GB2597764A

GB2597764A - Apparatus and method

Info

Publication number: GB2597764A
Application number: GB2012090.3A
Authority: GB
Inventors: Garg Manish; Talmage Andrew
Original assignee: John Crane UK Ltd
Current assignee: John Crane UK Ltd
Priority date: 2020-08-04
Filing date: 2020-08-04
Publication date: 2022-02-09
Anticipated expiration: 2040-08-04
Also published as: WO2022029406A1; GB2597764B; GB202012090D0

Abstract

A seal head assembly is provided. The seal head assembly 100 comprises: a retainer 101; springs 102; a thrust ring 103; a primary ring 104; a snap ring 105; and a channel 106. The retainer 1010 is configured to house therein: the springs 102; the thrust ring 103; the primary ring 104; and the snap ring 105; and further comprises an integrated upper detent for retention of the primary ring 104 in the retainer 101, the primary ring 104 having a radial through groove. The through groove is arranged to allow the primary ring 104 to move axially past the upper detent and the primary ring 104 is rotatable in the retainer 101 to align the through groove and the upper detent to permit axial movement of the primary ring 104 relative to the retainer 101. Circumferential misalignment of the upper detent with the groove restrains axial movement of the primary ring 104 relative to the retainer 101.

Description

Apparatus and Method

Technical field

The present disclosure relates to seals for rotating equipment, and more particularly to 5 seal head assemblies and methods of assembling seal heads.

Background

A mechanical seal is a component of a machine to prevent leakage of a fluid along a rotating shaft, either to the surroundings or to another part of the machine. Sealing takes 10 place in a plane perpendicular to the shaft, in systems such as pumps, compressors and turbines.

Where a rotating shaft enters a fluid-containing region of such a system a mechanical seal can be used at the point of entry to reduce leakage of so called "process fluid" from that region. Mechanical seals may use flat parallel surfaces held in close contact. These may include a "stator" seal face and a rotating "rotor seal face. This generally requires that a fluid, such as a lubricant, be disposed between the stationary and rotating seal faces.

Some process fluids may not have lubricating propertied or may be toxic or corrosive. In these circumstances a liquid or gas lubricant can be pumped into the seal under sufficient pressure to cause it to slowly leak through the seal into the process fluid. This can help to prevent escape of the process fluid through the seal. This approach is effective, but the complexity and expense may not be justified in all circumstances. In less demanding circumstances, the process fluid can be used as the seal lubricant. This is cheaper, but some process fluid necessarily is allowed to leak.

If such leakage is unacceptable a "dry" running and wet running contacting seals can be used in addition to the primary seal. These contacting mechanical seals can contain a slow leak of process fluid from the primary seal to prevent it from escaping into the environment. The process of assembly of such seals may be complex, which can increase the expense and time involved in their maintenance and manufacture. -2 -

Summary

Aspects of the disclosure are set out in the independent claims and optional features are set out in the dependent claims. Aspects of the disclosure may be provided in conjunction with each other, and features of one aspect may be applied to other aspects.

An aspect provides a seal head assembly comprising: a retainer configured to receive a primary ring therein and comprising an integrated upper detent for retaining said primary ring in the retainer; and, a primary ring with a through groove disposed in a radial edge thereof; wherein the through groove is arranged to allow the primary ring to move axially past the upper detent and the primary ring is rotatable in the retainer selectively to align the through groove and the upper detent wherein circumferential alignment of the upper detent with the groove permits axial movement of the primary ring relative to the retainer; and, wherein circumferential misalignment of the upper detent with the groove restrains axial movement of the primary ring relative to the retainer.

The seal head assembly does not require a snap ring. Accordingly, the seal head assembly may be assembled using fewer components (e.g. without a snap ring). Advantageously, the cost of manufacturing the seal head assembly may be reduced in comparison to the cost of manufacturing seal head assemblies comprising a snap ring.

Advantageously, the cost of assembling the seal head assembly may be reduced in comparison to the cost of assembling seal head assemblies comprising a snap ring.

The seal head assembly may have two positions: * A first position in which the upper detent is misaligned with the through groove to hold the primary ring in the seal head assembly, for example, the upper detent may be seated in the blind groove. In this position the through groove may be aligned with the lower detent so that when the seal head assembly is installed the primary ring can simply be advanced axially so that the through groove moves over the lower detent e.g. to seat the lower detent in the through groove; * An second position in which the lower detent is seated in the through groove.

