Claims:We Claim:
1. An improved method (100) of induction heating for carrying out post-weld heat treatment (PWHT) of welds made in high wall thickness pipes, the method comprising
- winding (101) a pattern of a flexible induction heating coil (4) around the pipe weld; and
- providing (102) a multiple turns around the pipe spanning across the weld that an inter-turn spacing is at least (2 x D) in a plurality of clock locations on the outer surface of the pipe weld and inter-turn spacing is zero in a plurality of yet another set of clock locations with the former and latter locations occurring alternately and in equal numbers.

2. The method as claimed in claim 1, wherein ‘D’ is referring to the diameter of the flexible induction heating coil (4).

3. The method as claimed in claim 1, wherein the method is using a dual slope for the heating ramp (10) of the PWHT cycle.

4. The method as claimed in claim 3, wherein heating takes place using the pattern of winding the flexible induction heating coils (4) until a temperature of soaking temperature minus 50° C is reached.

5. The method as claimed in claim 4, wherein the arrangement of flexible induction heating coils (4) is changed from the one stated in claim 1 to the helical pattern at the instant when the temperature of the weld in the outer surface reaches soaking temperature minus 50° C.

6. The method as claimed in claim 5, wherein heating takes place at the rate of 40° C/hour until the designated soaking temperature is reached.

7. The method as claimed in claim 1, wherein at least one feedback thermocouple is taken from outer surface of the pipe at the 12 o clock position (6) or at the 6 o clock position.

8. The method as claimed in claim 1, wherein the inter-turn spacing is varies from (2 x D) at 12 o clock position and 6 o clock position to zero at both the 3 o clock position and 9 o clock position

9. The method as claimed in claim 7, wherein the outputs of thermocouples are connected to a temperature recorder (9) to get a print of the ‘Time (vs) Temperature’ plot of the PWHT cycle.

