GB2578782A

GB2578782A - A split gasket

Info

Publication number: GB2578782A
Application number: GB1818278.2A
Authority: GB
Inventors: Ingles Mood Geoffrey
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-11-09
Filing date: 2018-11-09
Publication date: 2020-05-27
Also published as: GB201818278D0

Abstract

Split gasket 101 comprises at least two arcuate sections 103, which are assembled end-to-end to form a uniformly-thick annular ring, and have ends 115, 117 that overlap partway along the lengths of sections 103. Gasket sections 103 may be made of a flexible material such as rubber, nylon, or polytetrafluoroethylene; and have frangibly-attached radially-extending tabs (551, Figure 9). The overlapping/overlapped portions 109, 107 may have deformable or adhesive coatings, and the overlapped/overlapping gasket section ends 115, 117 may have deformable protrusions extending from their surfaces. At least one of ends 115, 117 includes means for restraining relative sliding movement of gasket sections 103. Sections 103 may have axially-stepped shoulders 119, 121 respectively, each shoulder 119, 121 extending across the width of each gasket section 103; and sections 103 may taper from shoulders 119, 121 to ends 115, 117 respectively.

Description

A SPLIT GASKET

FIELD OF THE INVENTION

The invention disclosed herein relates to a split gasket used to fill the space between mating surfaces of objects to prevent leakage from or into the joined objects.

BACKGROUND TO THE INVENTION

A gasket is a mechanical seal which fills the space between two or more mating surfaces to prevent leakage from or into the joined objects while the gasket is under compression. A gasket is typically made from a material that deforms when compressed to a sufficient extent to fill the space between two mating surfaces to achieve a seal. Gaskets may be made from a variety of different materials and may be designed or optimised for a specific end use, the chemicals or environment it may be in contact with and other physical parameters.

A gasket, often also referred to as a "sealing washer", may be used to provide ingress protection at the joint of objects joined by a screw thread. For example, a gasket is used in electrical equipment to seal a threaded cable gland to the equipment to provide ingress protection that may be of a prescribed rating. A cable passes through a tubular and threaded cable gland that is connected to the wall of a junction box or other electrical equipment by way of a complementary thread defined therein.

Existing gaskets often fail or gradually lose their ingress protection rating due to an uneven distributed pressing force and/or stress relaxation and torque loss due to vibration, temperature changes and other environmental factors affecting the integrity of the gasket.

If a gasket has failed or a technician has neglected to install a gasket, the cable gland must be removed from the equipment. This entails the disconnection of cable cores from their terminals. The replacement or installation of a sealing gasket is a disruptive process and may be costly since the electrical cables cannot be used while a gasket is replaced or installed resulting in downtime.

The applicant is aware of split or segmental repair washers comprising two semi-circular sections or halves that are connected together so that the washer can be inserted onto a shaft between bearings or collars to fill up space and take up lost motion. These washers have a different function and do not seal a joint or provide ingress protection as is evident from the manner in which the sections are joined and the materials they are made of.

Split washers or gaskets which include interlocking or engagement formations that extend along the width of the ends of the sections have been proposed. These formations are generally defined in the minor end surfaces of the washer sections or halves. Complementary interlocking or engagement formations such as dovetail formations have been proposed which are weak and break from the action of the frictional forces applied to the gasket when a fastener is tightened onto the gasket in use. When a threaded cable gland is screwed home to connect it to equipment, the gasket it makes contact with experiences a frictional force which acts in a tangential direction to cause part of the segmental gasket to be forced out of position. This may result in complete or partial loss of the gasket's ingress protection and the relatively weak engagement lugs or dovetails may break. Furthermore, such engagement formations may be cumbersome to join together or assemble, particularly if the gasket is relatively small, such as an M20 gasket.

The preceding discussion of the background to the invention is intended only to facilitate an understanding of the present invention. It should be appreciated that the discussion is not an acknowledgment or admission that any of the material referred to was part of the common general knowledge in the art as at the priority date of the application.

