Pipes and tubular conduits – Distinct layers – With intermediate insulation layer
Patent
1985-12-26
1990-05-01
Bryant, III, James E.
Pipes and tubular conduits
Distinct layers
With intermediate insulation layer
138148, 285 47, F16L 914
Patent
active
049210181
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a heat insulated line or conduit for the transport of fluids, usable in particular but not exclusively for transporting hydrocarbon products from undersea wells.
The problem of thermal insulation of undersea production conduits arises in particular in the exploitation of deposits of heavy oils which risk congealing during their transport between the well and the platform, due to heat losses in the line surrounded by sea water, thermal insulation also being necessary to prevent the formation of hydrates, which certain crude oils are subject to do during chilling.
It has already been proposed to make thermal insulated conduits comprising an essentially central pipe or core, whose outer wall is surrounded concentrically by an also rigid tubular casing, and in which insulation material, such as a polyurethane foam, is injected in the annular space around the outer surface of the core. This injection of foam can be carried out either on land or on a barge or ship. It is established in practice that such foam injections are difficult to perform on board ship before the line is installed or laid and, when injections are carried out on land, significant problems arise concerning the handling of the resulting rigid line. Another disadvantage of the lines made up to the present, is their low resistance to crushing, generally now exceeding 5 bars, which is insufficient to resist outside pressures and in particular the hydrostatic pressure which under modern conditions of exploitation can be greater than 20 bars.
The present invention proposes to provide a thermally insulated line comprising around a preferably flexible pipe or core a thermal insulating structure offering in particular good resistance to outside pressures in particular with respect to crushing, having a low coefficient of thermal conductivity, able to maintain its physical properties in the presence of sea water and having very low water absorption, even under pressure and at relatively high temperature, especially on the order of 60 degrees to 100 degrees Centigrade.
In the present application, the term "flexible" is intended to designate any structure, even a rigid one, able to be wound without damage on small reels or drums whose diameter does not exceed 10 m.
The invention is more particularly applicable with flexible pipes or cores comprising an inner sealed casing, reinforcing sheathing and an outer protective casing. These pipes can also comprise a metal carcass for resistance to crushing. Such pipes are made and sold in long lengths and in different diameters by Societe Coflexip.
The line or conduit according to the invention is essentially characterized by the fact that it comprises, around the inner pipe or core, a plurality of annular walls or partititions spaced along the length of the core and fixed thereto, an insulation material filling the annular chambers provided between the front faces of successive partitions and the outer covering of the inner core, and a continuously extruded outer casing concentric to the core and fixed to the peripheral surfaces of the annular partitions and the insulation material.
In one particular embodiment, the partitions are separate from each other and are preferably made individually, particularly by molding, directly on the core, from an appropriate material, particularly modified polyurethane, and are spaced apart along the length of the core at intervals of from 20 to 200 m, as a function of the conditions of service.
These partitions have a radial length beginning from their inner diameter of between 20 and 100 mm, and a thickness of between 100 and 250 mm.
In a second embodiment, the annular walls or partitions are interconnected by a tubular core from which they extend, the tubular core coaxially surrounding the inner core.
In the two embodiments, the outer peripheral surfaces of the partitions can comprise means, such as grooves and/or projections for improving the application and retention of an adhesive product for joining the outer casing extruded around the co
REFERENCES:
patent: 2857931 (1958-10-01), Lawton
patent: 3830899 (1974-08-01), Piccioli et al.
patent: 4025091 (1977-05-01), Zeile
patent: 4241762 (1980-12-01), Link et al.
patent: 4417603 (1983-11-01), Argy
patent: 4509561 (1985-04-01), Litz
patent: 4590971 (1986-05-01), Webster et al.
Dewimille Bernard
Dridi Hamadi
Bryant III James E.
Coflexip
Fallow Charles
Hoffman Martin
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