Pipe for carrying fluids, particularly hydrocarbons

Details Pipe for carrying fluids, particularly hydrocarbons Pipe for carrying fluids, particularly hydrocarbons

1994-02-22

1995-09-05

Arola, Dave W.

Pipe joints or couplings

With casing, lining or protector

Insulated

285114, 285138, 285286, 285355, 285369, 285906, F16L 1112

Patent

active

054473390

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to a pipe for carrying fluids, particularly hydrocarbons, made by assembling heat-insulated metal tubes.
It is known that in a number of cases, crude oil is extracted from the ground at a temperature which is several tens of degrees greater than the ambient temperature and that, when this crude oil contains paraffinic products, its cooling to ambient temperature (or even to temperatures greater than the ambient temperature) causes for example precipitation of these products which progressively leads to blockage of the pipe.
It has already been attempted to overcome these difficulties by surrounding the pipes with thick insulators based on expanded materials which must themselves be protected by a layer of rigid materials, so as to withstand the various stresses to which the pipe is subjected both when it is fitted and when it is used.
These insulators have the drawback of being bulky, and of considerably increasing the external dimensions of the pipe. They also greatly increase its buoyancy, which often requires its ballasting to be increased.
In the latter case, it is then necessary to weight the pipe by encasing it in concrete, which is almost always difficult to make adhere to the outer wall of the insulator.
These known pipes also have the drawback of corroding easily when the outer insulator becomes degraded or because of the thermal expansions which are different between the steel tube and the insulator.
It also been envisaged to produce insulating tube sections consisting of an outer tubular element and an inner tubular element which are welded at their ends and which contain between them an insulating element in order to constitute pipes.
The use of such tube sections has proved unsatisfactory, in particular because of the difficulties which are encountered in joining the tubular elements together in order to constitute the pipes.
The object of the present invention is to obtain, in a simple and economical manner, a pipe produced from thermally insulated steel tube sections, but which include no outer insulator and which can be handled, fitted and used for producing submerged or overland pipes, exactly in the same way as conventional steel tube sections which include no insulator.
The subject of the present invention is a pipe for carrying fluids, particularly hydrocarbons, consisting of thermally insulated steel tube sections, of the type comprising an outer tubular steel shell, an inner cylindrical steel shell of smaller diameter, the inner shell being welded in a leaktight manner to the outer shell at each of the ends of the tube sections, while leaving between the two shells a closed annular volume, preferably containing a heat insulating material, which pipe is characterized in that, at each joint between two tube sections, the ends of the inner shells of the two pipe sections are welded to one another, while a sleeve joins the ends of the outer shells, such that when traction, compression or bending forces are exerted on the pipe, the said sleeve communicates these forces to the outer shells while imparting to the pipe a mechanical strength at each joint which is at least equal to that of the tube sections.
According to a first embodiment of the invention, the sleeve is screwed onto each outer shell by a cylindrical thread, preferably with straight turn fronts, which includes between the male and female turns a clearance which is sufficient to compensate for alignment and positioning defects in the two sections when they are joined by welding their inner shells, and the space contained between the male turns and the female turns is lined with a substance, for example a polymerizable substance, which transmits the compression or traction forces which are to be exerted between the sleeve and the outer shells.
In order to do this, the total surface areas of the turn flanks must be chosen to be sufficiently large to allow for the crushing strength of the substance which is introduced between the male turns of the outer shells and the female turns of the sleeve.
This

REFERENCES:
patent: 4524996 (1985-06-01), Hunt
patent: 4635967 (1987-01-01), Stephenson
patent: 4660861 (1987-04-01), Argy et al.
patent: 4793383 (1988-12-01), Gyory et al.

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