Wellhead Hanger Gripping System and Method

This patent application claims benefit of U.S. Provisional Patent Application Ser. No. 63/639,099 filed Apr. 26, 2024, which is entirely incorporated herein by reference.

This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the presently described embodiments. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present embodiments. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

In order to meet consumer and industrial demand for natural resources, companies often invest significant amounts of time and money in finding and extracting oil, natural gas, and other subterranean resources from the earth. Particularly, once a desired subterranean resource such as oil or natural gas is discovered, drilling and production systems are often employed to access and extract the resource. These systems may be located onshore or offshore depending on the location of a desired resource. Further, such systems generally include a wellhead assembly mounted on a well through which the resource is accessed or extracted. These wellhead assemblies may include a wide variety of components, such as various housings, casings, valves, hangers, pumps, fluid conduits, and the like, that facilitate drilling or production operations.

As will be appreciated, various tubular strings can be run into wells through wellhead assemblies. For instance, wells are often lined with casing that generally serves to stabilize the well and to isolate fluids within the wellbore from certain formations penetrated by the well (e.g., to prevent contamination of freshwater reservoirs). Such casing is frequently cemented into place within the well. During a cement job, cement can be pumped down a casing string in a well, out the bottom of the casing string, and then up the annular space surrounding the casing string. The cement is then allowed to set in the annular space. Wells can also include tubing strings that facilitate flow of fluids through the wells. Hangers can be attached to the casing and tubing strings and received within wellheads to enable these tubular strings to be suspended in the wells from the hangers.

Certain aspects of some embodiments disclosed herein are set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of certain forms the invention might take and that these aspects are not intended to limit the scope of the invention. Indeed, the invention may encompass a variety of aspects that may not be set forth below.

Certain embodiments of the present disclosure generally relate to the use of a wellhead clamp to elastically deform a wellhead housing to grip a wellhead hanger or other component positioned within the wellhead housing. The wellhead clamp can provide an inward compression force that elastically deforms the wellhead housing into tight, gripping engagement with a wellhead hanger (or other body) received within the wellhead housing. More particularly, some embodiments relate to assessing the grip on the wellhead hanger based on a change in a wall of the wellhead housing elastically deformed by actuation of the wellhead clamp. In some instances, the change in the wall is a change in strain or thickness of the wall. Assessing the grip on the wellhead hanger can include determining a parameter related to the grip, such as a force or pressure applied to the hanger from the grip, or determining in some other manner whether the grip strength is sufficient to securely hold the wellhead hanger within the wellhead housing. A grip strength measuring device is used to assess gripping integrity of the wall of the wellhead housing against the wellhead hanger in some embodiments. Some examples of such a grip strength measuring device include an ultrasonic meter, an acoustic meter, a capacitive sensor, an eddy current sensor, a depth gauge, and a strain gauge.

Various refinements of the features noted above may exist in relation to various aspects of the present embodiments. Further features may also be incorporated in these various aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. A gain, the brief summary presented above is intended only to familiarize the reader with certain aspects and contexts of some embodiments without limitation to the claimed subject matter.

Specific embodiments of the present disclosure are described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Moreover, any use of “top,” “bottom,” “above,” “below,” other directional terms, and variations of these terms is made for convenience, but does not require any particular orientation of the components.

Turning now to the present figures, a systemis illustrated inin accordance with one embodiment. Notably, the systemis a production system that facilitates extraction of a resource, such as oil, from a reservoirthrough a well, such as an onshore well. Wellhead equipmentis installed on the well. As depicted, the wellhead equipmentincludes a wellhead housingand wellhead hangers. The wellhead housingmay include one or more casing heads and a tubing head in some instances. In some cases, the wellhead housingincludes a single-piece body designed to receive multiple hangers, such as a casing hanger and a tubing hanger. The hangerscan be mandrel-style hangers or slip-style hangers. The components of the wellhead equipmentcan differ between applications, and could include a variety of casing heads, tubing heads, spools, housings, hangers, sealing assemblies, stuffing boxes, pumping tees, and pressure gauges, to name only a few possibilities.

