The present application is directed to tubular connections and, more particularly, to a tubular connection having a helical torque shoulder arrangement.
The Oil & Gas upstream production industry drills wells of ever increasing depth and complexity to find and produce raw hydrocarbons. The industry routinely uses steel pipe (Oil Country Tubular Goods) to protect the borehole (casing) and to control the fluids produced therein (tubing). Casing and tubing are made and transported in relatively short lengths and installed in the borehole one length at a time, each length being connected to the next. As the search for oil and gas has driven companies to drill deeper and more difficult wells, the demands on the casing and tubing have grown proportionately greater in terms of both tensile and pressure forces. The developing technology of deviated and horizontal wells have exacerbated this trend, adding to the casing and tubing requirements a further consideration of increasing torsional loads.
Two general classes of connectors exist within this field. The most common is the threaded and coupled connector, wherein two pin, or male threads, which are machined on the ends of two long joints of pipe, are joined by two box, or female threads, machined on a relatively short member, a coupling, with a larger outside diameter than the pipe, and approximately the same inside diameter. The other class is the integral connector, wherein the pin member is threaded onto one end of a full-length joint of pipe and the box member is threaded into the second full-length joint. The two joints can then be directly joined without the need for an intermediate coupling member. The ends of the pipe body may be processed further to facilitate the threading of the connection.
A thread profile is generally defined by a thread root, a thread crest, a stab flank, and a load flank as generally shown in
A number of advancements over the years have given rise to “premium” connections. One can generally characterize these connections, compared to the connections specified by API (American Petroleum Institute) and other like organizations, in that they feature: 1), more sophisticated thread profiles; 2), one or more metal-to-metal sealing surfaces; and 3), one or more torque shoulders. The torque shoulder(s) are a mechanism used to geometrically position the metal seal(s) and to react against the threads to resist externally applied torque, while maintaining relatively low circumferential stress within the threaded section(s) of the connection. The torque resistance is a function of the torque shoulder area.
Another type of thread system that has been used in this field is known as a “wedge” thread, which is formed by a system of dovetail threads of varying width or varying pitch. This type of thread arrangement allows threads to easily be engaged and assembled, and yet to develop positive interference between opposing flanks of the thread in the fully assembled position. The wedge thread generally has a greater torque resistance than other premium threaded connections. The “wedge thread” has certain disadvantages, the principal one being that it is far more difficult to manufacture and measure than a thread with only a single pitch. Manufacturing a wedge thread on a taper further increases the difficulty of both the threading process and the measurement process.
What is needed by the drillers and producers of deep, high-pressure, hot, and/or deviated oil and gas wells is a threaded connection that has high-torque characteristics with relative ease of machining and production cost.
In one aspect, a method of joining tubular length of oil country tubular casing or piping involves the steps of: utilizing a first tubular member having an associated pin member with a first thread structure and a first helical torque shoulder spaced axially along the pin member from the first thread structure; utilizing a second tubular member having an associated box member with a second thread structure and a second helical torque shoulder spaced axially along the box member from the second thread structure; engaging the pin member and box member with each other into a stab position that is defined by interaction of the first thread structure and the second thread structure, in the stab position the first helical torque shoulder does not contact or axially overlap with the second helical torque shoulder; rotating at least one of the first tubular member or the second tubular member such that interaction between the first thread structure and the second thread structure guides the first helical torque shoulder into cooperating alignment with the second helical torque shoulder; and continuing rotation of at least one of the first tubular member or the second tubular member until the first helical torque shoulder fully engages with the second helical torque shoulder.
In another aspect, a tubular connection includes a pin member and a box member. The pin member has a first thread structure and a helical torque shoulder spaced axially along the pin member from the first thread structure. The box member has a second thread structure and a second helical torque shoulder spaced axially along the box member from the second thread structure. The first thread structure and the second thread structure are sized and located to control a stab position of the tubular connection, and in the stab position the first helical torque shoulder does not engage or axially overlap with the second helical torque shoulder.
In one example, the first thread structure and the second thread structure may be respective tapered constant pitch threads and the first and second helical torque shoulder may be formed by respective non-tapered structures.
The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.
Various aspects and attendant advantages of one or more exemplary embodiments and modifications thereto will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:
The current tubular connection provides a helical torque shoulder arrangement.
In the primary embodiment, the conventional circumferentially extending torque shoulder (e.g., the shoulder normally found at the pin-nose to box-base of a threaded and coupled premium connection, or a center shoulder) is supplemented or supplanted by a helically extending torque shoulder.