SUMMARY OF THE INVENTION

In accordance with the invention, there is provided a split gasket comprising at least two arcuate gasket sections configured to be assembled end-to-end to form an annular ring of a substantially uniform thickness in an assembled condition, each gasket section having a pair of opposite ends shaped such that, in the assembled condition, each end axially overlaps an adjacent gasket section end partway along its length.

In the assembled condition, one end may axially overlap an adjacent gasket section end partway along its length, and the opposite end may be axially overlapped by the adjacent or another gasket section end partway along its length.

At least two axially stepped shoulders may extend across the width of each gasket section, spaced apart from each end and in opposite sides thereof. The gasket section may taper from each shoulder to the end. The axially stepped shoulders may be inclined and the ends bevelled to provide a complementary fit of the bevelled ends with the inclined shoulders of adjacent gasket sections in the assembled condition.

At least one of the ends may include restraining means for restraining relative sliding movement of the gasket sections in use.

At least two grooves may extend at least partially across the width of each gasket section, spaced apart from each end and in opposite sides thereof, the grooves being complementarily shaped to tongues on opposite sides of opposite ends of an adjacent gasket section for locating or nesting together the overlapping ends of adjacent gasket sections in the assembled condition. Each groove may extend across the width of the gasket section and between the axially stepped shoulder and a second axially stepped shoulder generally opposite thereto and the complementarily shaped tongue may extend from the second axially stepped shoulder to the end.

At least part of the surface of each gasket section end that overlaps or is overlapped by an adjacent gasket section end in the assembled condition may be coated with a deformable material. At least part of the surface of each gasket section end that overlaps or is overlapped by an adjacent gasket section end in the assembled condition may be coated with an adhesive. At least part of the surface of each gasket section end that overlaps or is overlapped by an adjacent gasket section end in the assembled condition may be coated with a deformable material, which deformable coating may be coated with an adhesive.

A protrusion of a deformable material may project from the surface of at least one of the gasket section ends which overlaps or is overlapped by an adjacent gasket section end in the assembled condition A tab may extend radially from each gasket section. The tab may be removably attached to the gasket section, preferably through a frangible connection.

The split gasket may comprising two C-shaped gasket sections that are greater than a semi-circle.

The gasket sections may be made of a flexible material. The flexible material may be rubber or a plastics material such as nylon or polytetrafluoroethylene (PTFE).

Any particular feature described herein may form part of an embodiment alone or in combination with any one or more features.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings: Figure 1 is a perspective view of a first embodiment of a split gasket; Figure 2 is a top view of the embodiment of Figure 1; Figure 3 is a side view of the embodiment of Figure 1; Figure 4 is a perspective view of the embodiment of Figure 1 in an assembled condition; Figure 5 is a side elevation of the embodiment of Figure 1 in an assembled condition; Figure 6 is a perspective view of a second embodiment of a split gasket; Figure 7 is a top view of the embodiment of Figure 6; Figure 8 is a side view of the embodiment of Figure 6; Figure 9 is a perspective view of a third embodiment of a split gasket; Figure 10 is a top view of the embodiment of Figure 9; Figure 11 is a side view of the embodiment of Figure 9; Figure 12 is a perspective view of the embodiment of Figure 9 in an assembled condition; Figure 13 is a side elevation of the embodiment of Figure 9 in an assembled condition; Figure 14 is a perspective view of a fourth embodiment of a split gasket; Figure 15 is a top view of the embodiment of Figure 14; Figure 16 is a side view of the embodiment of Figure 14; Figure 17 is a perspective view of a fifth embodiment of a split gasket; Figure 18 is a top view of the embodiment of Figure 17; Figure 19 is a side view of the embodiment of Figure 17; Figure 20 Figure 21 Figure 22 Figure 23 is a perspective view of a sixth embodiment of a split gasket; is a top view of the embodiment of Figure 20; is a side view of the embodiment of Figure 20; and is an illustration of an electrical termination in which two electrical cables are terminated in a junction box with the embodiment of the split gasket of Figure 9 shown in a disassembled condition in association with the electrical cable on the right and in an assembled condition and in use between a gland and the junction box in association with the electrical cable on the left.

DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS

A split gasket is provided which comprises at least two arcuate gasket sections configured to be assembled end-to-end to form an annular ring of a substantially uniform thickness. The gasket preferably comprises two gasket sections, but may also comprise three or more gasket sections. Each gasket section has a pair of opposite ends shaped such that, in the assembled condition, each end axially overlaps an adjacent gasket section end partway along its length. The opposite ends of each gasket section that overlap or are overlapped by those of an adjacent gasket section in the assembled condition are dimensioned to maintain a substantially uniform thickness about the circumference of the split gasket.

The pair of opposite ends of the same gasket section may have different but complementary side profiles that allow the ends of adjacent gasket section to overlap in an axial direction relative to the plane of the annular ring in the assembled condition whilst maintaining a uniform thickness of the assembly. The gasket sections may be completely interchangeable so that the manufacturing of the split gasket is thereby simplified.

The overlapping ends of the split gasket provide an interface of a substantial surface area between gasket sections and result in easy assembly and good leakage protection in use. The length of the overlapping ends may be selected to provide an optimum area of overlap and to obtain a particular degree of leakage protection. The larger the area of overlap, the more frictional resistance the overlapping surfaces provide to resist displacement of the gasket sections relative to each other during use.

At least one of the gasket section ends may include restraining means for resisting and restraining relative sliding movement of the gasket sections in use. The restraining means may be configured to resist relative movement or slippage of the gasket sections in one or more directions. The restraining means may restrain relative movement of the gasket sections about their length, width or a combination of these directions to avoid the overlapping ends from moving apart and/or shifting sideways in use. The restraining means may be one or more of a suitably shaped detent, a tongue and groove formation, an adhesive or roughened surfaces on overlapping gasket section ends which serve to increase the frictional coefficient of the interacting surfaces to be proportionally greater than the frictional coefficient of the outer surfaces of the gasket sections that make frictional contact with fasteners in use.

Where there are two gasket sections, each of these will be C-shaped and extend through more than 1800 to permit there to be an overlap at the ends. In other words, each of the gasket sections are greater than a semi-circle so that the gasket sections can flexibly locate over a tubular object such as gland, cable, tube or spigot. The degree to which the material of the gasket is able to flex or deform to permit insertion over a spigot or the like will also determine the maximum arc through which each gasket section can extend. The degree of flexibility of the material will also determine the maximum area of overlap between the overlapping ends.

It is preferred that, in the assembled condition, one end axially overlaps an adjacent gasket section end partway along its length, and the opposite end is axially overlapped by the adjacent or another mutually adjacent gasket section end partway along its length. Opposite sides or faces of opposite ends of each gasket section are overlapped by the ends of adjacent gasket sections and as a result the relatively thinner or weaker portion of the gasket section is driven against the relatively stronger and main portion of each gasket section when a twisting force is applied to the gasket in use. It has been found that when the ends of the gasket section overlap on opposite sides or faces of the split gasket, one end of the split gasket will not be forced apart when a twisting force is applied to the split gasket in use.

In one embodiment, at least two axially stepped shoulders extend across the width of each gasket section, spaced apart from each end and in opposite sides thereof The shoulders are arranged to operatively engage or abut against the end surface of an adjacent gasket section end in the assembled condition.

The gasket section may taper from each shoulder to the end so that the thickness of the gasket section gradually decreases from the shoulder to the end. Alternatively, the gasket section may taper from the ends to the shoulders so that the overlapping ends may clip together in the assembled condition, providing a detent to hold the overlapping ends of the gasket sections in the assembled condition in use.