The wellhead hangerscan be positioned on landing shoulderswithin hollow wellhead bodies (e.g., within the wellhead housing). These landing shoulderscan be integral parts of the wellhead housingor can be provided by other components, such as sealing assemblies or landing rings disposed in the wellhead housing. In some instances, a wellhead hangercan be secured within a hollow wellhead body using a gripping device without landing the wellhead hangeron a landing shoulder. In such an embodiment, landing shouldersmay be omitted from the wellhead housing. Each of the hangerscan be connected to a tubular string, such as a tubing stringor a casing string, to suspend the string within the well. The wellcan include a single casing stringor include multiple casing stringsof different diameters. Casing stringsare often cemented in place within the well.

By way of further example, a wellhead assemblyis depicted inas having a hollow wellhead housingwith an axial boreextending from a lower endof the housingto an upper end. The wellhead assemblyofincludes gripping devices, which may also be referred to as wellhead clamps, positioned to elastically deform the wellhead housingto securely grip wellhead hangers within the bore. The depicted wellhead clampseach include a compression ring with compression segments, a lower energizing ring, and an upper energizing ring. These components can have any suitable form. In some embodiments, the compression ring is a segmented annular ring formed of four compression segmentsarranged circumferentially about the wellhead housing, although some other number of compression segmentscould be used. Separation of adjacent segmentsfacilitates contraction of the compression ring about the wellhead housing. The compression ring could be provided as an annular ring with one split in its circumference (i.e., a C-ring) in other instances.

Through the tapered engagement of the compression segmentswith the energizing ringsand, drawing the energizing ringsandtoward one another applies a radially inward compression force to the compression ring segments, which contract and elastically deform the wellhead housingto grip a wellhead hanger positioned along the boreinside the clamp. Although a wellhead hanger is not depicted inside the clampin, such a wellhead hanger could be installed and gripped inside the clampat some other time. The energizing ringsandcan be connected to one another in any suitable manner, such as with studsand nuts. It will be appreciated that the clampcan include any suitable number of studsand nuts, such as twelve or sixteen pairs of circumferentially arrayed studsand nuts. In some instances, the energizing ringsandinclude tool recesses(e.g., annular grooves) to facilitate use of a tool, such as a hydraulic tool, for drawing the ringsandtogether to actuate the clamp.

The compression ring segmentsmay be positioned in recessed portionsof the outer surface of the wellhead housingto facilitate elastic deformation of the wellhead housingwhen the clampsare actuated. As shown in, one clampis positioned near the top of the wellhead housingto elastically deform the wellhead housingand grip a hanger of a tubular string, such as a tubing string, while another clampis positioned lower along the wellhead housingto elastically deform the wellhead housingand grip a hanger of another tubular string, such as a casing string. But in other embodiments, the wellhead housingmay have more or fewer clamps, such as a single clampfor elastically deforming the wellhead housingto grip a single hanger within the bore.

To facilitate installation of a wellhead hanger, when the clampis in a relaxed state and is not elastically deforming the wellhead housing, the diameter of the borecan be sufficiently greater than the outer diameter of the wellhead hanger to allow free movement of the wellhead hanger within the boreto its desired position. The wellhead hanger can be lowered into the wellhead housingand moved to this desired position, after which the clampcan be energized to compress the wellhead housingradially inward to elastically deform the wellhead housingand cause the inside wall of the wellhead housingto contact and grip the wellhead hanger. In some instances, the wellhead hanger includes teeth on its external surface to bite against the inside wall of the wellhead housingand facilitate gripping of the hanger by the housing. The extent of actuation of the clampcan be adjusted to vary the gripping force of the wellhead housingon the hanger.

As noted above, some embodiments of the present disclosure facilitate assessment of the integrity of the gripping of a wellhead housing, such as the housing, to a wellhead hanger. This gripping can be used to carry the weight of the hanger (and attached equipment, such as a tubular string) and to resist any vertical forces, either downward due to weight or upward due to well pressure. Various examples for sensing the integrity of this gripping are provided herein. At least some embodiments include a sensing technique that does not introduce any new leak paths to a wellhead assembly or any other modifications that would compromise sealing or safety of such assemblies. The presently described sensing systems can be used to provide feedback on gripping integrity during installation of a wellhead hanger. In some instances, such systems may also or instead be used to monitor gripping in situ following installation (e.g., periodically, continually, or continuously monitoring gripping during installation or throughout the lifetime of the wellhead). In at least some embodiments, assessing the grip of the wellhead housing on a wellhead hanger includes detecting a change in a wall of the wellhead housing elastically deformed through actuation of a wellhead clamp.