As aforementioned, most “premium” connections, per the schematic partial pin 10 and box 12 connection shown in
The conventional torque shoulder normally found at the pin-nose to box-base interface of a threaded and coupled premium connection is a cylindrical shoulder surface as represented in
Once the load flanks of the threads are engaged, any increasing additional externally applied moment causes a reaction between the load flanks of the thread and the metal to metal seal forcing the first member into the second along the path defined by the thread geometry, and further engaging the metal seals, overcoming the resistance of the seals interfering fit. Once the torque shoulder surface 18A of the first member contacts the torque shoulder surface 18B of the second member, further rotation is not possible. The contact between each members torque shoulders resists further circumferential movement.
If the external moment is sufficiently large, and the bearing and shear capacity of the threads sufficiently large, the torque shoulder(s) themselves will yield, the force reacting between the shoulders of each member becoming greater than the shear or bearing capacity of the shoulder.
The present disclosure is directed to a solution to increase the torque resistance of a connection by increasing the surface area of the torque shoulder, as contact stress is directly proportional to force and inversely proportional to area. For a given pipe wall thickness, the threads must utilize a certain percentage of the radial depth of thickness of the wall section to generate the required bearing and shear area necessary for the threads to transmit the pipe load. The actual percentage of cross-sectional area is a function of thread geometry: thread pitch, thread height, and thread taper. The remaining portion of the radial depth or thickness of the wall section may be used for metal-to metal sealing surfaces and the torque shoulder.
Cold forming the pin nose to reduce the internal diameter of the pin member enables the designer to increase the torque shoulder surface area, but has limitations. One of the most important requirements of Oil Country Tubular Goods is the “drift diameter”, the largest cylinder of a specified diameter and length that will pass through the assembled tubes and connections. Drift diameter is only slightly smaller than the nominal inside diameter of the pipe body. Hence the pin can only be formed a small amount, limiting the increase in shoulder surface area to a small amount.
In the embodiments illustrated in
In the embodiments illustrated, the helical torque shoulder is in the nature of a trapezoidal “Flank-to-Flank” design. As seen in
The flank surfaces, machined on a mild angle measured from the perpendicular to the longitudinal axis of the pipe body, allow further rotation of the connection driven by the externally applied moment. As the flank surfaces are driven further together, the normal force between the flank surfaces increases, and the resulting increased force of friction resists the externally applied moment; i.e., it requires a greater moment, torque, to continue to drive the two members together.
As the members are fully assembled, the helical torques shoulder form ends and the two cylindrical torque shoulder surfaces engage, greatly increasing the assembly torque requirements. Furthermore, once the engaging member is arrested by the perpendicular, cylindrical shoulder, any increasing externally applied moment continues to force a larger and larger reaction between the load flanks of the helical torque shoulder surfaces and the cylindrical shoulder surfaces.
The reaction between the load flanks of the pin and the load flanks of the box results in a compressive force acting on the pin member as the load flanks of the box force the load flanks and the entire pin member into the box member. The reaction between the load flanks of the box and the load flanks of the pin results in a tension force acting on the box member as the load flanks of the pin force the load flanks and the entire box member away from the cylindrical torque shoulder.
As the forces increase driven by the increasing external moment, Poisson's effect drives both the pin and box members: diametrically increasing the circumference of the pin, which is in compression; diametrically decreasing the circumference of the box, which is in tension. This reaction initiates at the cylindrical shoulder surfaces and transfers back the connection, starting with the helical torque shoulder. Poison's effect locks the helical surfaces, starting immediately at the intersection of the cylindrical torque shoulder and working through the helical torque shoulders in the direction of the threads. This locking mechanism enables both flanks of the helical torque shoulder to increase the effective area of the combined torque shoulder.
This embodiment of the invention offers a number of advantages.
The helical torque shoulder requires only a few helically machined surfaces.
The surfaces are similar to thread form, albeit with different function, and can be machined in similar manner to threads.
The helical torque shoulder of the illustrated embodiment is machined on a cylindrical path, parallel to the pipe body longitudinal axis, further simplifying both machining and measuring the surfaces. However, in other embodiments the helical torque shoulder could be machined on a tapered path.
The engaged surface area may be enlarged by either changing the form (e.g., for thicker-walled tubes, the height of the surfaces may be increased, or the pitch varied).
