WO1995031386A1

WO1995031386A1 - Neck seal

Info

Publication number: WO1995031386A1
Application number: PCT/GB1995/001067
Authority: WO
Inventors: Michael Jennings
Original assignee: Fibresec Holdings Limited
Priority date: 1994-05-14
Filing date: 1995-05-12
Publication date: 1995-11-23
Also published as: GB9409698D0; DE19580741T1

Abstract

A seal member (10) for sealing the base of an access chamber (30) to the neck region of an underground storage tank (40) comprises first and second edge portions (2, 4) for connecting to the tank neck region and the base of the access chamber, respectively, as well as a series of pairs of diametrically opposed short, upstanding collars (6, 8, 12) which are initially blanked off, and opened as necessary to allow passage therethrough and sealing of certain pipes from the tank system.

Description

NECK SEAL The present invention relates to a method of sealing the base of an access chamber to the neck region of underground storage tanks of the type used for storing for example petroleum products, as well as a modified access chamber and seal.

Access chambers of this type generally have an open top and open base, and conventionally these have been secured to the neck region of the tank by first fitting to the tank a short upstanding box or skirt which is then secured to the base of the access chamber by bolting the two together with a gasket interposed between the skirt and the chamber. This method of fitting does not pose any particular problem with regard to pipes passing upwardly from the tank through the interior of the access chamber, but with for example double skinned tanks these are sometimes fitted with leak detection systems incorporating upstanding pipes which pass from the space between the two skins up into the interior of the access chamber and these can be a problem where there is no skirt fitted, as the chamber then has to be sealed between the chamber and the neck of the tank, thus blocking the space required for the pipes to pass through.

It is therefore the aim of the present invention to provide a modified access chamber and method of sealing same to the tank which can be readily utilised regardless of whether or not the tank has a skirt already fitted, as well as a seal for sealing the chamber to the tank where there is no skirt fitted.

According to a first aspect of the present invention there is provided a seal member for sealing the base of an access chamber to the neck region of an underground storage tank, the seal member comprising a first edge portion which, in use, is secured to the neck of the tank either directly or via one or more intermediate members , a second edge portion which, in use, is secured to the base of the access chamber either directly or via one or more intermediate members, and an intermediate portion extending between said first and second edges and including a series of upstanding collars all of which are initially blanked off but which may be opened at will to allow passage therethrough and sealing of any upstanding pipes from the tank system.

Preferably, there are three pairs of diametrically opposed upstanding collars, disposed around the seal in an arrangement to match the position of the upstanding pipes in most tank installations.

Conveniently, the upstanding collars are blanked off at the uppermost surface, but they could alternatively be blanked off at the bottom.

The material for the seal may be nitrile rubber or EPDM, but the exact material used is not important, merely that it should be chemically compatible with the products being stored in the tank.

Preferably, the first edge portion actually comprises an inner first edge portion and an outer first edge portion, each corresponding to a different neck size, such that the seal would be cut to either the inner edge or the outer edge, according to the size of the neck to which the seal is to be fitted.

According to the first aspect of the present invention there is further provided a method of sealing the base of an access chamber to the neck region of an underground storage tank, said neck region comprising an upstanding neck closed by a manway lid and flange assembly, the method including providing a seal member having a first edge portion, a second edge portion, and an intermediate portion extending between said first and second edges and including a series of upstanding collars all of which are initially blanked off, opening one or more of the upstanding collars as required to allow passage therethrough and sealing of any upstanding pipes from the tank system, securing said first edge of the seal member to the neck region of the tank either directly or via one or more intermediate members, and securing said second edge to the base of the access chamber either directly or via one or more intermediate members.

Whilst in most cases it would be possible to secure the second edge of the seal member to the access chamber base directly, in some cases it is not possible to secure the first edge of the seal member to the tank neck since during installation the tank is occasionally concreted in right up to the level of the manway lid (which includes a manway lid neck flange) , and thus the bolts and the whole of the neck flange are inaccessible. In such a case the method according to the first aspect of the invention further includes the step of securing a rolled angle section to the outer edge of the manway lid, so as to provide a generally vertical surface around the extremity of the lid, against which the first edge of the seal member may be clamped.

