Note: Descriptions are shown in the official language in which they were submitted.
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1 METHOD FOR SEPARATING FLANGES
2 FIELD OF THE INVENTION
3 [00011 The present invention relates to an improved method of separating
flanges connected
4 together with bolts to form a joint in pipes and the like. More
particularly, the invention relates
to a method of flanges by the cutting of shearing of the bolts joining such
flanges together.
6 DESCRIPTION OF THE PRIOR ART
7 [0002] The use of flanges on pipes is well known. Flanges serve to connect
the ends of
8 pipes to other pipes, vessels or other such equipment. Generally, a flange
includes a stem
9 portion that is permanently secured (normally with welds) to the end of a
pipe or similar
structure. The flange includes a face portion opposite to the stem. The flange
face includes a
11 rim or disc with a plurality of circum ferenti ally spaced boltholes. In
connecting, for example,
12 two pipe segments together, the stems of two flanges are first each secured
to one end of the
13 respective pipe segments. The segments are then axially advanced towards
each other so that the
14 flange faces are brought into opposition, with the respective boltholes
aligned. The flanges are
then secured to each other by inserting bolts through the boltholes. One or
both ends of the bolts
16 may be provided with threaded portions to receive nuts as is commonly known
in the art. The
17 nuts are tightened to join the flanges together. In some cases, the
boltholes of the flanges may be
18 provided with threading to engage the bolts.
19 [0003] It is sometimes necessary to separate flanges from each other. To do
so, the above
mentioned nuts are first removed followed by removal of the bolts and,
subsequently, separation
21 of the flanges. However, it is commonly known that the nuts and/or bolts
are subject to
22 corrosion or other such damage and, in the result, removal of the nuts
and/or bolts is rendered
23 difficult or impossible. In such cases, the bolts are removed with a
cutting torch. As will be
24 appreciated, this process is time consuming and expensive. Moreover, the
use of a torch may
pose a significant hazard such as in cases where the pipes had contained
flammable chemicals.
26 [00041 Various devices have been provided in the art for cutting sections
of pipe. One such
27 cutting apparatus that has been found to be relatively efficient is known
in the art as a
28 "clamshell" pipe cutter or pipe lathe. Examples of clamshell cutters are
provided in US patent
29 numbers 5,189,933, 5,549,024 and 7,000,510. In general, a clamshell
apparatus includes two
concentric annular rings that are adapted to circumferentially surround the
pipe to be cut. In
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1 such apparatus, one of the rings is stationary and is secured to the outer
wall of the pipe. The
2 other of the rings is capable of being rotated circumferentially about the
pipe. The rotating ring
3 is provided with a cutting tool that is adapted to be gradually advanced
against the pipe outer
4 wall in a radially inward direction. In operation, the second ring is
rotated (by means of a motor
for example) and the cutting tool is advanced against the pipe wall. The
advancement of the
6 cutting tool progresses until the cutting tool cuts through the pipe wall.
Although clamshell
7 devices are well designed for cutting pipes, they are not used for
separation of flanges from each
8 other.
9 [0005) The present invention serves to provide an efficient method of
separating flanges.
SUMMARY OF THE INVENTION
11 [00061 In one aspect, the present invention provides a method of separating
a joint formed by
12 two flanges, the flanges being connected together by means of bolts
extending through boltholes
13 provided on each of the flanges, the method comprising:
14 - providing a cutting apparatus proximal to the joint, the cutting
apparatus having a
rotating annulus, the annulus having an inner diameter greater than the outer
diameter of the
16 flanges, wherein the annulus includes at least one cutting tool on the
inner diameter, the cutting
17 tool being directed radially inwardly and wherein the cutting tools are
moveable radially
18 inwardly;
19 - positioning the cutting apparatus circumferentially over the joint and
over the flanges;
- positioning the cutting apparatus whereby the cutting tool is positioned
adjacent the
21 bolts;
22 - rotating the annulus circumferentially about the joint;
23 - advancing the cutting tool radially inwardly until the bolts are sheared;
and
24 - separating the flanges.
