Note: Descriptions are shown in the official language in which they were submitted.
CA 02358977 2007-12-04
1 WELD TESTING ASSEMBLY
2
3 BACKGROUND OF THE INVENTION
4 [0001] This invention relates to the testing of welds, and particularly but
not necessariiy, the
hydrostatic testing of welds for nozzies, studs, flanges, patches, etc. on or
connected to pressure
6 tanks or vessels.
7 [0002] The testing of weld integrity on nozzles or other components welded
to pressure vessels
8 traditionally involves the whole vessel having to be filled with a
pressurizing fluid medium. This
9 usually means that a large volume of fluid is required, and, if the fluid is
not used in the actual
operation of the system of which the vessel is a part, purging of the
equipment has to be performed
11 both before and after weld testing.
12 SUMMARY OF THE INVENTION
13 [0003] In one embodiment, the present invention provides a weld testing
assembly for
14 hydrostatic pressure testing of welds between two components, the weld
testing assembly
comprising: a body securable against at least one surface of at least one of
the components so as to
16 define a sealed space adjacent to the weld to be tested; and, at least one
port for receiving a
17 pressurized test fluid into the sealed space; the body being provided with
one or more threaded tie
18 rods and one or more nuts adapted to be threaded on the tie rods; wherein
the weld is provided
19 between a vessel and a patch thereon, and wherein the at least one tie rod
is secured to the patch
and tightening of the nut forces the body against the patch, the body
extending beyond the patch
21 such that the sealed space includes the weld.
22 [0004] In another embodiment, the invention provides a method for testing a
weld between a
23 first component and a patch on the first component, comprising the steps
of: providing a sealing
24 assembly comprising a body adapted to be forced into engagement with at
least one surface of the
first component, the body extending beyond the patch; providing at least one
threaded tie rod
26 secured to the patch; securing the sealing assembly against the at least
one surface so as to define
27 a sealed space adjacent to, and including, the weld to be tested, the
sealing assembly being
28 secured against the at least on surface by tightening a nut on each of the
at least one threaded tie
29 rod such that tightening of the nut pulls the body towards the patch;
injecting a pressurized test fluid
into the sealed space; and monitoring the seaied space fcx indkia of a leak of
the test fluid from the
31 sealed space.
32 10005] In a further embodiment, the invention provides a weld testing
assembly for hydrostatic
33 pressure testing of welds between two components, the weld testing assembly
c.omprising: a body
34 securable against at least one surface of at least one of the components so
as to define a sealed
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1 space adjacent to the weld to be tested; and, at least one port for
receiving a pressurized test fluid
2 into the sealed space; the body being provided with one or more threaded tie
rods and one or more
3 nuts adapted to be threaded on the tie rods; wherein the body is comprised
of two or more sections,
4 each of the sections including a means for joining the sections together to
form the body.
[0006] Further features of the invention will be described or will become
apparent in the
6 following description.
7 BRiEi; OESCR#PTiON OF THE DRAWINGS
8 [0007] In order that the invention may be more ciearly understood, the
preferred embodiment
9 thereof will now be described in detail by way of example, with reference to
the accompanying
drawings, in which:
11 [0008] FIG. 1 is a cross-sectionai view of one embodiment of a weld testing
assembly for a
12 nozzle extending from a pressure vessel;
13 [0009] FIG. 2 is a cross-sectional view of an alter+native weld testing
assembly for a nozzle;
14 [0010] FIG. 3 is a cross-sectional view of another altemative weld testing
assembly for a nozzle;
[0011] FIG. 4 is a cross-sectional view of a more complex weld tes4ng assembly
for a nozzle,
16 useful for large welds;
17 [0012] FIG. 5 is a cross-secbonat view of a weld testing assembly for a
spigot extending from a
18 pressure vessel;
19 [0013] FIG. 6 is a cross-sectional view of a weld testing assembly for a
patch in the wall of a
pressure vessel;
21 [0014] FIG. 7 Is a cross-sectional view of an aitemative embodiment of a
weld testing assembly
22 for a patch; and
23 [0015] FIG. 8 is a cross-sectional view of another altemative embodiment of
a weld testing
24 assembly for a patch.
