A pressure-resistant helical corrugated pipe comprises a helical corrugated pipe wall formed by a top portion, opposite side wall portions and a bottom portion; a wide metal belt plate of a thin metal plate disposed at least at the top portion and the opposite side wall portions; and a small width metal belt plate being separate from the wide metal belt plate and disposed at the top portion of the pipe wall in overlapping relation to the wide metal belt plate in the direction of the thickness of the pipe wall. The two metal belt plates are integrally connected together at an overlap portion by a synthetic resin material or a rubber material.
This is a continuation of application Ser. No. 07/887,661 filed May 26, 1992, now abandoned which is a continuation of application Ser. No. 07/454,562 filed Dec. 21, 1989, now abandoned.
A scuff cover (10) for protecting an elongate inner element (14), such as a hose or a cable, comprises a flexible base tube (30) having an inner surface (34) defining a central passage (38) for movably receiving the inner element. The base tube (30) has an outer surface (36). A rub strip (40) projects from the outer surface (36) of the base tube (30). The rub strip (40) comprises an inner layer of material (42) on the base tube (30) and an outer layer of material (44). The outer layer of material (44) has a lower coefficient of friction than the inner layer of material (42) and forms the radially outermost surface of the scuff cover (10). The outer layer of material (44) is preferably ultrahigh molecular weight polyethylene.
An object of the present invention is to provide a synthetic resin pipe configured to perform water stop accurately by forming a part connecting convex portions of an outer pipe to be flat without reducing flexibility in order to compose a synthetic resin pipe having flat inner and outer surfaces. A synthetic resin pipe according to the present invention includes an inner pipe formed by spirally winding a belt-like synthetic resin; a spiral reinforcing part formed by spirally winding a synthetic resin having a projected rim with convex portions projecting outside; an outer pipe of belt-like synthetic resin provided so as to connect a part or all of the convex portions arranged in a pipe axis direction; and a shape retaining material for the outer pipe made of a belt-like metal sheet for retaining a shape of the outer pipe flat and buried in or provide to an inner surface of the outer pipe; wherein the shape retaining material for the outer pipe is a synthetic resin pipe wound around the convex portions of the projected rim at predetermined intervals and connecting the convex portions of the projected rim.
A flexible conduit formed by a helically wound band of metal that resists burst pressure. The band has a leading edge hook and a trailing edge hook that engage and interlock. The cross-section of the band has a radially asymmetrical Z-shaped profile. When the band is helically wound, the downstream hook of one turn of the band is received in the upstream valley of the previous turn of the band so that the downstream and upstream hooks form an interlock holding the windings together. In the wound configuration, the thickness of the profile between the upstream valley and the internal surface of the tube is greater than the thickness of the profile between the downstream valley and the external surface of the tube to provide greater material thickness to reduce contact stress at the hook and valley interface and to reduce alternating stresses in the valley corners. The outer surface of the profile tapers towards the center of the tube to direct externally applied radial compression forces toward the thickest section of the profile. A multilayer conduit employing the band may include a central, helically wound collapse-resistant layer disposed within a flexible fluid barrier that in turn is disposed within the tube formed by the band. The conduit may be wrapped with one or more tensile strength layers, anti-wear layers, and additional fluid barriers.