The axially stepped shoulders of a gasket section may be inclined and the ends of an adjacent gasket section correspondingly bevelled to provide a complementary fit of the oppositely inclined end surface of the bevelled end with the inclined shoulders in the assembled condition. The inclination of the stepped shoulders that operatively engage oppositely inclined ends of an adjacent gasket section in the assembled condition is thought to provide further ingress protection, especially when overlapping ends taper from the shoulders to the ends.

In a preferred embodiment, at least two grooves may extend at least partially across the width of each gasket section, spaced apart from each end and in opposite sides thereof Complementary tongues are provided in the adjacent gasket section ends to assist in locating the overlapping ends of adjacent gasket sections together in the assembled condition before fastening a fastener to the assembled split gasket. The complementary tongue and groove formations help to resist the radially outward displacement of the ends during the fastening of a threaded fastener onto the split gasket. It has been found that the cooperating tongue and groove provide resistance to the movement of the overlapping ends relative to each other when frictional forces that act in a tangential direction are applied to the gasket in use. As a result, the ends are less likely to be displaced and the split gasket is more likely to stay intact after fastening.

The grooves need not extend across the entire width of the gasket section. The groove at one end of the gasket section may be interrupted by one or more protrusions, ribs or other formations, with one or more complementary recesses, channels or other complementary formations in the opposite end that are arranged to cooperate with the one or more protrusions, ribs or other formations of an adjacent gasket section. Such additional complementary formations on opposite sides of a gasket section may assist in increasing the length of any potential leak path at the interfaces between gasket sections.

Alternatively, the groove at either one of the ends of the gasket section may be interrupted by one or more protrusions, ribs or other formations made of a relatively softer and more deformable material than the ends of the gasket section. The protrusion(s), rib(s) or other formation(s) may be made of a suitably deformable material so as to yield and deform between the relatively harder overlapping ends when the overlapping ends are forced together in use.

Such a deformable protrusion or other formation projecting from the surface of a gasket section end that overlaps or is overlapped by an adjacent gasket section end may be included to improve the seal between the overlapping ends, thereby improving the leakage protection afforded by the split gasket in use. For example, one end of the gasket section may include a rib that is made of a deformable material in which case the opposite end need not include a complementarily shaped channel. The opposite end, may include a channel that is wider than the rib so as to accommodate the lateral deformation of the rib when the overlapping ends of the split gasket are pressed together in use. The depth of the channel would be selected to ensure that the channel is completely filled by the deformed rib to provide an improved seal between the overlapping ends.

At least part of the surface of each gasket section end which overlaps or is overlapped by an adjacent, interchangeable gasket section end in the assembled condition may be coated with a material that yields when a mechanical force is applied to it, such as a deformable or relatively softer material than that which the gasket section and the objects that are joined are made of.

The gasket section may be made of a relatively hard material for structural integrity, with the overlapping surfaces or selected parts thereof coated in a softer and deformable material to improve the seal between overlapping gasket section ends or across the split At least part of the surface of each gasket section end that overlaps or is overlapped by an adjacent gasket section end in the assembled condition may be coated with an adhesive to adhere gasket sections together in the assembled condition. The adhesive may be used for ease of assembly and to maintain the sections in an assembled condition in use, or it may be selected for its ability to assist in resisting the displacement and further sealing the overlapping ends of gasket sections to make it impervious and add to the impenetrability of the split gasket in use. The part of the surface coated with a deformable material may be coated with an adhesive as well.

In one embodiment of the split gasket, the surface or part thereof on opposite sides of both ends of the same gasket section are coated with a deformable material or an adhesive or first with a deformable material and then with an adhesive. Accordingly, there will be two layers of deformable material and/or two layers of adhesive at each interface between overlapping ends.

The deformable material used to coat or create formations on the surfaces of the overlapping ends may be rubber or a relatively soft plastic.

A further alternative is for the entire gasket section to be made of a flexible and/or deformable material. The flexible material may be rubber. A wide range of elastomers can be used, such as neoprene, nitrile, EPDM and natural rubber. Alternatively, the flexible material may be a plastics material such as nylon or polytetrafluoroethylene (PTFE).

