Electricity: conductors and insulators – Conduits – cables or conductors – Combined
Patent
1993-11-30
1995-04-04
Nimmo, Morris H.
Electricity: conductors and insulators
Conduits, cables or conductors
Combined
156 49, 174 76, 174 88R, 174DIG8, 428 68, H02G 1508, B32B 1100
Patent
active
054039770
DESCRIPTION:
BRIEF SUMMARY
This invention relates to cable-sealing mastic material, by which is meant a mastic or similar material which is capable of use for sealing cables; and to a kit of parts for cable sealing including such material; and to methods of cable sealing using such material.
It is known to seal cables in order to prevent water or other fluids from travelling along inside the cable, and especially to prevent ingress of water into cable joints, splices or terminations, where bare electrical connections are usually present. Relatively free-flowing materials may be squeezed or pumped into the cable for this purpose, for example as described in GB-A-2100281; free-pouring curable resins are known for filling cable splices; high viscosity hot melt materials have been used, for example as described in GB-B-2087203. The high-viscosity hot melt materials are conveniently provided on the inner surface of a heat-recoverable sleeve used to seal a cable joint. This is very successful in joints where the amount of free space to be filled by the hot melt material is relatively small and of relatively uniform diameter, as illustrated in the aforementioned GB-B-2097203. However, this technique is unsatisfactory where larger volumes of irregular diameter must be filled, since it is difficult or impossible to heat the necessary large volume of hot melt material sufficiently for adequate flow without overheating and damaging the heat-recoverable sleeve.
The present invention provides cable-sealing material in an unusual form which overcomes or alleviates this difficulty and is more convenient to use than the known alternatives of pumping or pouring flowable materials into the cable.
The invention accordingly provides cable-sealing mastic material inherently capable of significant creeping flow in storage, which material is in sheet form in a close-fitting storage container, which container (a) is arranged to resist the said flow in all directions and so maintains the material substantially in the said sheet form in storage, and (b) is lined and/or otherwise arranged to permit application of the material substantially still in the said sheet form to parts of a cable to be sealed by the said material in use.
We have discovered that provision of the cable-sealing material in this unconventional form enables relatively low-melting-point mastic materials to be handled conveniently in large amounts, which have been found impracticable to carry on the inner surface of a heat-recoverable sleeve.
The materials may thus be selected to be sufficiently fluid, at temperatures to be encountered inside a heat-recoverable sleeve during heat recovery, to ensure complete and uniform filling of quite large and irregular volumes, for example those found in low-voltage or medium-voltage cable splices, as hereinafter described. We have found that the best materials of this kind for the present purposes tend to undergo significant creeping flow in storage, which will be understood to mean sufficient creeping flow to distort the sheet to an inconvenient or unacceptable extent. By maintaining the mastic in sheet form, the storage container tends to prevent the inherent creeping flow of such materials from distorting the sheet during storage into inconvenient or unusable forms, which, for example could not readily be wrapped around parts of a cable to be sealed. Tacky and highly adherent mastic formulations, which are advantageous for cable sealing but especially difficult to handle, can thus be made more acceptable for commercial use.
The term "mastic" is generally understood by people familiar with this field of technology to indicate materials which are capable of some degree of cold flow or creeping flow in use, which enables mastic materials, when used as sealants, to take up irregularities or dimensional variations caused by thermal expansion and contraction of the parts to be sealed. Such materials normally undergo such creeping flow in storage, as well as in use, which makes them difficult to handle. For example, a 1 cm thick sheet, even if stored flat,
REFERENCES:
patent: 3852516 (1974-12-01), Vander Ploog et al.
patent: 4485269 (1984-11-01), Steinberg
patent: 4589939 (1986-05-01), Mohebban et al.
patent: 4622252 (1986-11-01), Strobeck
patent: 4624720 (1986-11-01), Pithouse et al.
patent: 4741709 (1988-05-01), Jervis
patent: 4755241 (1988-07-01), Steinberg
patent: 4761193 (1988-08-01), Pithouse et al.
patent: 4849580 (1989-07-01), Feuter
patent: 4863535 (1989-09-01), More
patent: 4935582 (1990-06-01), Calligaris
patent: 4940820 (1990-07-01), Pithouse et al.
patent: 4963700 (1990-10-01), Olsen et al.
patent: 5281763 (1994-01-01), Hey et al.
Derwent abstract 84-108565/18 (abstract of DE 3327821).
Steptoe Neil J.
Taylor Paul
Burkard Herbert G.
Chao Yuan
Nimmo Morris H.
Raychem Limited
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