Pipes and tubular conduits – Combined – With hose protector
Patent
1993-12-21
1996-01-09
Bryant, III, James E.
Pipes and tubular conduits
Combined
With hose protector
138 99, 138103, 285381R, 174DIG8, 428 349, F16L 5916
Patent
active
054820871
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to coverings for pipelines, and in particular to coverings which comprise a heat recoverable sheet or tape coated on its inner surface with a hot-melt adhesive comprising a blend of polyethylene alkyl acrylates, particularly for covering pre-polymeric coated or thermally insulated pipelines, or where the heat recoverable backing is a tape, for helically wrapping around bare metal pipe, or polymeric coating of a thermally insulated pipe.
2. Introduction to the Invention
Heat recoverable articles are well known. They are articles the dimensional configuration of which may be made substantially to change when subjected to heat treatment.
Usually these articles recover, on heating, towards an original shape from which they have previously been deformed but the term "heat recoverable" as used herein, also includes an article, which, on heating, adopts a new configuration, even if it has not been previously deformed. Examples of such heat recoverable articles based on polymeric sheet material are found in U.S. Pat. Nos. 2,027,962, 3,086,242, and 3,597,372. Heat recoverable articles based on fabrics are also known. Typically these comprise a recoverable fabric in conjunction with a polymeric matrix formed by laminating a polymeric material to one or both sides of the fabric to render it impervious. Examples are described in European Patent Publication Nos. 116,393, 117,026, and 116,392.
The use of a polyethylene alkyl acrylate on a heat recoverable sleeve for environmental protection, particularly of a cable splice, is described in European Patent Publication No. 330,480, which is the counterpart of U.S. Pat. No. 4,965,320. The entire disclosure of U.S. Pat. No. 4,965,320 is incorporated herein by reference.
SUMMARY OF THE INVENTION
The present invention provides particular methods of applying a recoverable sheet or tape coated with the specified hot-melt adhesive around pipelines.
A first aspect of the invention provides a method of environmentally protecting a polymer-coated metal pipeline, or a joint between two such pipelines where the pipelines have been bared of polymer coating at the joint region, the method comprising: thereof with a hot melt adhesive composition, such that the adhesive faces the pipeline, and such that the adhesive-coated sheet at least overlaps the polymer coating, the adhesive comprising a mixture of 25 to 40 parts by weight of a polyethylene alkyl acrylate terpolymer containing maleic anhydride and having a melt flow index as determined according to ASTM D1238-70 of at least 40, and 25 to 70 parts by weight of a polyethylene alkyl acrylate copolymer having a melt flow index as determined according to ASTM D1238-70 of at least 40; and adhesive.
DETAILED DESCRIPTION OF THE INVENTION
The heat-recoverable sheet which is preferably shrinkable may be tubular, i.e. of closed cross-section, or may be wraparound, that is it may be in the form of a sheet wrapped around the pipelines, such that longitudinal edges thereof abut or overlap. The longitudinal edges may be held in position relative to each by any of a number of known closure mechanisms, e.g. a polymeric patch may be bonded to overlapped edges of the wraparound, or a penetrating closure e.g. stitching or riveting, can be used, or the overlapped edges may simply be bonded or fused to each other.
One particular application of the first aspect of the present invention is for covering a joint, e.g. a weld between two metal pipes coated with a corrosion protection layer. As an example steel or other metal pipes are often pre-coated in the factory with a polyethylene coating. This coating may be so-called "three-layer-PE coating". The polyethylene coating is typically extruded. As another example a coating comprising sintered polyethylene maybe used. In order to join such pipes they are usually bared of coating at their ends, and then welded. In order to protect the joint it is therefore necessary to make good the coating in the joint region.
A number
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Leest Yvo
Overbergh Noel M. M.
Bryant III James E.
Burkard Herbert G.
Gerstner Marguerite E.
N.V. Raychem S.A.
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