The first position may be suitable for transportation and/or storage of the seal head assembly prior to use, for example, because the upper detent is seated in the blind -3 -groove the assembly is held together conveniently.

Then when the seal assembly needs to be installed into a machine for use the primary ring is advanced axially over the lower detent into the second position for operation of the 5 seal head assembly.

The second position may be suitable for operation of the seal assembly e.g. the seal head assembly is in the second position when the seal assembly is operated. The second position may thus be referred to as an operational position.

There may be multiple first positions for a given seal head assembly. The first position may be suitable for transporting the seal head assembly without the components of the seal head assembly becoming loose and/or disassembling during transportation. For example, seal head assemblies in accordance with the present disclosure may be configured to the first position upon assembly (e.g. initial assembly in a manufacturing plant). The seal head assembly may be subsequently transported to a desired location.

In the first position, a shortest distance between the primary ring and a closed end of the retainer may be referred to as the transportation length of the seal head assembly.

The primary ring may comprise a blind groove wherein: the blind groove is configured to receive at least a portion of the upper detent; and, the blind groove is circumferentially offset from the through groove; and; wherein the seal head assembly is configured such that, positioning at least a portion of the upper detent within the blind groove restrains circumferential movement of the primary ring relative to the retainer.

Restraining the circumferential movement of the primary ring by the upper detent may prevent the primary ring moving due to external forces applied during transportation. Therefore, undesirable circumferential alignment of the through groove of the primary ring and the integrated upper detent of the retainer may be avoided (e.g. alignment during use of the seal head assembly).

The seal head assembly may comprise: a thrust ring disposed within the retainer for -4 -holding the primary ring against the upper detent. Together the thrust ring and the upper detent may be configured to hold the primary ring in the retainer in the first position (e.g. to prevent the primary ring exiting the retainer via an open end of the retainer). The thrust ring may be configured to apply an evenly spatially distributed force from springs in the retainer to the seal face.

The thrust ring may be configured to be resiliently depressed by the primary ring to permit alignment of the blind groove with the upper detent.

Conveniently, a gap (e.g. void space) between the upper detent and the blind groove may be provided to allow relative rotation between the upper detent and the blind groove (e.g. between the primary ring and the retainer) about the longitudinal axis to permit alignment (for example, circumferential alignment) of the upper detent and the blind groove.

The primary ring and the thrust ring may be sized and arranged so that when the primary ring is in the retainer with the blind groove aligned with the upper detent the thrust ring and springs hold the upper detent in the blind groove.

Depression of the thrust ring and the primary ring may be terminated upon alignment of the blind groove and the upper detent to allow the blind groove to receive at least part of the upper detent.

Conveniently, assembling the seal head assembly may require manipulation of a single 25 component (e.g. axial movement of the primary ring and then rotation of the primary ring relative the retainer). Therefore, a simplified assembling process of the seal head assembly may be provided by the seal head assembly.

The retainer may further comprise a lower detent for preventing rotation of the primary 30 ring relative to the retainer.

In examples, the lower detent may be an integrated lower detent for preventing rotation of the primary ring relative to the retainer. -5 -

The second position comprises at least part of the lower detent seated in the through groove.

In examples, the second position comprises the lower detent seated in the through groove.

For example, when the through groove receives (at least part of) the lower detent, the through groove and the lower detent may synergistically prevent rotation of the primary 10 ring relative to the retainer.

The through groove may be arranged to allow the primary ring to move axially past the lower detent. The through groove is configured to permit the lower detent to be axially slid through the length of the through groove. For example, the through groove may be sized and shaped to receive the lower detent. In examples, an axial cross-sectional profile of the through groove may have a congruent shape and larger size than an axial cross-sectional profile of the lower detent.

The shortest distance between the primary ring and the closed end of the retainer in the 20 second position may be referred to as the working length of the seal head assembly.

The working length of the seal head assembly may be less than the transportation length of the assembly.

Restraining the circumferential movement of the primary ring by the lower detent may prevent the primary ring moving due to external forces applied during operation of the seal head assembly (e.g. vibrations). Accordingly, the risk of the primary ring exiting the retainer in use is reduced.

An aspect provides a contacting seal comprising a seal head assembly according to aspects of the disclosure.

