GB2624198A

GB2624198A - Ground surface access assemblies

Info

Publication number: GB2624198A
Application number: GB2216721.7A
Authority: GB
Inventors: Turner Barry; John Gibson Simon
Original assignee: Wrekin Holdings Ltd
Current assignee: Wrekin Holdings Ltd
Priority date: 2022-11-09
Filing date: 2022-11-09
Publication date: 2024-05-15
Also published as: GB202216721D0

Abstract

A ground surface access assembly or manhole cover 10 comprises a ground surface access assembly component 12. The component includes a seating surface region 18. The seating surface region includes a seating surface 30, which, in an assembled condition, contacts a seating surface of a second ground surface access assembly component to transmit, in use, load therethrough. The seating surface region comprises a seating surface material, which comprises a metal having a relatively high electrode potential. The component includes an anti-corrosion formation which comprises an anti-corrosion material. The anti-corrosion material comprises a metal having a relatively low electrode potential. The component is arranged to permit electrically conductive communication between the seating surface material metal and the anti-corrosion material metal.

Description

Ground Surface Access Assemblies

Technical Field

The present invention relates to ground surface access assemblies.

Background

Conventionally, ground surface access assemblies comprise a relatively small number of components: usually, a frame defining an opening and one or more covers which locate onto the frame in or above the opening. The or one or each cover is openable or removable to permit access to underground services via the opening.

Both the frame and the cover(s) include seating surfaces and, generally, in an assembled condition, the frame and the covers contact each other via the seating surfaces, which transmit load therethrough.

Conventionally, the components are formed of cast iron. Cast iron is relatively resistant to corrosion and is usually coated with a non-porous coating such as paint or bitumen for increased corrosion resistance. However, at the contact areas between the components, and in particular at the seating surfaces, the non-porous coating can wear away due to the combination of corrosion and relative movement under trafficking. The corrosion causes the formation of weakly adhered corrosion products.

Until recently, ground surface access assemblies were designed to permit water to flow freely therethrough and the surfaces would dry out between rainfall events, so that the deterioration described above was relatively slow.

However, environmental change and increased urbanisation has led to an increase in flooding events. To counteract this, measures have been taken to slow the ingress of surface water into water courses. These measures have included the use of sealed ground surface access assemblies which comprise a seal plate which is located below the cover(s) to prevent or reduce surface water entry into the underground services.

A consequent effect of this is to increase the time in which the cover and frame seating surfaces are immersed in water, which, combined with the high oxygenation and salts present in the shallow pool of water, creates an aggressive electrolyte for corrosion conditions at the seating surfaces. This situation is aggravated by removal of the resulting poorly-adhered corrosion products from the seating surfaces as a direct result of movement of the covers relative to the frame under the influence of traffic and the flushing effect of the water.

This corrosion-removal mechanism then produces fresh seating surfaces which are vulnerable to further corrosion due to the loss of the corrosion layer. The process is cyclic under traffic loads and results in more rapid deterioration of the cover-to-frame seating surfaces than hitherto experienced, which can eventually lead to "cover drop" in which, over time, the cover sinks in height relative to the frame. This presents a serious hazard to road users and can result in the ground surface access assembly requiring replacement.

In this specification, the terms inner, outer, inwardly and outwardly, when used in relation to the frame, are used with respect to the opening, which is inward of the frame, and the terms upward and downward are used in relation to the in use orientation of a ground surface access assembly, in which downward means down into the ground.

In this specification the term "cover" is used to include covers which have a substantially solid upper surface and those which might be called gratings, having an upper surface defining a plurality of waterway apertures.

In chemistry in general and in this specification, the terms "electrode potential" and "noble" are used to classify metals in relation to their reducing strength, ie, their readiness to gain electrons or lose positive metal ions, and hence as to how they will perform in a galvanic cell. In a galvanic cell comprising two electrodes in an electrolyte solution with each electrode formed of a different metal, the metal with the lower electrode potential (less noble) will lose metal ions to the solution and thus undergo material loss, while the metal with the higher electrode potential (more noble) will attract the metal ions and become plated with the less noble metal.

Statements of Invention

According to a first aspect of the present invention, there is provided a ground surface access assembly, the assembly including a component, the component comprising a seating surface region, the seating surface region including a seating surface which, in an assembled condition, contacts a seating surface of a second ground surface access assembly component to transmit, in use, load therethrough, the seating surface region comprising a seating surface material; the seating surface material comprising a metal having a relatively high electrode potential; the component including an anti-corrosion formation, the anti-corrosion formation comprising an anti-corrosion material, the anti-corrosion material comprising a metal having a relatively low electrode potential; the component being arranged to permit electrically conductive communication between the seating surface material metal and the anticorrosion material metal.

