AU771888B2

AU771888B2 - Tank liners

Info

Publication number: AU771888B2
Application number: AU39437/00A
Authority: AU
Inventors: Geoffrey Ronald Oxenford; Andrew Jason Roubin
Original assignee: TYCO FLOW CONTROL PACIFIC Pty
Current assignee: Emerson Automation Solutions Final Control Australia Pty Ltd
Priority date: 1999-06-10
Filing date: 2000-06-13
Publication date: 2004-04-08
Anticipated expiration: 2020-06-13
Also published as: AU3943700A

Description

P/00/01i1 Regulation 3.2

AUSTRALIA

Patents Act 1990 I.

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: "TANK LINERS" I. The following statement is a full description of this invention, including the best method of performing it known to us: 2

TITLE:

"TANK LINERS" THIS INVENTION relates to the establishment of liners to storage volumes, in particular to the support of membranes beneath a roof to a storage volume, and to parts and accessories therefore particularly but not exclusively for use with storage volumes for liquids, such as tanks in which to retain demineralised water.

BACKGROUND ART It is known to construct large tanks for the storage of liquids from mainly sheet metals. An example of such a tank is seen in the specification to Australian patent number 687987 to the present applicant.

These tanks need to be lined in some circumstances to isolate a contained liquid from contact with the tank materials. An example where a liner is needed is when the storage tank is to hold demineralised water.

This liquid is to be kept isolated from the usual metals by which the more standard tanks are produced.

It is known to line tanks with materials interposed between tank materials and the liquid being stored. Tanks are typically formed from galvanised steel, in sheet form, bolted together to form the walls, the walls being stood over a concrete slab base. Isolation of stored fluid from the tank materials may be achieved generally by either application of a coating to the inner surfaces of the tank, or by insertion of a membrane as liner. A liner membrane, typically a heavy duty industrial containment liner as is known to those skilled in the art is readily draped down the walls of a tank and across its floor. However, inserting a liner which also isolates the roof of the tank is another matter.

When the liquid being stored in a storage volume is demineralised water, there is a need to consider evaporation and condensation which will result in liquid contact with a storage volume roof, and the dripping of liquid back into the main body of fluid. The roof needs to be lined. The roof area of the usual tank is considerable in extent and the area to be covered poses a problem. Something is needed by which to support the roof membrane against sag.

OBJECT OF THE INVENTION It is an object of the present invention to provide a means by which a roofed space may be covered or lined with an added membrane, extended or spread across, but beneath, the under surface of its roof, 15 and, ideally, depending on circumstance, all of its remaining internal surfaces. Other preferred objects and particular advantages will hereinafter become apparent.

NATURE OF THE INVENTION The invention achieves its objects in the provision of a roof membrane liner which is engaged by or fitted with a plurality of membrane supports arrayed across the area of the membrane, respectively operative at strategic locations to attach or join the roof membrane liner, in use, to fixtures of the roof, to hold the roof membrane liner beneath the roof.

The invention includes in a preferred form, as a novel 4 component or element thereof, membrane support means which ideally comprise clamping means which sandwich and/or engage the membrane over a distributed area. Additionally, the invention includes in a particular preferred form, a novel edge seal which may be used in sealing upper surface membranes to wall liners.

The upper surface membrane may be hung using sufficient membrane supports distributed thereabout so as to hold its weight and ideally generally supported against significant sag. Such membrane supports ideally engage the liner and extend to suitable framing, ideally by means of ties which may be straps and the like and ideally might be standard plastic cable ties.

°°log The upper surface membrane may be engaged with or sealed to an internal wall liner, the two being joined by a flap, extended off the upper surface membrane, which flap may be site welded to the wall liner.

The membrane supports ideally work to clamp the membrane between distributed clamping surfaces, held together by a suitable connector, ideally an eyebolt and nut. The eyebolt provides a "point at which a cable tie may attach. The clamping surfaces, eyebolt and nut are preferably formed in stainless steel to prevent contamination of the tank content. A fibre washer may be used to effect better sealing.

Additionally, the clamping surface to liner contact might be provided with a sealant applied there-between. The distributed clamping surfaces are ideally realised in plate material which is stamped to give it a domed shape and a peripheral flange. Two domed plates are oriented with their cavities facing the membrane to achieve maximum forceful engagement therewith around their complementary shaped peripheries. They are ideally flanged outwardly to add resistance to flexing of the clamping edges.

to various drawings in FIG. 1 FIG. 2 FIG. 3 BRIEF DESCRIPTION OF THE DRAWINGS The invention will herein below be described with reference preferred embodiments as illustrated in the accompanying which: is a perspective view of a roof of a tank with the roof cladding removed to reveal the roof liner therein; is a detailed view showing a perimeter attachment and edge seal, in accordance with the invention, as may be applied to the roof liner of FIG. 1; is a detailed view of a roof liner support, in accordance with the invention, as may be applied to the roof liner of FIG. 1; is a detailed view of the method of sealing the roof liner to the wall liner; is a detailed view of an alternative sealing method; is a detailed view showing a roof access hatch for the liner; and is a detailed view of a roof pipe connection for the liner.