An aspect provides a method of assembly of a seal head assembly comprising: moving -6 -an integrated upper detent of a retainer into circumferential alignment with a through groove of a primary ring; moving the integrated upper detent axially relative to the through groove; moving the primary ring relative to the retainer to circumferentially misalign the upper detent and the groove thereby to hold the primary ring in the retainer.

The seal head assembly may not require a snap ring. Accordingly, the seal head assembly may be assembled using fewer components (e.g. without a snap ring). Advantageously, the cost of manufacturing the seal head assembly may be reduced in comparison to the cost of manufacturing seal head assemblies comprising a snap ring.

The method may comprise moving the upper detent into a blind groove in the retainer to thereby restrain circumferential movement of the face relative to the retainer.

The method may comprise moving the through groove into circumferential alignment with a lower detent of the retainer.

The method may comprise moving the through groove of the primary ring axially relative 20 to the lower detent thereby seating at least pad of the lower detent in the through groove to restrain circumferential movement of the primary ring relative to the retainer.

Restraining the circumferential movement of the primary ring may prevent the primary ring moving due to external forces applied to the seal head assembly in use (e.g. vibrations). Therefore, undesirable circumferential alignment of the through groove of the primary ring and the integrated upper detent of the retainer may be avoided (e.g. alignment during use of the seal head assembly). Accordingly, the risk of the primary ring exiting the retainer in use is reduced.

In examples, methods according to an aspect of the disclosure may be performed to assemble seal head assemblies according to aspects of the disclosure.

An operating temperature of the seal head assembly may be within the range of -40 °C -7 -to 260 °C. An operating pressure of the seal head assembly may be within the range of 0 bar g to 76 bar g. An operating speed of the seal head assembly may be approximately 25 ms-1.

In examples, retainers may have a generally annular cylindrical shape. In these examples, the retainers may have a diameter within the range of 26.00 mm to 203.50 mm. In these examples, retainers may have an axial length (e.g. a length along a longitudinal axis of the retainer) within the range of 18.0 mm to 47.0 mm. In these examples, upper detents of the retainers may have an axial length (e.g. a length along the longitudinal axis of the retainer) within the range of 1.0 mm to 2.0 mm. In these examples, lower detents of the retainers may have an axial length (e.g. a length along the longitudinal axis of the retainer) within the range of 5.0 mm to 19.0 mm.

In examples, retainers may comprise any of: one upper detent; two upper detents; three 15 upper detents; four upper detents.

The upper detents may be equidistantly spaced from one another (e.g. equidistantly spaced around the longitudinal axis of the retainer).

In examples, retainers may comprise any of: one lower detent two lower detents three lower detents; four lower detents.

The lower detents may be equidistantly spaced from one another (e.g. equidistantly spaced around the longitudinal axis of the retainer).

In examples, the through groove and the blind groove may be angularly separated by a selected groove angular offset e.g. the selected groove angular offset may be the smallest angle subtended by a radius from the through groove, a longitudinal axis of the retainer and a radius to the blind groove. In examples, the selected groove angular offset may be 61.50.

In examples, the upper detent may be angularly separated from a lower detent by a selected detent angular offset e.g. when viewed along the longitudinal axis, the selected -8 -detent angular offset may be the smallest angle subtended by a radius from the upper detent to a longitudinal axis of the retainer and a radius to the lower detent.

In examples, the selected detent angular offset separation between the lower detent and 5 the upper detent may be the same as the selected groove angular offset. Accordingly, circumferential alignment of the upper detent and the blind groove may additionally provide circumferential alignment of lower detent and the through groove.

A may be appreciated that the term "detent" an inwardly projecting protrusion on an inner 10 circumference of a cylinder (for example, projecting toward a central axis of that cylinder).

Figures Some examples will now be described, by way of example only, with reference to the 15 figures, in which: Figure 1 illustrates a longitudinal cross-sectional view of a seal head assembly comprising a snap ring; Figure 2 illustrates a flow chart of a method of assembling the seal head assembly of Figure 1; Figure 3 illustrates a longitudinal cross-sectional view a seal head assembly comprising an upper detent in a first position; Figure 4 illustrates a perspective view of a portion of the seal head assembly of Figure 3; Figure 5 illustrates an axial perspective view of primary ring of the seal head assembly of Figures 3 and 4; Figure 6 illustrates a longitudinal cross-sectional view of a seal head assembly comprising an upper detent in an second position; Figure 7 illustrates a perspective view of a portion of the seal head assembly of Figure 6;Figure 8 illustrates a flow chart of a method of assembling the seal head assembly into a first position as illustrated in Figures 3 to 4 and into an second position as illustrated in 30 Figures 6 to 7.