Possibly, in use and in a galvanic condition, the seating surface material metal and the anti-corrosion material metal operate as a galvanic cell. Possibly, in use and in the galvanic condition, the galvanic cell comprises the seating surface material metal, the anti-corrosion material metal, and an electrolyte which extends therebetween. Possibly, the electrolyte comprises water.

Possibly, in the galvanic condition, the seating surface material metal and the anti-corrosion material metal are exposed to and in contact with the electrolyte.

Possibly, the seating surface material metal and the anti-corrosion material metal metals are in direct (metal to metal) contact.

Possibly, the component has a component surface area.

Possibly, the component includes a body, which may be formed by casting. Possibly, the body has a surface, which may have a surface area, which may comprise a major part of the component surface area.

Possibly, the body is formed of the seating surface material.

Possibly, the anti-corrosion formation has a surface, which may have a surface area, which may comprise a minor pad of the component surface area.

Possibly, the anti-corrosion formation surface comprises part of, and/or overlaps, or is adjacent to, or abuts, the seating surface. Possibly, the anticorrosion formation surface is located a minimum surface distance from the seating surface. Possibly, the minimum surface distance is no more than 70mm, desirably no more than 60mm and optimally no more than 50mm.

Possibly, the seating surface has a seating surface area. Possibly, the ratio of the surface area of the seating surface to the surface area of the anticorrosion formation surface area is no more than 20:1, desirably is no more than 10: 1 and optimally is no more than 5:1.

Possibly, the anti-corrosion formation is located on and, possibly, covers part of the surface of the body.

Possibly, the body defines a recess, in which the anti-corrosion formation is located. Possibly, the anti-corrosion formation comprises an anti-corrosion insert member.

Possibly, the component comprises a fastener for fastening the insert member in the recess.

Possibly, the insert member and/or the body include securing formations (possibly threaded formations) to secure the insert member in the recess.

Possibly, the insert member is in the form of a screw or bolt.

Possibly, the anti-corrosion formation surface is level or flush with the body surface.

Possibly, the anti-corrosion formation has a depth, which may be no more than 10m m, and desirably is no less than 2mm. Possibly, the recess has a depth, which may be substantially the same as or greater than the depth of the anti-corrosion formation.

Possibly, the body includes a body surface coating, which may substantially cover the body surface, possibly including the seating surface. The body surface coating may be formed of a barrier material, which may comprise paint and/or bitumen.

Possibly, the anti-corrosion formation surface is uncoated.

Possibly, the anti-corrosion formation surface does not comprise part of the seating surface and is uncoated.

Possibly, the anti-corrosion formation includes a surface coating, which may be formed of a barrier material and may be formed at the same time as, and possibly of the same material as, the surface coating of the body.

Possibly, the anti-corrosion formation surface comprises part of the seating surface and is coated with the surface coating.

Possibly, the anti-corrosion material comprises a settable material which is movable from a flowable condition to a set condition by a hardening process.

Possibly, the anti-corrosion material is located on or in the body in the flowable condition. Possibly, the hardening process moves the settable material to the set condition with the anti-corrosion material located on or in the body.

Possibly, the body includes a wear and/or location insert which locates in a recess defined by the body and is fixed in the recess by the settable material. Possibly, the wear and/or location insert comprises the seating surface region and may include the seating surface. The wear and/or location insert may be formed of a material which comprises the seating surface material.

Possibly, the anti-corrosion material provides a barrier between the metals of the wear and/or location insert and the body.

Possibly, the component includes a plurality of anti-corrosion formations.

Possibly, the component includes a plurality of seating surfaces. Possibly, the anti-corrosion formations are arranged in sets. Possibly, one set is associated with the or each seating surface. Possibly, each set includes at least one anticorrosion formation, and, desirably, at least two anti-corrosion formations.

Possibly, the ratio of the surface area of the respective seating surface to the total of the anti-corrosion formation surface areas of the associated one set is no more than 20:1, desirably is no more than 10: 1 and optimally is no more than 5:1.

Possibly, the component comprises a frame, a cover or a grating of the ground surface access assembly.

Possibly, the assembly comprises a plurality of the ground surface access assembly components. Possibly, one of the components is a frame and one of the components is a cover.