By way of example, in some instances assessing grip of a wellhead housing on a wellhead hanger includes measuring strain following actuation of the wellhead clamp. In, the wellhead assemblyis depicted as having strain gaugesandto measure strain on the wellhead housing. The strain gaugesmay be positioned on an exterior surface of the wellhead housing, while the strain gaugesmay be positioned on an interior surface of the wellhead housing. Although two strain gaugesand two strain gaugesare depicted in, it will be appreciated that the wellhead assemblycould include any suitable number of strain gauges, which could be more or fewer than four strain gauges depicted in. Indeed, in some embodiments the wellhead assemblywill not include strain gauges, and grip on the wellhead hanger may be assessed in some other manner. Further, when present, a strain gauge may also or instead be positioned on some other component of the wellhead assembly, besides the wellhead housing, to measure strain and facilitate grip assessment. For instance, as shown in at least, a strain gaugemay be positioned on a wellhead hangerpositioned within the wellhead housingto measure strain on the wellhead hanger(e.g., from gripping by the wellhead housing). But other sensing systems to assess grip strength are also shown inand in other figures, and it will be appreciated that the strain gaugemay be omitted, used in place of, or used in addition to such other sensing systems described elsewhere herein. When present, a strain gauge,, orcan be positioned at any suitable location, such as radially inward of a clamp, or above or below the clamp.

In some other embodiments, detecting a change in a wall of the wellhead housing elastically deformed through actuation of a wellhead clamp includes detecting a change in a thickness of the wall of the wellhead housing. More specifically, in certain embodiments a compression force from the wellhead housingon a wellhead hanger (e.g., on wellhead hanger), and thus the vertical load carrying capacity, is assessed by measuring a thickness change of the wellhead housingat or near the hanger position as a result of the wellhead wall being compressed radially inward by the external clamp. When the inside wall of the wellhead housingcontacts the outside wall of the hangerduring actuation of the clamp, the hangerstarts to exert radially outward resistance forces. As the wall of the wellhead housingis squeezed between the hangerand the clamp, the radial thickness of the wall located directly between, and compressed by, the hangerand the clampdecreases; this thickness change may be proportional to the squeeze force, which in turn may be proportional to the vertical load carrying capacity of the hanger-wellhead housing interface.

The outward force that the hangertransfers to the wellhead housingand the deformation it imparts on the housingcan therefore be indirectly measured by measuring the wellhead wall thickness. A wellhead wall thickness measurement location along a portion of the wall located directly between the hangerand the clampmay give the greatest thickness change, but an axial location along the wellhead housingabove or below the clampmay be more accessible in practice. For example, the apparatus depicted inincludes a meteris used to measure wall thickness of the wellhead housingat an axial location above the hangerand clamp. The metercan take any suitable form, such as an ultrasonic meter or acoustic meter. The meteris positioned to measure thickness of the wall between an outer surfaceand inner surfaceof the wellhead housing. A signal(e.g., an ultrasonic or acoustic sound pulse) may be transmitted by the meterinto the wall from the outer surface, at least a portion of which is reflected by the inner surfaceback to the meter. The travel time for the signal transmitted through the wall and reflected back to the meteris used to calculate the thickness of the wall. The metercould be used to measure thickness of the wall multiple times to detect deformation of the wellhead housing by actuation of the clamp. For instance, a series of thickness measurements could be taken during actuation of the clampto detect changes in the wall thickness during actuation.

In another embodiment generally depicted in, the wellhead housingincludes a measurement hole, which may be a hole drilled into the outer surfaceof the housing. As illustrated, the holedoes not extend into the boreand has a hole bottomlocated in the wall of the housing. When the housinggets squeezed during actuation of the clampthe wall thickness may decrease, which causes the depth of hole(from the outer surfaceto the hole bottom) to decrease. Although a depth gaugehaving a rodis generally depicted in, the depth of the holecan be measured in any other suitable manner. In at least some instances, depth measurements are taken at multiple times during installation to see the wall thickness change.