In the drawings like reference numerals are used to indicate like elements. -9 -

Specific description

Figure 1 illustrates a longitudinal cross-sectional view of a seal head assembly comprising a snap ring. The seal head assembly 100 comprises: a retainer 101; springs 102; a thrust ring 103; a primary ring 104; a snap ring 105; a channel 106; and; a 5 longitudinal axis 107.

The retainer 101 is an open cylinder comprising an open end 111 and a closed end 121. The retainer 101 is rotationally symmetrical about the longitudinal axis 107. The retainer 101 is configured to house (e.g. contain) therein: the springs 102; the thrust ring 103; the 10 primary ring 104; and the snap ring 105 The channel 106 is disposed in an inside surface of the retainer 101 near the open end 111 of the retainer 101 (e.g. closer to the open end 111 than the closed end 121). The channel 106 circumscribes the longitudinal axis. The channel 106 is configured to 15 receive the snap ring 105.

The springs 102 are disposed within the retainer and are mounted on the closed end 121 of the retainer 101. The springs 102 are arranged around the longitudinal axis 107. The springs 102 are configured to be resiliently depressed (e.g. elastically compressed) in 20 response to an applied force parallel to the longitudinal axis 107.

The thrust ring 103 has an annular shape. The thrust ring 103 is disposed within the retainer 101 such that thrust ring surrounds the longitudinal axis 107. The thrust ring 103 is mounted on the springs 102. The springs 102 are located between: the closed end 121 of the retainer 101; and, the thrust ring 103. The thrust ring 103 is configured to be resiliently depressed towards the closed end 121 of the retainer 101 e.g. when an external force parallel to the longitudinal axis of 107 is applied to the thrust ring 103 in a direction from the open end 111 to the closed end 121.

The primary ring 104 has an annular shape. The primary ring 104 is disposed within the retainer 101 such that primary ring 104 surrounds the longitudinal axis 107. The primary ring 104 is disposed between the thrust ring 103 and the snap ring 105. The thrust ring 303 is configured to hold the primary ring 304 against the snap ring 105.

-10 -The snap ring 105 has an annular shape. The snap ring is disposed within the channel 106 in the retainer 101 such that snap ring 105 surrounds the longitudinal axis 107. The snap ring 105 is configured to hold the primary ring 104 in the retainer 101 e.g. the snap ring 105 is configured to prevent the primary ring 104 from exiting the retainer 101 via the open end 111.

The snap ring 105 is selectively deformable (e.g. in response to an applied force applied in a radial direction of the snap ring) to adjust an effective radius of the snap ring 105.

The effective radius of a snap ring is a radius of an arc or circle which defines the snap ring. The snap ring 105 has a natural effective radius when no force is applied to the snap ring 105. The snap ring 105 is deformable to decrease the effective radius of the snap ring from the natural effective radius (e.g. in response to an external force applied in a radial direction of the snap ring 105). The snap ring 105 is deformable to increase the effective radius to the natural effective radius (e.g. in response to removal of an external force applied in a radial direction of the snap ring 105).

Figure 2 illustrates a flow chart of a method of assembling the seal head assembly of 20 Figure 1. The method may comprise the following steps.

Mounting S201, the springs 102 in the retainer 101. For example, the springs 102 are inserted into the retainer 101 and are mounted on the closed end 121 of the retainer 101 (e.g. the springs are attached to the closed end 121 inside the retainer 101). The springs 25 102 are arranged around the longitudinal axis 107.

Mounting S202, the thrust ring 103 on the springs 102. For example, the thrust ring 103 is inserted into the retainer 101 via the open end 111 such that the thrust ring 103 surrounds the longitudinal axis 107. The thrust ring 103 is attached on the springs 102.

Moving S203, the primary ring 104 into the retainer 101 towards the thrust ring 103. For example, the primary ring 104 is inserted into the retainer 101 via the open end 101 such that the thrust ring surrounds the longitudinal axis 107. The primary ring 104 may be pushed into contact with the thrust ring 103. The thrust ring 103 is resiliently depressed towards the closed end 121 of the retainer 101. Resilient depression of the thrust ring 103 provides a corresponding compression of the springs 102 (e.g. the springs 102 are compressed). The compression of the spring is maintained for the following step (S204 and S205).