10. The method as claimed in claim 1, which results in the least possible through thickness temperature gradient in PWHT of the high wall thickness pipe welds.
, Description:IMPROVED METHOD OF INDUCTION HEATING FOR PWHT OF PIPE WELDS WITH LEAST THROUGH-THICKNESS TEMPERATURE GRADIENT
- FIELD OF INVENTION
[0001] The present disclosure, in general, relates to improved method of induction heating for PWHT of pipe welds with least through-thickness temperature gradient. More particularly, the present invention relates to the field of fabrication of piping circuits used in thermal power boiler and discloses a novel method for performing post weld heat treatment (PWHT) of circumferential butt welds made in such piping circuits, with the least possible temperature gradient between the outer radius and inner radius of such pipe welds.
BACKGROUND OF INVENTION
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Many engineering applications call for fabrication of piping components. One important application is found in the thermal power boiler wherein the superheated steam from the boiler outlet is transmitted to the turbine for generation of electricity via a piping circuit comprising many pipe weld joints along the length. This requires high wall thickness pipes to be used for transmission of hot steam without much loss of temperature. Therefore, the chemical composition of materials used in boiler piping applications are so designed that they can withstand continued exposure to such harsh operating environments. The creep strength enhanced ferritic (CSEF) steels are a class of materials that are mainly intended for such high temperature applications. It is quite common to see the boiler piping made out of materials like the ASME SA 335 P91, ASME SA 335 P22, SA 335 P23 etc. When piping unit made of such materials get welded, the heating and cooling cycle associated with welding results in the formation of hard microstructures that have poor toughness and creep life. Hence, after completion of welding, these pipe welds are subjected to PWHT at a specified temperature in order to partially restore the toughness and creep life. Thus, the PWHT is an important process in the building of long piping units especially those that are used for high temperature application.
[0004] The PWHT operation in boiler piping erection sites are commonly performed using induction heating process. In this process, flexible induction heating coils (with ceramic sheathing) are wound around the pipe weld that is required to be heat treated. Then, an alternating current of sufficiently high frequency is allowed to pass through these coils during which, an alternating magnetic field is created around the coils. This field induces eddy currents in the pipe material which produces heating on account of the material’s resistance offered for the flow of eddy current. The manner in which the heat is produced in the pipe weld largely depends on the manner in which the induction heating coils are wound around the weld. In general, the coils are wound helically around the pipe weld and PWHT is performed. But, it is found in many practical cases that such arrangement leads to a finite temperature gradient between the outer surface and inner surface of pipe weld (commonly referred to as the ‘through-thickness temperature gradient’) which gradually rises with time when the temperature is ramped up in the PWHT process. But, many codes specify a mandate that the whole of the weld region (including the face and root of the weld) needs to be held within a narrow band of temperature during soaking stage of the heat treatment process. On account of the above-mentioned through-thickness temperature gradient, many a times, it will not be possible to heat treat the whole of the weld within the code-specified temperature band. This is a major technical conundrum being faced by the boiler industry. The present invention proposes to offer a solution by developing a novel method of induction heating for such thick-wall pipe weld heat treatment applications, wherein the through-thickness temperature gradient can be effectively controlled within the code-specified temperature bands.
PRIOR ART SEARCH
[0005] The US patent US2511026A specifies a method for controlling the heating rate using an induction heating circuit. This method consists of tuning a load circuit, supplied by a radio frequency generator or oscillator so as to control power being supplied to an inductor by the generator for heating a magnetic article. This arrangement enables reaching temperatures which are normally not attainable only by using an oscillator connected to an ordinary inductor circuit. This is significantly different from the proposed invention because the latter specifies a novel method for minimizing the through-thickness temperature gradient to the fullest possible extent in PWHT of pipe welds performed by induction heating, by employing a special pattern of windings which creates alternately placed intense heating zones and diffuse heating zones, so as to bring about a good uniformity in the temperatures reached across the wall thickness of the pipe being heat treated.
[0006] The WIPO patent WO2016030078A1 describes a special induction heating arrangement for energizing an induction cooking hob, in order to produce an energy efficient heating system. This arrangement consists of two sets of induction heating coils arranged in two different planes. There is a common power supply to these two sets of coils and one among them is energised at a time and the other is disconnected from power supply, based on a selector setting. But, the proposed invention is aimed at providing a novel method of induction heating system for the purpose of PWHT of thick wall pipe welds, with least possible temperature gradient, which is achieved by winding the induction coils following a special pattern.
[0007] The European Patent EP2842724A1 (the US patent US10111283B2) describes a method of indirect heating of CFRP components by heating a first magnetic material which then transfers the heat to the CFRP component. Temperature control is achieved by controlling the current flowing through the inductor. But, the present invention relates to a novel method of producing a uniform temperature (with least through-thickness temperature gradient) across the face and root of a pipe weld subjected to PWHT by induction heating using flexible induction heating coils. The said method employs a special pattern of winding the induction heating coils around the pipe weld so as to achieve the above mentioned objective and hence it is different from the prior art EP2842724A1 wherein the temperature control is achieved by controlling the current flowing the inductor.
[0008] The US patent US10638554B2 provides an induction heating system that includes interchangeable secondary induction heating assemblies and/or secondary induction heating coil flux concentrators that are specifically configured for the particular type of weld being created and/or the particular weld joint where the weld is created, mainly for the purpose of achieving a focussed heating on the work-piece (pipe welds). This prior art specifies a method to create a focussed heating during PWHT of pipe welds, by using a magnetic flux concentrator which focusses all the magnetic flux lines into one region, depending on the configuration of the job and the shape of the flux concentrator, whereas the present invention specifies a method of creating a uniform temperature rise during PWHT of thick wall pipe welds, using induction heating method without the use of such flux concentrators. Instead, the coil winding pattern is modified to achieve heating of pipe with least possible through-thickness temperature gradient and hence significantly different from this prior art.
[0009] Therefore, there is a requirement to develop improved method of induction heating for PWHT of pipe welds with least through-thickness temperature gradient. Hence, the present invention has been introduced.

