Metal working – Method of mechanical manufacture – Combined manufacture including applying or shaping of fluent...
Reexamination Certificate
1999-11-15
2003-03-11
Vidovich, Gregory M. (Department: 3726)
Metal working
Method of mechanical manufacture
Combined manufacture including applying or shaping of fluent...
C029S458000, C138S119000, C138S140000, C138S144000, C138S145000, C138S149000, C264S171120
Reexamination Certificate
active
06530137
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a heat-insulated flexible pipe used for example for carrying effluents produced by oilwells, or for shipping or land carriage of liquid requiring thermal insulation.
The problem of thermal insulation of subsea petroleum production pipes arises in particular for reservoirs whose effluents, subjected to fast cooling due to the sea bottom temperature and to the thickness of the water depth, undergo physico-chemical phenomena that disturb their flow in the pipe. Hydrate formation, paraffin, asphaltene deposition or oil gelation may notably occur.
The term flexible pipes refers here to pipes consisting of polymer layers and metal reinforcing armours, and also to wound, then unwound metal tubes. In fact, the problem of thermal insulation is the same for both types of pipe: the thickness of the insulating material must not stiffen the pipe so that it can be used in the same way as a pipe without an insulant. In other words, the “flexibility” or the “rigidity” of the pipe must be substantially identical, with or without an insulant.
BACKGROUND OF THE INVENTION
Document EP-4,006,689 describes a flexible pipe thermally insulated by helical winding of strips made of expanded plastic. These relatively thin strips are wound by elastic deformation around the core of the flexible pipe. The insulating material selected should therefore allow implementation of this winding operation, which is furthermore quite extensive since several layers are necessary, while having a sufficient characteristic as regards heat insulation and mechanical strength under difficult hydrostatic pressure conditions. However, this solution is not appropriate with a high outside pressure because the wound strips do not withstand high compressive stresses.
Rigid plastic materials are well-suited for insulation and mechanical strength, but stiffening of the pipe is problematic with great thicknesses.
SUMMARY OF THE INVENTION
The present invention thus relates to a method intended for heat insulation of a flexible pipe according to the definition given here, comprising the following successive stages:
depositing, on the outer surface of the pipe moving longitudinally, a thickness of extrudable and rigid insulating material,
cooling the insulating material over a substantially rectilinear part downstream from the deposition area,
forming at least one circumferential slot in said thickness of the material in relation to the axis of the pipe so as to restore the flexibility of the pipe once coated with the rigid insulating material.
In a first variant, the slot can be made by machining.
In a second variant, the slot can be made as the material is deposited on the pipe.
According to the invention, the slot can be helical, with a determined width and pitch according to the allowable bending radius of the flexible pipe.
In a variant, the slot can consist of a succession of circular slots having a determined width and pitch according to the allowable bending radius of the flexible pipe. The term pitch refers here to the distance between two slots on a generatrix of the pipe.
An extruding head can be concentric to the pipe.
In a variant, an extruding head can be arranged laterally to the pipe and revolve in relation to the pipe so as to deposit said material in the form of a helical strip.
Extrusion can be performed in several successive layers so as to reach great insulant thicknesses.
A layer of sticking preventive material, for example an antiadhesive strip coating, or grease or equivalent, can be deposited on the outside of each layer of extruded material.
In the case where the operation is carried out with several layers, each layer can comprise machined slots.
The invention also relates to a heat-insulated flexible pipe comprising at least one layer of rigid and extruded insulating material on the outside of said pipe. The layer comprises means for restoring the flexibility of the insulated pipe in the form of at least one circumferential slot.
In the pipe, the width and the pitch of the slots can be calculated according to the allowable bending radius of the pipe.
In the pipe, the slot can be filled with a material that can flow, such as a gel or grease.
REFERENCES:
patent: 3404203 (1968-10-01), Donald
patent: 3607505 (1971-09-01), Schirmer
patent: 3642396 (1972-02-01), Meneidis
patent: 3877136 (1975-04-01), Groch et al.
patent: 3879505 (1975-04-01), Boutillier et al.
patent: 3957942 (1976-05-01), Meudec
patent: 3979818 (1976-09-01), Groch et al.
patent: 4006920 (1977-02-01), Sadler et al.
patent: 4009975 (1977-03-01), Ninomiya et al.
patent: 4115502 (1978-09-01), Rasmussen
patent: 4146562 (1979-03-01), Fukushima et al.
patent: 4209476 (1980-06-01), Harris
patent: 4289716 (1981-09-01), Voigt
patent: 4345363 (1982-08-01), Leuchs
patent: 4389366 (1983-06-01), Hoesslin et al.
patent: 4397797 (1983-08-01), Nojiri et al.
patent: 4484877 (1984-11-01), Stucke et al.
patent: 4519863 (1985-05-01), Landgraf et al.
patent: 4657050 (1987-04-01), Patterson
patent: 4669172 (1987-06-01), Petruzzi
patent: 4729807 (1988-03-01), Hede et al.
patent: 4878520 (1989-11-01), Nakamura et al.
patent: 4921018 (1990-05-01), Dridi et al.
patent: 4929409 (1990-05-01), Agren et al.
patent: 5722462 (1998-03-01), Dridi et al.
patent: 5927344 (1999-07-01), Nobileau
patent: 6012494 (2000-01-01), Balazs
patent: 6058979 (2000-05-01), Watkins
patent: 6283160 (2001-09-01), Hardy et al.
patent: 6305429 (2001-10-01), Welch et al.
patent: 6318681 (2001-11-01), Vitoorapakorn
patent: 6461554 (2002-10-01), Dewimille et al.
patent: 400689 (1990-12-01), None
patent: 2169478 (1973-09-01), None
patent: 2350943 (1977-12-01), None
patent: 2081415 (1982-02-01), None
Patent Abstracts of Japan, vol. 098, No. 010, 31 Aout 1998, JP 10 141587 (Fujimori Kogyo) May 29, 1998.
Dal Maso Fabrice
Dewimille Bernard
Jarrin Jacques
Antonelli Terry Stout & Kraus LLP
Institut Francais du Pe'trole
Omgba Essama
Vidovich Gregory M.
LandOfFree
Heat-insulated pipe and manufacturing method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Heat-insulated pipe and manufacturing method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Heat-insulated pipe and manufacturing method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3051541