FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10, rule 13)
1. Title of the invention: WELDED PART INSPECTION DEVICE AND METHOD FOR BOILER WATER-WALL
2. Applicant(s)
NAME NATIONALITY ADDRESS
MITSUBISHI HEAVY
INDUSTRIES, LTD.
Japanese 16-5, Konan 2-chome, Minato-ku,
Tokyo 1088215, Japan
3. Preamble to the description
COMPLETE SPECIFICATION
The following specification particularly describes the invention and the manner in which it
is to be performed.

TECHNICAL FIELD
[0001] The present invention relates to a welded part inspection device 5 and a welded part
inspection method for a boiler water-wall.
BACKGROUND
[0002] JIS Z2329 2002 specifies a vacuum method for a bubble leak test. According to
10 this vacuum method, a vacuum box is brought into airtight contact with a test surface, the
pressure inside the vacuum box is reduced, and then gas leakage and its location on the test
surface are checked by determining whether the bubble solution having been applied to the
test surface is bubbling.
Patent Document 1 describes a leakage testing device for a tube sheet of a condenser,
15 capable of checking leakage in a cooling pipe of a condenser based on the above vacuum
method. Two attachment boxes of the leakage testing device is brought into contact with a
flat tube sheet, and thereby leakage in the cooling pipe extending between the tube sheets is
tested.
[0003] On the other hand, PT (Penetrant Test) is known as a leakage testing method for a
20 welded part. In the case of PT, a test objective part is cleaned with a cleaning liquid, and
then a penetrant is applied thereto. Next, extra penetrant on the surface of the test objective
part is wiped off, and then a developing solution is applied to the test objective part. With
PT, it is possible to visually check the existence of a defect by the color development of the
penetrant having penetrated through the defect of the welded part.
25
Citation List
Patent Literature
3
[0004]
Patent Document 1: JPS62-148933
SUMMARY
5 Technical Problem
[0005] In a boiler water-wall, water-wall tubes are arranged parallel and fins are welded
to the water-wall tubes along the longitudinal direction. These fins fill the gaps between the
water-wall tubes. Thus, the boiler water-wall has concavity and convexity corresponding to
the curvature of the outer circumferential surface of the water-wall tubes. Therefore, when
10 using the leakage testing device for a tube sheet of a condenser disclosed in Patent Document
1, the attachment box cannot be brought into airtight contact with the boiler water-wall.
Accordingly, it is impossible to perform the vacuum method defined in JIS Z2329 2002 for a
welded part of a boiler water-wall even if the leakage testing device for a tube sheet of a
condenser disclosed in Patent Document 1 is used.
15 [0006] In view of this, the PT has been conventionally performed to test a welded part of
a boiler water-wall. However, some solutions used in PT are flammable, which raises a
problem that the solutions require to be handled with care, causing the test to be complex.
Also, PT has problems such as a number of processes causing the test to be time consuming,
and the detection accuracy for a through-defect not being high.
20 [0007] The present invention was made in view of the above circumstances and is to
provide a welded part inspection device and a welded part inspection method for a boiler
water-wall, capable of easily and securely detecting a through-defect of a welded part
between the water-wall tube and the fin, or between the fins in a short period of time.
25
Solution to Problem
[0008] In order to achieve the above object, the present invention provides a welded part
inspection device for a boiler water-wall including a plurality of parallel water-wall tubes
4
arranged parallel and fins configured to fill gaps by welding, each of the gaps existing
between two of the parallel water-wall tubes which are arranged adjacent to each other, the
welded part inspection device comprising: a vacuum box configured to form a vacuum
chamber with an inspection objective part comprising a part of at least adjacent two of the
parallel water-wall tubes and a part of the fin; and an air exhauster connected 5 to the vacuum
box,
the vacuum box including: a window part having translucency; two side walls each of which
arranged along corresponding one of the two parallel water-wall tubes; at least one end wall
arranged to intersect with a longitudinal direction of the parallel water-wall tubes; side edge
10 sealing members attached to edges of the side walls, respectively, so as to seal gaps between
the edges of the side walls and the parallel water-wall tubes; and an end edge sealing member
attached to an edge of the end wall so as to seal a gap formed by the edge of the end wall, the
parallel water-wall tubes and the fin,
the edge of the end wall having: a straight edge portion to be disposed along the fin; and an
15 arc edge portion to be disposed along the parallel water-wall tubes,
the end edge sealing member having: a straight sealing portion attached to the straight edge
portion; and an arc sealing portion attached to the arc edge portion.
[0009] According to the welded part inspection device for a boiler water-wall of the
present invention, the edge of the end wall has an arc edge portion and the end edge sealing
20 member has an arc sealing portion attached to the arc edge portion. Thus, even when the
inspection objective part of the boiler water-wall has convexity and concavity formed by the
parallel water-wall tubes and the fins, the vacuum box is capable of forming an airtight
vacuum chamber along with the inspection objective part. Therefore, according to this
welded part inspection device, it is possible to easily and securely detect a through-defect of
25 the welded part within the inspection objective part in a short period of time regardless of the
convexity and concavity in the inspection objective part of the boiler water-wall.
