METHOD FOR SEPARATING FLANGES
A method for separating two flanges joined by bolts extending through boltholes provided therein comprises the use of a clamshell cutting apparatus having a rotating annulus with at least one cutting tool. The cutting tools are rotated and advanced against the bolts until they are sheared. The flanges are then separated from each other.
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This application claims priority from U.S. application Ser. No. 60/778,415, filed on Mar. 3, 2006, the entire contents of which are incorporated herein by reference.
FIELD OF THE INVENTIONThe present invention relates to an improved method of separating flanges connected 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.
DESCRIPTION OF THE PRIOR ARTThe use of flanges on pipes is well known. Flanges serve to connect the ends of pipes to other pipes, vessels or other such equipment. Generally, a flange includes a stem 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 rim or disc with a plurality of circumferentially spaced boltholes. In connecting, for example, two pipe segments together, the stems of two flanges are first each secured to one end of the respective pipe segments. The segments are then axially advanced towards each other so that the 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 may be provided with threaded portions to receive nuts as is commonly known in the art. The nuts are tightened to join the flanges together. In some cases, the boltholes of the flanges may be provided with threading to engage the bolts.
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 of the flanges. However, it is commonly known that the nuts and/or bolts are subject to corrosion of other such damage and, in the result, removal of the nuts and/or bolts is rendered difficult or impossible. In such cases, the bolts are removed with a cutting torch. As will be 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.
Various devices have been provided in the art for cutting sections of pipe. One such cutting apparatus that has been found to be relatively efficient is known in the art as a “clamshell” pipe cutter or pipe lathe. Examples of clamshell cutters are provided in U.S. Pat. Nos. 5,189,933, 5,549,024 and 7,000,510, the entire contents of which are incorporated herein by reference. In general, a clamshell apparatus includes two concentric annular rings that are adapted to circumferentially surround the pipe to be cut. In such apparatus, one of the rings is stationary and is secured to the outer wall of the pipe. The other of the rings is capable of being rotated circumferentially about the pipe. The rotating ring is provided with a cutting tool that is adapted to be gradually advanced against the pipe outer 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 cutting tool progresses until the cutting tool cuts through the pipe wall. Although clamshell devices are well designed for cutting pipes, they are not used for separation of flanges from each other.
SUMMARY OF THE INVENTIONIn one aspect, the present invention provides a method of separating a joint formed by two flanges, the flanges being connected together by means of bolts extending through boltholes provided on each of the flanges, the method comprising:
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- 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 flanges, wherein the annulus includes at least one cutting tool on the inner diameter, the cutting tool being directed radially inwardly and wherein the cutting tools are moveable radially inwardly;
- positioning the cutting apparatus circumferentially over the joint and over the flanges;
- positioning the cutting apparatus whereby the cutting tool is positioned adjacent the bolts;
- rotating the annulus circumferentially about the joint;
- advancing the cutting tool radially inwardly until the bolts are sheared; and
- separating the flanges.
These and other features of the invention will become more apparent in the following detailed description in which reference is made to the appended drawings wherein:
As discussed above, when separation of a flange joint is desired, the nuts 32 are removed so as to allow the bolts 30 to be removed. The flanges can then be separated. However, as also discussed above, it is often found that either the nuts 32 or bolts 30 are either 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.
As mentioned above, examples of clamshell pipe cutters are provided in U.S. Pat. Nos. 5,189,933, 5,549,024 and 7,000,510. The tools described in these references generally comprise first and second semi-circular segments that are designed to be joined together to form 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 affixed to the stationary ring. The rotatable ring includes a spur gear on its outer peripheral surface and is journaled to the stationary ring for rotation about a concentrically disposed pipe or work piece. A motor is attached to the stationary assembly and includes a drive gear designed to 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 advanced in small incremental steps in a radial direction against the pipe to be machined upon each orbit of the ring gear about the work piece. Various other examples of clamshell cutting apparatus are known in the art.
As discussed above, clamshell type cutting apparatus are known for the purpose of 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 purpose of cutting the bolts and/or nuts used in a flange joint.
More specifically,
In some situations the loosening of the nuts 32 as described above is not possible. In such case, the clamshell apparatus discussed above may be used to shear both the nut and the bolt. Such a situation is illustrated in
In the description provided above, it has been assumed that the bolts are provided with nuts on both ends thereof. It will be appreciated that it is common for one set of nuts to be integral with the bolts or welded (or otherwise attached) thereto. In such case, only one set of nuts would be rotatable or removable.
In a further embodiment, one of the flanges may be provided with a threaded bolthole to receive and engage a bolt. In such case, it will be understood that no nuts may be required and that the bolts are screwed into the threaded boltholes instead.
A further embodiment of the invention is illustrated in
The method of the invention can be used or adapted for any of the embodiments described above and other embodiments that would be known to persons skilled in the art.
It will be understood that the material chosen for manufacturing the cutting tools will be of sufficient strength as to withstand the cutting of the bolts and/or nut. In addition, it will be 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 between the outer diameter of the flanges and the inner diameter of the annuli of the cutting apparatus so as to facilitate positioning of the device. Such sizing criteria will be apparent to persons skilled in the art.
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 departing from the spirit and scope of the invention as outlined in the claims appended hereto. The disclosure of all prior art recited herein are incorporated herein by reference in their entirety.
Claims
1. A method of separating a joint formed by two flanges, said flanges being connected together by means of bolts extending through boltholes provided on each of the flanges, the method comprising:
- providing a cutting apparatus proximal to said joint, the cutting apparatus having a rotating annulus, the annulus having an inner diameter greater than the outer diameter of the flanges, wherein the annulus includes at least one cutting tool on said inner diameter, said cutting tool being directed radially inwardly and wherein said cutting tools are moveable radially inwardly;
- positioning said cutting apparatus circumferentially over said joint and over said flanges;
- positioning said cutting apparatus whereby said cutting tool is positioned adjacent said bolts;
- rotating said annulus circumferentially about said joint;
- advancing said cutting tool radially inwardly until said bolts are sheared; and
- separating said flanges.
2. The method of claim 1 wherein said cutting tool is first advanced against nuts provided over said bolts.
3. The method of claim 1 wherein said cutting apparatus comprises a clamshell cutting apparatus.
Type: Application
Filed: Mar 2, 2007
Publication Date: Jan 17, 2008
Applicant: CAR-BER INVESTMENTS, INC. (Point Edward)
Inventors: Glenn Carson (Point Edward), Thomas Lannan (Baytown, TX)
Application Number: 11/681,566
International Classification: B21D 39/04 (20060101);