TITLE CONCRETE PIPE LAGGING ASSEMBLY

FIELD OF THE INVENTION

This invention relates to a lagging assembly which is used to protect pipes or conduits passing through concrete.

BACKGROUND OF THE INVENTION

A conventional concrete pipe lagging assembly includes a strap of cushioning or flexible material that is wound around a pipe and is taped to the pipe. This is achieved by adhesive tape which is wrapped around the cushioning material and thereby securely attaches the cushioning material to the pipe. However it has been found that there are disadvantages in using this conventional lagging assembly of cushioning material and adhesive tape because:

(i) wrapping the strap of cushioning material around the pipe is time consuming especially if the installer must squat in a narrow trench to first wrap the cushioning material around the pipe and then use the adhesive tape to fasten the cushioning material in place;

(ii) sometimes debris or mud will be inadvertently located between the pipe and the lagging assembly and this will damage the pipe which is usually made from soft walled plastics material;

(iii) sometimes after the lagging assembly is wound around the pipe small gaps may be present because of not sufficient care being taken by the installer or the installer may be inexperienced. This means that concrete will fill in the gaps and press against the pipe and cause damage to

the pipe or deform it;

(iv) adjustment of the lagging assembly is not possible once the concrete pour has finished and the concrete set. Thus in this situation it is necessary to cut the concrete away from the pipe, replace reinforcing steel and repour the concrete; and

(v) if gaps are present in the lagging assembly by virtue of (ii) or (iii) above this will encourage white ants or termites to pass through the concrete and into a wooden part of a building erected or the concrete which is usually a concrete slab. The abovementioned disadvantages of the prior art have been addressed to some extent by Australian Specification 706693 which refers to a lagging material which is a flexible pre-formed protective tube which is slid over a pipe prior to a concrete pour with the tube being adjustable along the pipe to allow the tube to be readily positioned on the pipe in the desired position. The tube may have a thickness of 5mm-100mm and has a diameter only slightly larger than the pipe and thus has a snug fit with the pipe. The tube has advantages over the prior art because adhesive tape is no longer required and also the length of the tube may be slightly larger than the concrete surround so that it can be trimmed to size and this also facilitates installation and ensures that no gaps are present in the lagging material.

However the preformed tube of Australian Patent 706693 is time consuming in installation because it is necessary to insert the tube over the sleeve and in some cases, i.e. in situ when the pipe has already been installed or secured in place prior to the concrete pour then it would be

necessary to cut the pipe and slide the preformed tube over the cut pipe. Alternatively it would be necessary to remove the pipe from the installed position. It therefore will be appreciated that this could create problems in certain respects. SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide a concrete pipe lagging assembly which may at least reduce the disadvantage(s) of the prior art.

The concrete pipe lagging assembly of the invention is a sheet of flexible material or fabric having one or more metal straps located within the sheet which functions as an internal spring or springs which thereby provides the sheet with a bias that facilitates coiling of the sheet about a pipe prior to a concrete pour in use.

The sheet of flexible material may comprise any suitable resilient or elastomeric material which is suitably water impervious. Closed cell foam material may be used such as polyurethane or polyisocyanate. Natural or synthetic rubber may also be used if required. The thickness of the flexible material may be from 5-50mm and more preferably 5-15mm thick and most preferably 8mm thick. The sheet of flexible material may also be formed with ribs, ridges, protrusions formed on an external wall thereof for providing a physical deterrent to passage of white ants or termites into the house interior through concrete surrounding the lagging assembly which may be a concrete slab or concrete footing for example.

The sheet of resilient material also has one or more straps of metal which is relatively thin, i.e. about 0.5-4. Omm thick which may function in some respects similar to a leaf spring and thus when the lagging material is wrapped around a pipe the natural bias of the metal strap(s) will be retain the sheet in a wound or coiled position around the pipe with adjacent edges of the resilient material abutting each other. In this regard it will be appreciated that there is no need for any additional attachment means to the pipe such as adhesive tape because of the bias of the metal springs favouring the coiled position. While it is preferred that the springs be made from metal such as stainless steel, spring steel, aluminium or copper it will also be appreciated that the springs may be from plastics material such as a nylon, high density polyethylene, polyethylene or polypropylene.

Thus in installation all that is necessary for the installer, such as a plumber or drainer, is to wrap the sheet of flexible material around the pipe prior to the concrete pour. Preferably the length of the lagging material may only slightly exceed the length of the pipe so that no gaps are present when the concrete pour occurs.