According to a second aspect of the present invention, there is provided a method of improving corrosion resistance and/or reducing wear of a ground surface access assembly, the method including providing a ground surface access assembly, the assembly including a component, the component comprising a seating surface region, the seating surface region including a seating surface which, in an assembled condition, contacts a seating surface of a second ground surface access assembly component to transmit, in use, load therethrough, the seating surface region comprising a seating surface material; the seating surface material comprising a metal having a relatively high electrode potential; the component including an anti-corrosion formation, the anti-corrosion formation comprising anti-corrosion material, the anti-corrosion material comprising a metal having a relatively low electrode potential; the component being arranged to permit electrically conductive communication between the seating surface material metal and the anticorrosion material metal.

Possibly, the assembly includes any of the features described in any of the preceding statements or following description Possibly, the method includes any of the steps described in any of the preceding statements or following description.

Figures Embodiments of the present invention will now be described, by way of example only, and with reference to the accompanying drawings, in which:-Fig. 1 is an exploded perspective view of a ground surface access assembly; Fig. 2 is a relatively enlarged detail of a frame mounting indicated by box II in Fig. 1 showing anti-corrosion formations located embedded below a seating surface of a frame of the ground surface access assembly; Fig. 3 is a relatively enlarged detail of a cover mounting indicated by box III in Fig. 1 showing anti-corrosion formations located below a seating surface of a cover of the ground surface access assembly; Fig. 4 is a plan view of the assembly; Fig. 5 is a side cross-sectional view of the assembly as indicated by arrows V-V; Fig. 6 is a relatively enlarged detail of a mounting indicated by box VI in Fig. 5 showing some of the seating surfaces and the anti-corrosion inserts with the assembly in an assembled condition; Fig. 7 is a diagrammatic scrap side cross-sectional view of the frame mounting after a period of use and immersed in water; Figs. 8A and 8B are diagrammatic scrap side cross-sectional views of a frame mounting of a second embodiment, with Fig. 8A showing the frame mounting in an initial condition before use and Fig. 8B showing the frame mounting after a period of use; Fig. 9 is a diagrammatic scrap side cross-sectional view of a frame mounting of a third embodiment; and Fig. 10 is a diagrammatic scrap side cross-sectional view of a frame mounting of a fourth embodiment.

In the drawings, where multiple instances of the same or similar features exist, only a representative one or some of the instances of the features have been provided with numeric references for clarity.

Description

Figs. 1 to 7 show a ground surface access assembly 10. The ground surface access assembly 10 comprises a plurality of ground surface access 5 assembly components 12.

Each component 12 includes a seating surface region 18. Each seating surface region 18 includes a seating surface 30, which, in an assembled condition, contacts a seating surface 30 of a second ground surface access assembly component 12, to transmit, in use, load therethrough.

Each seating surface region 18 comprises a seating surface material, which comprises a metal having a relatively high electrode potential.

Each component 12 includes an anti-corrosion formation 26. Each anti-corrosion formation 26 comprises an anti-corrosion material, which comprises a metal having a relatively low electrode potential.

Each component 12 is arranged to permit electrically conductive 20 communication between the seating surface material metal and the anticorrosion material metal.

Each component 12 has a component surface area, and includes a body 22, which is formed by casting and which has a surface 24 which has a body 25 surface area which comprises a major part of the component surface area.

In one example, the body surface area could be greater than 50% of the component surface area, could desirably be greater than 75% of the component surface area and optimally could be greater than 90% of the component surface 30 area.

The anti-corrosion formation 26 is associated with the seating surface 30 and has a surface 28 which has a surface area which comprises a minor part of the component surface area.

In the example shown, the body 22 is formed of the same material as the seating surface material and is integral therewith.

In the example shown, each component 12 includes a plurality of seating surfaces 30 and a plurality of anti-corrosion formations 26. Each of the seating surfaces 30 has one anti-corrosion formation 26 associated therewith. In the example shown, each of the anti-corrosion formations 26 is associated with one seating surface 30.

The anti-corrosion formations 26 are arranged in sets 80, with one set 80 being associated with each seating surface 30. Each set 80 includes at least one anti-corrosion formation 26, and, desirably, at least two spaced apart anticorrosion formations 26. In the example shown, each set 80 includes two anticorrosion formations 26.

In one example, the ratio of the surface area of the respective seating surface 30 to the total of the anti-corrosion formation surface areas of the one associated set 80 is no more than 20:1, desirably could be no more than 10: 1 and optimally could be no more than 5:1.

The Applicant has found that, as the ratio of the surface area of the respective seating surface 30 to the total of the anti-corrosion formation surface areas of the one associated set 80 reduces (ie the size of the anti-corrosion formation surfaces 28 increase relative to the seating surface 30) the effectiveness of the invention in reducing or preventing corrosion increases.