Other embodiments of this invention may offer additional or complementary advantages. For example, the above description described trapezoidal formed surfaces with a mild angle to the perpendicular to the axis of the tube. Even a mild angle will generate some radial forces. These radial forces will tend to force the two members apart, with the most detrimental effect upon the member with the thinner cross-section; in the embodiment illustrated the pin. An alternate embodiment may use helical surfaces of square or rectangular shape, with the angle between flank surfaces and the perpendicular to the longitudinal pipe axis at or near zero.
Other embodiments may use a more complex form, with some flanks having negative angles, or dovetail angles. The illustrated helical torque shoulder follows a cylindrical profile relative to the axis of the connection, and therefore does not require an axial engagement clearance as make-up thread forms used in oilfield casing or tubing applications do. Threaded connections must have the characteristic of being able to be assembled on a drilling rig. This requires some “stabbing” depth to stabilize the length of pipe hanging in the derrick whilst the rig workers initialize contact between the two members and rotate them together. The primary threads 14 in this connection perform that function, whilst the helical torque shoulder need only be optimized to react to the externally applied moment, the “make-up” torque. Thus, in the contemplated connection the helical torque shoulder surfaces will not be engaged or axially overlapped when the two members are in the stab position defined by the primary threads that control the make-up operation. Only after relative rotation of one member causes axial movement of the members together will the helical shoulder surfaces begin to axially overlap and move into each other.
Other embodiments may actually use a variable width form of square, near-square, or dovetail design, in which the flank contact may be enhanced by the wedging mechanisms of the aforementioned wedge thread. Increased torque capacity is a function of the increased surface contact area of both flanks of the tooth and groove pairs within the wedged torque shoulder. This value can be optimized based upon available section height and the assembly rotations of the principal driver threads (the conventional threads located elsewhere in the connection). By way of example,
Torque capacity is also enhanced by any conventional torque shoulder that may exist within the threaded connection, and should work in conjunction with the helical torque shoulder described above. A conventional torque shoulder may be an extension of the helical torque shoulder or be located independently of it, elsewhere within the connection.
Premium connections have shoulders in different locations, and in some cases, multiple shoulders. The primary locations are:
Pin-Nose/Box-Base, intersecting the inside diameter of the connection (the example given herein).
Pin-Base/Box-Face; i.e., intersecting the outside diameter of the connection.
The middle-wall section of the connection, the “center shoulder” (e.g., per shoulder location shown in U.S. Pat. No. 5,415,442, which is incorporated herein by reference).
One skilled in the art will recognize that the concept of a helical torque shoulder can be utilized in any and all of these shoulder configurations, with appropriate modifications.
Although a metal seal may or may not be present within the threaded connection, a configuration utilizing a metal-to-metal seal between the helical torque shoulder and conventional threads will have an additional advantage over a conventional premium connection in that the helical torque shoulder will isolate the metal-to-metal seal from the compressive loading experienced by the pin member.
Metal seals are formed by interferingly fitting two smooth metal surfaces together. During compressive loading, the metal seal, particularly of the pin member, may be deformed because of excessive compressive loading. Because of the contact pressure produced by the interference fit, the two surfaces try to separate. Although conventional designs use techniques to keep the two surfaces together, analysis shows some degree of separation and resultant loss of contact pressure. The helical torque shoulder will isolate the seal surfaces from the effect of axial loads and produce a more stable and consistent metal seal under a variety of loading conditions.
The helical torque shoulder structures described herein provide a torque shoulder surface that extends through more than 360 degrees and, preferably through more than 720 degrees. When following the helical shoulder surface at a given radial distance from the central longitudinal axis, the resulting track will not lie within a plane substantially perpendicular to the longitudinal axis of the pipe or connection body, or even a narrow extent as suggested in
In one implementation, an axial length LHTS of the helical torque shoulder may be 30% or less of the overall length L of the connection, while length of LPT the primary thread may be about 50% or more (e.g., 60% or more) of the overall length L of the connection, it being understood that the length L of the connection is defined as axial distance between (i) the shoulder, metal to metal seal or thread located furthest toward one end of the connection and (ii) the shoulder, metal to metal seal or thread located furthest toward an opposite end of the connection).
In one implementation, the axial length LHTS of the helical torque shoulder may be between about 15% and 45% of the axial length LPT of the primary thread.
In one implementation, the helical torque shoulder extends through no more than four turns, while the primary thread form extends through at least ten turns.
