US3005742A - Method of forming a pipe covering - Google Patents

Description

Oct. 24, 1961 T. KENNEDY, JR 3,005,742

METHOD OF FORMING A PIPE COVERING Filed May 16, 1958 INVENTOR.

W BY W 5 v United States The present invention relates to an improved method of forming a wrapped covering for pipes, conduits, and like structures which are installed underground, hence subject ater mastic condition preceding the application of the covering 12. Coating compound 14 may be a known bituminous, petroleum wax, or other adhesive composition having desired rust inhibitors and wetting agents. Such waxes 5 are well known in the art, possessing excellent corrosion to attack or deteriorative action by chemicals, fungi or known synthetic plastic or resin film, such as polyethylother conditions or elements present in the soil. The method produces a continuous dielectric shield for the pipe which is proof against penetration at the zone of its wrapped overlap.

It is an object of the inventionto pro ideamethodof n coate ipipaihehlmrwehtmstripldmayalsohecwn'app ni.

preparing and applying a pipe covering in which a suitable plastic protective film is wrapped spirally or longitudinally over the pipe, without requiring'any necessary preliminary preparation, and is autogenously sealed in a novel manner to protect the pipe.

Another object is to provide a method as described in which a plastic film of known type is spirally or longitudinally wrapped over a bare or appropriately undercoated pipe, and in which overlapped seam zones of the film are effectivelyfused andeeaied te em another 'by ae -appar q as ze ier the lf desired a saitahle ad an application of appropriate solvent, so as to provide,

in effect, a continuous, joint-free plastic cover for the A still further object is to provide a method as described, in which the plastic protective film provides a continuous dielectric shield, proof also against penetration or deterioration by moisture or chemicals of the soil, or oil or other fluid carried by the pipe.

Another object is to provide a wrapped pipe covering and method of the sort referred to, in which the protective joint seal at the overlap of the Wraps is as permanent as the plastic protective film itself, in which the covering can be applied without special preliminary preparation of the surface of the sealed plastic wrapper, and in which the pipe can be lowered into a ditch or trench immediately upon the application of the wrapped covering. There is no adhesive or like material left at the zone of wrap overlap which is apt to deteriorate.

A still further object is to provide a covering capable of being applied by a method of dissolving and fusing overlapped seams, in which the application of the solvent is made during the operation of wrapping.

The foregoing as well as other objects will become more apparent as this description proceeds, especially when considered in connection with the accompanying drawing illustrating a preferred embodiment of the invention, wherein:

FIG. 1 is a fragmentary perspective view, partially broken away, illustrating the improved method of applying a covering to a pipe; and 7 FIG. 2 is a view in enlarged scale and transverse section along line 2-2 of FIG. 1.

The reference numeral 10 generally designates a pipe or conduit which is to be installed in the ground, bare or coated, to carry oil, gas or other fluids and which is protected against attack and deterioration'as the result of various conditions, phenomena or elements of the soil by the covering of the invention, generally designated 12. The reference numeral 14 designates a coating compound applied to the pipe, in a hot molten condition or in a cold ene, polyvinylidine chloride, polyvinylchloride, or the like, in a relatively wide size. It is wrapped directly on the undercoating either by a spiral wrap as shown or longitudinally. However, although shown as applied to a on a bare pipe.

In accordance with the invention, as the plastic film strip 16 is wound upon the'coated pipe 10 a suitable solvent 18 for the plastic, such as tetrahydrafurane, benzyl 20 alcohol, or methalethyl ketone, is applied to the lap of the film along which the latter is seamed in wrapping. This solvent may be sprayed, brushed, wiped or otherwise applied on and into the laps of the primary wrapper 16, and FIG. 1 schematically depicts the use of spray hesive additive may be incorporated to enhance the bond.

As a result theta eatitanstrip l is welded er autog enously fused at the overlap, providing what is in eifect a continuous plastic cover over the pipe 10. The fused material sets quickly, and the covered pipe may be lowered immediately into a ditch after the seal is completed.

The method of the invention provides a continuous dielectric shield for the pipe, which is also proof against penetration by soil moisture, fungi or chemicals, as well as attack by oil or other fluids handled by the pipe, which shield is as permanent as the plastic itself. Exposed adhesive material at the laps, such as might deteriorate and defeat the purpose of the invention, is avoided. The covering can be applied without preliminary preparation of the plastic film, and, as indicated in 'FIG. 1, the application of the solvent is made in the same operation with the wrapping.

In this connection, the spray apparatus 20 shown in FIG. 1 of the drawings may be supported upon pipe wrapping equipment of the type illustrated and described in my copending application Serial No. 735,839, filed May 16, 1958, with the device 20 fixedly disposed at a stationery coating location. In the alternative an apparatus in which the pipe is held stationary and the wrapping mechanism rotated therearound, the spray mechanism 20 the conduit with a flexible tape of a synthetic resinous plastic material by continuously helically winding the tape about the conduit with a lead such that each convolution marginally overlaps the next preceding convolution in continuous pressure contact therewith so that a continuous seam develops at the overlap as the convolutions develop, interposing a solvent for the plastic material between the overlapping convolutions by locally applying the solvent during winding of the tape as aforesaid to the seam forming margin only of the tape at a point only slightly ahead of the developing seam and moving the V References Cited in the file of this patent UNITED STATES PATENTS 2,291,838 Shoan Aug. 4, 1942 4 Hosfield Me I 19% 'Ccihvefse Oct. 10, I944 Snyder Feb. 7, 1950 Von Stackelberg Mar. 3, 1953 Harder Dec. 11, 1956 Hopkins Apr. 1, 1958

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