In some embodiments, changes in thickness of a wall of the wellhead housingare identified by detecting relative displacement of a surface of the wellhead housing. In, for instance, a wall of the wellhead housingincludes a measurement holeformed in the outer surface. The holehas a bottomand does not penetrate to the bore. The holesurrounds a measurement coresuch that an end faceof the coreis separated, by the hole, from the portion of the outer surfacesurrounding the hole. The holecan be provided in any suitable shape but is shown as an annular holeencircling and defining the corein. Further, the holecan be formed in any suitable manner. In some instances, the holecan be formed via electrical discharge machining, with a core bit, or in some other way that leaves the coreas an integral portion of the wall of the wellhead housing(i.e., the coreis material of the wall remaining within the holefollowing formation of the hole). In at least such instances, certain physical properties of the core(e.g., thermal expansion and elasticity properties) can be the same as the material of the surrounding wall of the wellhead housing. In some other instances, the corein the wall of the wellhead housingmay be an insert positioned within the hole, such as an insert threaded into a tapped hole at the bottomof the holeor an insert welded into place within the hole.

Measuring the amount by which the core facedeflects (e.g., radially moves) with respect to the outer surfacesurrounding the hole(e.g., the core faceprotruding beyond the outer surfacesurrounding the holeor retracting into the hole) gives an indication of the change in wall thickness when the wall of the housingis elastically deformed via the clamp. This measurement can be taken in any appropriate fashion. For instance, this measurement could be taken manually using a depth gauge or could be taken using a sensor(e.g., a capacitive sensor, an eddy current sensor, or any other suitable sensor) positioned radially outward of the end face. In at least some embodiments, the holeis formed in a flat housing face of the outer surface(i.e., the core faceand the portion of the outer surfacesurrounding the holeare flat surfaces) to facilitate measurement.

Although a single holeand coreare depicted in, it will be appreciated that multiple holesand coresmay be arranged about the wellhead housingto allow measurement at various locations. In, for example, two holesand coresare shown at locations axially above the clamp, two holesand coresare shown at locations axially below the clamp, and an additional holeand coreare shown in a location axially aligned with and radially inward of the clamp. Holesand coresmay also or instead be arranged at other circumferential locations about the housing

Another example of a wellhead housinghaving measurement holes, cores, and sensorsfor assessing gripping integrity of the housingon a hangeris shown in. In this embodiment, the holes, cores, and sensorsare depicted in three locations along the housing. Moving from top to bottom in, these locations are a first location above the clamp, a second location above the clamp(between the first location and the upper end of the clamp), and a third location radially inward of the clamp. The sensors(e.g., a capacitive sensor or some other suitable sensor) are positioned to detect relative movement of the coreswhen the wellhead housingis elastically deformed via the clamp, such as described above. As will be appreciated, the separation provided by the holescause the end faces of the coresto move toward or away from the boreby different amounts than the outer surface of the wellhead housingsurrounding the holeswhen the housingis deformed via the clamp.

Examples of distances measured from the sensorsinto the end faces of the coresover time during actuation of the clampare generally depicted in. More particularly,represents distance measured by the uppermost sensorin,represents distance measured by the next sensor(below the uppermost sensorand above the clamp) in, andrepresents distance measured by the lowermost sensorin. The graphical depictions ofare provided by way of example. It will be appreciated that distance measured can vary between locations and between different embodiments (e.g., based on the physical characteristics and geometries of different embodiments), and that the shapes of the graphical depictions of the sensor response may vary from those shown in. Each ofdepicts measured distance changing over a time period in which the clampmoves from a relaxed state to an energized state in which the clamphas elastically deformed the wellhead housinginto gripping engagement with the hanger. In the present example of, the clampis actuated to provide a linear compression force to the wellhead housingover time. While the time scale is identical among, the distance scales are not identical in this example. In some instances, the magnitude of the change in distance measured infrom the starting time to the ending time (from the relaxed state to the energized state) is 3.0-3.5 microns, the magnitude of the change in distance measured infrom the starting time to the ending time is 8-9 microns, and the magnitude of the difference between the minimum and maximum distance recorded inis 6-7 microns. In, the measured distance is shown generally increasing over time during actuation of the clamp. In contrast, inthe measured distance (by the lowermost sensorin) begins to rise as the clampis actuated but reaches a maximum and begins to fall while the clampcontinues to be actuated and while the distances measured by the other sensorsofcontinue to rise. This difference in behavior at the lowermost coremay be due to resistance of the hangerto the compression of the housingby the clamp.