In the example shown, one of the components 12 is a frame 14 and another of the components 12 is a cover 16. In describing the features of the invention herein, the features will be described in relation to a generalised component 12 and the skilled person will understand that the description applies similarly and separately to respective features of the frame 14 and the cover 16. In the figures, respective reference numerals have been given the suffix "C" when relating to the cover 16 and "F" when relating to the frame 14.

The ground surface access assembly 10 includes a plurality of mountings 64. Each mounting 64 includes a frame mounting 66 (comprising part of the frame 14) and at least one cover mounting 68 (comprising part of the or one of the covers 16). Each frame mounting 66 includes one of the seating surfaces 30F of the frame 14. The or each cover mounting 68 includes one of the seating surfaces 30C of the or one of the covers 16.

Each of the anti-corrosion formation surfaces 28 is located a minimum surface distance 32 from the seating surface 30, the surface distance being the distance along the surface of the component 12. In one example, the minimum surface distance 32 could be no more than 70mm, desirably no more than 60mm and optimally no more than 50mm.

The Applicant has found that, for the formation, effectiveness and efficiency of a galvanic cell, the surface distance 32 should be minimised and it is advantageous if the anti-corrosion formation surface 28 comprises part of, and/or overlaps, or is adjacent to, and/or abuts, the associated seating surface 30.

In the example shown, each anti-corrosion formation 26 comprises an anti-corrosion insert member 52 and the body 22 defines a plurality of recesses 38. Each insert member 52 locates in one of the recesses 38, so that the surface 28 of the insert member 52 is level or flush with the body surface 24.

Each insert member 52 has a depth 44, may be no more than lOmm, desirably no less than 2mm. Each recess 38 has a depth 46, which is substantially the same as or greater than the depth 44 of the respective insert member 52.

The body 22 includes a surface coating 40, which substantially covers the whole of the body surface 24 including the seating surface 30. The surface coating 40 is formed of a barrier material, which may comprise paint and/or bitumen. In the case in which the seating surface 30 is coated (see for reference Fig. 8A of the second embodiment), the seating surface region 18 includes a part 40S of the surface coating 40 at the seating surface 30 and the seating surface material below the surface coating part 40S.

As shown in Fig. 7, the anti-corrosion formation surface 28 does not comprise pad of the seating surface 30 and is left uncoated.

In use In an initial condition, when newly installed and before use, the surface coating 40 of the body 22 is substantially complete and the material of the body 22 is protected from corrosion. Over time, with weathering and trafficking, a part of the surface coating 40 comprising the seating surface region 18 wears away, exposing a bare (uncoated) metal part 56 of the body 22, comprising the seating surface material metal.

In a conventional component, the body bare metal part 56 would be subjected to the cycles of corrosion and trafficking described earlier, leading to more of the surface coating 40 on the seating surface 30F being eroded and to material loss from the body bare metal part 56, which cycles are exacerbated in wet conditions.

In contrast, in the component 12 of the invention in use, the differing electrode potentials of the metals of the body 22 and the anti-corrosion formations 26 permit a galvanic cell 60 to form. This occurs as follows.

It will be noted, firstly, that in the component 12 of the invention, the metals of the body 22 and the anti-corrosion formation 26 are in direct (metal to metal) contact, to permit, in use, electrical conduction therebetween.

Secondly, in the example shown in Fig 7, in the initial condition, the anti-corrosion formation surface 28 is uncoated and comprises a bare metal part 70 which substantially extends over the whole of the anti-corrosion formation surface 28.

Although not shown in Fig. 7, in the initial condition, the seating surface would be coated with the surface coating 40.

Thirdly, in a wet condition, electrolyte 58 is present, comprising primarily water but frequently also comprising salts which enhance the electrolytic action of the water.

In a galvanic condition, the electrolyte 58 forms a continuous path between the body bare metal part 56 of the seating surface 30 and the bare metal pad 70 of the anti-corrosion formation surface 28. Although Fig. 7 shows the seating surface 30 immersed in the electrolyte 58, the electrolyte 58 could alternatively be in the form of a film or even just a relatively thin thread.

In the galvanic condition, the bare metal pads 56, 70 of the body 22 and the anti-corrosion formation 26 respectively form pads of an electrical circuit, which comprises the galvanic cell 60. The galvanic cell 60 comprises the metals of the body 22 and the anti-corrosion formation 26, and the electrolyte 58 which extends therebetween.

As the metal of the anti-corrosion formation 26 is lower in electrode potential (ie less noble) than the metal of the body 22, the metal of the anti-corrosion formation 26 will form a sacrificial anode and will corrode preferentially to the metal of the body 22.