OBJECTS OF THE INVENTION
[0010] Some of the objects of the present disclosure, which at least one embodiment herein satisfy, are listed herein below.
[0011] It is a general or primary object of the present disclosure to provide improved method of induction heating for PWHT of pipe welds with least through-thickness temperature gradient that results in uniform heating of the pipe weld across its wall thickness.
[0012] Another object of the invention is to provide an improved method of induction heating for PWHT of pipe welds with least through-thickness temperature gradient, which overcomes disadvantages of the prior arts.
[0013] Further object of the invention is to provide arrangement of induction heating coil when wound around the pipe weld, also results in the least possible through-thickness temperature gradient in PWHT of high wall thickness pipe welds performed by induction heating method.
[0014] These and other objects and advantages of the present disclosure will be apparent to those skilled in the art after a consideration of the following detailed description taken in conjunction with the accompanying drawings in which a preferred form of the present disclosure is illustrated.
SUMMARY OF THE INVENTION
[0015] This summary is provided to introduce concepts related to an improved method of induction heating for PWHT of pipe welds with least through-thickness temperature gradient. The concepts are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
[0016] According to this invention, an improved method of carrying out induction heating based PWHT of thick-wall pipe welds is disclosed. The method consists of laying the flexible induction heating coil in a specified manner which creates an efficient heating effect as a result of which the entire pipe weld (from root to face) gets heated uniformly, without significant difference in the temperatures reached at the root of the weld (pipe inner surface) and that at the face of the weld (pipe outer surface).
[0017] Induction heating based PWHT of pipe welds are generally performed using power sources and associated accessories that are specifically designed for this purpose. The induction heating machines designed for such heat treatment purpose are provided with flexible induction heating coil that is required to be wound around the job to be heat treated. Generally, these flexible coils are wound around the pipe weld joint in a helical manner in such a way that the weld region is located in the centre of the span within which the coil is wound. This is referred to as wound length. The thumb rule is that the wound length shall normally be kept in the range of (5 x T) to (10 x T) where ‘T’ is the weld thickness. The number of turns that are present within this wound length is an important factor deciding the heating effect. More the number of turns, greater will be magnetic flux density induced in the pipe material and higher will be eddy current heating effect and vice versa. Firstly, when thickness is known, the wound length can be calculated. The turns shall be wound within this length in such a way that there is a space of at least (1 x D) between any two consecutive turns. The ‘D’ here refers to diameter of the induction heating coil. The intensity of induced eddy current and thus the heat energy is largely dependent on the manner in which the flexible induction coils are wound around the pipe weld.
[0018] In the helical pattern of winding, which is a common practice used by majority of fabricators employing induction heating, there will always be a finite temperature gradient across the wall thickness of the pipe (i.e. the weld thickness) which will keep on increasing during the heating ramp stage. The reason behind the temperature gradient is attributable to the fact that the induction heating produces only a skin heating at the outer surface of the pipe and the rest of the pipe gets heated up by conduction of heat. Thus, the conventional helical pattern of winding cannot be used for high wall thickness pipes which are required to be heat treated in a narrow band of soaking temperature. So, the present invention offers a novel pattern of winding of the induction heating coils which is capable of producing a uniform heating across the wall thickness of pipe. This is described hereinafter.
[0019] Firstly, the flexible induction heating coil is wound around the pipe weld that is required to be post-weld heat treated in the conventional helical pattern of winding. Then, the winding is adjusted in such a way that there is an inter-turn spacing of a minimum of (2 x D) in the 12 o clock position and 6 o clock position and the inter-turn spacing shall gradually reduce down to zero at the 3 o clock and 9 o clock positions. The reduction of inter-turn spacing to zero paves the way for more concentration of magnetic flux in such zones. This in turn leads to generation of more eddy current in such regions/zones. Since the heating effect is directly proportional to the magnitude of eddy current, it makes the heating effect intense at the 3 o clock and 9 o clock positions and rather diffused at 12 o clock and 6 o clock positions. This is because there is more amount of eddy current flowing in the former locations on account of zero inter-turn spacing whereas the eddy current magnitude in latter locations will be lower than that seen in former locations and hence do not experience a lower heating effect. This type of winding pattern thus produces zones of intense heating and diffuse heating alternately along the circumference of the pipe weld’s outer surface. Creation of such alternate zones of intense heating and diffuse heating paves the way for uniform spread of heat along the thickness for 360° of the pipe cross section. This is because the heat flow happens uniformly in both circumferential and radial direction whereas the conventional helical pattern leads to heat flow which happens predominantly in the radial direction only. Such an arrangement of winding of induction heating coils is used until a temperature (T – 50) ° C is reached in the outer surface of the pipe during heating ramp stage of the PWHT process. Here, ‘T’ refers to the designated soaking temperature of the PWHT process. Upon reaching the above said temperature, the modified arrangement of the induction heating coils mentioned above is once again changed back to the conventional helical pattern of winding. Then, the rate of heating of the PWHT process shall be changed to 50° C/hour. The improvement arrangement of induction heating coil along with the procedural steps listed above ensures that there will be:
• A uniform spread of heat along the thickness across the whole cross section of the pipe weld.
• a minimum through thickness temperature gradient which will be less than 20° C in most of the cases. This is sufficient for satisfactory post-weld heat treatment for majority of applications which includes heating treating at temperatures exceeding 950° C.
• The through thickness temperature is normally very hard to be brought within 20° C especially when heat treating materials with very high thermal conductivity. But, the present method is very effective in controlling the through thickness temperature gradient in such materials also. For instance, the authors have experimented this pattern of winding for carrying out heat treatment of welds made in a 130 mm wall thickness pipe weld made of Nickel based alloy. The heat treatment was successfully carried out at a soaking temperature exceeding 950° C and all through the soaking duration which was roughly about 5 hours, it was observed that the temperatures reached in the pipe weld’s outer radius and inner radius could be maintained well within 20° C.
[0020] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0021] The illustrated embodiments of the subject matter will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. The following description is intended only by way of example, and simply illustrates certain selected embodiments of devices, systems, and methods that are consistent with the subject matter as claimed herein, wherein:
[0022] FIG. 1 shows flexible induction heating coils wound around pipe weld joint in the conventional helical pattern of winding;
[0023] Fig. 2 shows a flexible induction heating coils wound around pipe weld joint in the improved pattern of winding, in accordance with an embodiment of the present disclosure;
[0024] Fig. 3 shows position of thermocouples fixed on the pipe weld, in accordance with an embodiment of the present disclosure;
[0025] Fig. 4 shows post weld heat treatment cycle showing heating ramp stage, soaking time and cooling ramp, in accordance with an embodiment of the present disclosure; and
[0026] Fig. 5 shows a flow chart of an improved method of induction heating for PWHT of pipe welds, in accordance with an embodiment of the present disclosure.
[0027] The figures depict embodiments of the present subject matter for illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAIL DESCRIPTION OF INVENTION WITH REFERENCE TO THE DRAWINGS OF THE PREFERRED EMBODIMENTS
[0028] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to convey all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0029] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0030] According to this invention, there is disclosed an improved method of PWHT of thick-wall pipe weld joints using induction heating. When high wall thickness pipes are welded at erection sites, local post weld heat treatment (PWHT) is required to be performed after welding, so as to relieve the residual stresses and temper the microstructure of the weld. The PWHT is performed using specialized induction heating machines designed for carrying out local PWHT of welds.
[0031] Since such induction heating machines are provided with feedback control mechanism, one or two spot(s) on the outer surface of the weld is chosen and thermocouple(s) are fixed there and these thermocouples are then used for providing the feedback signal to the controller of the power source which then accordingly adjusts the current that flows through the flexible induction heating coils. It is to be noted that the intensity of current flowing through the induction coils and the magnetic flux generated therefrom, depends on the number of turns of coil present in a given location. If a larger number of turns are placed in one location of the work-piece (i.e. the pipe weld joint), then more magnetic flux will be generated and consequently greater magnitudes of eddy currents will be induced and thus greater will be intensity of heating realized at that location. Similarly, if there are fewer number of turns of the induction coil, then accordingly, there will be a lesser magnetic flux generated and consequently smaller magnitudes of eddy currents will be induced leading to a less intense heating. Thus, the extent of heating of the pipe material is largely dependent on the pattern of winding of the flexible induction heating coil, over the pipe weld joint.
[0032] Further, the nature of the induction heating is such that appreciable magnitudes of eddy currents are induced only up to a few millimeters of depth on the pipe outer surface. This is called as ‘skin effect’ or ‘skin heating’. Only a thin skin (on the pipe outer surface) is heated up by induction heating process whereas the rest of the pipe thickness is heated up by way of conduction of this heat from the heated skin portion. On account of this heat conduction, there will always be a finite temperature difference between the outer surface of the pipe (which is directly heated by induction heating) and the inner surface of the pipe (which receives heat from the outer surface by way of heat conduction). This is called Through-thickness Temperature Gradient (TTG).
