Sewing – Elements – Frames
Patent
1992-09-17
1994-02-15
Crowder, Clifford D.
Sewing
Elements
Frames
1122691, D05B 122
Patent
active
052857417
DESCRIPTION:
BRIEF SUMMARY
This invention relates to the manufacture of tubular materials, and in particular to the manufacture of tubular materials for use in connection with a lining process for underground pipelines and passageways.
Various processes are known for the lining of underground pipelines and passageways using flexible tubular materials, such tubular materials constituting linings which are applied to the pipeline or passageway surfaces and are held in position with fluid pressure until either the lining material is adhered to the pipeline or passageway surface by means of an adhesive or curable synthetic resin which impregnates the lining (the lining being of a suitable absorbent material) cures to a rigid form, in which case the combined tubular lining material and resin form a rigid pipe lining the pipeline or passageway surface. The rigid pipe may either be adhered or bonded to the said surface by virtue of the nature of the resin used, or the rigid pipe may be free standing and close fitting.
In all cases, the lining material is a soft and flexible material, and whilst it is being placed in position the adhesive and/or resin is also in fluent condition so that the combined adhesive and/or resin and the lining materials are soft whilst being applied, but may and usually do become hard to form the said pipe after the lining operation has been completed.
Consequently, these lining methods have become known as "soft lining" methods.
By far the most successful of these methods is the INSITUFORM (Trade Mark) method of soft lining, and the most practiced INSITUFORM method is disclosed in British Patent No. 1449455. As will be understood from that patent, the lining material used in comprises at least one layer of a resin absorbent material e.g. a fibrous felt, to the outside of which is an impermeable tubular membrane, and this lining material with the felt impregnated with resin is everted into the pipeline or passageway to line same, so that eventually the membrane lies to the inside of the applied lining, whilst the impregnated felt lies adjacent the surface to be lined.
A method of fabricating tubular lining material suitable for use in this method is set forth in European Patent Application No. 79301952.2 from which it will be seen that the lining material starts off initially as a flat web with a coating on one side thereof to form the impermeable membrane, and then the material is wrapped into tubular form so that the free edges come into butting relationship and are sewn together by means of a sewing machine, the coating side being to the outside of the tubular structure. In order to seal the stitches and in particular the needle holes created in the outer coating by the stitching operation, a strip of sealing tape is applied over the stitching so as to seal said holes, the tape being bonded to the outer membrane by means of any suitable system such as heat and pressure or solvent.
In the manufacture of lining materials for this process, it has been found convenient to construct the lining material in a number of layers. That is to say, if a thick lining material is required, it is more convenient to make the lining material of a number of layers of felt rather than to produce a single felt layer of the required thickness, because to produce needled felt in a thickness much in excess of say 6-8 mm is a rather inefficient and costly process. Consequently, when it is required to produce a thick lining, it has been the practice to construct the lining material of one or more inner layers of felt only, and the single outer layer which is coated with the impermeable membrane material. Conventionally, the inner layers are also constructed from flat webs which are wrapped into tubular form with the edges in overlapping arrangement. The outer layer is wrapped around the inner layer or inner layers and finally, the butted edges of the outer layer are sewn together as described in said European Patent application.
This method creates a difficulty in practice, because as regards the or each inner layer, that layer has a dou
REFERENCES:
patent: 1455384 (1923-05-01), Bates
patent: 2839020 (1958-06-01), Hopkins
patent: 3246621 (1966-04-01), Copeland
patent: 4009063 (1977-02-01), Wood
patent: 4446181 (1984-05-01), Wood
Crowder Clifford D.
Insituform (Netherlands) B. V.
Lewis Paul C.
Philpitt Fred
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