In an embodiment, the helical torque shoulder can be configured in combination with a conventional (cylindrical) torque shoulder to create a high-torque optimized hybrid helical and cylindrical torque shoulder (“high-torque hybrid torque shoulder”). In this embodiment, the helical torque shoulder portion of the high-torque hybrid torque shoulder are configured such that, if the cylindrical torque shoulder engages during make-up, such engagement will preferably occur after yielding of the helical torque shoulder has begun, but no later than 0.5 turns after that point. This allows the hybrid torque shoulder to optimally distribute stress between the helical torque shoulder and cylindrical torque shoulder sub-structures of the hybrid torque shoulder. Yielding includes plastic deformation of the helical torque shoulder threads and can be identified by a decrease in slope in a torque vs. turn make-up plot, such as those shown in
A lead is an axial advance of a helical thread during one complete turn. In a typical connection, the lead of the pin member will generally match the lead of the box member. The present invention, however, differs from a typical connection in a number of ways, including the use of both a constant pitch tapered thread and a variable pitch helical torque shoulder. Through testing of this design, it has been determined that one of either the load flank lead or the stab flank lead of the helical torque shoulder should preferably be configured to be substantially equal to the constant pitch thread lead.
Generally, it is preferred that interference is built on the stab flank side of the helical torque shoulder, rather than on the load flank side. By building interference against the stab flank side of the connection, reactionary forces are created against the load flanks of the constant pitch threads. If the reactionary forces were not in this direction, unloading and shifting of the load would occur to the stab flank, thereby creating a non-preferred stress distribution in the connection. Further, by building reactionary forces on the stab flank side, connection tightness is maintained.
One method of ensuring the matching of lead between the pin and the box members is by keeping the axial distance from a given load flank of the helical torque shoulder to a given load flank of the constant pitch threads substantially an interval of the lead of the constant pitch threads.
In an embodiment, the helical torque shoulder section threads are configured such that the interference generated between the thread root and thread crest from the respective box and pin members occurs, if at all, no earlier than 0.5 turns before the point at which the connection reaches its yield torque. Those of ordinary skill in the art are aware that any particular connection will have a designated yield torque. Until that time, a preferred configuration would build substantially no or very little interference between the root and crest of the helical torque shoulder. It should be noted that some of the limited interference that may occur can be due to variations in the manufacturing process such that small structural differences can result in some unintended interference occurring. Generally though, the configuration of the preferred embodiment would result in substantially no interference until within 0.5 turns of yield torque. By configuring the helical torque shoulder threads in this manner, galling between the threads can be minimized during make-up. During make-up the opposing seals and opposing tapered constant pitch threads will still experience interference during make-up as in a typical torque shoulder connection. This configuration allows for overall maximum torque load of the helical torque shoulder connection while maintaining connection integrity and robustness.
The make-up timing of the various parts of the high-torque hybrid torque shoulder connection can have a distinct effect on the overall torque handling capabilities of the connection. In an embodiment, and as illustrated in
It is to be clearly understood that the above description is intended by way of illustration and example only, is not intended to be taken by way of limitation, and that other changes and modifications are possible. For example, while tapered constant pitch threads of the type used in premium connections (e.g., per the ULTRA-DQX, ULTRA-FJ, ULTRA-QX and ULTRA-SF connections available from Ultra Premium Oilfield Products of Houston, Tex.) are primarily described in conjunction with the helical torque shoulder threads, other types of thread structures could be used in place of the premium connection threads, such as API Round threads, API Buttress threads or others.
This application is a continuation-in-part of U.S. patent application Ser. No. 13/798,330 which claims the benefit of U.S. Provisional Application Ser. No. 61/730,720, filed Nov. 28, 2012, both of which are herein incorporated by reference.
