U.S. patent number 3,812,283 [Application Number 05/347,318] was granted by the patent office on 1974-05-21 for pressure resistant cable.
This patent grant is currently assigned to The Anaconde Company. Invention is credited to Ralph C. D'Ascoli, Lawrence C. Ebel, Erich W. Kothe.
United States Patent |
3,812,283 |
Kothe , et al. |
May 21, 1974 |
PRESSURE RESISTANT CABLE
Abstract
A land lines communication cable system resistant to shock
pressures comprises an integral tensile unit wherein tensile tapes
covering the cable lengths are secured to splice cases, and an
integral compressive unit wherein a plurality of both cable lengths
and splice boxes are filled with an intercommunicating
incompressible pasty composition.
Inventors: |
Kothe; Erich W. (White Plaines,
NY), Ebel; Lawrence C. (Hastings-on-Hudson, NY),
D'Ascoli; Ralph C. (Yonkers, NY) |
Assignee: |
The Anaconde Company (New York,
NY)
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Family
ID: |
26814682 |
Appl.
No.: |
05/347,318 |
Filed: |
April 2, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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116845 |
Feb 19, 1971 |
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Current U.S.
Class: |
174/105R;
174/106R; 174/108; 174/23R; 174/107; 174/126.2 |
Current CPC
Class: |
H02G
15/10 (20130101); H01B 11/06 (20130101) |
Current International
Class: |
H01B
11/02 (20060101); H01B 11/06 (20060101); H02G
15/10 (20060101); H01b 011/06 () |
Field of
Search: |
;174/16R,16D,108,12D,107,15R,15B,36,126CD,128,23R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gilheany; Bernard A.
Assistant Examiner: Grimley; A. T.
Attorney, Agent or Firm: Volk; Victor F.
Parent Case Text
This is a division of application Ser. No. 116,845 filed Feb. 19,
1971 now abandoned.
Claims
1. A cable for a land lines communication system resistant to
destruction by high external shock pressures comprising:
A. a plurality of insulated communication conductors,
B. a wrapping comprising polyester film, surrounding said
conductors,
C. a continuous, extruded, tubular polymeric sheath directly
covering said polyester film,
D. an incompressible pasty composition completely filling all void
spaces within said sheath at atmospheric pressure,
E. a corrugated steel shielding tape wrapped with an overlapped
longitudinal seam surrounding said sheath,
F. a continuous extruded tubular polymeric jacket surrounding said
shielding tape,
G. a first layer of high-tensile-strength copper-clad steel armor
tapes helically wrapped around said jacket with a selected
direction of lay,
H. a second layer of high-tensile-strength copper-clad steel armor
tapes helically wrapped over said first layer with a direction of
lay in reverse of the direction of said first layer,
I. a continuous extruded polymeric outer jacket surrounding said
second
2. The cable of claim 1 wherein said sheath and said jackets
comprise polyethylene.
Description
BACKGROUND OF THE INVENTION
Communication cables, which in this application are construed to
include cables for communicating not only voice signals but signals
other than voice signals including what are sometimes designated
control cables, are herein designated land lines cables as
distinguished from submarine cables. Such cables in combination
with splices and/or auxiliarly equipment such as amplifiers
comprise a cable system which may be buried in whole or in part.
While it has been known to protect cables, including communications
cables, from mechanical damage by covering them with armor wires or
tapes, this has not provided protection against gaseous pressure
waves that pass through interstices in the armor, or tensile forces
so great in extent that they affect areas beyond the termination of
the armor. Conventional cables, even if they are protected by
armor, can be crushed by high external gas pressures so that the
conductors within the cables are severed or shorted to each other
by the destruction of their insulation. Although it has been known
to fill communication cables with pasty compositions to keep out
moisture, such compositions have not constituted any protection
against local crushing pressures since a filling of composition
would yield under pressure either by being extruded to an opening
in the cable sheath or swelling or bursting the sheath at a
low-pressure area.