That part of the rolled angle section which is secured to the manway lid may be positioned either on top of the manway lid or alternatively positioned and sealed between the manway lid and the lid neck flange.

However, it may not always be necessary to provide the rolled angle section, and in some circumstances the first edge of the seal member may be clamped onto the vertical face of the manway lid and manway lid neck flange with a simple flat seal (if required) interposed between the two to compensate for an uneven and poorly finished edge to the manway lid and neck flange.

According to a second aspect of the present invention there is provided a modified access chamber for securing to an underground storage tank which may or may not be fitted with an upstanding skirt, the chamber comprising an open top, an open base and a sidewall structure, wherein the open base includes around its edge a ledge having a first surface for receiving a first sealing member in accordance with the first aspect of the present invention for use where the tank has no skirt fitted, and a second surface for receiving a second, alternative sealing member for use where the tank is fitted with a skirt.

Preferably, the ledge takes the form of a substantially horizontal ledge portion which follows the profile of the chamber, this horizontal ledge continuing into a down-turned vertical face which also follows the profile of the chamber and continues into a base portion extending towards the interior of the chamber finally terminating in an annular up-turned vertical face. Thus, there is provided a recess between said down-turned vertical face and said up-turned vertical face, the recess having an inner annular wall formed by said up-turned face and an outer wall formed by said down-turned face, said outer wall corresponding to the shape of the chamber.

Part of the interior surface of this recess forms the aforesaid first surface, and the underneath surface of the horizontal ledge forms the aforesaid second surface.

Where the tank is not fitted with a skirt as described hereinbefore, the first surface is utilised by securing thereto a sealing member in accordance with the first aspect of the present invention, using a circular strap member to press the second edge portion of the sealing member against an interior side wall of the recess. Similarly, a circular strap member is used to press the first edge portion (cut to either the inner or outer edge) against the neck of the tank.

If on the other hand the tank is fitted with a skirt, then an alternative sealing member in the form of a gasket shaped to correspond to the shape of the chamber is utilised, bolting the horizontal ledge at the base of the access chamber to the edge of the skirt at intervals around the chamber. With this option, it is preferred that the recess is cut off at the base of the down-turned vertical face, but this is not essential.

Thus, by supplying a modified access chamber and either a seal according to the first aspect of the present invention, or a conventional gasket, the modified access chamber can be fitted to a tank with upstanding pipes regardless of the presence or absence of a skirt.

According to a third aspect of the present invention there is provided a method of sealing an access chamber to an underground storage tank which may or may not have an upstanding skirt fitted, the method comprising the steps of providing a modified access chamber comprising an open top, an open base and a sidewall structure, wherein the open base includes around its edge a ledge portion having a first surface and a second surface, sealing said first surface to the neck of said tank where the tank does not have a skirt fitted, or sealing said second surface to the skirt where the tank has a skirt fitted.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:-

Figure 1 is a perspective view of a seal in accordance with the first aspect of the present invention,

Figure 1A is a vertical section through part of the seal shown in Figure 1,

Figure IB is a plan view of the seal shown in Figure l,

Figure 2 illustrates how the seal shown in Figure 1 is used to seal the modified access chamber to a tank having no skirt fitted, Figure 3 illustrates in plan view the modified access chamber according to the second aspect of the present invention,

Figure 3A is a section on line A-A of Figure 3,

Figure 3B is an enlarged detail of part of Figure 3,

Figure 4 illustrates how the modified access chamber is sealed to the skirt of the tank,

Figure 4A is an enlarged detail of part of Figure 4,

Figure 4B is a plan view of the chamber shown in Figure 4,

Figure 5 illustrates the preferred method of connecting the seal member to the tank neck, when suitable access is possible,

Figure 6 illustrates one possible way in which the seal can be secured to the neck in restricted access circumstances, and

Figures 7 and 8 illustrate two variations on an alternative way of securing the seal to the neck in restricted access circumstances.