BRIEF DESCRIPTION OF THE DRAWINGS Reference may now be made to a preferred embodiment of the invention as shown in the attached drawings wherein:

FIG 1 is a sectional view of a plastics pipe extending through a concrete slab of a building which has the lagging assembly of the invention attached thereto;

FIG 2 is a sectional view of a concrete footing having a plastics pipe extending therethrough which has the lagging assembly of the invention attached thereto;

FIG 3 is a perspective view of one embodiment of the lagging assembly of the invention before installation to a pipe which is to be surrounded by concrete as shown in FIGS 1 to 2;

FIG 4 is a sectional view of the lagging assembly shown in FIG 3; FIG 5 is a perspective view of a second embodiment of the lagging assembly of the invention; FIG 6 is a sectional view of the lagging assembly shown in FIG 5;

FIG 7 is a perspective view of the lagging assembly of FIGS 3 to 4 before and after installation to the pipe;

FIG 8 is a perspective view of the lagging assembly of FIGS 5 to 6 before and after installation to a pipe; FIG 9 is a perspective view of another embodiment of the invention; and

FIG 10 is a perspective vie of another embodiment of the invention. DETAILED DESCRIPTION QF THE PREFERRED EMBODIMENTS

FIGS 1 to 2 show that the lagging assembly 10 of the invention can be utilised in the case of a concrete slab 16 as shown in FIG 1 or in the case of a concrete footing or pier 17 as shown in FIG 2. Also in the case when the pipe 13 is already installed in the situation of FIGS 1 to 2 by being attached or embedded in another support (not shown) then it will be appreciated that the lagging assembly can be quickly installed in situ because it can be wound

around the pipe and held in place by the self clamping action of metal straps 12 referred to hereinafter in FIGS 3 to 9.

In FIGS 3 to 4 there is shown a lagging assembly 10 of the invention comprising a sheet 11 of elastomeric or resilient material having a single metal strap 12 located within the interior of the sheet 11 and shown in phantom. FIG 4 shows that the strap 12 has a concave curvature 14 having regard to an adjacent pipe 13 shown in FIGS 1 to 2 and is sandwiched between two adjacent sheets or layers 15 and 16 of foam material and bonded thereto by suitable adhesive 17. When the sheet 11 is then coiled about a pipe 13 as shown in FIG 5 the natural bias of the single metal strap 12 is to maintain the sheet 11 in the coiled position as shown with the ends overlapping each other as shown in FIG 7 or FIG 8.

However it will be appreciated that the ends of sheet 11 need not overlap but in fact can abut each other if required. The relevant advantage of the lagging assembly of the invention 10 is that the sheet 11 and inbuilt metal strap 12 has a self clamping function in relation to attachment or installation to plastics pipe 13 and this means for example that the lagging assembly of the invention can be quickly and efficiently installed to pipe 13 without any requirement for the sheet to be stuck over pipe 13 in the manner of a preformed tube as was the case with the prior art.

Reference may now be made to another embodiment of the invention shown in FIGS 5 to 6 wherein there is shown lagging assembly 10A having a pair of sheets 20 of resilient material adapted to be bonded together by a

suitable adhesive 17 or attached together by another suitable method such as by stitching or by the use of suitable fasteners. Interposed between each sheet 20 are springs 12A, 12B and 12C which are all orientated longitudinally or lengthwise of each sheet 20. Each spring 12A is located adjacent each longitudinal edge 20 and 21 of sheets 20. Preferably there are provided two springs 12B between each spring 12A and 12C one on top of the other. Suitably each sheet 20 has a length of 500 mm, width of 100 mm and has a thickness of 8 mm. However it will be anticipated that such dimensions may be broadened to refer to a length range of 300-600 mm, width of 50-150 mm and thickness of 4-12 mm.

In FIG 7 the installation of lagging assembly 10 to pipe 13 is shown wherein initially sheet 11 is shown in an uncoiled or flat orientation as shown in position A before attachment to pipe 13 by adoption of a self coiling or overlapping position as shown by position B. FIG 8 as in the case of FIG 5 shows sheet 11A being in a coiled or flat or planar orientation as shown by position (A) before adopting a coiled or installed orientation as shown in position (B) wrapping around pipe 13.

It will be appreciated from the foregoing that the lagging assembly 10 or 10A as described above is ideally suitable for wrapping about pipe 13. Ideally the lagging assembly 10 or 10A will be wrapped 2-3 times around pipe 13 and because of this the length of lagging assembly 1OA may be of the order of 500m.

In an embodiment different to that shown in FIGS 6 to 8, it will be appreciated that there may be two pairs of longitudinal metal straps or

springs adjacent each longitudinal edge 20 and 21 of sheet 11A with one spring on top of the other and a single strap in the middle of sheet 11 A.

Also as shown in FIGS 4 and 6 the spring 12 as shown in FIG 4 or springs 12A, 12B and 12C shown in FIG 6 is typically self coiling and has an arcuate or concave cross sectional profile which operates to self roll the lagging assembly 10 or 1OA about pipe 13 and thus have an inner concave side enclosing pipe 13 and an outer convex side. Each of springs 12A, 12B and 12C may be oriented so that the concave side of each spring 12A, 12B and 12C faces a similar direction. It the embodiment of FIG 9 it will be appreciated that two adjacent lagging assemblies 10 may be wrapped around pipe 13 as shown in FIG 5.

In FIG 10 there is shown an additional embodiment showing concrete pipe lagging apparatus 10B wherein a single metal strap 12 is attached to an external surface 22 of a foam sheet 11 by bonding with a suitable adhesive. There is also shown an additional layer of flexible material 23 also bonded to external surface 22 by adhesive which covers metal strap 11.

It will also be appreciated from the foregoing that the concrete pipe lagging apparatus may also include a suitable termiticide or pesticide such as FIPRONIL to eliminate infestation by termites, white ants or other pests.