A tab may extend radially from each gasket section. The tabs allow a user to hold the gasket sections while fitting them. The tab may be removably attached to the gasket section by a frangible connection, such as a line of weakness or the like, so that the tabs can be snapped or torn off after the gasket is fitted.

The gasket sections may be made by moulding it from a mouldable material such as a plastics material.

A first embodiment of a split gasket (101) is shown in Figures 1 to Sand consists of two arcuate gasket sections (103). The gasket sections (103) are interchangeable and therefore the features of the first gasket section are also present in the second gasket section and like reference numerals are used to refer to the like features on both gasket sections.

The gasket sections (103) are annular disc-shaped, each having generally flat first and second major opposed surfaces (107, 109) and a curved, outer minor surface (111) and curved, inner minor surface (113). Each arcuate gasket section is longer circumferentially than one half of the annular ring formed when the sections (103) are assembled together. Each gasket section (103) has a pair of opposite ends (115, 117) shaped such that, in the assembled condition, one end (115) overlaps an adjacent gasket section end (117) partway along its length, and the opposite end (117) is overlapped by the adjacent gasket section end (115) partway along its length.

Thus, at one end (115) the first major surface (107) is overlapped by, or lies beneath, the second major surface (109) of the adjacent gasket section end (115), with the converse occurring at the opposite end (117). The ends (115, 117) can be said to overlap in an axial direction or a direction which corresponds to the axis about which the gasket is rotated.

Two axially stepped shoulders 019, 121) extend across the width of each gasket section (103), spaced apart from each end and in opposite sides thereof. The first axially stepped shoulder (119) is defined in the first major surface (107) spaced from the first end (115) and the second axially stepped shoulder (121) is defined in the second major surface (109) spaced from the second, opposite end (117). The generally flat end portions (123, 125) extending from the shoulders (119, 121) that overlap in the assembled condition have a thickness that is about half the thickness of the central portion (127) of the gasket section (103).

The split gasket (101) is shown in the assembled condition in Figures 4 and 5. The C-shaped gasket sections (103) are assembled end-to-end to form an annular ring of a substantially uniform thickness. A first end surface (129) of the end (115) abuts and operatively engages the shoulder (121) of the adjacent gasket section. The second end surface (131) of the end (117) abuts and operatively engages the shoulder (119) of the first gasket section.

A second embodiment of a split gasket (201) is shown in Figures 6 to 8. The second embodiment includes two gasket sections (203) which are interchangeable. The second embodiment has many features in common with the first embodiment of Figures 1 to 5. A first axially stepped shoulder (219) is defined in a first major surface (207) spaced from the first end (215) and a second axially stepped shoulder (221) is defined in the second major surface (209) spaced from the second, opposite end (217). However, in this embodiment, each gasket section (203) tapers from each shoulder (219, 221) to the end. The end portions (223, 225) extending from the shoulders (219, 221) and which overlap when gasket sections (203) are assembled, gradually decrease in thickness to the ends (215, 217). Each end (215, 217) has a substantially rectangular end surface (229, 231) that is complementarily sized to the shoulders (219, 221) of adjacent gasket sections (203) and respectively abut the shoulders (219, 221) in the assembled condition.

A third embodiment of a split gasket (301) which includes two interlocking gasket sections (303) is shown in Figures 9 to 13. In this embodiment, grooves (333, 335) extends across the width of each gasket section spaced apart from each end and in opposite sides thereof. A first groove (333) is provided in a first major surface (307) spaced from the first end (315) and a second groove (335) is provided in the second major surface (309) spaced from the second, opposite end (317). Each groove (333, 335) extends between a first axially stepped shoulder (319, 321) and a second axially stepped shoulder (337, 339) generally opposite thereto so as to face the first axially stepped shoulder (319, 321). Each groove (333, 335) is spaced from each end (315, 317) by a distance that is equal to the width of the groove itself, so that the groove is adjacent the complementary tongue (341, 343) which is configured or shaped to nest in a groove (333, 335) of an adjacent gasket section (303). Each tongue (341, 343) extends from the second axially stepped shoulder (337, 339) to the end (315, 317).