Referring to the drawings, a seal in accordance with the first aspect of the present invention comprises a generally disc shaped, flexible seal 10 in the form of a first edge portion 2 for fitting to the tank neck, a second edge portion 4 for fitting to the base of the access chamber, and an intermediate portion 3 having three pairs of diametrically opposed upstanding collars 6, 8 and 12, at least some of which will, in use, be clamped around upstanding pipes leading from the tank into the interior of the access chamber. The first edge 2 has an inner edge 2• and an outer edge 2' * , and the seal would be cut either to 2' or to 2" dependent upon the size of tank neck the seal has to fit. The collars 6, 8 and 12 are initially all blanked off at the top, and when fitting the seal the tops would be cut off the appropriate collars according to the number and position of the upstanding pipes.

Referring in particular to Figure 3, a modified access chamber 30 according to the second aspect of the present invention is provided with a ledge 32 comprising a horizontal ledge portion 32a and disposed interiorly of horizontal ledge 32a a recessed portion 32b terminating in an annular up-turned wall. The seal shown in Figure 1 is fitted into this recess 32b by inserting edge 4 into the recess 32b and securing it there by means of a circular strap member 22 as shown in Figure 3B. The other edge of the seal, either 2' or 2" is similarly clamped to the neck 36 of the tank 40 using circular strap 20. The upstanding collars either 6, 8 or 12 cut out accordingly are clamped around upstanding pipe 42.

The immediately foregoing description concerns a tank 40 without a skirt fitted, but where another tank 40' may have fitted thereto a short upstanding skirt 44, the same modified access chamber may be used, simply by ignoring the recess 32b and simply bolting the ledge 32a to the upper, turned in edge 44' of the skirt 44, using bolts 50 at intervals around the skirt and compressing in the space between the ledge 32a and the skirt edge 44' a nitrile rubber gasket 46. As the recess 32b is not required in this option, it is preferred that the recess is cut off at the base of the outer down-turned vertical face, as indicated by line x-x in Figures 4 and 4A, such that the chamber would appear in plan view as shown in Figure 4B.

The down-turned vertical face is retained for strength, and removal of the rest of the recess 32b prevents this being stood upon by operatives, instead they would have to stand on the body of the tank, which is preferred. Either way, once fitted, the modified access chamber 30 is sealed to the tank 40 (40') at the same time allowing the upstanding pipes to pass through without breaking the seal.

Figure 5 illustrates in detail the preferred way of connecting the first edge 2¹ (or 2") of the seal member 10 according to the first aspect of the invention, to the tank neck 40a, which is possible in cases when the bolts 40d and the whole of the neck flange are within the chamber and are accessible.

Figure 6 shows how the connection to the tank neck 40a can be achieved when access to the neck 40a and/or the bolts 40d is denied, for example by concrete. Instead of securing the edge 2'/²' ' ^{to tne} neck, it is instead secured, again by clamp means 20, to the combined vertical face composed of the edges of the manway lid 40b and the manway lid neck flange 40c. If necessary, a simple seal 51 may be provided between the edge 2¹/²'' and the lid/neck flange edge to give a good seal.

Figure 7 illustrates an alternative connection method for restricted access situations, and comprises bolting a rolled angle "L" section 52 to the top surface of the manway lid 40b using the existing lid bolts 40d and including a gasket 53 between the section 52 and the lid 40b. The edge 2^,/2'¹ is then clamped to the vertical face of the angle section 52.

In Figure 8, instead of bolting the section 52 to the top of the manway lid, it is instead trapped between the lid 40b and the neck flange 40c, using existing bolts 40d and sealing gaskets 54.

