Environmental protection

A method of protecting a substrate, which comprises: PA1 (a) providing an article having a first portion that has means allowing that portion to be deformed from a larger cross-sectional size to a smaller cross-sectional size and maintained at that smaller size, and that comprises a heat-shrinkable material, PA1 (b) positioning the article such that a first portion encloses at least a part of the substrate, PA1 (c) deforming the first portion to the smaller cross-sectional size at which it corresponds closely to the part of the substrate, and PA1 (d) heat-shrinking the material to cause the first portion of the article to engage the substrate.

BACKGROUND OF THE INVENTION 
The present invention relates to the environmental protection of substrates 
such as cables or pipes, particularly telecommunications cable splices 
especially by means that does not require a large input of energy for 
installation. 
A cable splice is in general formed by removing insulation from the ends of 
the cables to be joined, splicing the conductors therein, and forming 
around the resulting splice bundle a covering called a splice case, in 
order to protect the otherwise exposed conductors. The splice case may be 
required to offer protection against water, water vapour, dirt and other 
contaminants and against animal attack, and should have a life-time 
comparable to that of the cable insulation, typically at least 25 years. 
Many cables are internally pressurized to keep out water vapour or to 
provide a means of detecting leaks, and a splice case for such cables 
should also be pressure retaining. 
One of the most successful and widely used designs of cable splice is that 
marketed by Raychem under the trade marks XAGA and VASM. There a 
heat-shrinkable sleeve is installed around the splice to be protected, and 
heat is applied to cause it to shrink down into engagement with the cables 
either side of the splice. A propane torch is usually used to apply the 
heat. In order to provide further mechanical strength and, where desired 
to provide further resistance to water vapour penetration, an internal 
liner may be provided around the splice bundle. Such a liner and sleeve 
are disclosed in GB 1431167 (Raychem). These sleeves may be 
internally-coated with a hot-melt adhesive. 
Whilst this type of splice case is simple to install and has excellent 
performance, it has the disadvantage in requiring the use of a torch for 
installation. Where a cable to be spliced runs in, for example, a duct or 
manhole shared with gas pipes or where the substrate to be protected is 
itself a gas pipe the use of a torch is undesirable and may be forbidden. 
Attempts have been made to overcome this problem by providing an electrical 
source of heat, although that too may be unacceptable if the voltage 
required is sufficiently high that a short could cause sparking. Also, 
large, heavy, power supplies may be needed since access to mains power 
cannot be relied upon. A large amount of power is required since the 
sleeve must be heated to cause it to shrink, and any adhesive coating has 
to be heated to cause it to melt or otherwise to be activated. 
One electrical solution is disclosed in DE 2136739 (Siemens AG). There a 
splice case comprises two semi-cylindrical thermoplastic half-shells 
hinged together along respective edges, allowing the splice case to be 
closed like a clam-shell around the splice to be protected. 
U.S. Pat. No. 4,085,286 (Raychem) discloses a splice case having preformed 
shrinkable outlets having self-contained electrical heaters comprising a 
conductive polymer having a positive temperature coefficient of resistance 
(PTC). A PTC heater as part of a shrinkable sleeve is disclosed in EP 
0117762 (Raychem). 
EP 0236056 (Raychem) discloses a non-shrinkable splice case comprising a 
flexible sealing bag that is seam-sealed by a hot-melt adhesive activated 
by a self-contained, self-regulating, strip heater. 
Heat shrinkage is desirable, of course, since a sleeve or other protective 
article can easily be installed around a cable etc. since it can be 
supplied over-size. Close tolerances in manufacture can be avoided, and a 
single size of article can be used over various sizes of cables. After 
this preliminary installation the article is heat-shrunk causing it to 
engage the substrate and causing leak paths between it and the substrate 
to be eliminated. This is particularly useful where an outlet of an 
article is to be sealed to a cable etc. that passes through it. A problem 
arises, however, if the heater that is used to bring about heat-shrinkage 
is other than a flame, a hot-air gun, or a very high temperature radiative 
heater; and this problem is due to the changing dimension of the shrinking 
article. Somehow the heater must follow the article down as it shrinks 
since contact between the heater and the article will in general be 
necessary. 