Number | Name | Date | Kind |
---|---|---|---|
1927656 | Eaton et al. | Sep 1933 | A |
2006520 | Stone et al. | Jul 1935 | A |
2204754 | Frame | Jun 1940 | A |
2211179 | Stone | Aug 1940 | A |
2259232 | Stone | Oct 1941 | A |
2772102 | Webb | Nov 1956 | A |
2893759 | Blose | Jul 1959 | A |
2907589 | Knox | Oct 1959 | A |
3224799 | Blose et al. | Dec 1965 | A |
3336054 | Blount | Aug 1967 | A |
3359013 | Knox et al. | Dec 1967 | A |
3489438 | McClure | Jan 1970 | A |
3856337 | Ehm et al. | Dec 1974 | A |
3870351 | Matsuki | Mar 1975 | A |
3989284 | Blose | Nov 1976 | A |
4009893 | Schatton et al. | Mar 1977 | A |
4121862 | Greer | Oct 1978 | A |
4161332 | Blose | Jul 1979 | A |
4192533 | Blose | Mar 1980 | A |
4244607 | Blose | Jan 1981 | A |
4253687 | Maples | Mar 1981 | A |
4330142 | Paini | May 1982 | A |
4384737 | Reusser | May 1983 | A |
4398756 | Duret et al. | Aug 1983 | A |
4444421 | Ahlstone | Apr 1984 | A |
4494777 | Duret | Jan 1985 | A |
4508375 | Patterson et al. | Apr 1985 | A |
4538840 | DeLange | Sep 1985 | A |
4570892 | Czech et al. | Feb 1986 | A |
4577895 | Castille | Mar 1986 | A |
4600224 | Blose | Jul 1986 | A |
4603889 | Welsh | Aug 1986 | A |
4611838 | Heilmann et al. | Sep 1986 | A |
4629221 | Lumsden et al. | Dec 1986 | A |
4629224 | Landriault | Dec 1986 | A |
4662659 | Blose et al. | May 1987 | A |
4688832 | Ortloff et al. | Aug 1987 | A |
4707001 | Johnson | Nov 1987 | A |
4712815 | Reeves | Dec 1987 | A |
4728129 | Morris | Mar 1988 | A |
4730857 | Schwind | Mar 1988 | A |
4753460 | Tung | Jun 1988 | A |
4822081 | Blose | Apr 1989 | A |
4915426 | Skipper | Apr 1990 | A |
4917409 | Reeves | Apr 1990 | A |
4928999 | Landriault | May 1990 | A |
4944538 | Read | Jul 1990 | A |
4958862 | Cappelli et al. | Sep 1990 | A |
4962579 | Moyer et al. | Oct 1990 | A |
5066052 | Read | Nov 1991 | A |
5092635 | DeLange et al. | Mar 1992 | A |
5154452 | Johnson | Oct 1992 | A |
5236230 | Mudge, Jr. et al. | Aug 1993 | A |
5330239 | Blose et al. | Jul 1994 | A |
5338074 | Barringr et al. | Aug 1994 | A |
5348350 | Blose et al. | Sep 1994 | A |
5360240 | Mott | Nov 1994 | A |
5415442 | Klementich | May 1995 | A |
5427418 | Watts | Jun 1995 | A |
5454605 | Mott | Oct 1995 | A |
5462315 | Klementich | Oct 1995 | A |
5468029 | Blose et al. | Nov 1995 | A |
5492375 | Smith | Feb 1996 | A |
5498035 | Blose et al. | Mar 1996 | A |
5516158 | Watts | May 1996 | A |
5549336 | Hori et al. | Aug 1996 | A |
5709416 | Wood | Jan 1998 | A |
5765836 | Banker et al. | Jun 1998 | A |
5826921 | Woolley | Oct 1998 | A |
5829797 | Yamamoto et al. | Nov 1998 | A |
6010163 | Cerruti | Jan 2000 | A |
6024646 | Reed et al. | Feb 2000 | A |
6041487 | Banker et al. | Mar 2000 | A |
6045165 | Sugino et al. | Apr 2000 | A |
6158785 | Beaulier et al. | Dec 2000 | A |
6174001 | Enderle | Jan 2001 | B1 |
6206436 | Mallis | Mar 2001 | B1 |
6237967 | Yamamoto et al. | May 2001 | B1 |
6254146 | Church | Jul 2001 | B1 |
6270127 | Enderle | Aug 2001 | B1 |
6322110 | Banker | Nov 2001 | B1 |
6347814 | Cerruti | Feb 2002 | B1 |
6412831 | Noel et al. | Jul 2002 | B1 |
6478344 | Pallini, Jr. et al. | Nov 2002 | B2 |
6481760 | Noel | Nov 2002 | B1 |
6494499 | Galle, Sr. | Dec 2002 | B1 |
