Pipe joints or couplings – Particular interface – Tapered
Reexamination Certificate
1999-11-24
2001-11-06
Browne, Lynne H. (Department: 3629)
Pipe joints or couplings
Particular interface
Tapered
C285S055000
Reexamination Certificate
active
06312024
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a threaded connection between two metal pipes which may or may not be provided with an internal coating and is more particularly intended to contain a corrosive fluid.
2. Discussion of the Background
Threaded connections for metal pipe are already known for use in oil or gas wells such as production tubing to raise oil or gas to the surface, or as casing pipe to hold the ground around a well.
Such threaded connections are generally of two types:
a) integral, namely the end of a first pipe comprises a male connecting element and the end of a second pipe to be connected comprises a female connecting element.
b) coupled, namely the ends of the pipes to be connected each comprise a male connecting element, each end being screwed to a short coupling comprising a female connecting element at each end.
French patent FR-A-1 489 013 describes an integral threaded connection with trapezoidal threads, the end of the male element having a concave conical shape which, at the end of the connection makeup, bears against a convex conical shoulder located at the base of the thread of the female element; further, the outer terminal edge of the male element is slightly chamfered and comes into mating contact against a corresponding concave truncated conical portion on the female element thus ensuring an excellent gas seal even after several successive uses of the connecting elements.
That patent also describes an option in which a connection for pipes is coated internally with a layer of enamel or epoxy resin when the fluid circulating in the pipes is aggressive or corrosive as regards the metal of the pipes.
Internally coated pipes may also be required when the fluid circulating in the pipes comprises water with chlorides and/or dissolved oxygen or CO
2
and is thus highly corrosive towards the metal used.
In order to prevent any penetration of aggressive fluid into the shoulder, FR-A-1 489 013 proposes a housing on the inside of the male end for a complementary sealing ring which bears both on the coated zones of the male end and on the shoulder which is continuous with the internal coating of the pipes.
European patent application EP-A-0 759 497 describes a threaded connection which is intended for a water injection well to improve recovery of hydrocarbons from an oil field; the water injected into such a well is usually an oxygenated brine which is extremely corrosive.
EP-A-0 759 497 describes a threaded and coupled (T & C) connection, the coupling comprising internally, to either side of a protruding central portion, an annular shoulder followed by a female thread, the pipes comprising externally, moving towards their ends, a thread followed by an annular transverse bearing surface which is complementary to the shoulder of the coupling and finally a smooth zone terminated by an annular radial surface.
A sealing ring of soft synthetic material is interposed between the ends of the pipes and is compressed by the ends of the pipe, the position of which at the end of the connection makeup being determined by the thrust of the bearing surfaces of the pipes on the corresponding surfaces on the coupling. The internal surface and the annular end surfaces of the pipe are coated with a synthetic resin such that penetration of corrosive liquid into the metal parts of the connection is prevented by the compressed ring.
EP-A-0 759 497 also describes solutions for integrally threaded connections derived directly from the solution described for the T & C connection, the bearing surface in this case being moved to the free end of the female element.
Such a connection with a sealing ring of soft synthetic material cannot be completely tight, in particular gas tight, as the contact pressure exerted by the soft material ring is much lower than that resulting from elastic deformation of a metal on a metal as described in FR-A-1 489 013.
SUMMARY OF THE INVENTION
The present invention seeks to provide an extremely reliable and tight threaded connection for metal pipes, more particularly those intended to contain a corrosive fluid.
The threaded connection has to preserve a good seal and good resistance against mechanical stress despite several makeup/break-out cycles, as the metal pipes must be able to be detached then re-attached to others a number of times.
The threaded connection must also be capable of being in the form of an integral connection and as a T & C connection and in that case, must use couplings which are relatively economical to produce.
Further, the threaded connection must be capable of being made:
between two pipes of a metal which is resistant to corrosion by the fluid contained in them;
and between two pipes of a metal which is not resistant to corrosion but is provided with an internal coating which is inert to the corrosive fluid;
and between a pipe of a metal which is resistant to corrosion and a pipe provided with an internal coating.
Clearly, using an internal coating enables a less precious (and therefore cheaper) metal to be used.
When internally coated pipes are used, we have sought to produce a connection which is compatible both with thin coatings a few hundredths of mm thick and with coatings in the form of tubes with a thickness of the order of a few mm which internally line the main pipes and which are affixed thereto, the constituent materials of these internal lining tubes possibly being relatively brittle.
In a first aspect, the invention provides an integral threaded connection between two metal pipes, in particular pipes intended to contain a corrosive fluid, of the type comprising a male element externally formed at the end of a first pipe of the connection and a female element internally formed at the end of a second pipe.
The male element comprises a male threaded portion and a male non threaded portion, the latter being located at the free end side of the male element.
The female element comprises a female threaded portion and a female non threaded portion on the side opposite the free end of the female element.
The male or female threaded portions can, for example, be a conical thread or a combination of two cylindrical two-stage threads in known manner. The male threaded portion of the male element is screwed into the female threaded portion of the female element and the non threaded portion of the male element co-operates with that of the female portion.
The male non threaded portion of the male element comprises, moving towards the free end of that element:
an annular transverse bearing surface formed over a fraction of the pipe thickness;
the external peripheral surface of a nose with a reduced external diameter;
an annular radial surface which joins the internal peripheral surface of the first pipe.
Said annular radial surface will be termed the annular internal end surface of the first pipe in the remainder of the present document.
The female non threaded portion of the female element comprises, moving towards the side opposite the free end of said element:
an annular transverse bearing surface forming a shoulder which is complementary to the bearing surface of the male element,
the internal peripheral surface of a zone termed a reinforcing zone;
an internal peripheral housing surface for a sealing ring;
an annular radial surface which joins the internal peripheral surface of the second pipe.
This annular radial surface is termed the annular internal end surface of the second pipe in the remainder of the present document.
The bearing surface of the male element abuts against the bearing surface of the female element.
The annular internal end surfaces of the two pipes are located facing each other and at a distance from each other.
The term “radial” for the annular internal end surfaces of the pipes indicates in the present document that these surfaces are orientated perpendicular or almost perpendicular to the connection axis.
A sealing ring of synthetic material is directly or indirectly interposed between the annular internal end surfaces of the two pipes and provides a firs
Dutilleul Pierre
Noel Thierry
Bochna David E.
Browne Lynne H.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Vallourec Mannesmann Oil & Gas France
LandOfFree
Threaded assembly of metal tubes designed to contain a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Threaded assembly of metal tubes designed to contain a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Threaded assembly of metal tubes designed to contain a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2614481