Inserting S204, the snap ring 105 into the retainer 101. The snap ring 105 is inserted into the retainer 101 via the open end 111. The effective radius of the snap ring is decreased before insertion into the retainer 301. The snap ring 105 is axially aligned with the 10 channel 106 in the retainer 101.

Setting S205, the snap ring 105 into the channel 106 in the retainer 101. For example, setting the snap ring 105 may comprise increasing the effective radius of the snap ring 105. The effective radius of the snap ring 105 is increased and the snap ring 105 is received by the channel 106 in the retainer 101. For example, to increase the effective radius of the snap ring 105 is allowed the snap ring 105 to expand to its natural effective radius. When the snap ring 105 is received in the channel 106, the effective radius of the snap ring is less than or equal to the natural effective radius of the snap ring.

Ceasing S206, to maintain the compression of the springs 102. For example, the springs 102 are allowed to force the thrust ring 103 into the primary ring 104. The primary ring is forced by the thrust ring 103 into the snap ring 105. The snap ring 105 retains the primary ring 104 within the retainer 101 (e.g. the snap ring prevents the primary ring 104 exiting the container 101 via the open end 111). The primary ring 104 is held within the container 101 between the thrust ring 103 and the snap ring 105.

Figure 3 illustrates a longitudinal cross-sectional view a seal head assembly comprising an upper detent in a first position. The upper detent which integrated with the retainer and which avoids the need to use a snap ring. This may significantly simplify the manufacture and transportation of the seal head assembly, by providing a seal head assembly with a "snapless retainer", to which the independent claims of the present application are directed.

-12 -Figure 4 illustrates a perspective view of a portion of the seal head assembly of Figure 3. Figure 5 illustrates an axial perspective view of primary ring of the seal head assembly of Figures 3 and 4;The seal head assembly 300 comprises: a retainer 301; springs 302; a thrust ring 303; a primary ring 304; an upper detent 305; a longitudinal axis 307; a lower detent 308.

Figure 6 illustrates a longitudinal cross-sectional view of a seal head assembly comprising an upper detent in an second position; Figure 7 illustrates a perspective view of a portion of the seal head assembly of Figure 6.

The primary ring 304 is an annular ring, with a longitudinal through groove 314 running the axial length of the primary ring on its radial edge (e.g. its outside edge). The through groove 314 may be axially aligned, e.g. parallel with the longitudinal axis of the seal. The through groove 314 is open at both axial ends of the primary ring 304. A blind groove 324 is also disposed in the radial edge of the primary ring (e.g. its outside edge). The blind groove 324 is open at one axial end of the primary ring, and runs only part of the axial length of the primary ring, so it is closed at its other end.

The retainer 301 is an open cylinder comprising an open end 311 and a closed end 321. 20 The retainer 301 is rotationally symmetrical about the longitudinal axis 307. The retainer 301 is configured to house (e.g. contain) therein: the springs 302; the thrust ring 303; and, the primary ring 304.

The upper detent 305 is an integral part of the retainer 301 (e.g. the retainer 301 may be a monolithic body comprising an integrated upper detent 305). The upper detent 305 is disposed on an inside surface of the retainer 301 near the open end 311 of the retainer 301 (e.g. closer to the open end 311 than the closed end 321). The upper detent 305 protrudes from the inside surface of the retainer 301. In the first position, the upper detent 305 is configured to hold the primary ring 304 in the retainer 301 e.g. the upper detent 305 is configured to prevent the primary ring 304 from exiting the retainer 301 via the open end 311 when the seal head assembly is in a first position.

The lower detent 308 is an integral part of the retainer 301 (e.g. the retainer 301 may be -13 -a monolithic body comprising an integrated lower detent 308). The lower detent 308 is disposed on an inside surface of the retainer 301 near the closed end 321 of the retainer 301 (e.g. closer to the closed end 321 than the open end 311; the shortest distance between the upper detent 305 and the open end 311 is less than the shortest distance 5 between the lower detent 308 and the open end 311). The lower detent 308 protrudes from the inside surface of the retainer 301. In the second position, the lower detent 308 is configured to be at least partially received by the through groove 314. In the second position, the lower detent is configured to prevent rotation of the primary ring 304 about the rotational axis 307, relative to the retainer 301 when the lower detent 308 is a least 10 partially received by the through groove 314.