6550821 | DeLange et al. | Apr 2003 | B2 |
6578880 | Watts | Jun 2003 | B2 |
6581980 | DeLange et al. | Jun 2003 | B1 |
6619696 | Baugh et al. | Sep 2003 | B2 |
6622797 | Sivley, IV | Sep 2003 | B2 |
6626471 | Mallis | Sep 2003 | B2 |
6722706 | Church | Apr 2004 | B2 |
6764108 | Ernst et al. | Jul 2004 | B2 |
6832789 | Church | Dec 2004 | B2 |
6848724 | Kessler | Feb 2005 | B2 |
6877202 | Maeda | Apr 2005 | B2 |
6905149 | DeLange et al. | Jun 2005 | B2 |
7156676 | Reynolds, Jr. | Jan 2007 | B2 |
7243957 | Reynolds, Jr. | Jul 2007 | B2 |
7331614 | Noel et al. | Feb 2008 | B2 |
7334821 | Dutilleul et al. | Feb 2008 | B2 |
7350830 | DeLange et al. | Apr 2008 | B1 |
7380840 | Sivley, IV | Jun 2008 | B2 |
7431347 | Ernst et al. | Oct 2008 | B2 |
7438329 | DeLange et al. | Oct 2008 | B2 |
7458616 | Reynolds, Jr. | Dec 2008 | B2 |
7464612 | Manella et al. | Dec 2008 | B2 |
7475917 | Sivley, IV et al. | Jan 2009 | B2 |
7494159 | Sugino et al. | Feb 2009 | B2 |
7500698 | Reynolds, Jr. | Mar 2009 | B2 |
7527304 | Mallis et al. | May 2009 | B2 |
7562911 | Reynolds, Jr. et al. | Jul 2009 | B2 |
7575255 | Reynolds, Jr. et al. | Aug 2009 | B2 |
7578039 | Reynolds, Jr. et al. | Aug 2009 | B2 |
7588269 | Church | Sep 2009 | B2 |
7607333 | Sivley, IV et al. | Oct 2009 | B2 |
7686350 | Reynolds, Jr. et al. | Mar 2010 | B2 |
7690696 | Mallis et al. | Apr 2010 | B2 |
7690697 | Church | Apr 2010 | B2 |
7717478 | Reynolds, Jr. | May 2010 | B2 |
7780202 | Breihan et al. | Aug 2010 | B2 |
7784551 | Angman et al. | Aug 2010 | B2 |
7810849 | Reynolds, Jr. | Oct 2010 | B2 |
7828337 | Reynolds, Jr. | Nov 2010 | B2 |
7837210 | Kylstra et al. | Nov 2010 | B2 |
7850211 | Reynolds, Jr. et al. | Dec 2010 | B2 |
7942454 | Reynolds, Jr. | May 2011 | B2 |
7988205 | Mallis et al. | Aug 2011 | B2 |
8079623 | Pallini, Jr. et al. | Dec 2011 | B2 |
8562771 | Ribalta et al. | Oct 2013 | B2 |
8668233 | Mallis et al. | Mar 2014 | B2 |
8673828 | Pinel et al. | Mar 2014 | B2 |
8714243 | DeLange et al. | May 2014 | B2 |
20030122378 | Nagasaku | Jul 2003 | A1 |
20030168858 | Hashem | Sep 2003 | A1 |
20040090068 | Evans | May 2004 | A1 |
20040262919 | Dutilleul | Dec 2004 | A1 |
20060006648 | Grimmett | Jan 2006 | A1 |
20070236015 | Sugino | Oct 2007 | A1 |
20120043756 | Elder | Feb 2012 | A1 |
Number | Date | Country |
---|---|---|
2438387 | Feb 1976 | DE |
1130913 | Oct 1956 | FR |
1173471 | Dec 1969 | GB |
2161563 | Jan 1986 | GB |
215749 | Dec 2009 | PL |
500468 | Nov 1976 | SU |
8404352 | Nov 1984 | WO |
9215815 | Sep 1992 | WO |
02056778 | Jul 2002 | WO |
2007114460 | Oct 2007 | WO |
Entry |
---|
International Search Report; mailed Apr. 21, 2014; PCT US 2013/071652; Filed Nov. 25, 2013; 2 pages. |
Written Opinion; mailed Apr. 21, 2014; PCT US 2013/071652; filed Nov. 25, 2013; 7 pages. |
Poland Patent Office; Appn No. P.412632, Office Action dated Jan. 20, 2016 and English Translation. |
Number | Date | Country | |
---|---|---|---|
20160160575 A1 | Jun 2016 | US |
Number | Date | Country | |
---|---|---|---|
61730720 | Nov 2012 | US |
Number | Date | Country | |
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Parent | 13798330 | Mar 2013 | US |
Child | 15047165 | US |