PREFERRED EMBODIMENTS The invention is described below with particular reference to FIG. 4

FIG.

FIG. 7 6 a tank in which is to be stored de-mineralised water. It will be clear to those skilled in the art that the principles, techniques and parts described below may be applied to other storage volumes, and other fluids to be held thereby, with variation in materials of liner and supports being made to suit the fluid being stored. The particular techniques by which such storage volumes are assembled are well known to those skilled in the art and they are not described in any detail below. Those skilled in the art will appreciate that the techniques and methods by which an upper membrane may be hung beneath the roof of a tank will be applied across all of the broader range of storage volume types. Those skilled in the art will also appreciate that the means by which the membrane is supported will operate with all of the wide range of membranes and will enable their support whatever might be the purpose they will serve. The space over which a membrane is hung by means of the invention may extend beyond tanks.

In FIG. 1 is seen a tank 10 with its roof cladding removed to 0""0reveal roof framing 11 and upper surface membrane, more simply referred to hereinafter as roof liner 21. The roof may be a self supporting structure as seen in the specification to Australian patent number 692740 to the present applicant. The roof is typically manufactured from galvanised steel purlins, intermediate bridging, purlin brackets, with galvanised bolts nuts and washers. The liner may be a butyl rubber or other suitable material when the fluid it is to contain is de-mineralised water. The roof liner 21 may be supported against sag under its own 7 weight by suitable supports (described in greater detail below) which engage the liner and hang it off the roof framing 11 on suitable support means such as ties 13. The ties 13 may be straps and the like and ideally might be the standard plastic cable ties which may be looped through the liner support and over a roof frame. The larger of this style of cable tie will typically provide tensile strengths sufficient to support 100kgm. It will be clear to those skilled in the art that the storage volume might be accessed, vented and otherwise monitored by use of any of the standard tank accessories which are fitted for these purposes.

It will be clear to those skilled in the art that the number and distribution of supports will be determined by the properties of the membrane, the weight to be supported, the tensile properties of the membrane, the effectiveness of the support engagement with the

U

membrane.

In FIG. 2 is seen a detail showing the top edge of tank which has a tank shell 14, typically in bolted sheet material, fitted with the usual bracing perimeter angle ring 15, with internal wall liner 16 hung off a bolt 17 and clamped behind nut 18. A roof liner 21 may be connected "at its periphery at bolt 17 behind nut 19. The roof liner 21 can be sealed to the wall liner 16 by a edge flange or flap 22 which can be site welded or otherwise joined to the wall liner 16 after installation of the roof liner 21.

Referring to FIG. 4, the edge flange or flap 22 is sealed to the wall line 16 by bonding tape 23 hot air welded to the edge flange or flap 22 and to the wall liner 16.

Where the liner material is not suitable for hot air bonding, a mechanical clamping method, see FIG. 5, may be used. The edge flange or flap 22 is sealed to the wall line 16 by a stainless steel (or corrosion resistant) metal band 30 attached to the tank shell 14 by corrosion resistant fasteners 31 extending through the tank wall 14.

Preferably polyurethane sealant or equivalent 32 is interposed between the clamping band 24 and the shanks of the fasteners It will be clear to those skilled in the art that the flange to the roof liner by which to seal to the wall liner might be varied. The flange might be made a feature of the wall liner, to be site bonded to the roof liner. The object is to provide a useful all round perimeter seal. Site bonding might be by any of the various means known to those skilled in the art and as permitted by the choice of materials for the respective liners which may be the same or different.

C. be In FIG. 3 is seen a detail showing roof liner 21 engaged by a o support means, clamped between engagement means such as washers 23, 24, held together by nut .25 on threaded shaft 26 of eyebolt 27 to which cable tie 13 may attach. The washers 23,24, eyebolt 27 and nut are ideally in stainless steel when the fluid is de-mineralised water, to prevent contamination of the tank content. It will be clear to those skilled in the art that other approaches might be adopted to achieve an inert status in the respective parts. A fibre washer 28 may be used to effect 9 better sealing. Additionally, the washer to liner contact might be provided with a sealant applied there-between, ideally in a liquid state and allowed to set. As illustrated, the engagement means may each be domed, used with the concavity facing the membrane such that the engagement therewith is sufficiently distributed so as to hold the membrane. When a flat plate structure is used there is the fact that maximum compression of the membrane is at their centre and limited as the plate may flex to lose compression at increasing radius from the nut.