[0010] Preferably, the straight sealing portion is thicker than the arc sealing portion.
In this manner, even when the welded part between the parallel water-wall tube and the
5
fin, or the welded part between the plate sections constituting the fins protrude from the
surrounding part of the welded part, the straight sealing portion to be brought into contact
with the welded part is deformable in accordance with the protrusion of the welded part, since
the first straight sealing portion is thick. As a result, even with the welded part protruding,
the welded part and its surrounding part are securely sealed by the straight 5 sealing portion,
and thus an airtight vacuum chamber is formed by the vacuum box.
[0011] In the welded part inspection device for the boiler water-wall used for the
inspection objective part of the boiler water-wall, where the parallel water-wall tubes extend
straight, the vacuum box preferably includes two of the end walls distanced from each other
10 in the longitudinal direction of the parallel water-wall tubes, the end edge sealing member
being attached to each of the end walls.
With the above configuration, when the parallel water-wall tubes extend straight in the
inspection objective part of the boiler water-wall, the vacuum box is capable of forming an
airtight vacuum chamber with a simple configuration.
15 [0012] For the welded part inspection device for a boiler water-wall used for the
inspection objective part of the boiler water-wall, where the parallel water-wall tubes have an
arc curved portion in the longitudinal direction, the vacuum box preferably includes: two of
the end walls distanced from each other in the longitudinal direction of the parallel water-wall
tubes, the end edge sealing member being attached to each of the end walls; the side walls
20 each having the edge portion having an arc curved portion along the parallel water-wall tubes;
and the side edge sealing members attached along the edge portions of the side walls,
respectively.
With the above configuration, when the parallel water-wall tubes extend in a curved
shape in the inspection objective part of the boiler water-wall, the vacuum box is capable of
25 forming an airtight vacuum chamber with a simple configuration.
[0013] For the welded part inspection device used in a case in which a second fin is
configured to fill a gap formed by the fins, the parallel water-wall tubes, and crossing waterwall
tubes extending in a direction intersecting with the parallel water-wall tubes, where each
6
of gaps between adjacent two of the crossing water-wall tubes is filled by the fin, the vacuum
box preferably includes: the one end wall distanced from the second fin in the longitudinal
direction of the parallel water-wall tubes, the end edge sealing member being attached thereto;
the side walls extending between the end wall and the crossing water-wall; a top wall joined
to the end wall and the side walls; a sealing member including the end edge 5 sealing member
and the side edge sealing member, the sealing member being configured to seal gaps formed
by the side walls, the parallel water-wall tubes, the crossing water-wall tubes, and the second
fin; and a sealing member configured to seal a gap formed by the top wall and the crossing
water-wall tubes.
10 With the above configuration, when there are crossing water pipes in the vicinity of the
parallel water-wall tubes within the inspection objective part of the boiler water-wall, the
vacuum box is capable of forming an airtight vacuum chamber with a simple configuration.
[0014] Further, the present invention provides a welded part inspection method for a
boiler water-wall including a plurality of parallel water-wall tubes arranged parallel and fins
15 configured to fill gaps by welding, each of the gaps existing between two of the parallel
water-wall tubes which are arranged adjacent to each other, the welded part inspection method
comprising the steps of: preparing the above welded part inspection device for the boiler
water-wall; applying a bubble solution to the inspection objective part of the boiler waterwall;
forming the vacuum chamber by the vacuum box; reducing pressure inside the vacuum
20 chamber using an air exhauster connected to the vacuum box; and visually checking whether
the bubble solution is bubbling in the vacuum box.
[0015] According to the welded part inspection method for a boiler water-wall of the
present invention, the edge of the end wall of the prepared vacuum box has an arc edge
portion and the end edge sealing member has an arc sealing portion attached to the arc edge
25 portion. Thus, even when the inspection objective part of the boiler water-wall has
convexity and concavity formed by the parallel water-wall tubes and the fins, the vacuum box
is capable of forming an airtight vacuum chamber along with the inspection objective part.
Therefore, according to this welded part inspection method, it is possible to easily and
7
securely detect a through-defect of the welded part within the inspection objective part in a
short period of time regardless of the convexity and concavity in the inspection objective part
of the boiler water-wall.
[0016] According to the present invention, there are provided a welded part inspection
device and a welded part inspection method for a boiler water-wall, capable 5 of easily and
securely detecting a through-defect of the welded part within the inspection objective part in a
short period of time.
10 BRIEF DESCRIPTION OF DRAWINGS
[0017] FIG. 1 is a schematic diagram of the boiler water-wall, to which the welded part
inspection device according to one embodiment of the present invention is applied.
FIG. 2 is a schematic perspective view of the vacuum box of the welded part inspection device
for a boiler water-wall of the first embodiment, shown with the bottom water-wall of the
15 boiler water-wall.