SUMMARY
We have invented a land lines communication cable system at
atmospheric pressure that is highly resistant to destruction by
severe external shock pressures. This system comprises a plurality
of lengths of cable each comprising a plurality of insulated
communications conductors and a tubular sheath, such as a polymeric
extrudate, surrounding the conductors and a plurality of layers of
high-tensile-strength armor tapes surrounding the sheath. Our
system also comprises at least one connection between the cable
lengths comprising a splice between the conductors of the different
cable lengths and a splice case enclosing the splice and, possibly,
auxilliary apparatus. The splice case is characterized by the fact
that, although it is normally maintained at atmospheric pressure,
it has substantial hoop strength and is capable of withstanding
high tensile and compressive shock forces. The case comprises means
at both ends for securing the armor tapes of different lengths of
cable so that tensile stresses are carried through one of the
lengths, the case, and the tapes of another length acting as one
continuous tensile member. An incompressible pasty composition
fills all void spaces within the cable sheaths and the splice case
and can flow from one to the other under a high pressure
differential. Since, however, the case is filled with composition
and has an exceedingly high hoop strength the composition in the
cable has no outlet to flow into when a portion of the cable is
subject to compression. It cannot burst out of a remote section of
the cable itself because of the high tensile strength of the armor
tapes.
A preferred embodiment of cable for our system comprises a
continuous extruded tubular polymeric sheath surrounding a
plurality of insulated communication conductors, a corrugated steel
shielding tape wrapped with an overlapped longitudinal seam to
surround the sheath, and a continuous extruded polymeric jacket
over the shielding tape. This tape has an overlapping portion of
itself and would be free to yield under compression in the absence
of pasty filler. A first layer of high-tensile-strength armor tapes
is helically wrapped around the cable jacket with one direction of
lay and is directly covered with another layer of
high-tensile-strength armor tapes with a reverse direction of lay.
In addition to their structural effect the armor tapes provide
additional electric and magnetic shielding of the conductors and we
have found that this shielding is enhanced as a result of the
separation of the armor tapes from the corrugated shielding tapes
by the extruded sheath. A continuous, polymeric, outer jacket is
extruded over the second layer of armor tapes. These jackets and
also the sheath, preferably comprise a polyolefin and our system
may comprise a number of splice boxes and cover a distance miles in
extent.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a side view, partly in section, of the cable system of
our invention.
FIG. 2 shows a cut-away pictorial view of a cable of our
invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
A cable system, designated generally by the numeral 10, comprises a
plurality of cable lengths 11, 12, 13, 14 15 with interconnections
16, 17, 18 comprising splice cases 19, 21, 22 of which we shall
describe the interconnection 16 and splice case 19 in more detail
hereinbelow. The structure of a cable 23 forming the cable lengths
11-15 is shown in detail in FIG. 2 to comprise a plurality of
insulated conductors 24, twisted into pairs in a known manner. Each
of the insulated conductors has a copper wire 26 and a surrounding
wall of polyethylene insulation 27. Our invention is, of course,
not limited by the particular type of communication conductors in
the cable 23 which may include coaxial cables, quads, unpaired
conductors, and, indeed some additional strands other than
communication conductors. 25 pairs of the insulated conductors 24
are stranded together to form a core 28. In the illustrated cable
the conductors are No. 16 Awg (American Wire Gage) solid copper
with 20-mil walls of solid polyethylene insulation, and the core
formed by these conductors is wrapped with an 0.016-inch-thick tape
29 of SBR (styrene-butadiene rubber) backed with polyester film. A
sheath 31,90 mils thick, of low-density polyethylene is extruded
over the core 28 and over this has been folded a ten-mil corrugated
shielding tape 32 of low-carbon, tin-coated steel. Over the steel
tape 32 is extruded a 120-mil jacket 33 of low-density polyethylene
to a diameter of 1.845 inch. A plurality of high-tensile strength
tapes 34 are wrapped around the jacket 33 in two layers 36 and 37.
