Metal deforming – With use of control means energized in response to activator... – Metal deforming by use of roller or roller-like tool element
Reexamination Certificate
2000-03-15
2001-08-28
Crane, Daniel C. (Department: 3725)
Metal deforming
With use of control means energized in response to activator...
Metal deforming by use of roller or roller-like tool element
C072S011100, C072S164000, C072S183000
Reexamination Certificate
active
06279363
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and to a device for controlling deformations of a metal tube by measuring the stresses internal to the metallic material of the tube. The sphere of application of the invention is preferably the offshore petroleum industry using effluent transportation metal pipes that have been wound on large drums, carried, then unwound in order to be laid on the sea bottom, or suspended, by laying boats equipped with specific handling means, notably of the traction caterpillar type.
Coiled metal tubes referred to as coiled tubings are also used in another sphere such as drilling or operations in a production well. These tubes, whose diametric dimension ranges between 1″ (25.4 mm) and 4″ (101.6 mm), are also wound on a drum that is 2 to 3 m in diameter. They are used to be lowered into the well in order to carry out drilling, gas or liquid injection, cleaning, measuring operations, etc.
In these techniques, the tubes are wound under plastic deformation because the radii of curvature of the drums generate great flexural stresses in relation to the yield limit of the materials used.
When the tubes are unwound to be either laid on the sea bottom or suspended, or displaced in a well, the material can therefore keep an appreciable level of residual stresses. The handling means, such as traction caterpillars, generally include a tube straightening device consisting of a series of at least three rollers (or equivalent) that applies a flexural stress contrary to the remanent curvature of the tube once unwound, generally in a single plane.
It has been observed that the tubes once unwound generally have too great internal stresses that often generate bothersome geometric deformations that can even be harmful during operation.
SUMMARY OF THE INVENTION
The present invention thus relates to a method for handling a coiled tube comprising at least a metal casing plastically deformed through winding on a cylindrical drum, the tube once unwound being fed into a straightening system. According to the method, at least the following operations are carried out:
the stresses are measured in the tube once unwound,
said straightening system is controlled according to said stress measurements so as to obtain, at the straightener outlet, determined stress distribution and level in the metallic wall of said tube.
The stresses can be measured downstream and/or upstream from the straightener.
A stress distribution can be imposed in the tube so that the tube has a determined curvature after passage through the straightener.
The stresses can be measured susbtantially along all of the tube circumference.
A stress field can be imposed in the tube so as to optimize its compressive buckling limit in a well.
A bending moment can be calculated in at least one orthogonal direction to the axis of the tube, from stress measurements in said tube.
The invention also relates to a straightening device for handling a coiled tube comprising at least one metal casing plastically deformed through winding on a cylindrical drum, the tube once unwound being fed into said straightening system. The device comprises at least:
means for measuring the stresses in the tube once unwound,
straightening adjustment means,
means for controlling the adjustment of said straightening device according to said stress measurements so as to obtain, at the straightener outlet, determined stress distribution and level in the metallic wall of said tube.
The stress measuring means can be placed upstream from the straightening adjustment means.
Measuring mans can be placed downstream from the straightening adjustment means.
The two supporting and centering devices, placed at a given distance from one another, can hold up the tube and a series of jacks placed between said supporting devices can be controlled to deform the tube resting on both devices according to the desired stress field.
At least four jacks arranged opposite each other two by two and in two orthogonal directions can constitute the controlled straightening means.
At least three jacks arranged at 120 degrees around the tube can constitute the controlled straightening means.
The measuring means can comprise a series of stationary pickups distributed around the circumference of the tube.
The measuring means can comprise at least one pickup mounted on a device rotating around the tube.
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Averbuch Daniel
Perrin Gilles
Antonelli Terry Stout & Kraus LLP
Crane Daniel C.
Institut Francais du Pe'trole
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