PURGEUR SUR TUBAGE

TUBING DRAIN

Abrégé anglais

ABSTRACT OF THE DISCLOSURE
A well tubing drain assembly includes a tubing
wall containing a bore intersecting the tubing interior
and a counterbore intersecting the tubing exterior, an
annular retainer in the counterbore having connection to
the wall, the retainer forming a side drain passage, a
retainer member carried by the retainer and projecting
into the drain passage, a closure in alignment with the
drain passage and retained by the member at the side
thereof closest to the tubing bore interior, the closure
closing off said tubing wall bore, the closure adapted
to be blow out the drain passage when fluid pressure in
the tubing bore transmits sufficient force via the closure
to rupture said member, and a sealing washer located in
the counterbore and extending about the closure to have
sealing engagement therewith in response to pressure
exerted on the washer by the fluid in the tubing.
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Revendications

The embodiments or the invention in which an exclusive
property or privilege is claimed are defined as follows:
1. In an oil well tubing drain assembly,
a) a tubing wall containing a bore intersecting
the tubing interior and a counterbore intersecting the tubing
exterior,
b) an annular retainer in the counterbore having
connection to said wall, the retainer forming a side drain
passage,
c) a retaining member carried by the retainer
and projecting into said drain passage, said retaining member
comprising a pin extending across said drain passage and
received in drilled passages in the retainer,
d) a closure in alignment with said drain passage
and retained by said member with a surface of the closure
located at the side of said member closest to the tubing
bore interior, the closure closing off said tubing wall bore,
the closure adapted to be blown out said drain passage when
fluid pressure in the tubing bore transmits sufficient force
via said closure to rupture said member, said closure comprising
a disc-shaped piston having a diameter approximately the same
as the diameter of said drain passage,
e) and a sealing washer located in said counterbore
and extending about said closure to have sealing engagement
therewith in response to pressure exerted on the washer by the
fluid in said tubing, said washer being elastomeric and located
in engagement with the end of said retainer closest to the
tubing bore interior.
2. The assembly of claim 1 wherein the annular
retainer has threaded connection to said counterbore.
3. The assembly of claim 1 wherein the washer
has an inner diameter approximately the same as the outer
diameter of said piston.

4 The assembly of claim 1 including a tubular
sub defining said wall, the sub having threaded pin and box
ends for connection in a string of oil wall tubing.
5. The assembly of claim 1 wherein the piston is
entirely confined at the side of the pin closest the tubing
bore interior.
6. In a well tubing drain assembly to be received
in a tubing wall containing a bore intersecting the tubing
interior and a counterbore intersecting the tubing exterior,
the assembly comprising
a) an annular retainer receivable in the counterbore
for connection to said wall, the retainer forming a drain
passage,
b) a retaining member carried by the retainer and
projecting into said drain passage, said retaining member
comprising a pin extending across said drain passage and
received in drilled passages in the retainer,
c) a closure in alignment with said drain passage,
the entirety of the closure retained by said member with a
surface of the closure located at the side of said member
closest to the tubing bore interior, the closure adapted to
close off said tubing wall bore, the closure adapted to be
blown out said drain passage when fluid pressure in the tubing
bore transmits sufficient force via said closure to rupture
said member, said closure comprising a disc-shaped piston
having a diameter approximately the same as the diameter of
said drain passage,
d) and a sealing washer to be located in said
counterbore, and extending about said closure to have sealing
engagement therewith in response to pressure exerted on the
washer by the fluid in said tubing, said washer being elastomeric
and located in engagement with the end of said retainer closest
to the tubing bore interior.