FIG. 3 is an illustration for describing the welding structure of the water-wall tubes and the
fins at the bottom water-wall of the boiler water-wall of FIG. 2.
FIG. 4 is a schematic diagram of the configuration of the welded part inspection device of the
boiler water-wall according to the first embodiment.
20 FIG. 5 is a schematic perspective and exploded view of the vacuum box in FIG. 4.
FIG. 6 is a schematic front view of the vacuum box in FIG. 4, shown with a partial crosssection
of the bottom water-wall being the inspection objective part.
FIG. 7 is a schematic side view of the vacuum box constituting the welded part inspection
device of the boiler water-wall according to the second embodiment.
25 FIG. 8 is an illustration showing the end wall and the end edge sealing member as seen in the
direction of the arrow VIII of FIG. 7.
FIG. 9 is a schematic perspective view of the vacuum box of the welded part inspection device
of the boiler water-wall according to the third embodiment, shown with the corner of the
8
bottom water-wall and the side wall of the boiler water-wall being the inspection objective.
FIG. 10 is a schematic perspective and enlarged view of the vacuum box of FIG. 9.
FIG. 11 is a schematic perspective and enlarged view of the vacuum box of FIG. 9 as seen
from another direction.
FIGs. 12A to 12C are views of the three sides of the vacuum 5 box of FIG. 9.
DETAILED DESCRIPTION
[0018] Embodiments of the present invention will now be described in detail with
10 reference to the accompanying drawings. It is intended, however, that unless particularly
specified, dimensions, materials, shapes, relative positions and the like of components
described in the embodiments shall be interpreted as illustrative only and not limitative of the
scope of the present invention.
[0019] FIG. 1 is an illustration of a schematic configuration of a boiler water-wall 1
15 shown along with the vacuum boxes 100, 200, 300 of the welded part inspection device
according to the first to third embodiments, respectively. The boiler water-wall 1 includes a
bottom water-wall 2, a top water-wall 3, a front water-wall 4, and a side water-wall 5. The
water-wall tubes constituting the bottom water-wall 2, the front water-wall 4 and the top
water-wall 3 connect the steam drum 7 and the water drum 8.
20 [0020] (First embodiment)
FIG. 2 is a schematic perspective view of the vacuum box 100 of the welded part
inspection device of the first embodiment shown with a part of the bottom water-wall 2. The
bottom water-wall 2 includes a plurality of water-wall tubes 10 arranged parallel with a
predetermined interval between one another and fins 12 arranged so that each of the fins 12
25 fills a gap between two of the water-wall tubes 10. The fins 12 are welded to the water-wall
tubes 10 in the longitudinal direction of the water-wall tubes 10 to fill the gaps between the
water-wall tubes 10 in the longitudinal direction. Thus, the bottom water-wall 2 has
convexity and concavity corresponding to the curvatures of the outer circumferential surfaces
9
of the water-wall tubes 10.
[0021] More specifically, as shown in FIG. 3, each of the water-wall tubes 10 includes a
plurality of straight pipes 10a connected in series via welded parts 14. Also, each of the fins
12 includes a plurality of plate sections 12a, 12b. The water-wall tubes 10 are welded to the
plate sections 12a, 12b, while the plate sections 12a, 12b are also mutually 5 welded to each
other via welded parts 16.
The welded parts 16 in FIG. 3 are shaded for description.
[0022] FIG. 4 is a schematic view of the configuration of the welded part inspection
device according to the first embodiment. FIG. 5 is a schematic perspective and exploded
10 view of the vacuum box 100.
The vacuum box 100 forms an airtight vacuum chamber with a part of the water-wall
tubes 10 and a part of the fins 12 constituting the inspection objective part when contacting
the inspection objective part of the bottom water-wall 2.
A tube 102 is connected to the vacuum box 100 in communication with the vacuum
15 chamber. The tube 102 branches into two ways like a T-shape. An atmosphere releasing
valve 104 is provided in the middle of one branch, the tip end of the branch opening to the
atmosphere. Thus, by opening and closing the atmosphere releasing valve 104, it is possible
to cause the vacuum chamber to be in communication with, or to be shut from the atmosphere.
[0023]
20 An air exhaust valve 106 and an air exhauster inlet valve 108 are provided in the middle
of the other branch, the tip end of the other branch connected to the air exhauster 110.
The air exhauster 110 includes a vacuum pump and an air ejector, for instance. The air
exhauster 110 is configured to discharge the air inside the vacuum chamber to the outside
when the atmosphere releasing valve 104 is closed and the air exhaust valve 106 and the air
25 exhauster inlet valve 108 are open.
[0024]
The vacuum box 100 includes a pair of side walls 112, a pair of end walls 114, a top
wall 116, a gasket 118, a pair of long retainer plates 120, a pair of short retainer plates 121, a
10
plurality of screws 122, a pair of handles 124, a pressure gauge 126, a pair of side edge
sealing members 128, and a pair of end edge sealing members 130.