The tapes 34 are rolled from copper-clad steel to a dimension of
0.050 .times. 0.200 inch, the layer 36 being applied with a 12 1/2
inch right hand lay and the layer 37 with a 12 1/2 inch left hand
lay. The reverse lays of the layers 36 and 37 keep the cable
balanced under tension and the pitch diameter of the armor tape
layers is long enough to provide an extremely high tensile strength
for the cable as a whole, easily withstanding a pull of 30,000
pounds without damage, while at the same time being short enough to
provide the hoop strength necessary to confine the contents of the
core when portions of the cable are subjected to compression.
In addition the armor tapes 34 reinforce the shielding effect of
the tape 32. The shielding effect of the armor layers 36, 37 is
enhanced by the reverse lays of the two layers and the close
spacing of the tapes within each layer. A pasty composition 38
fills the space between the conductors 24 in the core 28. This
composition is essentially incompressible and preferably will be
water insoluble and have a high dielectric strength. A suitable
composition is described in U.S. Pat. NO. 3,539,708.
An overall low density polyethylene jacket 39 is extruded over the
layer 37 providing mechanical and moisture protection to the cable
23. The large size and weight of the cable 23 limits the continuous
length that can be delivered to any installation site so that
connections will be required even in the absence of amplification
or branching of the cable system.
To make a connection such as the interconnection 16, the wires 26
of the cable lengths 11 and 12 can be spliced by any suitable means
of which several are known, after cutting away the overlaying
layers as shall be explained. The splice is finally protected by
the heavy splice case 19 which is formed by bolting together upper
and lower flanged sections 41, 42 with a large plurality of bolts
and nuts 44 to provide a very high hoop strength. The ends of the
sections 41, 42 bolt to end plates 46, 47 by means of cap nuts 48.
The end plates 46, 47 have circular grooves 49 scored for firm
gripping of the armor tapes 34 which are wrapped around steel rings
51 shaped to fit the grooves 49 on one face 52 and flattened on the
other face 53. The flattened surface 53 serves to grip the ends of
the tapes 34 against a scored surface 54 of a facing plate 56 which
is locked against the ring 51 by means of long bolts 57 which
thread into taps in the plate 46. A gusseted stub tube 58 fits a
counter bore 59 in the facing plate 56, the plate 56 and tube 58
having an inside diameter closely fitting over the layer 37. The
case 19 encloses a split inner steel casing 61 having thin tubular
extensions 62 that fit closely over the shielding tape 32 and make
electrical contact with the shielding 32, such as by being wired
down upon the tape or soldered to it so that the casing 61 affords
shielding continuity between tapes 32 of the two lengths 11, and
12, and so on. Thus throughout our system the shielding is
continuous. Similarly the case 19 itself provides shielding
continuity as well as structural continuity of the layers 36, 37.
The splices in the wires 26 are staggered within the casing 61 and
the tapes 29, 32 and sheath, 31 are cut off so that they extend a
short distance within the casing 61 to expose the conductors 24 for
splicing. The jacket 33 is cut off so that it extends within the
case 19 a short distance from the extension 62. The tapes 34 are
cut so as to leave enough free length for wrapping around the ring
51, and the jacket 39 is cut just short of abutting the tube
58.
Surrounding the splice in the wires, the casing 61 is completely
filled with the pasty composition 38 forming a continuum with the
composition in the cable cores. Outside of the casing 61
composition fills the remaining space in the case 19. There is, in
fact, a continuous pressure contact of the composition 38 within
our system including the cable lengths 11, 12, 13, 14, 15 and cases
19, 21, 22. The case 22 is bifurcated at one end to provide for a
branched splice but each of bifurcations 63, 64 is provided with
plates 56, 46 and ring 51 to anchor the tape armors in the manner
of the case 19.
We have invented a new and useful cable system of which the
foregoing description has been exemplary rather than definitive,
and for which we desire an award of Letters Patent as defined in
the following claims.
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