Fig. 7 illustrates the galvanic cell 60 with metal positive ions (arrow M) (eg Zni"-) moving from the bare metal part 70 of the anti-corrosion formation surface 28 to the body bare metal part 56 on the seating surface 30F via the electrolyte 58, and electrons (arrow E) moving internally from the body 22 to the anti-corrosion formation 26. Advantageously, the Applicant has found that, in the components 12 of the invention, the seating surfaces 30 remain substantially uncorroded while the anti-corrosion formations 26 are present.

It will thus be realised that, in this example, the galvanic condition is only reached after a period of use, during which period the coating 40 on the seating surface 30 wears away until the body bare metal part 56 (which could be of any size) is exposed, as shown in Fig. 7. Advantageously, the coating 40 delays the onset of the period in which the metal of the anti-corrosion formation 26 is being depleted. Furthermore, advantageously, the action of the anti-corrosion formation 26 begins as soon as any size of the body bare metal part 56 is exposed, which slows or stops the rate of corrosion and hence growth of the body bare metal part 56.

In use, one or more covers 16 are located in the frame 14 with the seating surfaces 30C of the cover(s) 16 in contact with the seating surfaces 30F of the frame 14 to transmit load therethrough. While it is desirable for both the cover(s) 16 and the frame 14 to include anti-corrosion formations 26, the Applicant has surprisingly found that providing anti-corrosion formations 26 in only one of the complementary components (ie in the cover or the frame, but not both) provides a substantial benefit in the reduction of corrosion in both of the seating surfaces 30 local to the anti-corrosion formation 26 ie in both the frame 14 and the cover 16. The benefit provided is dependent on the minimum surface distances 32 of the seating surfaces 30 from the anti-corrosion formation surfaces 28. Similarly, in other examples, each of the mountings 64 could be associated with only one of the anti-corrosion formations 26.

Ground surface access assemblies 10 are installed in situ for many years and can undergo extremely arduous use in heavy trafficked areas. The rate of depletion of the anti-corrosion formations 26 is dependent on the types of metals, the prevalence of wet conditions and the surface area of the body metal part 56. The anti-corrosion insert members 52 can vary in surface area and depth and desirably should have a sufficient surface area to enable the galvanic cell 60 to function over the whole of the body metal part 56 and a sufficient depth to function for the expected installed life (15-20 years) of the component 12.

In one example, the body 22 could be formed of ductile cast iron and the anti-corrosion formations 26 could be formed of zinc. The initial coated areas of the seating surfaces 30 are in the region of 20mm x 30mm ie 600mm2. The surfaces 28 of the anti-corrosion insert members 52 are substantially circular with a diameter of around 10mm2 giving a surface area of the anti-corrosion formation surface 28 of 157mm2 for two insert members 52, the ratio of the surface area of the seating surface 30 to the surface area of the anti-corrosion formation surface 28 being in this example 3.8:1. In the same example the minimum surface distance 32 is around 40mm.

In the example shown, the insert members 52 are located away from the seating surfaces 30 and would not be expected to experience the same degree of wear and corrosion as the seating surfaces 30. To avoid the situation in which the body bare metal parts 56 have become exposed on the seating surfaces 30 but the anti-corrosion formation surfaces 28 are still coated and therefore the galvanic cell 60 cannot form, the anti-corrosion formation surfaces 28 should desirably not initially be coated when the insert members 52 are located away from the seating surfaces 30.

In an alternative situation, in which the anti-corrosion formation surface 28 comprises part of the seating surface 30, the anti-corrosion formation surface 28 could be coated at the same time and with the same material as the other areas of the seating surface 30. Then, as wear of the seating surface 30 takes place, the bare metal parts 56, 70 will be exposed at the same time, permitting the galvanic cell 60 to form.

The recesses 38 could be formed during casting, or could be formed by a machine operation eg drilling after casting. The metal of the anti-corrosion formation 26 could be melted and poured into the recesses 38 or could be in the form of a plug which is located and affixed into the recess 38. An important point to note is that there must be electrical contact between the metal of the anti-corrosion formation 26 and the metal of the body 22 to permit the galvanic cell 60 to form.

The component 12 could comprise fasteners (not shown) for fastening the insert members 52 in the recesses 38. The fasteners could comprise adhesive.

In the case in which the insert members 52 are held in place by adhesive, it is important that the adhesive does not form a continuous barrier between the seating surface material metal and the anti-corrosion material metal, since this would prevent the formation of the galvanic cell.

In other examples, the insert members 52 could be replaceable, or as 20 part of a maintenance programme, the insert members 52 could be "topped up" or renewed.