The membrane may pull away under tension, stretching to increase the size of the hole which passed the connector, resulting failures of the seal and bringing on likelihood of tearing and other failure. Doming throws contact out to a radially remote zone with increased area at maximum compression and better contact with the membrane. The peripheral flange adds strength against flexing at the edge of the dome.

It will be clear to those skilled in the art that the design of the supports may be varied, the object being a means by which to engage the membrane and take its weight. An inert character may be achieved by a number of ways in addition to selection of stainless steel, such as by coating using any of the many and varied techniques by which such things are achieved. An eyebolt is a convenient but not essential means of engaging a hanger to the membrane.

As shown in FIG. 6, a roof access hatch 33 has an access frame 34 secured to the roof sheeting 35 and selectively closed by a hatch lid 36.

A liner tube 37 (eg of butyl rubber) is supported within the hatch frame 34 and has a lower peripheral flange 38 to which the roof liner 21 is supported and bonded.

Referring to FIG. 7, a roof pipe connector 38 extends through the roof sheeting 35 and is supported by a connection support plate and cross member 39 (the cross members being connected to the purlins 11).

The roof liner 21 is sealaby secured to a peripheral flange via a gasket 41 and a plain pipe flange 42, the latter being fixed via corrosion resistant fasteners 43 to the flange Preferably an inverted bend overflow (not shown) incorporates a top cover plate to prevent suction of the roof liner 21 into the orifice during overflow situations.

'It will be readily apparent to the skilled addressee that the contents of the tank are isolated from any contaminating materials.

Various changes and modifications may be made to the embodiments described and illustrated without departing from the present invention.

*i ••o

Claims

1. A roof liner system for tanks or the like including: a roof membrane liner which is engaged by, or fitted with, a plurality of membrane supports arrayed across the area of the membrane, respectively operative at strategic locations to attach or join the roof membrane liner, in use, to fixtures of the roof, to hold the roof membrane liner beneath the roof.

2. A system as claimed in claim 1 wherein: the membrane support means comprise clamping means which sandwich and/or engage the membrane liner over a distributed area.

3. A system as claimed in claim 1 or claim 2 wherein: an edge seal is used in sealing upper surface membranes to wall liner(s).

4. A system as claimed in claim 3 wherein: the upper surface membrane is hung using sufficient membrane supports distributed thereabout so as to hold its weight and ideally generally supported against significant sag.

5. A system as claimed in claim 4 wherein: the membrane supports ideally engage the liner and extend to suitable framing by means of ties which may be straps and the like and may be standard plastic cable ties.

6. A system as claimed in claim 1 wherein: the upper surface membrane is engaged with or sealed to 12 an internal wall liner, the two being joined by a flap, extended off the upper surface membrane, which flap may be site welded to the wall liner.

7. A system as claimed in claim 1 wherein: the membrane supports work to clamp the membrane between distributed clamping surfaces, held together by a suitable connector such as an eyebolt and nut, the eyebolt providing a point at which a cable tie may attach.

8. A system as claimed in claim 7 wherein: the clamping surfaces, eyebolt and nut are formed in stainless steel to prevent contamination of the tank content and a fibre washer may be used to effect better sealing.

S9. A system as claimed in claim 8 wherein: the clamping surface to liner contact is provided with a Ssealant applied there-between.

10. A system as claimed in claim 7 wherein: the distributed clamping surfaces are realised in plate material which is stamped to give it a domed shape and a peripheral flange, where two domed plates are oriented with their cavities facing the *o membrane to achieve maximum forceful engagement therewith around their complementary shaped peripheries, they are optionally flanged outwardly to add resistance to flexing of the clamping edges.

11. A system as claimed in claim 1 wherein: an edge flange or flap on the roof liner is sealed to the wall liner by heat welding or bonding a sealing tape or by mechanical 13 clamping means.

12. A system as claimed in claim 1 wherein: a roof access hatch has a tube with a lower peripheral flange to which the roof liner is bonded for sealing support.

13. A system as claimed in claim 1 wherein: a roof connection pipe has a lower peripheral flange to which the roof liner is sealably secured by a flange and sealing gasket.

14. A roof liner for a tank or the like substantially as hereinbefore described with reference to FIG. 1; or FIGS. 1, 2 and 4; or FIGS. 1 and 3; or FIGS. 1, 2 and 5; or FIG. 6; or FIG. 7, of the accompanying drawings. Dated this Thirteenth day of June 2000.

15 ENCON IOLDINGS PTY LTD iyco Floi. ConIr,l PCC; C;i P 4 y LI4 SEC By its Patent Attorneys 113 FI R ADAMO KELLY -o2o I