The pressure gauge 126 comprises, for instance, a Bourdon tube gauge, displaying the
pressure inside the vacuum chamber.
[0025] Each of the top wall 116, the side walls 112, and the end walls 5 114 for instance
includes a thick plate of acrylic and has translucency. The top wall 116 has a rectangular flat
shape. A gasket 118 of a flat quadrangular and annular shape is placed on the periphery of
the top wall 116. The gasket 118 is a rubber seal, for instance. The side walls 112 and the
end walls 114 are fixed to the top wall 116 via the gasket 118 using the screws 122.
10 [0026] Accordingly, the top wall 116 is airtightly joined to the side walls 112 and the end
walls 114. Also, the side walls 112 and the end walls 114 are mutually joined via an
adhesive agent.
The heads of the screws 122 are in contact with the top wall 116 via the long retainer
plates 120 and the short retainer plates 121. As a result, the gasket 118 is uniformly
15 compressed and thus the gap formed by the top wall 116, the side walls 112, and the end walls
114 is appropriately sealed to be airtight.
[0027] Each of the side walls 112 have a rectangular flat shape. A side edge sealing
member 128 of a cuboid shape is fixed to an edge (sealing edge) of each of the side walls 112
on the opposite side to the top wall 116 using an adhesive agent. Each of the side edge
20 sealing members 128 has a length and a width corresponding to the size of the sealing edge of
each of the side walls 112 to cover each of the side walls 112 entirely. One of the side walls
112 has a through-hole 131 for attaching the pressure gauge 126.
[0028] FIG. 6 is a schematic front view of the vacuum box 100 shown with a part of the
bottom water-wall 2 being the inspection objective. The end wall 114 has a through-hole
25 132 to which the tube 102 is to be connected.
As shown in FIG. 6, the end wall 114 includes a rectangular portion 134 of a rectangular
flat shape and a trapezoidal portion 136 of a substantially trapezoidal flat shape continuing
from a side of the rectangular portion 132. Herein, each of the lateral sides of the trapezoidal
11
portion 136 has a quarter-circular arc shape.
[0029] Accordingly, the edge (sealing edge) 138 of the end wall 114 on the opposite side
to the top wall 116 includes a straight edge portion (the first straight edge portion) 140
including a short side of the trapezoidal portion 136, arc edge portions 142 each of which
including a lateral side of the trapezoidal portion 136, and straight edge portions 5 (the second
straight edge portions) 144 each of which including a part of one side of the rectangular
portion 134. The end edge sealing member 130 is fixed to the sealing edge 138 of the end
wall 114 using an adhesive agent. Also, the end edge sealing member 130 and the side edge
sealing member 128 are joined to be airtight by an adhesive agent.
10 [0030] The end edge sealing member 130 has a length and a width corresponding to the
size of the sealing edge 138 of the end wall 114, covering the sealing edge 138 entirely.
Accordingly, the end edge sealing member 130 includes a first straight sealing portion 146
covering the first straight edge portion 140, arc sealing portions 148 covering the arc edge
portions 142, and second straight sealing portions 150 covering the second straight edge
15 portions 144.
When the first straight sealing portion 146 is in the free state of not being in contact
with the inspection objective part of the bottom water-wall 2, the first straight sealing portion
146 has a thickness T1 and the outer surface of the first straight sealing portion 146 is parallel
to the first straight edge portion 140. For instance, the thickness T1 is 12mm.
20 [0031] On the other hand, when the arc sealing portions 148 and the second straight
sealing portions 150 are in the free state of not being in contact with the inspection objective
part of the bottom water-wall 2, the arc sealing portions 148 and the second straight sealing
portions 150 have the same thickness T2, and the outer surfaces of the arc sealing portions148
and the second straight sealing portions 150 are parallel to the arc edge portions 142 and the
25 straight edge portions 144. For instance, the thickness T2 is 10mm.
Herein, the second straight edge portions 144 and the second straight sealing portions
150 may have arc shapes, or may be omitted if it is possible to join the side edge sealing
member 128 and the end edge sealing member 130 to be airtight. That is, the second straight
12
edge portions 144 and the second straight sealing portions 150 are not indispensable
components.
[0032] Preferably, the thickness T1 is greater than the thickness T2. More preferably,
the thickness T1 is greater than the thickness T2 by the length corresponding to the protruding
height from the fins 12 of the welded part 16 (the thickness of the welding). 5 As a preferable
example, the difference between the thickness T1 and the thickness T2 (T1- T2) is not less
than 2mm and not greater than 4mm. In the present embodiment, the difference (T1- T2) is
2mm.
[0033] Further, each of the end edge sealing members 130 preferably has an outer surface
10 152 at a region where the outer surface of the first straight sealing portion 146 intersects with
the outer surface of each of the arc sealing portions 148, the outer surface 152 having a slant
surface provided as if by cutting off the region.