[0016] FIGS. 9 to 15 show cross-sectional views of alternate embodiments of
the invention.
26 [0017] FIG. 16 is a partial cross sectional view of another embodiment of
the invenfion.
27 [0018] FIG. 17 is an end view of the embodiment of FIG.16.
28 10019] FIG. 18 is a cross sectional view of the embodiment of FIG. 16 when
used with the
29 assembly of FIG. 1.
[0020] FIG. 19 is a cross sectional view of the embodiment of FIG. 16 for use
on a patch in the
31 wall of the vessel.
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1 DETAILED DESCRIPTION OF THE INVENTION
2 [00211 FIG. 1 shows a weld testing assembly configured to test a weld 5
which holds a nozzle 2
3 in a hole in the wall of a pressure vessel 1. A flange 3 is mounted on the
nozzle 2 via a flange weld
4 4. The weld testing assembly is secured against the inner wall of the
vessel, to define a sealed area
25. The assembly has an external blind 6, which matches the form and shape of
the flange 3. The
6 blind can be mounted on the flange using any appropriate fastening means,
such as nuts and bolts,
7 through corresponding holes in the flange and the blind. There is at least
one hole 20 in the blind 6,
8 and normally several such holes, each such holes accommodating a threaded
tie rod 9. The tie rod
9 9 connects the blind 6 to a body 8, which is situated inside the pressure
vessel 1 and which has
walls 16 which seal against the wall of the pressure vessel, outside the
nozzle weld 5. The seal is
11 achieved by any suitable means, such as by using a rubber 0-ring 14, held
in place by a groove 23
12 at the end of the walls 16. A lead seal could be used as one altemative.
Each tie rod 9 passes
13 through a hole 21 in the body and is threaded into a nut 10. Each nut 10 is
sealed to the body by a
14 seal wetd 19.
[0022] The tie rods 9 pull the body 8 towards the blind 6, via tightening of
the nuts 12, to create
16 the sealed area 25. Preferably, a packing box 11 is used to provide an
effective seal where the tie
17 rods extend through the blind, the packing box being mounted on the tie rod
9 on the outside of the
18 blind 6. In the preferred embodiments, an 0-ring 27, preferably
accommodated in suitable grooves
19 in the packing box and the blind, provides a seal between the packing box
assembly and the blind.
When the nut 12 is tightened, it creates a seal to define the sealed area 25,
but it also produces a
21 longitudinaily-oriented mechanical stress in the nozzle weld 5.
Accordingly, the weld's ability to
22 withstand the mechanical stress in addition to the hydrostatic pressure
created by the pressurizing
23 fluid during the test provides the operator with additional confidence in
the integrity of the weld,
24 because it will have to withstand more stress than it will experience
during norma[ operational use.
[0023] Clearly, altemative tightening and sealing arrangements could be used,
and the use of
26 such aftematives is within the scope of this invention.
27 [0024] In the embodiment shown in FIG. 1, the body 8 is generally cup-
shaped, having a disc 17
28 to which the wall 16 is via a body weld 18. The disc has one hole 21 for
each tie rod 9.
29 [0025J The weld testing assembly also has vent and filler pipes 7 and 15
respecfive[y, each
communicating with the sealed area 25, for passage of pressure testing fluid
into and from the
31 sealed area. The pressurizing fluid is normally water or conventional
antifreeze if the test is carried
32 out in cold temperatures. However, it should be understood that any number
of different fluids, such
33 as atmospheric air, nitrogen, or an inert gas, may also be used. Ports to
accommodate a vent and
34 filler pipe can be situated in the blind 6 (vent and filler port 7) or in
the body 8 (vent and filler port 15)
or in both (as illustrated in FiG.1). The vent and filler pipe are connected
to a pressurized fluid
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1 media container and a purge fluid container via one or more valves 13, shown
schematically in FIG.