In examples, the retainer may comprise a lower detent (e.g. wherein the lower detent is not an integral part of the retainer).

In examples wherein more than one upper detent is provided. The upper detents may be spaced equidistantly (e.g. equal angular spacing) around the circumference of the retainer from other upper detents. In examples wherein more than one lower detent is provided. The lower detents may be spaced equidistantly (e.g. equal angular spacing) around the circumference of the retainer from other lower detents.

In examples comprising multiple upper detents and/or lower detents, a corresponding number of through grooves are provided in the primary ring. In examples wherein a greater number of upper detents are provided in comparison to the number of lower detents provided, a primary ring is provided which comprises a sufficient number of through grooves to receive each of the upper detents. In examples wherein a greater number of lower detents are provided in comparison to the number of upper detents provided, a primary ring is provided which comprises a sufficient number of through grooves to receive each of the lower detents.

The springs 302 are disposed within the retainer 301 and are mounted inside the closed end 321 of the retainer 301. The springs 302 are arranged in a circle around the circumference of this end of the retainer 301. The springs 302 are held in longitudinal alignment, e.g. aligned with the longitudinal axis of the seal assembly. The springs 302 -14 -are thus configured to be resiliently compressed (e.g. elastically) in the longitudinal direction.

The thrust ring 303 is annular and is seated on the springs 302 in the retainer, where it fits within the internal edge of the retainer. The springs 302 are thus located between: the closed end 321 of the retainer 101; and, the thrust ring 303. The thrust ring 303 can thereby be resiliently depressed towards the closed end 321 of the retainer 301 e.g. when an external force parallel to the longitudinal axis of 307 is applied to the thrust ring it can be pressed in towards the closed end of the retainer.

The primary ring 304 is annular, and is disposed within the retainer 301 such that primary ring 304 surrounds the longitudinal axis 307. The primary ring 304 is disposed between the thrust ring 303 and the upper detent 305.

The primary ring 304 comprises: a through groove 314; and, a blind groove 324. Both the through groove 314 and the blind groove 324 are disposed in a radial edge of the primary ring 304. In examples the though groove may be disposed in a different radial edge than the blind groove e.g. the through groove may be disposed in an edge with a first radius and the blind groove may be disposed in an edge with a second radius wherein the first radius is different to the second radius. The through groove and the blind groove may be angularly separated by a selected groove angular offset e.g. the selected groove angular offset may be the smallest angle subtended by a radius from the through groove, the longitudinal axis 307 and a radius to the blind groove. In examples, the selected groove angular offset may be 61.5 °.

The upper detent may be angularly separated from a lower detent by a selected detent angular offset e.g. when viewed along the longitudinal axis, the selected detent angular offset may be the smallest angle subtended by a radius from the upper detent to the longitudinal axis 307 and a radius to the lower detent.

In examples the selected detent angular offset separation between the lower detent and the upper detent may be the same as the selected groove angular offset. Accordingly, circumferential alignment of the upper detent and the blind groove may additionally -15 -provide circumferential alignment of lower detent and the through groove.

In examples, the selected detent angular offset may be 61.5 °.

The through groove 314 is arranged to allow the primary ring 304 to move axially past the upper detent 305 and the primary ring 304. The through groove 314 is configured to permit the upper detent 305 to be axially slid through the length of the through groove 314. For example, the through groove may be sized and shaped to receive the upper detent. In examples, an axial cross-sectional profile of the through groove may have a congruent shape and larger size than an axial cross-sectional profile of the upper detent.

The primary ring 304 is rotatable in the retainer 301 selectively to align the through groove 314 and the upper detent 305 (e.g. circumferential alignment of the upper detent and the through groove). When the through groove 314 and the upper detent 305 are aligned (e.g. in circumferential alignment of the upper detent 305 with the through groove 314) axial movement of the primary ring 304 relative to the retainer 301 is permitted.

The primary ring 304 is rotatable in the retainer 301 selectively to misalign the upper detent with the groove restrains axial movement of the primary ring relative to the retainer (e.g. circumferential misalignment of the upper detent and the through). When the through groove 314 and the upper detent 305 are misaligned (e.g. in circumferential misalignment of the upper detent 305 with the through groove 314) axial movement of the primary ring 304 relative to the retainer 301 is not permitted. VVhen the through groove 314 and the upper detent 305 are misaligned, the primary ring is restrained in the retainer e.g. the primary ring 304 is trapped between, on one axial side, the thrust ring, and on the other axial side, the upper detent.