BRIEF DESCRIPTION OF THE DRAWINGS
26 [0007] These and other features of the invention will become more apparent
in the following
27 detailed description in which reference is made to the appended drawings
wherein:
28 [00081 Figure 1 is a side elevation illustrating the junction of two
flanges.
29 100091 Figure 2 is a side elevation of the junction of Figure 1 provided
with a cutting
apparatus.
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1 [0010] Figure 3 is a side elevation of the junction of Figure 1 provided
with a cutting
2 apparatus.
3 [0011] Figure 4 is a partial cross sectional view of a joint created with
two raised face
4 flanges.
DETAILED DESCRIPTION OF THE INVENTION
6 [0012] Figure 1 illustrates a typical junction of two flanges. As shown, the
flanges 12 and 14
7 include, respectively, stem portions 16 and 18 and face portions 20 and 22.
The stem portions
8 are secured, such as with welds 23 and 25, respectively to the ends of pipes
24 and 26. Each of
9 the face portions of the flanges include a plurality of circumferentially
spaced bolt holes 28. In
joining the flanges together, the bolt holes of each flange are aligned
together and bolts 30 are
11 passed there-through. The bolts are secured in position with nuts 32 that
can be provided on one
12 or both ends of the bolts 30. In some situations, the boltholes on the
flanges may be provided
13 with threads to engage the bolts. As will be apparent to persons skilled in
the art, it is common
14 to provide a gasket or other such sealing means between the opposed flange
faces. However, for
clarity, such gasket is not illustrated in the drawings.
16 [0013] As discussed above, when separation of a flange joint is desired,
the nuts 32 are
17 removed so as to allow the bolts 30 to be removed. The flanges can then be
separated.
18 However, as also discussed above, it is often found that either the nuts 32
or bolts 30 are either
19 corroded or otherwise damaged in such a manner that removal of the nuts is
not possible. In
such cases, the bolts 30 are cut with torches and the like.
21 [0014] As mentioned above, examples of clamshell pipe cutters are provided
in US patent
22 numbers 5,189,933, 5,549,024 and 7,000,510. The tools described in these
references generally
23 comprise first and second semi-circular segments that are designed to be
joined together to form
24 an annular assembly for encircling a shaft or pipe to be machined (i.e. cut
or lathed). The
assembly also generally includes a stationary ring, and a rotatable ring
supported by bearings
26 affixed to the stationary ring. The rotatable ring includes a spur gear on
its outer peripheral
27 surface and is journaled to the stationary ring for rotation about a
concentrically disposed pipe or
28 work piece. A motor is attached to the stationary assembly and includes a
drive gear designed to
29 mesh with the spur gear on the rotatable segment of the pipe lathe. A tool
block for supporting a
cutting tool is mounted to the rotatable segment and is designed such that a
cutting tool is
31 advanced in small incremental steps in a radial direction against the pipe
to be machined upon
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I each orbit of the ring gear about the work piece. Various other examples of
clamshell cutting
2 apparatus are known in the art.
3 [0015] As discussed above, clamshell type cutting apparatus are known for
the purpose of
4 completely or partially effecting a circumferential cut in a pipe. However,
with the present
invention, a method is provided wherein known clamshell cutting apparatus are
used for the
6 purpose of cutting the bolts and/or nuts used in a flange joint.
7 [0016] More specifically, Figure 2 illustrates the flange joint of Figure 1
wherein nuts 32 on
8 one side of the joint have been slightly loosened in order to expose a
portion of the underlying
9 bolts 30. A clamshell apparatus, generally indicated at 34 is positioned
over the joint between
the two flanges. The apparatus includes a stationary ring 36 and a rotating
ring 38. The rotating
11 ring 38 is provided with one or more cutting tools 40 comprising a blade.
As known in the art
12 and as described in the aforementioned US patents, the rotating ring 38 is
driven by a motor (not
13 shown) and is caused to rotate about the circumference of the flanges 20
and 22. In accordance
14 with the standard operation of the apparatus 34, as the ring 38 is rotated,
the cutting tools 40 are
gradually advanced radially inwardly until they begin contacting the bolts 30.
Such
16 advancement of the cutting tools 40 is continued gradually until the bolts
30 are sheared.