Each gasket section (303) tapers from the first axially stepped shoulders (319, 321) to the ends (315, 317). Accordingly the bottom faces (345, 349) or webs of the grooves (333, 335) and the faces (347, 351) of the cooperating tongues (341, 343) are inclined relative to the major opposed sides (307, 309) and the plane of the annular ring formed by assembled gasket sections (303).

In the assembled condition of the split gasket (301) shown in Figures 12 and 13, a first end surface (329) of the end (315) operatively engages the shoulder (321) of the adjacent gasket section whilst the second, opposite shoulder (337) operatively engages the second shoulder (339) of the adjacent gasket section with the tongue (341) nesting in the groove (335) of the adjacent gasket section. At the opposite end, the second end surface (331) of the end (317) operatively engages the shoulder (319) of the adjacent gasket section (303). At the same time the shoulder (339) operatively engages the second shoulder (337) of the adjacent gasket section, so that the tongue (343) nests in the groove (333) of the adjacent gasket section. The cooperating tongue and groove formations interlock the gasket sections in the assembled condition so that they resist being pulled apart or displaced rotationally or laterally relative to each other.

A fourth embodiment of a split gasket (401) is shown in Figures 14 to 16. In this embodiment, the gasket sections (403) include first shoulders (419, 421) and second shoulders (437, 439) which are oppositely inclined or sloped relative to the central axis of the annular ring formed by assembled gasket sections (403). The ends (415, 417) are correspondingly bevelled to provide a complementary fit of the bevelled ends (415, 417) having inclined end surfaces (429, 431) with the inclined first, shoulders (419, 421) of adjacent gasket sections (403) in the assembled condition. The second shoulders (437, 439) are sloped to provide a complementary fit of the second shoulders (437, 439) with the inclined second, shoulders (437, 439) of the adjacent gasket section (403) in the assembled condition. In this manner, the grooves (433, 435) defined between the shoulders are complementarily shaped to the tongues extending between the second shoulders (437, 439) and the ends (415, 417). The gasket sections (403) taper in terms of their thickness from the first shoulders (419, 421) to the ends (415, 417). Since the gasket section ends taper, the second shoulders (437, 439) extend generally transverse to the inclined, tapered faces of the grooves (433, 435) and tongues (441, 443). The inclined shoulders and bevelled ends provide complementary grooves and tongues with sloped edges which may be easier to assemble than those with normally extending shoulders and ends. They are also thought to further improve the ingress or leakage protection provided by the split gasket in use.

A fifth embodiment of a split gasket (501) is shown in Figures 17 to 19. This embodiment is similar to the third embodiment shown in Figures 9 to 13, but further includes tabs (551) extending radially outwardly from the central portions (527) of the gasket sections (503) and which are integrally formed therewith. The tabs (551) are equally spaced from the ends (515, 517).

The tabs (551) provide grips which can assist a user in locating and holding them together in use. The tabs (551) can be made to include a line of weakness (not shown), such as through sulcations in the material, extending along the circumference of each split gasket (501). This may enable the tab to be removed once the gasket has been secured in position.

A sixth embodiment of a split gasket (601) comprising two interchangeable, interlocking gasket sections (603) is shown in Figures 20 to 22. This embodiment is similar to that of Figures 9 to 13, but one end (615) of the gasket section (603) includes an elongate rib (657) which extends centrally from a first axially stepped shoulder (619) to the end (615). The opposite end (617) includes a complementary, elongate channel (667) on the opposite side of the gasket section (603) extending between an axially stepped shoulder (621) and the end (617). The channel (667) is arranged to receive the rib (657) of an adjacent gasket section (603) when the gasket sections are assembled end-to-end. The complementary ridge (657) and channel (667) formations defined in opposite sides of opposite gasket section ends (615, 617) assist in making a potential leak path between gasket sections longer.