[0034] Each of the side edge sealing members 128 and the end edge sealing members 130
includes a non-breathable foamed rubber, preferably, a chloroprene rubber. As a preferable
15 example, the Neoprene (Japanese trademark registered) sponge may be employed as the side
edge sealing members 128 and the end edge sealing members 130. Also, preferably, the side
edge sealing members 128 and the end edge sealing members 130 have hardness in the range
of 25 ± 5 degrees.
[0035] The inspection method for the welded part 16 using the welded part inspection
20 device for the boiler water-wall according to the first embodiment will now be described.
First, a bubble solution is applied to the inspection objective part of the boiler waterwall
1. The inspection objective part is a part of the boiler water-wall 1, where the waterwall
tubes 10 linearly extend. As a bubble solution, for instance, the Super-Bubble
(manufactured by MARKTEC Corp.) can be used.
25 [0036] Then, the vacuum box 100 is brought into contact with the inspection objective
part. In the present embodiment, when bringing the vacuum box 100 into contact with the
inspection objective part, the vacuum box 100 is arranged so that the side walls 112 are along
the longitudinal direction of the water-wall tubes 10 and the end walls 114 intersect with the
13
longitudinal direction of the water-wall tubes 10, as shown in FIG. 2. At this time, the
vacuum box 100 is arranged so that the side edge sealing members 128 are in contact with the
outer surfaces of the water-wall tubes 10, the first straight sealing portions 146 of the end
edge sealing members 130 are in contact with the fin 12, and the arc sealing portions 148 and
the second straight sealing portions 150 are in contact with the outer surfaces 5 of the waterwall
tubes 10.
[0037] After arranging the vacuum box 100 on the predetermined position, the
atmosphere releasing valve 104 is closed and the air exhaust valve 106 and the air exhauster
inlet valve 108 are opened, thereby starting operation of the air exhauster 110. As a result,
10 the air inside the vacuum chamber formed by the vacuum box 100 and the inspection
objective part is discharged to the outside, thereby reducing the pressure inside the vacuum
chamber.
[0038] According to JIS Z2329 2002, unless specifically defined, the method is
performed with the pressure inside the vacuum box reduced below the atmosphere by not less
15 than 0.015Mpa. In the present embodiment, the bubbling of the bubble solution is visually
checked after reducing the pressure to the testing pressure from 0.05MPa to 0.06MPa
inclusive. When the bubble solution is bubbling, it can be determined that there is a
through-defect such as a pinhole and a crack on the welded part 16 at the bubbling portion.
In the present embodiment, the top wall 116 has translucency and thus has a function of
20 a window part for visual check. The side walls 112 and the end walls 114 may be either
translucent or non-translucent.
[0039] Once the existence of bubble is visually checked, the inspection of the present
inspection objective part is completed. When inspecting another inspection objective part,
the air exhaust valve 106 is closed and the atmosphere releasing valve 104 is opened, thereby
25 introducing the outside air into the vacuum chamber. Then, the vacuum box 100 may be
moved to the next inspection objective part by holding the handles 124, and the above
procedure may be repeated. By moving the vacuum box 100 by the length of the vacuum
box 100 along the longitudinal direction of the water-wall tubes 10, it is possible to perform
14
the inspection efficiently.
[0040] According to the above described welded part inspection device of the boiler
water-wall according to the first embodiment, the edges of the end walls 114 have the arc
edge portions 142 and the end edge sealing members 130 have the arc sealing portions 148
mounted to the arc edge portions 142. Thus, even when the inspection objective 5 part of the
boiler water-wall 1 has convexity and concavity formed by the water-wall tubes (parallel
water-wall tubes) 10 and the fins 12, it is possible to form an airtight vacuum chamber by the
vacuum box 100 and the inspection objective part. As a result, according to this welded part
inspection device, it is possible to securely detect a through-defect of the welded part 16
10 within the inspection objective part regardless of the convexity and concavity of the
inspection objective part of the boiler water-wall 1.
[0041] Also, according to the above described welded part inspection device of the boiler
water-wall according to the first embodiment, even when the welded part 16 between the
water-wall tube 10 and the fin 12, or the welded part 16 between the plate sections 12a of the
15 fin 12 protrude from the surrounding part of the welded part 16, the first straight sealing
portion 146 to be brought into contact with the welded part 16 can deform in accordance with
the protrusion of the welded part 16, since the first straight sealing portion 146 is thick. As a
result, even with the welded part 16 protruding, the welded part 16 and its surrounding part
are securely sealed by the first straight sealing portion 146, and thereby the vacuum box 100
20 forms an airtight vacuum chamber.
[0042] Moreover, according to the above described welded part inspection device of the
boiler water-wall according to the first embodiment, where the water-wall tubes 10 extend
linearly in the inspection objective part of the boiler water-wall 1, the vacuum box 100 is
capable of forming an airtight vacuum chamber with a simple configuration.
