notched recessed portion 19 ( Wa
It is read whether or not it is between the mark 20a of 2) and the mark 20b of the minimum width (Wa1), and the front bead width Wa of the inspection target is read.
Instantly check if is the proper bead width.

● Weld condition measurement. Next, using the weld portion state measuring gauge portion (y portion) provided on the side 11b of the determination jig 10 for the weld portion of the present invention shown in FIG. 2, as shown in FIG. The state of the welded portion W of the pipes connected by butt welding is measured. When measuring, the welded part W
According to the specification of the front bead width Wa in the front bead width Wa evaluation gauge section (z section), a cutout concave portion having a bead width corresponding to the front bead width Wa is provided on the side 11b and the side 11c of the determination jig 10. And a recessed portion 15 (for bead width Amm) provided in the weld state measuring gauge portion (y portion),
16 (for the bead width B mm) and a recessed portion 17 (for the bead width C mm) cut out by the bead width dimension arranged on the side 11c.

Then, the front bead Wa of the welded portion W is aligned with the center Wao of the front bead width Wa and the center of the recessed recess 16a in a notch recess corresponding to the selected front bead width, for example, the notch recess 16. Therefore, before welding, pipe P
A marking line k imprinted at a predetermined distance L from the butt end face P0 is provided on the measuring gauge portion (z portion) at the center of the concave portion 1.
6a, a proper position suggestion line 18 marked at a predetermined distance L, and an allowable error dimension position suggestion line 18a marked ± minimum backside bead width × 1/2 from the suggestion line 18 Check. If the marking line k deviates from the permissible error dimension position suggestion line 18a, during butt welding,
This means that welding was performed with the electrodes and the abutting end faces of the pipes displaced from each other. As described above, although the butt weld end surface of the pipe cannot be confirmed by the welding, it is possible to easily confirm the deviation between the center Wao of the front bead width Wa of the welded portion W and the butt weld line, resulting in a welding defect. The presence or absence of can be determined.

In the welding state measuring gauge portion of the above-mentioned y portion, the notch recesses 15 and 1 having a width corresponding to the bead width Wa.
6 and 17 are provided, and the length from the center to the proper position suggestion line 18 is the length L to the marking line k drawn by the marking line jig.
However, it is not always necessary to provide the notch recess, and instead of the notch recess, a reference line is provided at the center position of the notch recess, and the length from the reference line to the proper position suggestion line is up to the marking line. The length L may be L.

Further, the scale distance measurement confirmation scale portion (w) of the marking line position of the present invention described above is used.
Part), the misalignment detection part (x part), the weld part state measurement gauge part (y part), and the bead width evaluation gauge part (z part) are all housed in one rectangular flat plate as shown in FIG. Since it is provided, the work of determining the welded portion can be performed efficiently. However, these may be produced separately. In addition, this jig for determining the welded part should be provided on one flat plate in such a manner that it can be applied to 1/4 inch, 3/8 inch and 1/2 inch outer diameters which are general-purpose pipes. Is desirable.

[0034]

EFFECTS OF THE INVENTION The welding portion determination method and the determination jig used therefor according to the present invention are embodied as described above and have the following effects. In butt welding of pipes, it was difficult to judge the defective defect in the welded part where a recess is formed on the inner wall surface of the pipe due to the deviation of the welding line from the butt welded end face. The marking line jig for drawing the marking line from the marking line, and the scale part for checking the length and distance of the marking line position (w
Part), the misalignment detection part (x part), the weld part state measurement gauge part (y part), and the bead width evaluation gauge part (z part) are used.
As a result, it is possible to easily confirm the defect in the welded portion due to the deviation of the welding line.

Further, by additionally using the scale distance measurement confirmation scale portion (w portion) at the marking line position, the reliability of the determination of the welded portion can be further improved. Further, by using the misalignment detection part (x part) in which the two opposite sides of the cutout recess are parallel and the size of the pipe outer diameter plus an allowable axial misalignment amount is used, defects in the welded part due to misalignment occur. Can be easily prevented.

Furthermore, since the presence / absence of a welding defect can be confirmed very accurately by the determination method of the present invention, the use of defective products can be reduced, and the mixing of impurities into the supply gas due to the welding defect can be prevented. In particular, a very remarkable effect is obtained as a pipe for supplying a semiconductor manufacturing gas in which impurities such as an extremely small amount of fine particles are not preferable.

[Brief description of drawings]

FIG. 1 is an explanatory view of an example of a marking line marking tool for marking a marking line and a pipe on which the marking line is marked.