Advantageously, the locating of the anti-corrosion formations 26 close to the seating surfaces 30 is efficient in that it enables the specific targeting of the seating surfaces 30 by the anti-corrosion formations 26. Only a relatively small amount of the metal of the anti-corrosion formation 26 is required since it is only the seating surfaces 30 which are of primary concern in terms of preventing corrosion. Also the additional process to form the recesses and locate the insert members in the recesses is relatively simple and can be easily added to the existing production process for forming the components. This is in contrast, for example, to hot dip galvanising in which the whole component is dipped in a bath of molten zinc, requiring a specialised process which cannot be justified in terms of the overall susceptibility of ground surface access assembly components to corrosion.

Other Embodiments Figs. 8A, 8B, 9 and 10 show other embodiments of the invention, many features of which are similar to those already described in relation to the embodiment of Figs 1 to 7. Therefore, for the sake of brevity, the following embodiments will only be described in so far as they differ from the embodiment already described. Where features are the same or similar, the same reference numerals have been used and the features will not be described again.

Second Embodiment Figs. 8A and 8B show a second embodiment of the invention, a ground surface access assembly 210.

In this embodiment, the anti-corrosion insert member receiving recess 38 is defined in the frame seating surface 30F and the anti-corrosion insert member 52 is located therein. The anti-corrosion formation surface 28 of the anti-corrosion insert member 52 could comprise part of the frame seating surface 30F.

In this embodiment, the anti-corrosion material comprises a settable material which is movable from a flowable condition to a set condition by a hardening process. The anti-corrosion material is located on or in the body 22 in the flowable condition. The hardening process moves the settable material to the set condition to form the insert member 52 with the anti-corrosion material located on or in the body 22.

The settable material 74 could be a paste, mastic, resin, epoxy, acrylic or adhesive.

The settable material 74 includes the lower electrode potential metal, which could be in the form of a plurality of particles, for example, granules, powder, strips or any combination thereof. In one example, the settable material 74 could be rich in the lower electrode potential metal and could comprise at least 60% by weight of the lower electrode potential metal, desirably at least 70% by weight and optimally at least 80% by weight.

Fig. 8A shows the frame mounting 66 in the initial condition before use. In this embodiment, before use, the anti-corrosion formation 26 includes a surface coating 82, which is formed at the same time as, and of the same material as, the surface coating 40 of the body 22. The surface coating 40 thus extends over the anti-corrosion formation surface 28 to form a continuously coated surface extending over the whole of the component 12.

In the example shown, the anti-corrosion formation surface 28 comprises part of the seating surface 30 and is coated with the surface coating 40.

In this example, the seating surface region 18 includes the part 40S of the surface coating 40 at the seating surface 30 and the seating surface material below the surface coating part 40S.

Fig. 8B shows the frame seating surface 30F after a period of use, in which the surface coating 40 has worn off the frame seating surface 30F, to expose the body bare metal part 56 and the anti-corrosion formation bare metal 25 part 70 Advantageously, in this embodiment, the action of the anti-corrosion formation 26 is delayed until both of the bare metal parts 56, 70 are exposed. The close location of the anti-corrosion formation 26 to the body bare metal part 56 means that during use, the surface coating 40 wears off both of the bare metal parts 56, 70 at substantially the same rate, so that both bare metal parts 56, 70 are exposed at the same time and the timing of the formation of the galvanic cell 60 is thus optimised.

Third Embodiment Fig. 9 shows a third embodiment of the invention, a ground surface 5 access assembly 310.

In this embodiment, the body 22 includes a wear and/or location insert 76 which locates in a recess 78 defined by the body 22.

The wear and/or location insert 76 is fixed in the recess 78 by the settable material 74 described above, which comprises the anti-corrosion formation 26 in this embodiment. In this embodiment, the wear and/or location insert 76 comprises the seating surface region 18 and includes the seating surface 30. The wear and/or location insert 76 is formed of a material which comprises the seating surface material.

Advantageously, in this embodiment, the provision of the anti-corrosion formation 26 requires no alteration to the material or the structure of the frame 14 beyond that already provided for the wear and/or location insert 76, and thus can be easily and economically provided while improving the corrosion resistance of the ground surface access assembly 310. Advantageously, the anti-corrosion formation 26 extends completely around and adjacent to the wear and/or location insert 76 and so is optimally located to provide corrosion resistance thereto.

The wear and/or location insert 76 could be of any suitable material, size and shape. The ground surface access assembly component 12 could include any suitable number of wear and/or location inserts 76, located in recesses 78.

The wear and/or location insert 76 could be coated with the surface coating 40, but the anti-corrosion formation surface 28 is not coated.