The blind groove is configured to receive at least a portion of the upper detent 305. The seal is configured such that at least a portion of the upper detent 305 is positioned within 30 the blind groove 324 to restrains circumferential movement of the primary ring 304 relative to the retainer 301.

The first position comprises misaligning the through groove 314 and the upper detent -16 - 305, to restrain the primary ring in the retainer e.g. the primary ring 304 is trapped between, on one axial side, the thrust ring, and on the other axial side, the upper detent. In the example shown in figures 3 and 4, the first position can be any position wherein the through groove 314 and the upper detent are misaligned to restrain the primary ring in the retainer, including misalignment wherein the blind groove 324 receives at least a portion of the upper detent 305.

In the first position, the shortest distance between the primary ring 304 and the closed end 321 of the retainer 301 in the first position may be referred to as the transportation 10 length of the seal head assembly.

The through groove 314 is arranged to allow the primary ring 304 to move axially past the lower detent 308 and the primary ring 304. The through groove 314 is configured to permit the lower detent 308 to be axially slid through the length of the through groove 314. For example, the through groove may be sized and shaped to receive the lower detent 308. In examples, an axial cross-sectional profile of the through groove 314 may have a congruent shape and larger size than an axial cross-sectional profile of the lower detent 308.

The second position comprises positioning the lower detent 308 with the through groove 314 of the primary ring 304. When the lower detent 308 is positioned within the through groove 314 (e.g. the seal head assembly is in a second position), relative rotation about the longitudinal axis 307 of the through primary ring 304 relative to the retainer 301 is prevented e.g. the lower detent 308 and the through groove 314 synergistically prevent rotation of the primary ring 304 relative to the retainer 301.

The shortest distance between the primary ring and the closed end of the retainer 301 in the second position may be referred to as the working length of the seal head assembly.

The working length of the seal head assembly is less than the transportation length of the assembly.

Figure 8 illustrates a flow chart of a method of assembling configuring the seal head -17 -assembly to a first position (e.g. illustrated in Figures 3 and 4) and configuring the seal head assembly from the first position to a second position (e.g. illustrated in Figures 6 and 7). The method may comprise the following steps.

Mounting S601, the springs 302 in the retainer 301. For example, the springs 302 are inserted into the retainer 301 and are mounted on the closed end 321 of the retainer 301 (e.g. the springs are attached to the closed end 321 inside the retainer 301). The springs 302 are arranged around the longitudinal axis 307.

Mounting S602, the thrust ring 303 on the springs 302. For example, the thrust ring 303 is inserted into the retainer 301 such that thrust ring surrounds the longitudinal axis 307. The thrust ring 303 is attached on the springs 302 Moving S603, the through groove of the primary ring into circumferential alignment with 15 the integrated upper detent of the retainer. For example, arranging the primary ring 304 to surround the longitudinal axis 307 and rotating the primary ring 304 relative to the retainer 301 so that the groove and the upper detent are aligned.

Moving S604, the integrated upper detent 305 through the through groove 314 by means 20 of relative axial movement of the retainer 301 and the primary ring 304. For example, inserting the primary ring 304 into the open end 311 of the retainer 301.

Inserting the primary ring 304 into the retainer 301 pushes the primary ring 304 into contact with the thrust ring 303. As the integrated upper detent 305 is moved further through the through groove 314 by means of relative axial movement of the retainer 301 and the primary ring 304, the thrust ring 303 is resiliently depressed towards the closed end 321 of the retainer 301. Resilient depression of the thrust ring 303 provides a corresponding compression of the springs 302 (e.g. the springs 302 are compressed).

Moving S605, the primary ring relative to the retainer to circumferentially misalign the upper detent and the groove thereby to hold the primary ring in the retainer 301 (e.g. configuring the seal head assembly to a first position). For example, the primary ring is rotated about the longitudinal axis 307 (e.g. circumferential movement of the primary ring -18 -about the longitudinal axis 307) relative to the retainer 301 e.g. into an arrangement wherein the upper detent 305 is no longer able to move through the through groove 314.

Moving S606, the upper detent 305 into the blind groove 324 in the retainer 301 to thereby restrain circumferential movement of the face relative to the retainer 301(e.g. configuring the seal head assembly to another first position). For example, the upper detent 305 and the blind groove 324 are circumferentially aligned then the springs 302 are allowed to push the primary ring 304 (including the blind groove 324) toward the upper detent, thereby receiving the upper detent 305.