FIG. 2 is a plan view illustrating an example of a welding portion determination jig used in the welding portion determination method of the present invention.

FIG. 3 is an explanatory diagram of a method for confirming the position of a marking line k imprinted on a pipe.

FIG. 4 is an explanatory view of a method for confirming misalignment of a butt set position of connecting pipes.

FIG. 5 is an explanatory diagram of a bead width evaluation method.

FIG. 6 is an explanatory diagram of a method for measuring a welded portion state.

[FIG. 7] When a welding line shift occurs in a butt welding state,
Explanatory drawing of a pipe welding part.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Marking line marking tool, 2 ... Through hole concave part, 3 ... Cylindrical pipe insertion part, 4 ... Holding part, 5 ... Lever, 6 ... Scribing needle, 10 ... Welding part judging jig, 11 ... Square plate,
11a, 11b, 11c, 11d ... One side of a quadrangle, 12
a ... One corner of a quadrangle, 12a-0 ... Intersections 12a-1, 12a-2 ... Sides intersecting at right angles formed by notching at right angles, 13 ... Notched recesses, 13a, 13b
... Opposing parallel sides of the cutout recess 13, 15, 16, 1
7 ... Recesses cut out with a predetermined bead width, 15a, 1
6a, 17a ... Center of notched concave portion, 18 ... Suggestive line showing proper position, 18a ... Suggestive line showing allowable error dimension position, 19 ... Tapered notched concave portion, 19a
… Short sides of two parallel upper and lower sides, 19b… Long sides of two parallel upper and lower sides, 20a ... Maximum mark of allowable bead width, 20b ... Minimum mark of allowable bead width, P ... Piping, P0 ... Butt end face, W: welded portion, Wa: front bead width, Wao: center of front bead width, Wb: backside bead width, k: marking line,
L ... Predetermined length distance, w ... Marked line position length distance measurement confirmation scale part x ... Misalignment detection part, y ... Welded part state measurement gauge part, z
… Bead width evaluation gauge

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tomoo Namiki             4-320-1, Tsukagoshi, Saiwai-ku, Kawasaki-shi, Kanagawa               NES Engineering Co., Ltd. (72) Inventor Hiroo Suzuki             4-320-1, Tsukagoshi, Saiwai-ku, Kawasaki-shi, Kanagawa               NES Engineering Co., Ltd. (72) Inventor Minoru Watanabe             4-320-1, Tsukagoshi, Saiwai-ku, Kawasaki-shi, Kanagawa               NES Engineering Co., Ltd.

Claims (5)

[Claims] 1. A scribe line is drawn from a butt end face of a joint portion of a pipe at a position of a constant length L, and then a butt-welded welded portion of the pipe is used as a reference based on a front bead width of the welded portion. A method for determining a weld portion, characterized in that it is confirmed that the marking line position is located at an appropriate position of a predetermined length distance L from the center of the front bead width or an allowable error dimension position. 2. The method for determining a welded portion according to claim 1, wherein the allowable error length distance is within L ± minimum backside bead width × ½. 3. The method for determining a welded portion according to claim 1, wherein the reference bead width is a bead width that is confirmed to be an appropriate width. 4. A pipe butting process is carried out by butt welding two marking lines drawn from a butt end face of a joint portion of a pipe at a position of a constant length L by measuring and confirming the length L. The method for determining a welded portion according to claim 1, wherein the butt welding is performed after confirming whether the butt portion of the pipe is misaligned. 5. A scale part for measuring and measuring a length distance at a marking line position, which is formed of a flat plate, one part of which is cut out at a right angle and each cutout side is marked with a length distance,
A cutout recess is provided on one side of the flat plate, and the gap dimension between the two opposite sides of the cutout recess is set to a size through which the target pipe can be inserted. From one pipe to be butt-welded to the other pipe through the butt joint. By moving it, the misalignment detection part that detects the presence or absence of a step, the recess on one side of the flat plate that has a predetermined bead width dimension that recognizes the appropriate bead width, and the side based on the center of the recess Along the left and right, a welded portion state measuring gauge portion consisting of a suggestion line indicating a proper position and a proper position permissible error position of a predetermined dimension L, and a substantially trapezoidal recessed portion which is notched to one side of the flat plate are provided. The shorter sides of the two parallel sides are smaller than the minimum allowable bead width, the long sides are larger than the maximum allowable bead width, and markers are provided at the maximum and minimum allowable bead widths. At least one of the bead width evaluation gauge section Determining jig welds characterized in that it comprises a.