17 Following this, the flanges are separated.
18 [0017] In some situations the loosening of the nuts 32 as described above
is not possible. In
19 such case, the clamshell apparatus discussed above may be used to shear
both the nut and the
bolt. Such a situation is illustrated in Figure 3, where like elements are
identified with like
21 reference numerals. As illustrated, the nuts 32 are not separated from the
respective flange face.
22 The clamshell apparatus is positioned similarly to that shown in Figure 2
but, in this case, the
23 cutting tools 40 are positioned so as to first contact the nuts 32. The
apparatus is operated in the
24 same manner as described above and advancement of the cutting tools 40
first results in shearing
of the nuts 32 followed by shearing of the bolts 30 as the tools 40 are
continually advanced.
26 [0018] In the description provided above, it has been assumed that the
bolts are provided
27 with nuts on both ends thereof. It will be appreciated that it is common
for one set of nuts to be
28 integral with the bolts or welded (or otherwise attached) thereto. In such
case, only one set of
29 nuts would be rotatable or removable.
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1 [0019] In a further embodiment, one of the flanges may be provided with a
threaded bolthole
2 to receive and engage a bolt. In such case, it will be understood that no
nuts may be required and
3 that the bolts are screwed into the threaded boltholes instead.
4 [00201 A further embodiment of the invention is illustrated in Figure 4,
which depicts a
"raised face flange". As will be known to persons skilled in the art, a raised
face flange
6 generally comprises the same shape as the flanges discussed above. However,
a raised face
7 flange includes a step portion forming the raised face. A shown in Figure 4,
flanges 42 and 44
8 are generally as described above. However, the faces of the flanges, 46 and
48, respectively,
9 include raised portions 50 and 52, respectively. When arranged to form a
joint, as shown in
Figure 4, the raised portions 50 and 52 are brought into contact and bolts 54
are inserted through
11 aligned boltholes 56a and 56b in each of the flanges 46 and 48. As shown,
the bolts 54 may
12 include integral nut portions 58 and opposite threaded portions 60. Nuts 62
are then provided on
13 the threaded portions 60 and tightened to force the flanges against each
other. As shown in
14 Figure 4, once joined together, the flange faces 46 and 48 are separated by
a gap 64 due to the
presence of the raised faces discussed above. The gap 64 exposes a section of
the bolts 54. The
16 gap may be wider if a gasket, such as that shown at 66 is provided.
According to the method of
17 the present invention, a clam shell cutting apparatus may be provided on
the joint shown in
18 Figure 4 with the cutting too] positioned over the gap 64. As will be
understood, the cutting tool
19 in this example is advanced and serves to cut the exposed section of the
bolts 54. It will also be
understood that although Figure 4 illustrates a joint involving two oppositely
oriented raised face
21 flanges, other joints may be possible with only one raised face flange,
with the opposite flange
22 including a flat face as shown in Figures 1 to 3. The size of the cutting
tool used in the
23 embodiments described in Figure 4 will be understood to be dependent upon
the width of the gap
24 64. Such sizing will be apparent to persons skilled in the art.
[0021] The method of the invention can be used or adapted for any of the
embodiments
26 described above and other embodiments that would be known to persons
skilled in the art.
27 [0022] It will be understood that the material chosen for manufacturing the
cutting tools will
28 be of sufficient strength as to withstand the cutting of the bolts and/or
nuts. In addition, it will be
29 understood that the clamshell cutting apparatus will be provided in a
variety of sizes depending
upon the diameter of the flanges. Normally, a certain amount of clearance will
be provided
31 between the outer diameter of the flanges and the inner diameter of the
annuli of the cutting
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I apparatus so as to facilitate positioning of the device. Such sizing
criteria will be apparent to
2 persons skilled in the art.
3
4 [0023] Although the invention has been described with reference to certain
specific
embodiments, various modifications thereof will be apparent to those skilled
in the art without
6 departing from the spirit and scope of the invention as outlined in the
claims appended hereto.
7 The disclosures of all prior art recited herein are incorporated herein by
reference in their
8 entirety.
9
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