25 [0043] (Second embodiment)
Hereinafter, the welded part inspection device for the boiler water-wall according to the
second embodiment will now be described. Among the configuration of the second
embodiment, the similar or identical component to that of the first embodiment is associated
15
with the same name or reference sign to simplify or omit description.
The welded part inspection device of the second embodiment is used to test a part where
the water-wall tubes are curved into an arc shape, for instance, to test a corner part formed by
the front water-wall 4 and the bottom water-wall 2. Thus, the welded part inspection device
of the second embodiment differs from that of the first embodiment only in 5 that a vacuum box
200, whose schematic configuration is shown in FIG. 7, is used instead of the vacuum box
100.
[0044] As shown in FIG. 7, each of the water-wall tubes 10 has a curved portion curved
into an arc shape in the longitudinal direction. Each of the side walls 202 of the vacuum box
10 200 has an edge (sealing edge) 206 having an arc curved portion on the opposite side of a top
wall 204. The curved portion of each of the sealing edges 206 has an appropriate curvature
corresponding to the curved portion of each of the water-wall tube 10. A side edge sealing
member 208 having a constant thickness is mounted to each of the sealing edges 206. The
side edge sealing members 208 extend along the water-wall tubes 10 having a curved portion
15 of an arc-like shape.
[0045] The end walls 210 of the vacuum box 200 are fixed to the top wall 204 so as to
intersect with the longitudinal direction of the water-wall tubes 10 when the vacuum box 200
is attached to the inspection objective part. Thus, the end walls 210 are fixed to the flat top
wall 204 slantwise in accordance with the curvatures of the water-wall tubes 10.
20 Although the gasket, long retainer plates, short retainer plates, screws and handles are
omitted from FIG. 7, the vacuum box 200 includes the above components.
[0046] FIG. 8 is an illustration showing the end walls 210 and an end edge sealing
member 212 as seen in the direction along the arrow VIII of FIG. 7.
The end wall 210 includes a rectangular portion 214 and a trapezoid portion 216. A
25 sealing edge 218 of the end wall 210 includes a first straight edge portion 220, arc edge
portions 222 and second straight portions 224. The end edge sealing member 212 includes a
first straight sealing portion 226, arc sealing portions 228, and second straight sealing portions
230. Preferably, the end edge sealing member 212 has an outer surface 232 at a region
16
where the outer surface of the first straight sealing portion 226 intersects with the outer
surface of each of the arc-like sealing portions 228, the outer surface 232 including a slant
surface provided as if by cutting off the region.
[0047] The method of using the welded part inspection device for the boiler water-wall
according to the second embodiment is similar to that in the case of the 5 first embodiment.
According to the welded part inspection device for the boiler water-wall of the second
embodiment, it is possible to securely detect a through-defect of the welded part 16 within the
inspection objective part regardless of the convexity and concavity of the inspection objective
part of the boiler water-wall 1, similarly to the case of the first embodiment.
10 [0048] Also, according to the welded part inspection device for the boiler water-wall of
the second embodiment, even with the welded part 16 protruding, the welded part 16 and its
surrounding part are securely sealed by the first straight sealing portion 226 and thus the
vacuum box 200 forms an airtight vacuum chamber, similarly to the first embodiment.
[0049] Further, according to the welded part inspection device for the boiler water-wall of
15 the second embodiment, when the water-wall tubes 10 extend in arc shapes in the inspection
objective part of the boiler water-wall 1, the vacuum box 200 is capable of forming an airtight
vacuum chamber along with a simple configuration.
[0050] (Third embodiment)
Hereinafter, the welded part inspection device for the boiler water-wall according to the
20 third embodiment will now be described. Among the configuration of the third embodiment,
the similar or identical component to that of the first embodiment or the second embodiment
is associated with the same name or reference sign to simplify or omit description.
[0051] As shown in FIG. 9, the welded part inspection device for the boiler water-wall
according to the third embodiment is used to test a corner of the water-wall 1, where the
25 water-wall tubes 10 are arranged so as to intersect with each other. The inspection objective
part is, for instance, a corner part formed by the bottom water-wall 2 and the side water-wall 5
of the boiler water-wall 1. The gap formed by the water-wall tubes (parallel water-wall
tubes) 10 of the side water-wall 5, the fins 12, and the water-wall tubes (crossing water-wall
17
tubes) 10 of the bottom water-wall 2 is filled by a fin 302 for a corner. The fin 302 is
welded to the water-wall tubes 10 of the side water-wall 5, the fins, and the water-wall tubes
10 of the bottom water-wall 2.
[0052] Thus, the welded part inspection device of the third embodiment is different from
that of the first embodiment only in that a vacuum box 300 is used instead 5 of the vacuum box
100.
FIGs. 10 and 11 are schematic perspective views of the vacuum box 300. The vacuum
box 300 includes one end wall 304, a pair of side walls 306, and a top wall 308 for testing the
corner of the boiler water-wall 1.