For this to occur the heater must be flexible and in particular must be 
able to shrink or be able to collapse under the force of the shrinking 
article. A heater having diamond shaped slots for this latter purpose is 
disclosed in U.S. Pat. No. 4,177,446 (Raychem). EP 0117762 (Raychem), 
mentioned above, employs a heater which itself shrinks. 
I have noticed a further problem resulting from shrinkage of the article. 
One reason a large supply of heat is required is that the article will not 
in general be thermally-insulated, it being difficult to provide an 
insulating housing that shrinks along with the sleeve. 
Furthermore, I have realized that it is possible to retain the benefits of 
heat-shrinkage, but avoid the disadvantages of what may be termed a "bulk" 
or "large-scale" change of dimension. Thus, a heater and an insulating 
housing may be provided that do not change size and which, with a small 
amount of power, cause localized shrinkage of an article which before 
shrinkage has a configuration which corresponds closely to that of the 
substrate to be protected. 
SUMMARY OF THE INVENTION 
Thus, the invention provides a method of protecting a substrate such as a 
cable splice, which comprises: 
(a) providing an article such as a sleeve, particularly a wraparound 
sleeve, having a first portion (for example an end portion or other 
outlet) that has means, preferably corrugations particularly extending 
longitudinally of the sleeve, allowing that portion to be deformed from a 
larger cross-sectional size to a smaller cross-sectional size and 
maintained at that smaller size, and that comprises a heat-shrinkable 
material, 
(b) positioning the article such that the first portion encloses at least a 
part of the substrate, 
(c) deforming (preferably by bunching together corrugations thereof) the 
first portion to the smaller cross-sectional size at which it corresponds 
closely to the part of the substrate, 
(d) heat shrinking the material to cause the first part to engage the 
substrate, 
(e) optionally positioning an electrical heater in thermal contact with the 
heat-shrinkable material and activating the heater to cause the 
heat-shrinkage of the step (d), and 
(f) optionally and generally before step (d) enclosing the first portion 
within a heat insulator. 
When I refer to the first part being deformed such that its size 
corresponds closely to that of the substrate, I mean that a significant 
part and preferably a majority of the change in dimension required is 
brought about in that way, thereby reducing the change that is required 
during the heat-shrinking step. Preferably, however, substantially all of 
the bulk dimensional change is brought about that way. Where the first 
part is corrugated (by which term I include the provision of means such as 
lines of weakness to aid subsequent corrugation at step c), the troughs of 
the corrugations will, after step c, touch the substrate. Thus, although 
the material may still be shrinkable by its full amount, that shrinkage 
will not result in a change in diameter or whatever of the article. The 
effect of shrinkage will, in general, be to remove the corrugations, 
thereby removing any leak paths that would otherwise exist through them. 
A sealing material, such as a hot-melt adhesive, or otherwise 
heat-activatable material, may be provided between the substrate and the 
article. Such a material may be provided as a coating on the article 
and/or as a separate article, for example in sheet form, particularly as a 
tape wrap. 
Also or alternatively, a heater, particularly an electrical heater may be 
provided which too is preferably positioned between the article and the 
substrate. The heater is also preferably in sheet form, particularly as a 
tape wrap, and may be provided as part of the same article as the sealing 
material. The heater may comprise a battery, which may generate heat 
through its internal resistance and/or through an external resistive 
heating element. 
Such a heating article may be used independently of the method defined 
above, and the invention therefore also provides an article for protecting 
a substrate (either on its own, or by facilitating the installation of 
some other article) which comprises a flexible sheet comprising: 
(a) a battery, preferably an alkali-metal battery, such as one based on 
lithium. 
(b) a heat activatable sealing material, 
(c) a resistive heating element, which may comprise the internal resistance 
of the battery, 
(d) means whereby the battery can be electrically connected to the heating 
element to cause the heating element to become hot, 
(e) optionally a device, which may comprise element (c), having a positive 
temperature coefficient of resistance connected in series with the battery 
and in thermal contact with the element (c), 
Step (c) of the method preferably brings the first portion of the article 
down onto the heating article that has previously been wrapped around the 
substrate. Then, an insulating housing made for example of foam, 
optionally as foam half-shells, is placed around the deformed first 
portion and held in place for example with tie wraps. The heater is then 
activated causing the sealing material to become activated and the 
material of the first portion to shrink. 