In use, the gasket sections are assembled around a member, such as a threaded tube, spigot or the like, so as to wholly surround the member in a radial plane. The member may be a tube or fitting in which one or more cables run so that the cables need not be removed from an electrical termination and can continue to be connected and used in association with electrical equipment while the split gasket is assembled around the tube or fitting. A fastener, such as a gland, may be used to directly fasten the gasket to the equipment, thereby compressing it to a sufficient extent so that it deforms to seal the joint. In the event that the fastener is a threaded fastener that is fastened onto the equipment having a complementary thread, the twisting or rotary force applied to the fastener is frictionally transferred to the split gasket without compromising the ingress or leakage protection afforded thereby by causing the sections to split or move apart.

Figure 23 illustrates the manner in which the split gasket (301) shown in Figures 9 to 13 may be assembled and fitted between a gland (703) in which an electrical cable (707) is supported and a junction box (705) that receives the cable (707). The gland (703) has a threaded connection to and through a wall (711) of the junction box (705). The tubular gland (703) may be disconnected from the junction box (705) or just loosened and displaced a small distance so that a failed gasket may be removed from the joint between the cable gland (703) and the junction box (705). The gasket sections (303) are then assembled end-to-end about the gland (703). The split gasket (301) are located together and interlocked by the complementary tongue and groove formations in the overlapping ends of the gasket sections (303) so as to resist sliding movement in a radial direction relative to each other.

In this example, the gasket sections (303) can be interlocked over the cable (707) and then slid over the end of the gland (703). Alternatively, being made of a flexible material, in this embodiment nylon, the ends of each section (303) can be moved away from each other to enable the section to be located over the gland and then in cooperation with the other section. The ends of each section (303) may be pressed against the threaded end of the gland (703) so that the ends of each section (303) deflect outward and away from each other to allow the gasket section (303) to snap over the end of the gland (703).

The assembled gasket sections (303) form a complete annular ring of a substantially uniform thickness that wholly surrounds the cable, and in this illustration also the external thread (709) of the cable gland (703). The cable gland is fastened to the internal thread of the junction box (705) and the split sealing gasket is compressed between the cable gland (703) and the wall (711) of the junction box (705) to form an ingress protection (IP) seal.

It will be understood by those skilled in the art that the split gasket may be used between any two objects, in particular between a fastener and another component, enclosure or equipment to provide protection against material ingress or leakage from the objects.

In the event that the fastener is a gland, the split gasket may be fastened in one of two ways: (i) the external thread of the gland may be passed through an aperture defined in a wall of the equipment and the gland secured in place using a locknut; or (ii) the threaded gland may be connected to a complemental threaded wall. The split gasket described herein, is particularly effective in providing ingress or leakage protection for glands secured directly to a threaded wall or other threaded object. When the gland comes into contact with the split gasket, friction between the gland and the split gasket acts to urge a part of the gasket section out of position.

Embodiments of the split gasket described herein provide improved resistance to the action of the frictional forces. The overlapping ends of the gasket sections may include tongue and groove formations or may be otherwise modified to resist the action of the frictional forces so that the ends of the split gasket are not displaced radially outward. The coefficient of friction at the interface between the overlapping ends needs to be proportionally higher than the coefficient of friction at the interface between the fastener and the split gasket to resist displacement of the ends when a force in a tangential direction is applied to the ends. Such gasket sections are more likely to remain in one piece after being secured in place between a threaded fastener and another object.

The split gasket used in association with a cable gland provides ingress protection, in particular protection against the ingress of water or other liquids that may cause shorting of the electrical conductors. Since the split gasket may be installed whilst the cables are in use, the replacement of failed gaskets during maintenance or the fitting of new gaskets during construction of electrical equipment need not result in downtime.