10 [0053] When the vacuum box 300 is installed on the inspection objective part, the end
wall 304 is arranged so as to intersect with the longitudinal direction of the water-wall tubes
10 of the side water-wall 5. An end edge sealing member 312 is attached to an edge (sealing
edge) 310 of the end wall 304, the edge 310 facing the side water-wall 5.
[0054] Further, when the vacuum box 300 is installed on the inspection objective part, the
15 side walls 306 are arranged along the longitudinal direction of the water-wall tubes 10 of the
side water-wall 5. A side edge sealing member 316 is mounted to an edge (sealing edge)
314 of each of the side walls 306 facing the side water-wall 5. On the other hand, a side
edge sealing member 320 is mounted to an edge (sealing edge) 318 of each of the side walls
306, the edge 318 facing the bottom water-wall 2.
20 [0055] Further, when the vacuum box 300 is installed on the inspection objective part, the
top wall 308 is arranged to face the side water-wall 5. A top edge sealing member 324 is
mounted to an edge (sealing edge) 322 of the top wall 308 facing the water-wall tubes 10 of
the bottom water-wall 2.
[0056] FIGs. 12A to 12C are views of the three sides of the vacuum box 300. The end
25 wall 304 includes a rectangular portion 325, and two trapezoid portions 326 integrally
continuing from one side of the rectangular portion 325. The sealing edge 310 of the end
wall 304 includes first straight edge portions 326, arc edge portions 328, second straight edge
portions 330, and a semicircular-arc edge portion 332. Further, the end edge sealing member
18
312 includes first straight sealing portions 334, arc sealing portions 336, second straight
sealing portions 338, and a semicircular-arc sealing portion 340 covering the arc-like edge
portion 332.
Preferably, each of the end edge sealing members 312 includes an outer surface 342 at a
region where the outer surface of each of the first straight sealing portions 5 334 intersect with
the outer surface of each of the arc sealing portions 336, 340, the outer surface 342 including
a slant surface provided as if by cutting off the region.
[0057] On the other hand, each of the side walls 306 includes a rectangular portion 343
and a trapezoid portion 344 integrally continuing from one side of the rectangular portion 343.
10 The sealing edge 314 of each of the side walls 306 includes a first straight edge portion 345,
an arc edge portion 346 and a second straight edge portion 348. Each of the side edge
sealing members 320 includes a first straight sealing portion 350, an arc sealing portion352,
and a second straight sealing portion 354.
[0058] Preferably, each of the side edge sealing members 320 has an outer surface 356 at
15 a region where the outer surface of the first straight sealing portion 350 intersects with the
outer surface of the arc sealing portion 352, the outer surface 356 including a slant surface
provided as if by cutting off the region. Although the gasket, long retainer plates, short
retainer plates, screws and handles are omitted from FIGs 10 to FIGs. 12C, the vacuum box
300 includes the above components.
20 [0059] According to the vacuum box 300 of the welded part inspection device of the third
embodiment, when vacuum box 300 is installed on the inspection objective part, the end edge
sealing member 314 is brought into contact with three of the water-wall tubes (parallel waterwall
tubes) 10 of the side water-wall 5 and the fins 12 between the water-wall tubes 10.
Then, the side edge sealing members 316 are brought into contact with the water-wall tubes
25 10 on both ends of the three water-wall tubes 10. The side edge sealing members 320 are
brought into contact with the fin for a corner (second fin) 302 and the water-wall tubes
(crossing water-wall tubes) 10 of the bottom water-wall 2. Further, the top edge sealing
member 324 is brought into contact with the water-wall tube 10 of the bottom water-wall 2.
19
[0060] The method of using the welded part inspection device for the boiler water-wall
according to the third embodiment is similar to that in the case of the first embodiment.
According to the welded part inspection device for the boiler water-wall of the third
embodiment, it is possible to securely detect a through-defect of the welded part 16 within the
inspection objective part regardless of the convexity and concavity of the inspection 5 objective
part of the boiler water-wall 1, similarly to the case of the first embodiment.
[0061] Also, according to the welded part inspection device for the boiler water-wall of
the third embodiment, even with the welded part 16 protruding, the welded part 16 and its
surrounding part are securely sealed by the first straight sealing portions 324, 350 and thus the
10 vacuum box 300 forms an airtight vacuum chamber, similarly to the case of the first
embodiment.
[0062] Further, according to the welded part inspection device for the boiler water-wall of
the third embodiment, the vacuum box 300 forms a vacuum chamber with two walls, namely
the bottom water-wall 2 and the side water-wall 5. Thus, it is possible to detect a through15
defect of the welded part 16 among the fin 302 for a corner, the water-wall tubes 10 of the
side water-wall 5, and the fins 12. That is, even when the inspection objective part of the
boiler water-wall 1 includes the water-wall tubes (parallel water-wall tubes) 10 of one of the
walls forming the corner of the boiler water-wall 1 and the water-wall tubes ( crossing waterwall
tubes) 10 of the other one of the walls in the vicinity of the water-wall tubes 10 of the
20 one of the walls, the vacuum box 300 is capable of forming an airtight vacuum chamber with
a simple configuration.