The means in the article of the method allowing deformation preferably 
allows the formation of a substantially frusto-conical portion at or 
adjacent one or each end of the sleeve, said substantially frusto-conical 
portion being formed in step (c). 
Preferably, that means allows formation of a substantially frusto-conical 
portion adjacent one or each end of the sleeve, and tapering towards that 
end, and a substantially cylindrical portion between that end and the 
narrow end of the frustum, said substantially frusto-conical and 
cylindrical portions being formed in step (c). 
The means allowing deformation may comprise corrugations (by which term we 
include lines of weakness or other means through which corrugations arise 
when the article is deformed). Thus, deformation may give rise to 
corrugations proper, or may merely cause existing corrugations to 
bunch-up, and thus adopt a certain size.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIGS. 1A and 1B show the most widely used shrinkable telecommunications 
cable splice cases, namely those marketed under the Raychem trademarks 
XAGA and VASM. A cable splice 1, which may be quite bulky due to a large 
number of conductor connectors, joins two cables 2. A liner 3 is wrapped 
around the splice in order to provide further protection. The liner 3 may 
have crowned ends which can be deformed to provide frusto-conical ends to 
the liner. The splice case is completed by a heat-shrinkable polymeric 
sleeve 5 that is wrapped-around the liner and secured in its 
wrapped-around configuration by bring together rails 6 and sliding over 
them channel 7. The sleeve is then shrunk by applying heat, generally 
using a propane torch, such that it engages the liner and the cables at 
each side of the splice. The finished splice case is shown in FIG. 2B. 
The corrugated material shown in FIGS. 2A, 2B and 3A, 3B is disclosed in EP 
42262 (Raychem). Shrinkability is induced into a material by a first 
expansion which is unidirectional but uniform and then by a second 
expansion which produces corrugations 8, which may increase in extent 
across the surface of the material. The material can be used to cover pipe 
branch-offs or splice cases. The material is wrapped to form a sleeve 5 
around a branch pipe 9 in order to seal its junction with a main pipe 10. 
The corrugated region is then splayed out to form a collar 11 which can 
overlie a hole in the main conduit. 
FIGS. 3A and 3B show a substrate having a transition from a larger diameter 
at 12 to a smaller diameter at 13. A tape 14 having corrugations 8 is 
wrapped around the substrate and then heated. FIG. 3B shows the smooth 
cover that results after installation. 
The invention is illustrated in FIGS. 4, 5 and 6. 
FIGS. 4A, 4B and 4C show various stages in the installation of a 
heat-shrinkable sleeve 5 around a splice between cables 2 to form a splice 
case. 
In FIG. 4A the sleeve 5 has been wrapped around the splice and the rails 6 
are about to be secured together with channel 7. Some sealing material, 
for example a gel, may be used to improve sealing between the rails 6. 
End portions of the sleeve have corrugations 8 therein, and in the 
embodiment illustrated the corrugations are provided in two portions 15 
and 16 at each end, optionally separated by some form of discontinuity. 
When the ends of the sleeve are deformed by radial compression (for 
example by hand) frusto-conical portions will be formed corresponding to 
portions 15 and cylindrical portions will be formed corresponding to 
portions 16. The frusto-conical portions will produce a taper down from 
the bulky splice to the cables 2, and the cylindrical portions will lie 
along the cable or cables 2. Thus, the end portions of the sleeve can be 
made to conform closely to the size of the cables. 
Before the deformation is carried out, however, tape wraps 17 are installed 
around the cables. These tape wraps may comprise one or more of a battery, 
a heating element, and a sealing material. Electrical leads 18 are shown 
by means of which a battery within wrap 17 can be activated, or by means 
of which an external power source can be connected to a heating element 
within wrap 17. 
After deformation of the portions 15 and 16 down onto the wraps 17, a 
thermal housing 19 may be applied and secured with tie wraps 20. 
This is the situation shown in FIG. 4B. FIG. 4B also shows further 
electrical leads whereby leads 18 are connected to an external power 
supply, which supplies power to cause heat-shrinkage of the regions 16. A 
portion of the sleeve between portions 15 (or that portion together with 
at least part of portions 15) is preferably not heat-shrinkable. 