Moving S607, the through groove 314 into circumferential alignment with the lower detent 308. For example, circumferential alignment of the upper detent 305 and the blind groove 324 (e.g. as in S606) may additionally provide circumferential alignment of the lower detent 308 and the through groove 314.

In examples, the through groove and the blind groove may be angularly separated by a selected groove angular offset e.g. the selected groove angular offset may be the smallest angle subtended by a radius from the through groove, the longitudinal axis and a radius to the blind groove. In examples, the selected groove angular offset may be 61.5°.

In examples, the upper detent may be angularly separated from a lower detent by a selected detent angular offset e.g. when viewed along the longitudinal axis, the selected detent angular offset may be the smallest angle subtended by a radius from the upper 25 detent to the longitudinal axis 307 and a radius to the lower detent.

In examples wherein the through groove and the blind groove may be angularly separated by a selected groove angular offset and the upper detent may be angularly separated from a lower detent by a selected detent angular offset, the selected detent angular offset separation between the lower detent and the upper detent may be the same as the selected groove angular offset. Accordingly, circumferential alignment of the upper detent and the blind groove may additionally provide circumferential alignment of lower detent and the through groove.

-19 -Moving S608, the lower detent 308 axially relative to the through groove 314 thereby seating at least part of the lower detent 308 in the through groove 314 to restrain circumferential movement of the primary ring 304 relative to the retainer 301 (e.g. 5 configuring the seal head assembly to an second position).

Further embodiments are envisaged. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.

Claims

-20 -Claims 1. A seal head assembly comprising: a retainer configured to receive a primary ring therein and comprising an integrated upper detent for retaining said primary ring in the retainer; and, a primary ring with a through groove disposed in a radial edge thereof; wherein the through groove is arranged to allow the primary ring to move axially past the upper detent and the primary ring is rotatable in the retainer selectively to align the through groove and the upper detent wherein circumferential alignment of the upper detent with the groove permits axial movement of the primary ring relative to the retainer; and, wherein circumferential misalignment of the upper detent with the groove restrains axial movement of the primary ring relative to the retainer.
2. The seal head assembly of claim 1, wherein: the primary ring comprises a blind groove wherein: the blind groove is configured to receive at least a portion of the upper detent; and, the blind groove is circumferentially offset from the through groove; and; wherein the seal head assembly is configured such that, positioning at least a portion of the upper detent within the blind groove restrains circumferential movement of the 20 primary ring relative to the retainer.
3. The seal head assembly of any preceding claim, comprising: a thrust ring disposed within the retainer for holding the primary ring against the upper detent.
4. The seal head assembly of claim 3, wherein: the thrust ring is configured to be resiliently depressed by the primary ring to permit alignment of the blind groove with the upper detent.
5. The seal head assembly of any of claims 3 to 4, wherein the primary ring and the thrust ring are sized and arranged so that when the primary ring is in the retainer with the blind groove aligned with the upper detent the thrust ring and springs hold the upper detent in the blind groove. -21 -
6. The seal head assembly of any of claims 3 to 5, wherein: the retainer further comprises a lower detent for preventing rotation of the primary ring relative to the retainer.
7. The seal head assembly of claim 6 wherein the through groove in the primary ring is configured to receive the lower detent. primary ring
8. A contacting seal comprising a seal head assembly according to any of the preceding claims.
9. A method of assembly of a seal head assembly comprising: moving an integrated upper detent of a retainer into circumferential alignment with 15 a through groove of a primary ring; moving the integrated upper detent axially relative to the through groove; moving the primary ring relative to the retainer to circumferentially misalign the upper detent and the groove thereby to hold the primary ring in the retainer.
10. The method of claim 9, comprising: moving the upper detent into a blind groove in the retainer to thereby restrain circumferential movement of the primary ring relative to the retainer.
11. The method of any of claims 9 and 10, comprising: moving the through groove of the primary ring into circumferential alignment with a lower detent of the retainer.
12. The method of claim 11, comprising: moving the through groove of the primary ring axially relative to the lower detent 30 thereby seating at least pad of the lower detent in the through groove to restrain circumferential movement of the primary ring relative to the retainer.
13. The method of any of claims 9 to 12 to assemble the seal head assembly of any -22 -of claims 1 to 7.