In some embodiments, assessing the grip on the hangerby the elastically deformed housingincludes comparing the distance measured by a sensor(or multiple sensors) to one or more thresholds. For instance, in certain embodiments distance measured by a sensor(e.g., the lowermost sensorof) can be compared to either or both of an upper threshold and a lower threshold. As represented in, by way of example, an upper thresholdcan be a minimum desired distance change(from a starting distance) during actuation of the clamp, and a lower thresholdcan be a maximum desired ending distance change(from the starting distance) after actuation of the clamphas finished and the hangeris set within the housing. In this example, the grip on the hangercan be considered sufficient if the magnitude of the maximum distance changeexceeds the minimum desired distance change(e.g., the distance measured exceeds the upper threshold) during actuation of the clampand if the ending distance measured after actuation of the clampdeviates from the starting distanceby less than the magnitude of the difference between the starting distanceand the lower threshold(e.g., the ending distance is below the lower threshold). Any suitable thresholds may be used. In some cases, the upper thresholdwill be 3-15 microns (at any point in this inclusive range) from the starting distance, while the lower thresholdwill be less than the upper thresholdand will be 1-5 microns (at any point in this inclusive range that is below the upper threshold) from the starting distance. In some other embodiments, the grip may be determined to be sufficient by comparison to a single threshold, such as the measured distance passing a thresholdat some point during actuation of the clampor the measured distance passing a thresholdin opposite directions (e.g., starting below the threshold, then exceeding the threshold, and then falling below the threshold during actuation). Grip can be determined to be insufficient if the measured distance does not meet the threshold expectations, such as if the measured distance does not rise to the upper thresholdor return to a distance below the lower threshold.

Still another example of a wellhead housinghaving measurement holes, cores, and sensors for assessing gripping integrity of the housingon a hangeris shown in. As best shown in, this embodiment includes two measurement locations having holesand coresalong the housing: a first measurement location located above the clampand a second measurement location radially inward of the clamp. Sensors may be used to detect relative movement of the coresand measure distances between the sensors and the cores, such as described above. The housingcan include recesses() for receiving such sensors near the cores. As also depicted in, the housingcan include one or more slotsto facilitate communication between a sensor installed in a recessthat is radially inward of the clampand a location axially offset from the clamp.

The apparatus can also include connectorsand a cover, as shown in. The connectorsfacilitate communication with an external controller or monitoring system, such as a processor-based system with memory and stored instructions that can be executed by a processor to perform various functionality described herein, such as receiving measurement signals, assessing grip integrity (e.g., by comparing measured values to one or more thresholds), and providing output (e.g., measurements or grip assessments) to a user. Although the connectorsare depicted with sockets for receiving cable plugs, in other instances connectorsmay be configured in some other manner, such as for wireless communication with an external system. The connectorsand covermay also protect internal components of the sensing system.

In the embodiment depicted in, the sensing system includes an upper assemblyfor the upper measurement location along housingand a lower assemblyfor the lower measurement location along housing. The upper assemblyincludes a connector, a circuit board, a spacer(e.g., an O-ring), and a sensorthat may be installed in the recessof the upper measurement location. The lower assemblyincludes a connector, the cover, a circuit board, a spring, a spacer(e.g., an O-ring), and a sensorthat may be installed in a recessof the lower measurement location. The sensorsmay be capacitive sensors or any other suitable sensors, and in some instances may be identical to sensors. The spacersmay help seat the sensorswithin the recesses. Although one springis depicted in, one or more springsmay be used in either or both the upper assemblyand the lower assemblyto bias other components to desired positions (e.g., to maintain seating of the sensorwithin the recess).