Claims

1. A seal member for sealing the base of an access chamber to the neck region of an underground storage tank, the seal member comprising a first edge portion which, in use, is secured to the neck region either directly or via one or more intermediate members , a second edge portion which, in use, is secured to the base of the access chamber either directly or via one or more intermediate members, and an intermediate portion extending between said first and second edges and including a series of upstanding collars all of which are initially blanked off but which may be opened at will to allow passage therethrough and sealing of any upstanding pipes from the tank system.

2. A seal according to Claim 1 wherein there are three pairs of diametrically opposed upstanding collars, disposed around the seal in an arrangement, to match the position of the upstanding pipes in most tank installations.

3. A seal according to Claim 1 or Claim 2, wherein the upstanding collars are blanked off at the uppermost surface, but they could alternatively be blanked off at the bottom.

4. A seal according to any of the preceding Claims wherein the material for the seal is either nitrile rubber or EPDM.

5. A seal according to any of the preceding Claims wherein the first edge portion actually comprises an inner first edge portion and an outer first edge portion, each corresponding to a different neck size, such that the seal would be cut to either the inner edge or the outer edge, according to the size of the neck to which the seal is to be fitted.

6. A method of sealing the base of an access chamber to the neck region of an underground storage tank, said neck region comprising an upstanding neck closed by a manway lid and flange assembly, the method including providing a seal member having a first edge portion, a second edge portion , and an intermediate portion extending between said first and second edges and including a series of upstanding collars all of which are initially blanked off, opening one or more of the upstanding collars as required to allow passage therethrough and sealing of any upstanding pipes from the tank system, securing said first edge of the seal member to the neck region of the tank either directly or via one or more intermediate members, and securing said second edge to the base of the access chamber either directly or via one or more intermediate members.

7. A method according to Claim 6 and further including the step of securing a rolled angle section to the outer edge of the manway lid of the tank, so as to provide a generally vertical surface around the extremity of the lid, against which the first edge of the seal member may be clamped.

8. A method according to Claim 7 wherein that part of the rolled angle section which is secured to the manway lid is positioned on top of the manway lid.

9. A method according to Claim 7 wherein that part of the rolled angle section which is secured to the manway lid is positioned and sealed between the manway lid and the flange.

10. A method according to Claim 6 and further including the step of securing the first edge of the seal member onto the vertical face composed of the manway lid and flange edges.

11. A method according to Claim 6 and wherein a simple flat seal is interposed between the first edge of the seal member and the vertical face.

12. A modified access chamber for securing to an underground storage tank which may or may not be fitted with an upstanding skirt, the chamber comprising an open top, an open base and a sidewall structure, wherein the open base includes around its edge a ledge having a first surface for receiving a first sealing member in accordance with any of Claims 1 to 5, for use where the tank has no skirt fitted, and a second surface for receiving a second, alternative sealing member for use where the tank is fitted with a skirt.

13. A modified access chamber according to Claim 12 wherein the ledge takes the form of a substantially horizontal ledge portion which follows the profile of the chamber, this horizontal ledge continuing into a down-turned vertical face which also follows the profile of the chamber and continues into a base portion extending towards the interior of the chamber finally terminating in an annular up-turned vertical face, thus providing a recess between said down-turned vertical face and said up-turned vertical face, the recess having an inner annular wall formed by said up-turned face and an outer wall formed by said down-turned face, said outer wall corresponding to the shape of the chamber.

14. A modified access chamber according to Claim 13 wherein part of the interior surface of this recess forms the aforesaid first surface, and the underneath surface of the horizontal ledge forms the aforesaid second surface.

15. A method of sealing an access chamber to an underground storage tank which may or may not have an upstanding skirt fitted, the method comprising the steps of providing a modified access chamber comprising an open top, an open base and a sidewall structure, wherein the open base includes around its edge a ledge portion having a first surface and a second surface, sealing said first surface to the neck of said tank where the tank does not have a skirt fitted, or sealing said second surface to the skirt where the tank has a skirt fitted.