Description

BACKGROUND OF THE INVENTION
This inven-tion relates generally to tubing
drains, and more particularly concerns a very simple drain
assembly characterized by ease oE removal and replacement
as well as by assured operation at predetermined pressure
level~
Oil well tubing drains are employed to drain
pressurized fluid from within the tuhiny when the fluid
pressure in the tubing is.increased. Prior tubing ..
drainsare characterized as excessively complex in
construction, which add to their original as well as
maintenance cost or expense. One example of such a
prior drain i5 that shown at page 4212 of the 1957
l 'IComposite Catalogue of Oil Field Equipment and Services",
published by ~Jorld Oil.
SUM~L~RY OF THE INVE~TION
I~ is a major object o~ the invention to provide
a signi~icantly improved tubing drain, as will be described.
Basically, the drain assembly is receivable in a tubing
29 wall containing a kore intersecting the tubing interior,
and a counterbore intersecting the tubing exterlor, the
assembly comprising
a~ an annular retainer receivable in the
counterbore for connection to said wall, the retainer
forming a drain passage,
b) a retaining member carried by the retainer
and projecting into said drain passage,
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c) a closure in alignment with said drain
phssage, the en-tirety of the closure retained by said
member a-t the side thereof closest to the tubing bo~e
interior, the closure adapted to close.off said -tubing
wall bore, the closure adapted to be blown out said
drain passage when fluid pressure in the tubing bore
transmits sufficient force via said closure to rupture
said member,
d) and a sealing washer to be located in said
counterbore, and exte.nding about said closure to have
sealing engagement therewith in response ~o pressure
exerted Qn the washer by the fluid in said tubing.
As will be seen, the annular retainer has
simple thxeaded connection to the counterbore to retain
the washer and closure piston in position so as to be
easily removable upon unthreading of the retainer from
the counterbore, and the piston is typically entirely
located or confined at the tubing bore side of the
retaining member in the form of a shear pin.
These and other objects and advantages of the
invention, as well as the details of an illustrative
embodiment, will be more fully understood from t~e
following description and drawings in which:
DRAWING DESCRIPTION
Fig. 1 is a vertical section through sub in a
pipe or tubing string, and
Fig. 2 is a fragmentary horizontal section
taken on lines 2-2 of Fig. 1.
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DETAILED DESCRIPTION
~ n Fig. 1 a pipe or tubing string 10 includes
a tubu-lar sub 11 having an externally threaded pin lla
connected at 12 wi-th box 13 of lower pipe or t~biny 1~,
and an internally threaded box llb connected at lS with
pin 16 of upper pip~ or tubing 17. At times, ik is
desired that the fluid in the tubing be released to the
tubing exteri.or or annulus 19, wit.hin well 20.
In accordance with the invention, a tubing
drain assembly 21 is provided in the wall of the tubing,
for automatically draining the fluid pressure when
it reach~s a predetermined level. ~he wall contai.ns a
cylindrical bore 22 and cylindrical counterbore 23, these
being coaxial, the bore 22 intersecting the tubing interior
18, and the coun~erbore intersectin~ th~.tubing interior
19. An annular shoulder 24 demarks the intersection of
the bore and counterbore.
The drain assen~ly includes an annular retainer
25 in the couI~terbore and havirlg conllection to -I:he tubin~
wall. Such connection may be afforded by threadin~ a~ 26,`
and the outer end of the retainer may be slotted at 27
to receive a tool to rotate the rekainer into or out of
position, thus facilitating qui~k disassembly and clean-out,
or replacement, of the drain assembly. The retainer carries
a retaining member such as a shear pin 28 projecting into
a central drain passa~e 29 formed by the annular retainer.
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Pin 28 pxeferably ex-tends completely across passage 29
and is supported in drilled openings 30 in opposite sides
of the retainer.
The ass~emblY also includes a closwre, as for
example disc-shaped piston 31, partly received in bore
portion 32 formed by the retainer, at the side of the
pin closesk to the sub in-terior 18. The closure inner
face 31a typically firmly engages shoulder 24, whereas
its outer face 31b firmly engages pin 28. Also, the
closure closes off the tubing wall bore 22. A sealing
washer 33 is located in counterbore 23 be-tween the inner
end 25a of the closure and the radially outer portion o
shoulder 24, to seal about the radially outer cylindrical
surface 31c of the piston closure Fluid pressure within
the sub interior 18, gaining access to the inner face 33a
i of the washer 33, s~ueezes it toward the retainer 25,
causing the inner diameter of the washer to increase its
sealing engagement with the piston and also with the
retainer face 25a. This prevents leak~ge from the drain
prior to sudden rupture of the assembly. Washer 33 is
typically elastomeric, and may consist of rubber.
Such rupture occurs when the fluid pressure
reaches a predetermined level, or level range, characterized
in t~at fluid pressure exerted on the piston face 31a
causes the piston to shear or fracture the pin 28. At
such time, the piston, and ruptured pin extent at the
outer side of the piston are blown out the drain passage
29, to the exterior, to relieve the pressure in the sub.
Of unusual advantage are the simplicity and
effectiveness of the assembly construction and mode oE

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operation, as described, as well as the ease of replacement
or repair. Thus, the user may quickly unscrew the retainer
25 and remove the elements 31 and 33. The Eractured pin
remnants may be removed from the retainer and replaced
by a new pin, and the par-ts quickly returned -to the
counterbore 23. The fewer number of par-ts, as compared
wlth prior devices, contributes to these advantages and
results. The fact that the piston is entirely confined
at the sub interior side of the rupturable pin contributes
to enhanced simplicity, and ease of parts removal and
- replacement, as well as assured pin rupture at predetermined
pressure level.
The outer diameter of circular disc or piston 21
is slightly less than the inner diameter or bore diameter
40 of the retainer, to facilitate blow-out o~ the piston.