2 1. If desired, a single port can be used for both filling and venting,
although purging of the test fluid
3 may then be less effective.
4 [0026] With the invention, pressurizing the sealed area 25 with fluid can
thus readily be
achieved, in order to test the strength and integrity of the weld using
conventional monitoring means,
6 e.g. visual leak inspection, measurement of pressure drop, measurement of
flow, etc. Of course, for
7 a secure weld, there should be no pressure drop or fluid flow once the
sea[ed area is pressurized.
8 [0027] FIG. 2 shows an altemative embodiment for the weld testing assembly,
where the body 8
9 is a one-piece hemispherical shape. A groove 23 is defined within the edge
of the body to
accommodate a seal 14, as in the embodiment of FIG. 1.
11 [0028] FIG. 3 shows another alternative embodiment of the weld testing
assembly, where the
12 body 8 is one piece which conforms to the shape of the inside of the vessel
1, in the area adjacent
13 the weld. There is a groove 23 in the body, to hold the seal 14.
14 [0029] FIG. 4 shows another alternative embodiment of the weld testing
assembly configured to
test a weld attaching a nozzle to a pressure vessel. This embodiment is
particularly advantageous
16 for a pressure test where the circumference of the weld to be tested is so
large that three or more tie
17 rods 9 are required to maintain the seal. This configuration provides a
cost and time savings by
18 eliminating the requirement of sealing every tie rod using a packing box.
Instead, the threaded tie
19 rods are tightening against the external blind 6 by conventional nuts to
create a seal between the
pressure vessel and the body 8 and between the circumferential edges of the
flange 3 and the
21 external blind. A conventional welineck flange 30 is secured to the top of
the external blind by a
22 weld 31. A second extemal blind 32 is sealably connected to the welineck
flange using conventional
23 studs (not shown) to seal the top of the test assembly. Three threaded
openings are drilled in the
24 second extemal blind to provide a vent port 33, a filler port 34, and a
gauge port 35. During the
pressure test, fluid is introduced through the filler port 34, and a gauge
port 35. During the pressure
26 test, fluid is introduced through the filler port and passes through holes
36 drilled in the external blind
27 6.
28 [0030] FIG. 5 shows an altemative embodiment of the weld testing assembly
configured to test
29 a weld 5 securing a spigot 52 to the wall of a pressure vessel. A groove 51
is machined in a
cylindrica{ plate 50, such that the spigot fits tightly into the groove. To
create a seal between the
31 plate and the spigot, an 0-ring 53 is inserted into the groove and then the
plate is fitted onto the
32 spigot. The assembly is then tightened using the rod, packing box, and
nuts, as previously
33 described.
34 [0031] FIG. 6 shows an altemative embodiment of the weld testing assembly
configured to test
a weld 41 securing a patch 40 to the wall of a pressure vessel. A tie rod
seals the body against the
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1 inside of the pressure vessel. The body has a sealing circumference around
the patch and the seal
2 between the body and the pressure vessel is accomplished by an O-ring 14
which fits into a groove
3 23 in the body, as described above. To provide a second seal between the
body and the opening to
4 accommodate the tie rod, preferably a packing box 11 and a second 0-ring 27
are provided. The tie
rod is screwed into the first nut 10, which is welded onto the patch by an
ordinary fillet weld 45. The
6 assembly is sealed by tightening the second nut 12, as described previously.
7 [0032] In certain situations, it may be advantageous to pre-weld the first
nut 10 to the patch in
8 anticipation of conducting the hydrostatic test using the invention.
9 [0033] FIG. 7 shows an altemative embodiment of the weld testing assembly
configured to test
a weld securing a patch to the wall of a pressure vessel. This embodiment is
required when the
11 patch is so large that the circumference of the weld to be tested requires
more than one tie rod to
12 maintain the seat during the pressure test.
13 [0034] FIG. 8 shows an altemative embodiment of the weld testing assembly
configured to test
14 a weld securing a patch to the wall of a pressure vessel, where the
assembly is sealed against the
outside of the vessel.