After shrinkage is complete the thermal insulation may be removed. The 
result is shown in FIG. 4C, where the corrugations can be seen to have 
been removed from portions 16. Also shown in FIG. 4C is a branch-off clip 
21 which has been used to form or maintain a plurality of conduits in an 
end portion of the sleeve 5. An excellent hot-melt bond can thus be made 
between the sleeve 5 and the cables 2 with very little electrical power. 
For typical splice case sizes a more than adequate power output of a 
battery within each tie wrap 17 would be 5-30 watt hours, particularly 
10-20, say about 15 watt hours. I prefer that a current of 5-35, 
especially 10-20 particularly about 20 amps be delivered to a PTC heating 
element within the wrap which autotherms to maintain the temperature 
between 110.degree. and 130.degree. C. An installation of time of less 
than 10 minutes, probably about 7 minutes, may be readily achieved. 
FIGS. 5A, 5B and 5C show a preferred cable wrap employing a lithium 
battery. A cable wrap may be made having sections such that it can be cut 
to length in the field. For example it could be produced in-line having 
sections such that, say, one section was suitable for a cable of about 15 
mm diameter and that four sections would be needed for a cable of 80 mm 
diameter, and 2 or 3 sections be needed for intermediate sizes. The tape 
could be 20-60 mm, say about 50 mm, wide and each section be about 50-80 
mm, say about 70 mm long. The preferred dimensions could result in a heat 
output of just above 3 watt hours per section. 
A tie wrap 17 is shown in FIG. 5A. It is coated with a hot-melt adhesive 22 
on each side. Electrical leads 18 are connected to the anode and the 
cathode of the internal battery, and as a result connection together of 
leads 18 causes current to flow through the internal resistance of the 
battery and any other heating element within the wrap. That causes the 
wrap to become hot and the adhesive 22 to be activated. 
A cross-section through the wrap is illustrated in FIG. 5B. One can see a 
lithium electrode 23, a porous membrane 24, an electrolyte 25, and a 
magnesium dioxide or other suitable electrode 26. 
The tie wrap 17 shown in FIG. 5C also has a PTC heating element 28 
connected in series with the lithium battery. Heat is generated at least 
in part within the element 28 which, due to its PTC behaviour, regulates 
the heat output of the strip. 
The conductors 18 have been connected together as shown at 27 to cause the 
internal battery 23,24,25,26 to power the internal PTC heating element 28. 
FIGS. 6A, 6B and 6C show a way in which the battery may be electrically 
connected to a heating element, be it either its own internal resistance 
or a separate element. 
The cable wrap illustrated, in perspective in FIG. 6A and in cross-section 
in FIGS. 6B and 6C, comprises a PTC heating strip 29 and a lithium battery 
30 together with a switching means 34,35,36. Slits or other means 31 may 
be provided in one or more components to improve flexibility of the strip 
allowing it to be wrapped around a cable. 
An aluminum or other electrode 32,33 is provided on each side of the 
PTC/battery laminate. When these two electrodes are connected together, an 
electric circuit is made and current will flow through the PTC strip 29 
causing the cable wrap to become hot. At one edge of the strip the two 
electrodes protrude, and are separated by an insulator 34. An insulating 
clip 35 retains the electrodes 32,33 close to one another, but on opposite 
sides of the insulator 34. When the clip is pulled to the right as drawn 
in FIG. 6B the electrodes move with it to a position away from the 
insulator 35. In this position, as shown in FIG. 6C, the electrodes can 
now touch one another, optionally under the influence of the clip 35 which 
forces them together. The electrodes may be provided with corrugations 36, 
allowing their extension to the right. Alternatively, the electrodes may 
remain fixed, and an insulator moved. 
For the avoidance of doubt it is here noted that the invention provides a 
method and articles for environmental protection which allow a high 
quality seal to be made under a heat-shrinkable sleeve, but avoid the bulk 
change of dimension usually associated with heat-shrinkable sleeves. Thus 
the amount of heat required is reduced. Any one or more of the sleeve 
configurations, heaters, power supplies, switches or sealing materials 
disclosed may be selected.