[0063] The present invention is not limited to the above described first to third
embodiments, and includes various amendments, modifications, and combinations of each of
the first to third embodiments.
25 For instance, while the vacuum box 100 of the first embodiment has the end walls 114
and the end edge sealing members 130 extending over two of the water-wall tubes 10, they
may extend over three or more of the water-wall tubes 10. That is, the vacuum box 100 may
form a vacuum chamber with three or more water-wall tubes 10 on both sides of the fins 12.
20
[0064] However, sealability decreases in accordance with increase in the length of the end
walls 114 and the end edge sealing members 130 due to the dimensional tolerance or
distortion of the water-wall tubes 10 or the fins 12. Therefore, it is preferable that the end
walls 114 and the end edge sealing members 130 extend over three or less of the water-wall
tubes 10 at the most. It is more preferable that they extend over two or less 5 of the water-wall
tubes 10.
21

I/We Claim:
1. A welded part inspection device for a boiler water-wall including a plurality of parallel
water-wall tubes arranged parallel and fins configured to fill gaps by welding, each of the
gaps existing between two of the parallel water-wall tubes which are arranged 5 adjacent to
each other, the welded part inspection device comprising:
a vacuum box configured to form a vacuum chamber with an inspection objective part
comprising a part of at least adjacent two of the parallel water-wall tubes and a part of the fin;
and
10 an air exhauster connected to the vacuum box,
the vacuum box including:
a window part having translucency;
two side walls each of which arranged along corresponding one of the two parallel
water-wall tubes;
15 at least one end wall arranged to intersect with a longitudinal direction of the parallel
water-wall tubes;
side edge sealing members attached to edges of the side walls, respectively, so as to seal
gaps between the edges of the side walls and the parallel water-wall tubes; and
an end edge sealing member attached to an edge of the end wall so as to seal a gap
20 formed by the edge of the end wall, the parallel water-wall tubes and the fin,
the edge of the end wall having:
a straight edge portion to be disposed along the fin; and
an arc edge portion to be disposed along the parallel water-wall tubes,
the end edge sealing member having:
25 a straight sealing portion attached to the straight edge portion; and
an arc sealing portion attached to the arc edge portion.
2. The welded part inspection device according to claim 1, wherein the straight sealing
22
portion is thicker than the arc sealing portion.
3. The welded part inspection device according to claim 1 or 2,
wherein the welded part inspection device is used for the inspection objective part of the
boiler water-wall, where the parallel water-wall tubes extend 5 straight, and
wherein the vacuum box includes two of the end walls distanced from each other in the
longitudinal direction of the parallel water-wall tubes, the end edge sealing member being
attached to each of the end walls.
10 4. The welded part inspection device according to claim 1 or 2,
wherein the welded part inspection device is used for the inspection objective part of the
boiler water-wall, where the parallel water-wall tubes have an arc curved portion in the
longitudinal direction, and
wherein the vacuum box includes:
15 two of the end walls distanced from each other in the longitudinal direction of the parallel
water-wall tubes, the end edge sealing member being attached to each of the end walls;
the side walls each having the edge portion having an arc curved portion along the parallel
water-wall tubes; and
the side edge sealing members attached along the edge portions of the side walls, respectively.
20
5. The welded part inspection device according to claim 1 or 2,
wherein the welded part inspection device is used in a case in which a second fin is
configured to fill a gap formed by the fins, the parallel water-wall tubes, and crossing waterwall
tubes extending in a direction intersecting with the parallel water-wall tubes, where each
25 of gaps between adjacent two of the crossing water-wall tubes is filled by the fin, and
the vacuum box includes:
the one end wall distanced from the second fin in the longitudinal direction of the parallel
water-wall tubes, the end edge sealing member being attached thereto;
23
the side walls extending between the end wall and the crossing water-wall;
a top wall joined to the end wall and the side walls;
a sealing member including the end edge sealing member and the side edge sealing member,
the sealing member being configured to seal gaps formed by the side walls, the parallel waterwall
tubes, the crossing water-wall tubes, and the 5 second fin; and
a sealing member configured to seal a gap formed by the top wall and the crossing water-wall
tubes.
6. A welded part inspection method for a boiler water-wall including a plurality of parallel
10 water-wall tubes arranged parallel and fins configured to fill gaps by welding, each of the
gaps existing between two of the parallel water-wall tubes which are arranged adjacent to
each other, the welded part inspection method comprising the steps of:
preparing the welded part inspection device for the boiler water-wall according to any one of
claims 1 to 5;
15 applying a bubble solution to the inspection objective part of the boiler water-wall;
forming the vacuum chamber by the vacuum box;
reducing pressure inside the vacuum chamber using an air exhauster connected to the vacuum
box; and
visually checking whether the bubble solution is bubbling in the vacuum box.