16 10035] It will be understood that the materials for the components of the
weld test assembly
17 have to be chosen according to the specific demands of the particular
pressure vessel environment
18 to be tested. In most cases, a carbon steel body will suffice. In other
cases, a stainless steel body
19 will have to be employed.
[0036] It should be appreciated that although the invention is particularly
adapted to use In
21 testing welds in pressure vessels, as described above, the invention can be
readily adapted to
22 testing any other welds, whether in pressure vesse[s or elsewhere.
23 [0037] The invention provides an effective and efficient means for testing
the integrity of welds,
24 particularly but not necessarily only in pressure vessels.
[0038] Returning to F{G.1, as mentfoned previously, the external blind 6 is
preferably mounted
26 to the flange 3 by means of bolts, which extend through the holes 72 and 74
in the blind 6 and flange
27 3, respectively. This arrangement ensures that the blind 6 is properiy
positioned over the flange 3 so
28 that the required seal is established. Further, in such arrangement, the
tie rods 9 only serve to draw
29 the body 8 towards the blind 6 to create the required seal for conducting
the test.
[0039] FIG. 9 illustrates a further embodiment of the invention similar to
that of FIG. 4 with
31 different but similar elements being designated with the letter "a" for
convenience. As shown, the
32 weld testing assembly includes a body 8, which may be of a single piece or
a combination of pieces
33 as described above. The body 8 is placed inside of a pressure vessel 1 and
includes an 0-ring 14 to
34 effect sealing of the body 8 against it. Tie rods 9 extend from the body 8
to the extemal blind 6a Is
mounted to the flange 3 by means of bolts 76, which secure the blind 6a to the
flange 3. As
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1 mentioned above, such arrangement ensures that the blind 6a is properly
placed and secured
2 against the flange 3. As before, the blind 6a and the flange 3 are provided
with openings 36 to
3 enable the pressurized fluid for the test to enter the sealed area 25. A
weilneck flange 30a is
4 attached to the blind 6a by welding. A second extemal blind 32a is then
bolted on the wetlneck
flange 30a. Both the wellneck flange 30a and the second blind 32a are provided
with openings
6 through which extends ports 78 and 80 forfrlling and venting the sealed area
25 and, if required, for
7 providing a pressure gauge.
8 [0040] In FIG. 10, a further embodiment of the invention is provided wherein
the testing
9 assembly is adapted for use in nozzles incorporating a bend. Elements in
this figure that are similar
to those in the previous drawings are designated with the letter "b" for
convenience. In this case, the
11 nozzle 2b includes a bend 82 between the vessel 1 and the flange 3b. The
testing assembly
12 includes a body 8b within the vessel and an extemai blind 6b connected by
at least one tie rod 9b.
13 As before, the body 8b includes a sealing element such as an O-ring 23b for
creating a seal between
14 the body 8b and the vessel 1. The externai biind 6b is secured to the
flange 3b by means of bolts 84
or other such securing means. The body is provided with a port 86 and the
blind 6b is provided with
16 ports 88 and 90 for filling and venting the sealed area 25b. In the case of
the external blind, one of
17 the ports can also be used for adding a pressure gauge. The tie rods 9b, in
this embodiment, are
18 flexible material in order to navigate through the bend 82 and preferably
comprise chains. However,
19 the tie rods 9b stiii perform the same function as before, namely, they are
used to tighten the body
8b against the inner wall of the vessel 1 by pulling it towards the externai
blind 6b. In order to
21 ensure that the force on the body 8b is applied generaliy perpendiculariy,
a guide 92 is placed within
22 the bend to the guide the tie rods 9b in the required directions. The guide
92 thus ensures that the
23 body 8b bears against the vessel wall equally on all sides so that an
adequate seal is established.
24 As before, the tie rods 9b are connected by means af nuts 10b and 12b and
packing boxes 11 b.
The tie rods 9b, or chains, are also preferably provided with links or
grommets 93 for attaching the
26 chains tagether.