[0033] The figure 1 shows the normal practice of winding the flexible induction heating coils over the pipe weld joint. It is seen in this figure that two pipes (1) and (2) are joined by the weld (3) and the flexible induction heating coil (4) is wound around the pipe, spanning across the weld, in a helical manner, in such a way that the number of turns are symmetrically positioned with respect the weld centerline A-A. The ends of the flexible induction heating coil (5) are connected to the power source that supplies an alternating current at high frequency which is sufficient enough to induce eddy currents in the work-piece (pipe material). In this pattern of winding the flexible induction heating coil (4) around the pipe weld joint (Figure 1), there will exist a finite Through-thickness Temperature Gradient (TTG), as described earlier. Since the power source supplies the current to the flexible induction heating coil (4) based on the value of temperature feedback obtained from the thermocouples fixed on the pipe weld, any requirement of increasing (or) decreasing the heat intensity is possible only by adjusting the pattern of winding the flexible induction heating coil (4). The authors of the present invention experimented with various types of windings patterns of winding the flexible induction heating coil (4) so as to achieve a near-zero TTG. It was found that a specific pattern of winding the flexible induction heating coil has a phenomenal effect in bringing down the TTG to near-zero level. This is described below
[0034] Firstly, the flexible induction heating coil (4) is wound around the pipe weld, with an inter-turn spacing of at least (2 x D), in the conventional helical pattern as shown in figure 1. The term inter-turn spacing refers to distance between one turn and adjacent turn of the flexible induction heating coil (4). The ‘D’ denotes the diameter of the flexible induction heating coil. Then, the pattern of winding of flexible induction heating coil (4) is adjusted as shown in Figure 2. The winding pattern of the flexible induction heating coil (4) is adjusted so that the inter-turn spacing is at least equal to (2 x D) at the 12 o clock position of the pipe weld (marked as (6) in figure 2) and the inter-turn spacing is gradually allowed to vary from (2 x D) to zero at both the 9 o clock position (shown as (7) in figure 2) and 3 o clock position. Then, again the inter-turn spacing is allowed to gradually vary from zero at the 9 o clock and 3 o clock positions back to (2 x D) at the 6 o clock position. The pattern of winding resembles the shape of a venturi-meter. For correctly achieving the inter-turn spacing as mentioned above, the turns of the coil can be taut together using heat resistant ceramic fiber cord (8) as shown in figure 2.
[0035] When using the improved pattern of winding the flexible induction heating coil (4), the scheme of thermocouple (9) placement shall be as shown in figure 3 which shows the cut sectional view of the pipe weld in Figure 1. It is seen from figure 3 that there are two thermocouples placed on the pipe outer surface one each at the 12 o clock position (6) and 6 o clock position. There are two more thermocouples placed at the inner surface of the pipe weld one each at the 3 o clock position (7) and 9 o clock position. The outputs of these thermocouples are connected to a temperature recorder so as to get a print of the ‘Time (vs) Temperature’ plot of the PWHT cycle. In most of the cases, the inner surface of the pipe will not be accessible for placement of thermocouples since the pipes may be of very large length. In such cases, it is enough to place thermocouples only on the outer surface of the pipe as mentioned above. Either of the two thermocouples placed on the outer surface of the pipe weld can be used as a feedback thermocouple for the ramped heating and subsequent soaking of the pipe weld in the PWHT process.
[0036] Once the flexible induction heating coil (4) is wound around the pipe weld joint as shown in Figure 2 and feedback thermocouples are placed as shown in figure 3, then the PWHT process is allowed to run following the cycle as depicted in figure 4. The slope of first heating ramp (10) is calculated using the formula (222/t) where ‘t’ refers to thickness of pipe weld in ‘inches’. With the flexible induction heating coil (4) laid as per the improved pattern shown in figure 2 and as described above, the pipe weld is heated up until a temperature of ‘(T – 50)’ is reached at the pipe outer surface. The value of ‘T’ here refers to the soaking temperature (shown as ‘T’ in figure 4). At this point of time, the heating is paused, the pattern of winding is changed from that shown in figure 2 back to the one shown in figure 1 i.e. pattern of winding is again changed to the helical type. Then, the heating is again continued with a second slope (11) which is less than or equal to 40° C/hour. Then, the pipe weld is allowed to soak at the temperature ‘T’ for the desired duration (12) and the weld is allowed to cool following the cooling ramp (13).
[0037] The above steps result in following advantages
• A uniform heating effect is achieved in the pipe weld across the entire thickness and cross section
• The through-thickness temperature gradient is reduced to the least possible extent and can be brought down to a near-zero level in PWHT applications with soaking temperature less than 800° C and to less than 20° C in PWHT applications with soaking temperature exceeding 950° C.
[0038] The above mentioned method comprising the improved pattern of winding and following a heating ramp with dual slope is ideally suited for PWHT of welds made in high wall thickness pipes.
[0039] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particulars claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances, where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B”.
[0040] The above description does not provide specific details of manufacture or design of the various components. Those of skill in the art are familiar with such details, and unless departures from those techniques are set out, techniques, known, related art or later developed designs and materials should be employed. Those in the art are capable of choosing suitable manufacturing and design details.
[0041] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be combined into other systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.
[0042] The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.
[0043] While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.