In one example, the wear and/or location insert 76 could be formed of a wear resistant material (such as hardened steel, nitrided steel etc) which in the assembled condition locates against the cover 16. The wear resistant material comprises a more noble metal with a higher electrode potential than the metal of the settable material 74. Optimally, the metal of the anti-corrosion formation 26 is a less noble metal and has a lower electrode potential than the metals of both the wear and/or location insert 76 and the body 22, so that it will corrode preferentially to the metals of both the wear and/or location insert 76 and the body 22 A further advantage of this embodiment is that the anti-corrosion formation 26 provides a barrier between the metals of the wear and/or location insert 76 and the body 22, thus preventing the formation of a galvanic cell between these metals should they be of different electrode potentials.

In one example, the wear and/or location insert 76 projects clear of the surrounding surface to reduce wear of the surrounding surface and act as a focus for wear. The wear and/or location insert 76 could be replaceable. In the example shown, the wear and/or location insert 76 projects clear of the surrounding surface and is convexly rounded. Thus, in this example, the wear and/or location insert 76 provides a preferential wear location.

In another example, the wear and/or location insert 76 projects clear of the surrounding surface to provide an engagement location for a recess defined in the cover 16 to aid correct location of the cover 16 on the frame 14. In this example, the wear and/or location insert 76 could be formed of the same material as the body 22.

In another example, the wear and/or location insert 76 provides both an engagement location and a preferential wear location.

Fourth Embodiment Fig. 10 shows a fourth embodiment of the invention, a ground surface access assembly 410.

In this embodiment, the insert members 52 and the body 22 could include securing formations such as threaded formations 36 to secure the insert members 52 in the recesses 38.

In one embodiment, the insert members 52 could be in the form of zinc or zinc plated steel screws or bolts 62. In manufacture, the body surface 24 could be coated completely, for example by bitumen dipping or painting. The recesses 38 could be in the form of drilled and tapped holes which are then formed in the coated body 22 and the insert members 52 could be simply screwed into the holes of the recesses 38. Advantageously, the drilling and tapping of the recesses 38 ensures good metal-to-metal contact between the seating surface material metal and the anti-corrosion material metal. A further advantage is that the insert members 52 are easily replaced.

Other Modifications Various other modifications could be made without departing from the scope of the invention. The anti-corrosion formations 26 could be of any suitable size and shape, and could be formed of any suitable material (within the scope of the specific definitions herein). For example, the anti-corrosion formations 26 could be formed of any material which is less noble than the seating surface material metal. Thus, when the seating surface material metal comprises a ferrous material such as cast iron, possible metals for the anticorrosion formations 26 could include aluminium, magnesium, sodium, calcium, potassium, alloys of any of these metals, or materials rich in any of these metals.

In some examples, rather than being located in a recess 38, the anticorrosion formation 26 could be located on and cover part of the body surface 24 close to the seating surface 30. In one example, the anti-corrosion formation 26 could comprise a relatively small area of zinc-rich paint or other coating material comprising zinc which is applied to the bare metal part of the body 22.

Any of the features or steps of any of the embodiments shown or described could be combined in any suitable way, within the scope of the overall disclosure of this document.

Concluding Remarks There is thus provided a ground surface access assembly component with a number of advantages over conventional arrangements. In particular, the component of the invention efficiently reduces the degradation of the seating surfaces due to corrosion and wear cycles. The invention results in extended installation life of the ground surface access assemblies of the invention, reducing energy and material use, maintenance and whole life costs.

