Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~927~
DESCRIPTION
TI TL~:
PIPEL,INE WRAPPING MATERIAL
This invention relates to a strip or sheet like
product useful as a pipeline ~rapping material for
protecting pipes, particularly although not
exclusively, hot pipes.
There are numerous situations in which pipelines
requireprotection from the elements, from subterranean
hazards or, as the case may be, submarine hazards, and
from corrosive influences. Further, pipes for conducting
oil from oil wells, whether submarine or not, are
10 frequently hot, because the oil itself is hot.
Equally, if a crude oil is "waxy" it needs to be heated
in order to be economicall~ pumped. In the case of
natural gas, pipelines often have spaced apart booster
stations to increase the pressure, and the pressure
15 increas~s lead to corresponding temperature imcreases
so that in the region of such stations the pipes are
hot.
Thermo~lastic self adhesive tapes are known for
the wrapping of pipelines, but are unsatisfactory for
20 pipelines operating at elevated temperatures, for
instance 80-220C, because the adhesive becomes soft
7~
-- 2
and plastic and the protection impaired. Thus at t~e present
time the temperatures prevailing at the surface of hot pipelines
cause problems in applying to them and main-taining on them
appropriate protective coverings.
According to the invention there is provided a pipe-
line wrapping material comprising a layer of a thermosetting
compound on a perforated polymeric film, wherein said thermo-
setting compound extends through the perforations in said
polymeric film and said thermosetting compound layer has a
thickness of from Q.125 mm to 1.5 mm.
The thermosetting compound will preferably be self
adhesive at ambient temperature, that is to say it will be
adherent to a steel or concrete pipeline surface when applied
manually.
If the material is applied to a pipe which is or
becomes hot, the therrnosetting compound will shortly cure as
a result of the heat of the pipe and be ahle to withstand
temperatures up to 220C. Preferably the thermosetting com-
pound is also such that if applied to an unheated pipeline,
it will, for instance in about six months, still cure to a thermo-
set condition at ambient temperatures in temperate zones.
The polymeric film is primarily for -the purpose of
acting as a carrier for the thermosetting compound so that
the product can be actory made and thus uniform, leading to
a uniform application of protecting material on the pipeline.
The reason for the perforations is to increase security of
,~f ~
. A~
~g~7~s
adhesion between the film and thermoset-ting compound, both
before curing and afterwards where, as a secondary function,
the film itself imparts protection and reinforcement. The
compound :is forced throuyh -the perforations so that to some
extent the film can be regarded as embedded therein. ~fter
settiny, the compound which has been forced through usually
adopts a "mushroom head" configuration, thus effectively
"rive-tting" the film ;n place.
Normally, the material will be applied to a pipe by
helical wrapping, and at least some overlap between adjacent
turns will be provided. In this way the compound forced
through the perforations in one layer of wrapping will contact
the main layer of compound on the overwrap, so that the poly-
meric film will be truly embedded, and the resulting protection
will be much improved given the problems normally encountered
in attempting to effect adhesionl at high temperature, between
for instance a polypropylene or polyester film and a cured
thermosetting compound.
A plastics film, preferably of polypropylene, or
polyester is preferable for supporting the compound and pro-
viding reinforcement on the pipe. The preferred thickness of
this film which could be of other suita~le materials, is in
the range la to 20Q microns, most preferably about 50 to lO0
microns. The perfora-tions should be small and numerous,
there being prefera~ly between 3 to 30 perforations per
squaxe centimetre and most preferably 9 to 18 per square
J
,.. ..
7~S
-- 4
centimetre. The perforations together preferably provide an
open area in the polymeric film of not more than 40~, and
most prefera~ly between 5 and 20o~
Various thermosetting resins can be used for the
compound, but the compound is preferabl~ essen-tially epichlor-
hydrin based, including secondary materials to allow flexi-
bility in both the green and cured s-tates. The layer of
compound desirably has a thickness of 0.5 to 1.0 mm.
Although It is expected to provide a layer of the
thermosetting compound on only one side of the polymeric film,
it is within the scope of the invention to provide such a
layer on both sides, in which case of course, compound will
be forced through the perforations so as to secure both
layers to the film.
The material will normally be supplied in rolls, in
strip or sheet like form, for instance in a width of 4 to 6
ins, or up to or even exceeding 1 metre. In such cases, a
release sheet will be provided at least on the surface of
the compound layer remote
2Q
"~"'
'~
7~5
from the polymeric film, and prefelably on both si~es of
the material. Such sheets will ~e between adj~cent
layers in the roll and the pressure of the roll will
bring about the flow of the compound through the
perforations in the film even before application to a
pipeO
A siliconised, waxed or pvc coated paper will
be preferable for the release sheet, though certain
plastics materials offering little adhesion with the
10 compound may alternatively be used. Upon application
to a pipe, the release sheet or sheets will be peeled
off as the material is unrolled.
It is important to the invention that the
thermosetting compound should be such that it will not
15 self cure too soon J for instance in temperate zones
for a period of at least six months, but that it will
appropriately cure upon the application of heat, such
that curing will be brought about when a material is
wrapped around a hot pipe. Even on a non-heated pipe,
20 as mentioned, curing will occur eventually so that the
material is useful without regard to the heating or
otherwise of ~he pipe.
Figure 1 of the accompanying drawings is a
perspective view of a strip of material of the invention the
25 thicknesses of the different components of which ~re
much exaggerated for clarity~ The strip comprises
an upperrnost perforated plastics poLypropyLene film 10
on one face of which is suppor-ted a thermosetting
compound layer.
On the free face of layer 11 is a siliconised
release paper sheet 12. ~his material is to be
supplied in rolls so that the release paper will
contact the surface of the plastics film remote from
the thermosetting resin in the preceding turn on the
roll. ~lthough not shown, a release sheet i5 preferably
10 pxovided on each side of the material. While the
material is in the roll, the thermosetting compound
will be forced through the perforations in the plastics
film 10 and form "pimples" upon the other side thereof.
Figure 2 schematically illus-trates a pipe 20, to
15 convey a flowable substance such as oil or natural gas
which may be hot, and wrapped around which is a strip
21 of the material of the invention. It will be seen
that the material is so wrapped that at any point on
the pipe there are two layers of the material, thus
20 allowing the previously mentioned pimples of compGund
on the lower wrap to engage with the layer 12 on the
next overwrapO