27 [0041] FIG. 11 illustrates a further embodiment of the invention with
similar elements designated
28 with the letter "c for convenience. In this embodiment, the nozzle 2c is
offset and attached to a
29 vessel 1 at an angle. Accordingly, to create the required sealed area 25c,
the body as shown In FIG.
2 is used and comprises a"universaP" body that can be used for different
orientations of the nozzle.
31 In this case, the tie rod 9c is capable of being directed in the required
direction. This is
32 accomplished by anchoring the tie rod 9c to the body 8c with a swivel
joint. The swivel joint
33 preferably comprises a ball 94, such as that of a trailer hitch, to which
the tie rod 9c is attached. The
34 means of attachment may be by screwing or welding the rod to the ball or
any other means. An
opening is provided in the body 8c through which the tie rod 9c is passed, but
which is not wide
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1 enough for the ball 94 to rotate within. The ball 94 is also provided with a
sealing means such as a
2 gasket type material (for example, TeflonTM) so that once the tie rod 9c is
tightened, the ball 94
3 forms a leak-proof seal against the opening In the body Bc. In the preferred
embodiment, the
4 assembly is provided with one or three tie rods 9c as this arrangement has
been found to minimize
the "walking", or movement, of the body Bc along the inner wall of the vessel
1.
6 [0042] FIG. 12 illustrates yet a further embodiment of the invention with
similar elements
7 identified with the letter "d" for convenience. In this embodiment, the
nozzle 2d includes a threaded
8 end 96 and does not have a flange. Accordingly, in this embodiment, the
external blind Is replaced
9 with a sleeve 98 that is screwed onto the threaded portion 96. A tie rod 9d
is attached to a body 8d
similar to that shown in FIG. 2 and is secured to the sleeve 98 with a nut
100. The sleeve is
11 provided with ports 102 and 104 for filling and venting the sealed area
25d. Further, a port 106 may
12 be provided on the body 8d also for filling or venting the sealed area 25d.
13 [0043] FIG. 13 illustrates another embodiment of the invention with similar
elements Identifted
14 with the letter "e" for convenience. In this instance, the nozzle 2e
extends into the vessel 1 by a
16 certain distance to create a protruding portion 110. Accordingly, the body
8e must be designed so
16 that is has elongated side walls 16e that can extend beyond the protrusion
110 of the nozzle 2e in
17 order to contact the inner wall of the vessel 1. A spacer 108 is provided
over the protrusion of the
18 nozzle so that the body 8e can be centered over it and also to prevent any
movement of the body
19 8e. The spacer may be an annular structure that is fitted over the
protruding portion 110 of the
nozzle 2e.
21 [0044] FIG. 14 illustrates an embodiment of the invention, with similar
elements identified with
22 "f', wherein the vessel is provided with a pipe 112 with a valve 114, such
as a gate or metering
23 valve. Again, the body 8f is similar to that of FIG. 2 and is attached to a
tie rod 9f, which is
24 connected, at its other end, to a plate 116 by means of a nut 118. The body
8f is provided with ports
120 and 122 for filling and ventfng the sealed area 25f.
26 [0045] FIG. 15 is a variant of the embodiment shown In FIG. 5, with similar
elements identified
27 with "g", wherein the plate 50g Is provided with two ports 124 and 126 for
filling or venting the sealed
28 area 25g.
29 [0046} in most vessels, the largest opening is generally in the range of
20" to 24" in diameter.
However, in order to test welds around such openings, the body of the test
assembly must be
31 smaller than the largest opening in order to have such body enter into the
vessel. Therefore, a
32 problem occurs when testing such large openings (i.e. openings greater than
20" in diameter) since
33 the body of the test assembly, required for conducting the test, cannot fit
into the vessel. For
34 example, for testing vessel openings greater than 20" in diameter, the body
of the test assembly is
usually 30" in diameter. As such, the body will not be able to enter the
vessel in order to conduct the
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1 required test. Normally, tests on such "large" openings are carried out by
cutting the body into two
2 pieces and welding them together inside the vessel. After the test is
complete, the body is once
3 again cut and removed from the vessel. As will be understood, this process
involves much more
4 time than regular tests and the life span of the body is reduced. To
overcome this problem, the
present invention, according to another embodiment, comprises a test assembly
generally as
6 described above but including a body consisting of two pieces, or halves,
and being capable of being
7 joined together with connectors, such as nuts and bolts and the like.