Claims

CLAIMS 1.COC\J 15 o CY) A ground surface access assembly, the assembly including a component, the component comprising a seating surface region, the seating surface region including a seating surface which, in an assembled condition, contacts a seating surface of a second ground surface access assembly component to transmit, in use, load therethrough, the seating surface region comprising a seating surface material; the seating surface material comprising a metal having a relatively high electrode potential; the component including an anti-corrosion formation, the anti-corrosion formation comprising an anti-corrosion material, the anti-corrosion material comprising a metal having a relatively low electrode potential; the component being arranged to permit electrically conductive communication between the seating surface material metal and the anticorrosion material metal, wherein, in use and in a galvanic condition, the seating surface material metal and the anti-corrosion material metal operate as a galvanic cell, the galvanic cell comprising the seating surface material metal, the anticorrosion material metal, and an electrolyte which extends therebetween, the electrolyte comprising water, and in which, in the galvanic condition, the seating surface material metal and the anti-corrosion material metal are exposed to and in contact with the electrolyte.
An assembly according to claim 1, in which the seating surface material metal and the anti-corrosion material metal metals are in direct (metal to metal) contact.
3. An assembly according to claims 1 or 2, in which the anti-corrosion formation has a surface which is located a minimum surface distance from the seating surface, and wherein the minimum surface distance is no more than 70mm, desirably no more than 60mm and optimally no more than 50mm.
4. An assembly according to claim 3, in which the anti-corrosion formation surface comprises part of, and/or overlaps, or is adjacent to, or abuts, the seating surface.
5. An assembly according to claims 3 or 4, in which the anti-corrosion formation surface has a surface area, the component has a surface area, and the anti-corrosion formation surface area comprises a minor part (ie, less than 50%) of the component surface area.
6. An assembly according to claim 5, in which the seating surface has a seating CO surface area, and in which the ratio of the surface area of the seating surface to the surface area of the anti-corrosion formation surface area is no more than 20:1, desirably is no more than 10: 1 and optimally is no more than 5:1.
7. An assembly according to any of the preceding claims, in which the component includes a body which has a surface, and the anti-corrosion formation is located on or into the body surface.
8. An assembly according to claim 7, in which the anti-corrosion formation surface is level or flush with the body surface.
9. An assembly according to claims 7 or 8, in which the body defines a recess, in which the anti-corrosion formation is located.
10.An assembly according to claim 9, in which the anti-corrosion formation comprises an anti-corrosion insert member.
11. An assembly according to claim 10, in which the component comprises a fastener for fastening the insert member in the recess.
12.An assembly according to claims 10 or 11, in which the insert member and/or the body include securing formations (which may be threaded formations) to secure the insert member in the recess.
13. An assembly according to any of claims 10 to 12, in which the insert member is in the form of a screw or bolt.
14. An assembly according to any of the preceding claims, in which the anticorrosion formation has a depth, which is no more than 10mm. 10
15. An assembly according to claim 14 when dependent on claim 9 or any claim dependent thereon, in which the recess has a depth, which may be substantially the same as or greater than the depth of the anti-corrosion CO formation.
16. An assembly according to claim 7 or any claim dependent thereon, in which the body includes a body surface coating, which may substantially cover the body surface, possibly including the seating surface, and in which the body surface coating is formed of a barrier material, which may comprise paint and/or bitumen.
17. An assembly according to claim 3 or any claim dependent thereon, in which the anti-corrosion formation surface is uncoated.
18. An assembly according to claim 3 or any claim dependent thereon, in which the anti-corrosion formation surface does not comprise part of the seating surface.
19.An assembly according to claim 16 or any claim dependent thereon, in which the anti-corrosion formation includes a surface coating, which may be formed of a barrier material and may be formed at the same time as, and possibly of the same material as, the surface coating of the body.
20. An assembly according to claim 19 when dependent on claim 3 or any claim dependent thereon, in which the anti-corrosion formation surface comprises part of the seating surface and is coated with the surface coating.
21 An assembly according to claim 7, in which the anti-corrosion material comprises a settable material which is movable from a flowable condition to a set condition by a hardening process; the anti-corrosion material is located on or in the body in the flowable condition; and in which the hardening process moves the settable material to the set condition with the anti-corrosion material located on or in the body.
22. An assembly according to claim 7, in which the anti-corrosion material comprises a settable material which is movable from a flowable condition to CO a set condition by a hardening process; the component includes a wear and/or location insert which locates in a recess defined by the body and is fixed in the recess by the settable material; and the wear and/or location insert comprises the seating surface region and includes the seating surface; and the wear and/or location insert is formed of a material which comprises the seating surface material.
23. An assembly according to claim 22, in which the anti-corrosion material provides a barrier between the metals of the wear and/or location insert and the body.
24. An assembly according to any of the preceding claims, in which the component comprises a frame, a cover or a grating of the ground surface access assembly.
25.A method of improving corrosion resistance and/or reducing wear of a ground surface access assembly, the method including providing a ground surface access assembly, the assembly including a component, the component comprising a seating surface region, the seating surface region including a seating surface which, in an assembled condition, contacts a seating surface of a second ground surface access assembly component to transmit, in use, load therethrough, the seating surface region comprising a seating surface material; the seating surface material comprising a metal having a relatively high electrode potential; the component including an anti-corrosion formation, the anti-corrosion formation comprising an anti-corrosion material, the anti-corrosion material comprising a metal having a relatively low electrode potential; the component being arranged to permit electrically conductive communication between the seating surface material metal and the anticorrosion material metal, CO wherein, in use and in a galvanic condition, the seating surface material is metal and the anti-corrosion material metal operate as a galvanic cell, the galvanic cell comprising the seating surface material metal, the anticorrosion material metal, and an electrolyte which extends therebetween, the electrolyte comprising water, and in which, in the galvanic condition, the seating surface material metal and the anti-corrosion material metal are exposed to and in contact with the electrolyte.