It will be appreciated by those skilled in the art that the split gasket may be shaped differently to the embodiments shown in the accompanying figures. The split gasket may for example be cylindrical like an 0-ring. The split gasket may be of any suitable size depending on its application, and may also be made to standard gasket or washer sizes with reference diameters M16, M20, M25, M32, M40, M50, M63, M75 or M90.

The split gasket may be made of a suitably flexible material and dimensioned to provide a degree of flexibility that allows the gasket sections to be fitted to a member. A flexible arcuate gasket section has an opening or discontinuity between the gasket section ends that is able to increase in size when the ends are forced apart to permit the member to pass through the opening and locate in the central cavity of the arcuate gasket section.

Throughout the specification and claims unless the contents requires otherwise the word 'comprise' or variations such as 'comprises' or 'comprising' will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Claims

CLAIMS: 1. A split gasket comprising at least two arcuate gasket sections configured to be assembled end-to-end to form an annular ring of a substantially uniform thickness in an assembled condition, each gasket section having a pair of opposite ends shaped such that, in the assembled condition, each end axially overlaps an adjacent gasket section end partway along its length. 2. 3. 4. 5. 6. 7.
A split gasket as claimed in claim 1, wherein, in the assembled condition, one end axially overlaps an adjacent gasket section end partway along its length, and the opposite end is axially overlapped by the adjacent or another gasket section end partway along its length.
A split gasket as claimed in claim 2 in which at least two axially stepped shoulders extend across the width of each gasket section, spaced apart from each end and in opposite sides thereof.
A split gasket as claimed in claim 3, wherein the gasket section tapers from each shoulder to the end.
The split gasket as claimed in claim 3 or claim 4 in which the axially stepped shoulders are inclined and the ends are correspondingly bevelled to provide a complementary fit of the bevelled ends with the inclined shoulders of adjacent gasket sections in the assembled condition.
The split gasket as claimed in any one of the preceding claims in which at least one of the ends includes restraining means for restraining relative sliding movement of the gasket sections in use.
The split gasket as claimed in any one of claims 2 to 6 in which at least two grooves extend at least partially across the width of each gasket section, spaced apart from each end and in opposite sides thereof, the grooves being complementarily shaped to tongues on opposite sides of opposite ends of an adjacent gasket section for locating the overlapping ends of adjacent gasket sections in the assembled condition.
The split gasket as claimed in claim 7 in which each groove extends across the width of the gasket section and between the axially stepped shoulder to a second axially stepped shoulder generally opposite thereto and the complementarily shaped tongue extends from the second axially stepped shoulder to the end.
9. The split gasket as claimed in any one of the preceding claims in which at least part of the surface of at least one gasket section end which overlaps or is overlapped by an adjacent gasket section end in the assembled condition is coated with a deformable material.
10. The split gasket as claimed in any one of the preceding claims in which at least part of the surface of at least one gasket section end which overlaps or is overlapped by an adjacent gasket section end in the assembled condition is coated with an adhesive.
11. The split gasket as claimed in any one of the preceding claims in which a protrusion of a deformable material projects from the surface of at least one of the gasket section ends which overlaps or is overlapped by an adjacent gasket section end in the assembled condition.
12. The split gasket as claimed in any one of the preceding claims in which a tab extends radially from each gasket section.
13. The split gasket as claimed in claim 12 in which the tab is removably attached to the gasket section.
14. The split gasket as claimed in claim 13 in which the tab is removably attached to the gasket section with a frangible connection.
15. The split gasket as claimed in any one of the preceding claims, comprising two C-shaped gasket sections that are greater than a semi-circle.
16. The split gasket as claimed in any one of the preceding claims, wherein the gasket sections are made of a flexible material.
17. The split sealing gasket as claimed in claim 16, wherein the flexible material is rubber or a plastics material.
18. The split gasket as claimed in claim 17, wherein the plastics material is nylon or polytetrafluoroethylene.