Pipe joints or couplings – With casing – lining or protector – Insulated
Reexamination Certificate
2001-10-31
2004-05-18
Bochna, David (Department: 3679)
Pipe joints or couplings
With casing, lining or protector
Insulated
C285S915000, C285S381100, C156S308400
Reexamination Certificate
active
06736430
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to coated recoverable articles for use in protecting insulated pipes from corrosive or other damage or from heat loss, and in particular for sealing joints in district heating pipes against water ingress. Such articles and methods, and assemblies using them are described in EP-B-0079702 (B073), the disclosure of which is incorporated herein by reference.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides a joint between insulated pipes, which comprises:
(a) two transport pipes joined together;
(b) insulation on each transport pipe which ends short of the joint;
(c) a casing surrounding the exposed portion of pipe;
(d) a sleeve which provides a seal between an end of the casing and the adjacent pipe insulation, wherein the sleeve comprises recoverable polymeric material coated at discrete regions with a sealant and/or a heat-activatable adhesive, (preferably with the sealant bridging the end of the casing and the pipe insulation to form a seal therebetween which can accommodate movement of the casing relative to the pipe insulation, and the adhesive forming substantially annular bonds between the sleeve and the casing and between the sleeve and pipe insulation), characterised in that at least one region (
4
) of the sleeve, preferably between the sealant-coated and the adhesive-coated regions or at the edge of the sleeve, remains uncoated to provide a relatively high-friction slip-resisting grip when the sleeve is being recovered in use.
The sealant (or the adhesive) constituting a region of a principal surface of the sleeve is an outwardly facing layer at that region rather than some intermediate layer of a multi-layer laminate, although the sealant may be covered, by, for example, a release layer which has no function in the installed product. Where the sleeve is used to protect the outside of the pipe, the sealant and adhesive will of course be on the internal surface of the sleeve.
In a preferred embodiment, the present invention provides an assembly for use in the sealing of a cavity around an uninsulated portion of an insulated pipe, which comprises:
(a) a casing arranged substantially to surround the uninsulated portion of the pipe; and
(b) a sleeve comprising a recoverable polymeric sheet, wherein the sleeve has a layer of a heat-activatable adhesive at a first region of a principle surface thereof, the layer of adhesive being arranged so as, in use, to provide a substantially annular bond between the polymeric sheet and the insulation of the pipe, which can resist movement of the sheet relative to the insulation; and/or a layer of a sealant at a second region of the said principle surface, the layer of sealant being arranged, in use, to overlap the casing and the pipe insulation, so as to provide a flexible seal between the casing and the insulation which can accommodate relative movement between the casing and the insulation, characterised in that at least one region (
4
) of the sleeve, preferably between the sealant-coated and the adhesive-coated regions or at the edge of the sleeve, remains uncoated to provide a relatively high-friction slip-resisting grip when the sleeve is being recovered in use.
The invention also provides a method of sealing a joint between two insulated pipes, the insulation of each of which ends short of the joint, which comprises:
(a) surrounding the exposed portion of pipe with a casing;
(b) joining an end of the casing to the adjacent pipe insulation by installing around the end of the casing a sleeve comprising a recoverably polymeric material coated with a sealant and/or a heat-activatable adhesive, (preferably with the sealant being positioned to overlap the end of the casing around substantially its entire periphery, and the heat-activatable adhesive being positioned to form substantially annular bonds between the sleeve and the casing and between the sleeve and the pipe insulation); and
(c) causing the polymeric material to recover, the sealant (if present) to soften and the heat activatable adhesive (if present) to be activated, characterised in that at least one region (
4
) of the sleeve, preferably between the sealant-coated and the adhesive-coated regions or at the edge of the sleeve remains uncoated to provide a relatively high-friction slip-resisting grip when the sleeve is being recovered in use.
The recoverable polymeric sheet material is preferably heat recoverable, and heating will cause the sheet to recover, the sealant to soften and the heat-activatable adhesive to melt or otherwise to become activated and bond to the pipe insulation or to the casing. The size and shape of the region of hot-melt or other heat-activatable adhesive is not critical, but the uncoated slip-resisting region will generally be such as to prevent slipping of the sleeve or prevent the ends of the sleeve parting company from the pipe. We have found that an annular bond will give the desired benefits , but this is not to be construed as limited to a complete closed ring of bonding around the pipe. In some circumstances it will be sufficient to provide spots or patches of heat-activatable adhesive arranged around the circumference of the pipe such that the envelope of such spots or patches is generally annular in shape. Although one region of heat-activatable adhesive can be sufficient we prefer that two be provided, one at each end portion of the sleeve. The sleeve will then have a middle region of sealant, which can overlap the casing and the pipe insulation, and two end regions of heat-activatable adhesive which can bond to the pipe insulation and to the casing respectively and which are each separated from the sealant region by a said uncoated-region. In less preferred forms of the invention, the uncoated region(s) could possibly, if desired, be at the outer edge of the sleeve instead of between the adhesive sealant regions. The usual coating equipment can readily be adjusted to provide the uncoated region in the desired position on the sleeve.
The precise construction of the sleeve will depend on the specific application, and the variables to be considered include the following; width of sleeve, shrink ratio of sleeve, size, shape and number of regions of heat-activatable adhesive, thickness of sealant and thickness of adhesive, and the nature of the sealant and of the adhesive. The sleeve will conveniently be produced and supplied in long spooled lengths so that a suitable length can be cut-off, depending on the diameter of pipe to be protected.
The nature of the sealant and adhesive will first be considered. Where the recoverable material is heat recoverable it is preferred that the recovery temperature of the material, the softening temperature of the sealant and the activation temperature of the adhesive be compatible. The sleeve can be coated with a temperature indicating composition to give the worker an indication when sufficient heat has been applied. For examples of suitable compositions see our UK patent specifications 2038478 and 2077919. Typical installation temperatures are from 90-150° C., preferably 110-135° C. and a typical range of safe operating temperature of the installed sleeve is from −30° to 70° C. The adhesive of the sleeve (and of a closure patch where used) is preferably a hot-melt adhesive, and many types can be used, see for example U.S. Pat. Nos. 4,181,775 and 4,018,733 which disclose formulations comprising polyamides modified with hydrocarbon waxes, and mixtures of acidic ethylene polymers polyamides and tackifiers. Also suitable are EVA compositions including hydrocarbon waxes and optionally butyl rubber. A particularly preferred adhesive, especially for use on untreated substrates and where excellent low temperature performance is required, is that disclosed in UK patent publication 2075991, incorporated herein by reference. This publication discloses a hot-melt adhesive composition by comprising a polyamide and up to 10% by weight, preferably up to 5%, more preferably from 0.25-0.75% of an acrylic rubber. The composition preferably incl
Meulemans Dirk
Peigneur Paul
Bochna David
Chaletsky Lawrence A.
Jay Anthony William
O'Brien Elizabeth A.
Tyco Electronics Raychem NV
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