8 [0047] The test assemblies Illustrated in FIGS. 16 to 18 may be used for the
large vessel
9 openings mentioned above. In FIGS. 16-18, elements that are similar to those
mentioned above
with reference to other figures are identified with like reference numerals
but with the letter "h" added
11 for ciarity. For the purpose of the present description, the term "large
openings" is considered to
12 comprise openings having a diameter greater than 20". However, it will be
understood by persons
13 skilled in the art that the term "large" is discretionary and may comprise
any size opening for which a
14 test assembly body is too large to fit inside a vessel.
[0048] FIG.16 illustrates a partial view of a test assembly for use on
openings for which a single
16 piece test body cannot be used. As mentioned above, such test assembly is
provided with a disc
17 17h, which includes two separate pieces or sections 150 and 152. The
sections 150 and 152 of the
18 disc 17h are provided with a plurality of flanges 154 and 156,
respectivety, extending generally
19 perpendicularly from the plane of the disc 17h on both sides thereof,
Sealing flanges 154 and 156
are provided on pieces 150 and 152 in such manner as to allow the flanges of
each piece to oppose
21 each other. The flanges 154 and 156 are also provided with opposing
apertures 158 and 160,
22 respectiveiy, through which is passed a bolt 162. Nuts 164 and 166 are
provided on opposite ends
23 of bolt 162 whereby tightening of the nuts 164 and 166 forces opposing
flanges 154 and 156 to
24 approach each other. In the result, the separate pieces 150 and 152 are
brought together thereby to
form the disc 17h. In order to achieve a sealing relationship between the
pieces 150 and 152 each
26 piece is provided with a notch or groove 168 and 170, respectiveiy, on the
adjacent ends thereof. A
27 sealing material such as an "O" ring or gasket, 172, is provided within the
space formed by the
28 opposing notches or grooves, 168 and 170. The sealing flanges 154 and 156
may be either formed
29 with each piece 150, 152, or, as shawn, may be separate pieces that are
attached to each piece
150, 152 by welds 174.
31 [0049] Although the above preferred embodiment describes the use of sealing
flanges and
32 associated bolts to connect the pieces, 150 and 152, of the disc 17h, other
means of connecting
33 such pieces wiii be apparent to persons skilled in the art. Further the
flanges 154, 156 may be
34 attached to the pieces or sections 150 and 152 in a number of ways as known
in the art.
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1 [0050] FIG. 17 illustrates an end view of the assembly of FIG. 16. As can be
seen, each piece
2 or section, 150 and 152, forming the disc 17h, is provided with a plurality
of sealing flanges 154 and
3 156, respectively. It will be appreciated that the number of flanges
required will be dependent on the
4 diameter of the disc 17h being formed. Further, it will be apparent to
persons skilled in the art that
the number of flanges 154, 156 may be reduced by providing one or more long
flanges on each
6 piece 150, 152, each of such flanges being connected to an opposing flange
by one or more bolts.
7 [0051] FIG. 18 illustrates the assembly of FIG. 1 wherein the opening to be
tested has a
8 diameter greater than 24". In such case, the disc 17 is formed with the
embodiment shown in FIG.
9 16. Therefore, the disc 17h is formed by the opposing pieces or halves 154
and 156.
[0052] FIG. 19 illustrates the two part test assembly for testing the welds of
a patch on a vessel
11 wall.
12 [0053] Although the invention has been described with reference to certain
specific
13 embodiments, various modifications thereof will be apparent to those
skilled in the art without
14 departing from the spirit and scope of the invention as outiined in the
claims appended hereto.
16
17
18
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