The circuit boardsandcan be provided in any suitable form but are printed circuit boards in at least one embodiment. The depicted circuit boardsandenable electrical communication between the sensorsand external devices via the connectors. In, the circuit boardhas an elongated shape configured to be received in a slotand to generally allow communication to travel axially between the sensorof the lower assemblyand the connectorof the lower assembly. In other instances, a communication cable may also or instead be used in the slotto communicate between the sensorand the connector. The covercan be a shield used to reduce interference on the communication path between the sensorand the connectorof the lower assemblyin some instances.

As noted above, a sensor (e.g., sensoror) may be used to measure a distance to an end faceof a coreof the wellhead housingat a measurement location. This may be better understood with reference to, which generally depicts a sensorinstalled in a recessat a measurement location. The sensormay be seated in the recess so as to provide a gapbetween the end faceand the sensor. The width of this gapand the measured distance to the end facechanges as the wellhead housingis elastically deformed by the clampto grip the hanger. In some cases, the width of the gapis 40-70 microns before actuation of the clamp.

Various embodiments described herein include measuring a parameter (e.g., strain, thickness, depth, or distance) that changes in response to deformation of a wall of the wellhead housingby the clamp. In addition to radial deformation of the wellhead housing through actuation of the clamp, the compressed wellhead wall may also experience axial deformation generally perpendicular to the radial deformation due to the Poisson effect. In certain instances, the Poisson effect may cause a wall of the wellhead housing at a measurement location (e.g., a location above or below the clamp) to increase in thickness rather than decrease in thickness. The strain, thickness, depth, distance, or other parameter measured to assess grip of the wellhead housingon a hanger(or on some other component within the bore) can be compared to one or more threshold levels that may be above or below a starting value of that parameter before elastic deformation of the wellhead housing. These one or more threshold levels can be determined through prior modeling, testing, or in any other suitable manner. For instance, a given threshold level can be set, based on prior testing, at a level for which the parameter to be measured would be deemed sufficient to indicate at least a minimum desired grip strength by the elastically deformed wellhead housingon the hanger, and assessing the grip strength includes determining whether the measured parameter has reached the desired threshold level.

In some embodiments, the wellhead housingmay also or instead include a visual indicator to facilitate assessment of the grip of the housingon a hanger. One such embodiment is depicted in, in which the housingincludes a measurement holeformed in the outer surfaceabove the clamp. The depicted holehas a threaded portion near a bottomof the hole. This threaded portion of the holemay have a narrower diameter than the portion of the holecloser to the outer surface. A cap screwhaving a threaded endand headmay be screwed into the holewhen the housingis not under stress (e.g., when the housingis not being elastically deformed by the clamp), such as shown in. A capis retained on the cap screwby the head. The capcan include a tool access portto allow a tool (e.g., a screwdriver) to thread the cap screwinto or out of the hole.

As depicted in, the cap screwand capare configured such that the capis free to rotate about the headwhen the wellhead housingis not being elastically deformed by the clamp. In this example, the holeis at a location in the wall of the wellhead housingat which the wall thickness increases (due to the Poisson effect) as the clampis actuated to elastically deform the housing. As the clampis actuated, the thickness of the wall of the wellhead housingat the holeincreases, causing a tensile strain force on the cap screwand an end of the capto be squeezed between the headof the cap screwand the outer surfaceof the housing, such as shown in. In this state, the capis held tightly and is no longer free to rotate about the head. The dimensions of the cap screwand capmay be selected to allow free rotation of the capuntil the clampis actuated and the grip of the elastically deformed housingon the hangeris sufficiently strong to provide a desired load carrying capacity. Once the capcannot be rotated, it is an indication that the wellhead wall thickness has increased to a desired value, which is an indirect indication that the hangerhas been adequately gripped. In this manner, an operator may determine whether the grip of the housingon the hangeris sufficiently strong based on the state of the cap(freely rotatable or fixedly held).

While the aspects of the present disclosure may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. But it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.